A mask and its application in sequential lateral solidification (SLS) crystallization of amorphous silicon. The mask includes a light absorptive portion for blocking a laser beam and first and second light-transmitting portions each having an echelon formation with a tier-shaped outline. The first and second light-transmitting portions pass a laser beam and include a plurality of adjacent rectangular-shaped patterns that comprise the echelon formation. The second light-transmitting portion is located between the first light-transmitting portions and has fewer shaped-shaped patterns than the first light-transmitting portions. In operation, the mask moves transversely by no more than the width of the shaped-shaped patterns as a laser performs SLS crystallization. The first and second light-transmitting portions control grain growth such that high quality polycrystalline silicon is formed.

This application claims the benefit of Korean Patent Application No. 2001-31624, filed on Jun. 7, 2001 in Korea, which is hereby incorporated by reference as it fully set forth herein.
1. Field of the Invention
The present invention relates to crystallizing an amorphous silicon film, and, more particularly, to a sequential lateral solidification (SLS) crystallization method.
2. Discussion of Related Art
Polycrystalline silicon (p-Si) and amorphous silicon (a-Si) are often used as active layer materials for thin film transistors (TFTs) in liquid crystal display (LCD) devices. Since amorphous silicon (a-Si) can be deposited at a low temperature to form a thin film on a glass substrate, amorphous silicon (a-Si) is commonly used in liquid crystal displays (LCDs). Unfortunately, amorphous silicon (a-Si) TFTs have relatively slow display response times that limit their suitability for large area LCDs.
In contrast, polycrystalline silicon TFTs provide much faster display response times. Thus, polycrystalline silicon (p-Si) is well suited for use in large LCD devices, such as laptop computers and wall-mounted television sets. Such applications often require TFTs having a field effect mobility greater than 30 cm2/Vs and a low leakage current.
A polycrystalline silicon film is comprised of crystal grains having grain boundaries. The larger the grains and the more regular the grains boundaries, the better the field effect mobility. Thus, a crystallization method that produces large grains, ideally a single crystal, would be useful.
One method of crystallizing amorphous silicon into polycrystalline silicon is sequential lateral solidification (SLS). SLS crystallization uses the fact that silicon grains tend to grow laterally from the interface between liquid and solid silicon. With SLS, amorphous silicon is crystallized using a laser beam having a magnitude that melts amorphous silicon such that the melted silicon forms laterally grown silicon grains upon re-crystallization.
FIG. 1A is a schematic configuration of a conventional sequential lateral solidification (SLS) apparatus, while FIG. 1B shows a plan view of a conventional mask 38 that is used in the apparatus of FIG. 1A. In FIG. 1A, the SLS apparatus 32 includes a laser source 36, a mask 38, a condenser lens 40, and an objective lens 42. The laser source 36 emits a laser beam 34. The intensity of the laser beam 34 is adjusted by an attenuator (not shown) that is located in the path of the laser beam 34. The laser beam 34 is condensed by the condenser lens 40 and is then directed onto the mask 38.
The mask 38 includes a plurality of slits xe2x80x9cAxe2x80x9d that pass the laser beam 34 and light absorptive areas xe2x80x9cBxe2x80x9d that absorb the laser beam 34. The width of each slit xe2x80x9cAxe2x80x9d effectively defines the grain size of the crystallized silicon produced by a first laser irradiation. Furthermore, the distance between the slits xe2x80x9cAxe2x80x9d defines the size of the lateral grain growth of amorphous silicon crystallized by the SLS method. The objective lens 42 is arranged below the mask and reduces the shape of the laser beam 34 that passed through the mask 38.
Still referring to FIG. 1A, an X-Y stage 46 is arranged adjacent the objective lens 42. The X-Y stage 46, which is movable in two orthogonal axial directions, includes an x-axial direction drive unit for driving the x-axis stage and a y-axial direction drive unit for driving the y-axis stage. A substrate 44 is placed on the X-Y stage 46 so as to receive light from the objective lens 42. Although not shown in FIG. 1A, it should be understood that an amorphous silicon film is on the substrate 44, thereby defining a sample substrate.
To use the conventional SLS apparatus, the laser source 36 and the mask 38 are typically fixed in a predetermined position while the X-Y stage 46 moves the amorphous silicon film on the sample substrate 44 in the x-axial and/or y-axial direction. Alternatively, the X-Y stage 46 may be fixed while the mask 38 moves to crystallize the amorphous silicon film on the sample substrate 44.
When performing SLS crystallization, a buffer layer is typically formed between the substrate and the amorphous silicon film. Then, the amorphous silicon film is deposited on the buffer layer. Thereafter, the amorphous silicon is crystallized as described above. The amorphous silicon film is usually deposited on the buffer layer using chemical vapor deposition (CVD). Unfortunately, that method produces amorphous silicon with a lot of hydrogen. To reduce the hydrogen content the amorphous silicon film is typically thermal-treated, which causes de-hydrogenation, which results in a smoother crystalline silicon film. If de-hydrogenation is not performed, the surface of the crystalline silicon film is rough and the electrical characteristics of the crystalline silicon film are degraded.
FIG. 2 is a plan view showing a substrate 44 having a partially-crystallized amorphous silicon film 52. When performing SLS crystallization, it is difficult to crystallize all of the amorphous silicon film 52 at once because the laser beam 34 has a limited beam width, and because the mask 38 also has a limited size. Therefore, the substrate 38 is typically moved numerous times such that crystallization is repeated at various locations such that the substrate is completely crystallized. In FIG. 2, an area xe2x80x9cCxe2x80x9d that corresponds to one mask position is called a block. Crystallization of the amorphous silicon within the block xe2x80x9cCxe2x80x9d is achieved by irradiating the laser beam several times.
SLS crystallization of the amorphous silicon film 52 will be explained as follows. FIGS. 3A to 3C are plan views showing one block of an amorphous silicon film 52 being crystallized using a conventional SLS method. In the illustrated crystallization, it should be understood that the mask 38 (see FIGS. 1A and 1B) has three slits.
The length of the lateral growth of a grain is determined by the energy density of the laser beam, by the temperature of the substrate, and by the thickness of amorphous silicon film (as well as other factors). The maximum lateral grain growth should be understood as being dependent on optimized conditions. In the SLS method shown in FIGS. 3A to 3C, the width of a slit is twice as large as the maximum lateral grain growth.
FIG. 3A shows the initial step of crystallizing the amorphous silicon film 52 using a first laser beam irradiation. As described with reference to FIG. 1A, the laser beam 34 passes through the mask 38 and irradiates one block of an amorphous silicon film 52 on the sample substrate 44. The laser beam 34 is divided into three line beams by the three slits xe2x80x9cA.xe2x80x9d The three line beams irradiate and melt regions xe2x80x9cDxe2x80x9d, xe2x80x9cExe2x80x9d and xe2x80x9cFxe2x80x9d of the amorphous silicon film 52, reference FIG. 3A. The energy density of the line beams should be sufficient to induce complete melting of the amorphous silicon film 52. That is, the portion of the amorphous silicon film that is irradiated by the laser beam 34 is completely melted through to the buffer layer.
Still referring to FIG. 3A, after complete melting the liquid phase silicon begins to crystallize at the interfaces 56a and 56b of the solid phase amorphous silicon and the liquid phase silicon. Crystallization occurs such that grains grow laterally. Thus, as shown, lateral grain growth of grains 58a and 58b proceeds from the un-melted regions to the fully melted regions. Lateral growth stops when: (1) grains grown from interfaces collide near the middle section 50a of the melted silicon region; or (2) polycrystalline silicon particles are formed in the middle section 50a as the melted silicon region solidifies sufficiently to generate solidification nuclei.
Since the width of the slits xe2x80x9cAxe2x80x9d (see FIG. 1B) is twice as large as the maximum lateral growth of the grains 58a and 58b, the width of the melted silicon region xe2x80x9cD,xe2x80x9d xe2x80x9cE,xe2x80x9d and xe2x80x9cFxe2x80x9d is also twice as large as the maximum lateral growth length of the grains. Therefore, the lateral grain growth stops when the polycrystalline silicon particles are formed in the middle section 50a. Such polycrystalline silicon particles act as solidification nuclei in a subsequent crystallization step.
As discussed above, the grain boundaries in directionally solidified silicon tend to form perpendicular to the interfaces 56a and 56b between the solid phase amorphous silicon and the liquid phase silicon. Thus, as a result of the first laser beam irradiation, crystallized regions xe2x80x9cD,xe2x80x9d xe2x80x9cE,xe2x80x9d and xe2x80x9cFxe2x80x9d are formed. Additionally solidification nuclei regions 50a are also formed.
As previously mentioned, the length of lateral grain growth attained by a single laser irradiation depends on the laser energy density, the temperature of substrate, and the thickness of the amorphous silicon film. Typically, lateral grain growth ranges from 1 to 1.5 micrometers (xcexcm).
FIG. 3B illustrates crystallizing the amorphous silicon film 52 of FIG. 3A using a second laser beam irradiation. After the first laser beam irradiation, the X-Y stage or the mask 38 moves in a direction along the lateral grain growth of the grains 58a or 58b (in FIG. 3A), i.e., in the X direction, by a distance that is no more than the maximum length of the lateral grain growth. Then, a second laser beam irradiation is conducted. The regions irradiated by the second laser beam are melted and crystallized as described above. The silicon grains 58a and 58b and/or the nuclei regions 50a produced by the first laser beam irradiation serve as seeds for the second crystallization. Thus the lateral grain growth proceeds in the second melted regions. Silicon grains 58c formed by the second laser beam irradiation continue to grow adjacent to the silicon grains 58a formed by the first laser beam irradiation, and silicon grains 58d grown from an interface 56c are also formed. The lateral growth of these grains 58c and 58d stops when the nuclei regions 50b are formed in a middle section of the silicon region melted by the second laser beam irradiation.
Accordingly, by repeating the foregoing steps of melting and crystallizing, one block of the amorphous silicon film is crystallized to form grains 58e as shown in FIG. 3C.
The above-mentioned crystallization processes conducted within one block are repeated block by block across the amorphous silicon film. Therefore, the large size amorphous silicon film is converted into a crystalline silicon film. While generally successful, the conventional SLS method described above has disadvantages.
Although the conventional SLS method produces large size grains, the X-Y stage or the mask must repeatedly move a distance of several micrometers to induce lateral grain growth. Therefore, the time required to move the X-Y stage or the mask 38 occupies a major part in the total process time. This significantly decreases manufacturing efficiency.
FIG. 4 is a plan view of a mask 60 that is used in another SLS method. The mask 60 has light slits xe2x80x9cGxe2x80x9d and light absorptive areas xe2x80x9cH.xe2x80x9d Although the mask 60 is similar to the mask 38 shown in FIG. 1B, the width of the lateral stripe-shaped slits xe2x80x9cGxe2x80x9d is less than twice the maximum lateral grain growth length. Due to the smaller width of the slits xe2x80x9cGxe2x80x9d the lateral grain growth stops when the grains generated at the interface between the un-melted regions and the fully melted regions. In contrast to the crystallization described in FIGS. 3A to 3C, solidification nuclei regions 50a and 50b are not formed when using the mask.
The SLS using the mask 60 will now be discussed. As described with reference to FIG. 1A, the laser beam 34 passes through the mask 60 and irradiates the amorphous silicon film on the sample substrate 44. The laser beam 34 is divided into three line beams because there are three slits xe2x80x9cGxe2x80x9d. Those line beams are reduced by the objective lens 42 to create beam patterns on the amorphous silicon film 52. As crystallization proceeds, the beam patterns move in an X-axis direction. Because of the X-axis directional movement, crystallization is conducted along a length of the beam pattern. As previously described, the X-Y stage 46 or the mask 60 moves by a distance of several millimeters (mm). The larger movement reduces processing time when compared to the SLS method described with reference to FIGS. 3A to 3C.
FIGS. 5A to 5C are plan views showing an amorphous silicon film in the crystallization being crystallized using the mask shown in FIG. 4. It is assumed that the mask 60 has three slits. As mentioned above, the length of lateral grain growth is determined by the energy density of the laser beam 34, the temperature of substrate, the thickness of amorphous silicon film, etc. Thus lateral grain growth of the grains is the maximized under optimized conditions. In FIGS. 5A to 5C, it should be understood that the width of the slits xe2x80x9cGxe2x80x9d (in FIG. 4) is smaller than twice the maximum length of lateral grain growth.
FIG. 5A shows an initial step of crystallizing the amorphous silicon film. Referring to FIGS. 1A and 5A, the laser beam 34 emitted from the laser source 36 passes through the mask 60 (which replaces the mask 38) and irradiates a first block E1 of an amorphous silicon film 62 deposited on the sample substrate 44. The laser beam 34 is divided into three line beams by the slits xe2x80x9cG.xe2x80x9d The three line beams irradiate and melt regions xe2x80x9cI,xe2x80x9d xe2x80x9cJ,xe2x80x9d and xe2x80x9cKxe2x80x9d of the amorphous silicon film 62. Since each of the melted regions xe2x80x9cI,xe2x80x9d xe2x80x9cJ,xe2x80x9d and xe2x80x9cKxe2x80x9d corresponds to a slit xe2x80x9cGxe2x80x9d the width of the melted regions xe2x80x9cI,xe2x80x9d xe2x80x9cJ,xe2x80x9d and xe2x80x9cKxe2x80x9d is less than twice the maximum lateral grain growth. The energy density of the line beams should be sufficient to induce complete melting of the amorphous silicon film.
The liquid phase silicon begins crystallize at the interfaces 66a and 66b of the solid phase amorphous silicon and the liquid phase silicon. Namely, lateral grain growth of the grains 68a and 68b proceeds from un-melted regions to the fully melted regions. Then, lateral growth stops where the grains 68a and 68b collide along a middle line 60a of the melted silicon region. The grain boundaries tend to form perpendicular to the interfaces 66a and 66b. As a result of the first laser beam irradiation, the first block E1 is partially crystallized. Thereafter, by moving the X-Y stage the beam patterns move in the X-axis direction. A second irradiation is conducted and the second block E2 is partially crystallized. The crystallization in the X-axis direction is then repeated to form a third block E3.
As a result of the first to third laser beam irradiations described in FIG. 5A, crystallized regions xe2x80x9cI,xe2x80x9d xe2x80x9cJ,xe2x80x9d and xe2x80x9cKxe2x80x9d are formed, each having first to third blocks E1, E2 and E3.
In FIG. 5B, after the first set of laser beam irradiations the X-Y stage or the mask moves in a direction opposite to the lateral growth of the grains 68a or 68b by a distance equal to or less than the maximum length of the lateral growth. Crystallization is then conducted block by block in the X-axis direction. Therefore, the regions irradiated by the laser beam are melted and then crystallized in the manner described in FIG. 5A. At this time, the silicon grains 68a or/and 68b grown by the first to third laser beam irradiations serve as seeds for this crystallization. Silicon grains 68c formed by sequential lateral solidification (SLS) continue to grow adjacent to the silicon grains 68a of FIG. 5A, and silicon grains 68d solidified from an interface 66c are also formed. These grains 68c and 68d collide with each other at a middle line 60b of the silicon regions melted by the laser beam irradiation, thereby stopping the lateral grain growth.
Accordingly, by repeating the foregoing steps of melting and crystallizing the amorphous silicon, the blocks E1, E2 and E3 of the amorphous silicon film become crystallized to form grains 68e as shown in FIG. 5C. FIG. 5C is a plan view showing a crystalline silicon film that resulted from lateral growth of grains to predetermined sizes.
The conventional SLS methods described in FIGS. 3A to 3C and 5A and 5C have some disadvantages. The conventional SLS method takes a relatively long time to crystallize the amorphous silicon film, thereby causing a decrease in manufacturing efficiency. Furthermore, due to the width of the slits of the mask, the length of lateral grain growth is limited.
More rapid crystallization can be achieved using masks having different slit patterns and laser beam scanning in a horizontal direction as shown in FIG. 6. As shown in FIG. 6, a mask 70 includes a plurality of slit patterns 72 that are divided into a first group xe2x80x9cMxe2x80x9d and a second group xe2x80x9cN.xe2x80x9d First slit patterns 72a are in the first group xe2x80x9cMxe2x80x9d and second slit patterns 72b are in the second group xe2x80x9cNxe2x80x9d. Intervals xe2x80x9cOxe2x80x9d are between the first slit patterns 72a and between the second slit patterns 72b. Thus, as shown in FIG. 6, each first slit pattern 72a is opposite an interval xe2x80x9cOxe2x80x9d between the second slit patterns 72b, and each second slit pattern 72b is opposite an interval xe2x80x9cOxe2x80x9d between the first slit patterns 72a. Referring to FIG. 6, it can be seen that the width of the slit patterns 72 is greater than the interval xe2x80x9cO.xe2x80x9d The width of the slit patterns 72 should be the same as or less than the maximum lateral grain growth.
Therefore, when the mask 70 or a X-Y stage moves in a transverse direction (i.e., x-axial direction and to the right) after a first amorphous silicon crystallization step, the first slit patterns of the first group xe2x80x9cMxe2x80x9d are positioned over locations previously covered by the intervals xe2x80x9cO.xe2x80x9d Accordingly, grains having a desired grain size can be obtained by repeatedly moving the mask 70 in the transverse direction during the amorphous silicon crystallization. Crystallization of amorphous silicon film using the mask 70 will be explained in detail with reference to FIGS. 7A to 7F.
FIG. 7A shows an initial step of crystallizing an amorphous silicon film using the mask of FIG. 6. As described with reference to FIG. 1A, the laser beam 34 passes through the mask 70 (which replaces the mask 38) and irradiates the amorphous silicon film 80 on the sample substrate 44. When applying the laser beam 34 to the amorphous silicon film 80, the laser beam 34 scans along the x-axial direction. Laser beam patterns having the same shape as the slit patterns 72 of the mask 70 partially melt the amorphous silicon film 80 and make first and second melted regions 86a and 86b, respectively, in first and second melted groups xe2x80x9cP1xe2x80x9d and xe2x80x9cP2.xe2x80x9d The first and second melted groups correspond to the first and second slit groups xe2x80x9cMxe2x80x9d and xe2x80x9cNxe2x80x9d. The energy density of the line beams should be sufficient to induce complete melting of the amorphous silicon film 80 through to an underlying buffer layer.
Still referring to FIG. 7A, after complete melting, the liquid phase silicon begins to crystallize at the interfaces 84a and 84b between the solid phase amorphous silicon and the liquid phase silicon. Namely, lateral grain growth of grains 82a and 82b proceeds from the un-melted regions to the fully melted regions. Then, lateral growth stops in accordance with the width of the melted silicon regions 86a and 86b where the grains 82a and 82b collide along the middle lines 84c of the melted silicon regions. The grain boundaries in directionally solidified silicon tend to form perpendicular to the interfaces 84a and 84b between the solid phase amorphous silicon and the liquid phase silicon. As a result of the first laser beam scanning, the first and second melted groups xe2x80x9cP1xe2x80x9d and xe2x80x9cP2xe2x80x9d are partially crystallized. Here, all of the crystallized regions 86 have the same size and shape, and thus, the first partially crystallized group xe2x80x9cP1xe2x80x9d is the same as, but offset from, the second partially crystallized group xe2x80x9cP2.xe2x80x9d
Referring now to FIG. 7B, thereafter, by moving the X-Y stage where the substrate is mounted, the beam patterns move in the X-axis direction by the length xe2x80x9cQxe2x80x9d of the crystallized regions 86. Thus, the first slit patterns 72a of the first slit group xe2x80x9cMxe2x80x9d are located over the second partially crystallized group xe2x80x9cP2,xe2x80x9d and the second slit patterns 72b of the second slit group xe2x80x9cNxe2x80x9d are located over a new regions of the amorphous silicon film 80. Especially, the first slit patterns 72a is positioned between the second crystallized regions 86b. Thereafter, second laser beam scanning is conducted, and thus, the silicon regions irradiated by the second laser beam are melted and crystallized.
Now referring to FIG. 7C, an overlapped region xe2x80x9cR1xe2x80x9d which is exposed to the first and second laser beam scanning is completely crystallized to have a predetermined width xe2x80x9cT.xe2x80x9d Simultaneously, another partially crystallized group xe2x80x9cR2xe2x80x9d is formed next to the region xe2x80x9cR1xe2x80x9d. In other words, after the second laser beam scanning and crystallization, new grains having a laterally growing grain length xe2x80x9cSxe2x80x9d are then formed. Since the new grains 88 continue to grow adjacent to the first grains 82a, the grain length xe2x80x9cSxe2x80x9d of the new grains 88 is the same as a length from the first middle line 84c (which is formed by the first crystallization) to a second middle line 84d (which is formed by the second crystallization).
After the second laser beam scanning and crystallization, the mask 70 moves again in an x-axial direction for a third laser beam scanning by the length xe2x80x9cQxe2x80x9d of the crystallized regions. Thus, the first slit group xe2x80x9cMxe2x80x9d having the first slit patterns 72a is located over the partially crystallized group xe2x80x9cR2,xe2x80x9d as shown in FIG. 7D. By a third laser beam scanning and crystallization, the partially crystallized group xe2x80x9cR1xe2x80x9d becomes a completely crystallized region xe2x80x9cR3xe2x80x9d as shown in FIG. 7E.
By repeatedly carrying out the foregoing steps of melting and crystallizing, the amorphous silicon film 82 is converted into a polycrystalline silicon film 92 having grains 90 of length xe2x80x9cS,xe2x80x9d reference FIG. 7F.
However, the conventional SLS method described with reference to FIGS. 1 to 7F has some problems. For example, the SLS method described with reference to FIGS. 3A to 3C (i.e., often referred to as Scan and Step SLS method) takes a rather long time to crystallize the amorphous silicon film, thereby decreasing manufacturing yields and throughput. The SLS method described with reference to FIGS. 5A to 5C (i.e., often referred to as Continuous SLS method) and the SLS method described with reference to FIGS. 7A to 7F (i.e., often referred to as Single Scan SLS method) take a shorter time than the Scan and Step SLS method, but they have limited laser beam patterns widths. Namely, since the width of the laser beam patterns is less than or equal to the maximum length of the lateral grain growth, the grain size is limited. The sizes of the grains formed by the aforementioned methods are shown in Table 1. Table 1 also shows the number of substrates that are processed in accordance with the lateral grain growth length (micrometer; xcexcm) in each crystallization method.
From the results of Table 1, as the lateral grain growth length becomes larger, the manufacturing yields is reduced. Namely, the larger the lateral grain growth length, the less the throughput.
Accordingly, the present invention is directed to a method of crystallizing an amorphous silicon film using sequential lateral solidification (SLS) such that substantially obviates one or more of problems due to limitations and disadvantages of the related art.
An advantage of the present invention is to provide a sequential lateral solidification (SLS) method that saves time in crystallizing and increases productivity.
Another advantage of the present invention is crystallizing an amorphous silicon layer with increased manufacturing yield using an improved SLS method.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the method particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a method for crystallizing an amorphous silicon film includes locating a substrate having an amorphous silicon film in a sequential lateral solidification (SLS) apparatus; irradiating the amorphous silicon film using a laser beam that passes through a mask, wherein the mask includes a light absorptive portion for blocking the laser beam, a plurality of first echelon shaped light-transmitting portions having a tiered-pattern, and a second echelon shaped light-transmitting portion having a tiered-pattern, wherein the first and second echelon shaped light-transmitting portions pass the laser beam, wherein the second light-transmitting portion is located between the first light-transmitting portions, and wherein each tier has a fixed width, and wherein the laser beam portion that passes through the mask melts the amorphous silicon film into liquid silicon. The method further includes crystallizing melted regions such that the grain growth regions have laterally grown grains formed by growing laterally from an interface between liquid silicon and solid silicon. Then, transversely moving the mask to expose crystallized regions for a subsequent crystallization, and the performing a second crystallization such that laterally grown grains adjacent to the crystallized silicon particle regions continue to grow. The method further includes moving the mask in a longitudinal direction after the amorphous silicon film is crystallized in the transverse direction, and then conducting another transverse directional crystallization.
In another aspect, a mask for crystallizing an amorphous silicon film in a sequential lateral solidification (SLS) apparatus includes a light absorptive portion for blocking a laser beam; and first and second echelon shaped light-transmitting portions having a tier-shaped outline, wherein the first and second light-transmitting portions are for passing a laser beam. Each light-transmitting portion includes a plurality of adjacent rectangular patterns that form the echelon formation. The rectangular patterns beneficially have the same width, but different lengths. The width of the rectangular patterns range from 100 micrometers to 10 millimeters, whereas the lengths of the rectangular patterns are calculated using the following equation, XN=[X(Nxe2x88x921)+GN], where N is a natural number that is greater than one (N greater than 1), XN is the length of the Nth rectangular patterns, and GN is a length of lateral grain growth in the Nth rectangular pattern. Beneficially, GN is a variable and is less than and equal to twice the maximum length of lateral grain growth. Adjacent rectangular form steps that are less than or equal to the maximum length of lateral grain growth. The second light-transmitting portion is located between the first light-transmitting portions and there are fewer rectangular patterns in the second light-transmitting portion than in the first light-transmitting portions.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

Amorphous silicon crystallization method


The present invention relates to one-part cationically curable compositions with storage stability, wherein cure is independent of external stimuli such as heat and UV irradiation. In particular, the present invention provides for compositions with a long shelf life that will cure only upon application of the composition to the target surface, i.e. the surface is involved in initiating cure of the cationically curable component. Suitable compositions comprise those for curing on a surface comprising carbon-halogen covalent bonds comprising a cationically curable component and a non-halide silver salt. The present invention also relates to a primer capable of promoting cure of cationically curable non-halide silver salt compositions.

Cationically curable compositions are well known in the art. Such compositions find utility as adhesives, coating agents, sealing agents and as moulding agents. Typically, cationically curable compositions are latent one-part, e.g. based on onium salt cationic initiators, which are activated thermally or photochemically, or two/multi-component systems that are activated at room temperature by mixing.
There are numerous reports in the patent literature of two-part compositions, a first part comprising a hardener and a second part comprising a cationically curable monomer, which undergo cure when both parts are mixed. For example, U.S. Pat. No. 4,396,754 discloses two-part epoxy compositions comprising Group II metal fluoroborate salts as efficient curing agents for epoxy-based curable monomers. U.S. Pat. No. 4,241,204, and International Patent Publication numbers WO8001695, and WO8002839 disclose two-part epoxy curable compositions where the curing agent is described as an onium salt/reducing agent/copper salt combination. Upon mixing both parts, the copper salt is reduced by the reducing agent which in turn reduces the onium salt, thereby initiating cure of the epoxy monomer. Separate parts of the compositions contain an integral component of the curing agent combination.
U.S. Pat. No. 4,717,440 of Drain et al. describes a two component cationically curable composition wherein a first part comprises a curable epoxy monomer and an organic halide and a second part comprises a curable epoxy monomer and a silver salt of a non-nucleophilic anion. Cure is achieved by mixing the first and second parts of the two-part composition.
Aside from the issue of packaging two separate compositions, two-part cationically curable compositions may suffer in that efficient mixing of both parts is often necessary prior to cure. Furthermore, it may be necessary for the user to vary the mixing ratios of the two components depending on the end use. Thus one-part cationically curable compositions may be desirable in situations where efficient mixing is not possible and/or to avoid mixing ratio problems.
Known methods of circumventing the problems associated with formulating both a curable monomer and a hardener into a one-part composition include activating a latent curing agent utilising heat or UV irradiation. For example, U.S. Pat. No. 3,759,914 describes heat sensitive latent amines incorporated into one-part epoxy compositions. U.S. Pat. No. 6,376,368 describes one-part epoxy compositions comprising UV sensitive latent curing agents. Irradiation of a composition comprising an N-benzylpyrazinium hexafluoroantimonate and an epoxy resin with UV light results in cure of the epoxy resin.
Primers are preparatory coatings placed on a surface to enhance or promote cure of a curable composition applied thereto. Primers are often utilised to improve adhesion to problematic substrates. Application of a primer to such problematic substrates can result in greatly improved adhesion to these substrates. Primers may be applied soon before the application of an adhesive, or parts may be pre-treated with a primer for storage with a view to subsequent application of an adhesive composition some time in the future. In the latter case the applied primer must stable such that it retains its efficacy over time.
Notwithstanding the state of the art it would be desirable to provide one-part cationically curable compositions with long term storage stability, wherein cure is independent of external stimuli such as heat and UV irradiation. In particular, it would be desirable to provide compositions with a long shelf life that will cure only upon application of the composition to the "target surface", i.e. the surface is involved in initiating cure of the cationically curable component. It would additionally be desirable to render any surface as a "target surface" through provision of suitable primer compositions for priming surfaces to which cationically curable compositions can be applied.

Cationically curable compositions and a primer therefor


An intake control apparatus and methods that include an intake control valve disposed in an intake pipe of an internal combustion engine downstream of a throttle valve. From the start-up to the warm-up of the engine, the opening and closing of the intake control valve can be controlled based on the stability of combustion in the engine.

The disclosure of Japanese Patent Application No. 2001-88422 filed on Mar. 26, 2001 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
1. Field of Invention
The invention relates to an intake control apparatus and methods of an internal combustion engine that has an intake control valve in an intake pipe downstream of a throttle valve.
2. Description of Related Art
In a known technology, smaller particles of injected fuel during startup of an engine are formed to achieve a stable combustion by controlling the air current in an intake pipe. The air current is controlled through the use of an intake control valve disposed in the intake pipe and downstream of a throttle valve. Furthermore, by forming turbulences in the air current in cylinders of the engine, lean combustion is made possible which improves the exhaust emission quality.
An example of the aforementioned technology is described in Japanese Patent Application Laid-Open No. 4-191433. This patent application describes a process for detecting and determining a combustion property based on the combustion in an engine. The technology improves combustion by restricting the closing action of the intake control valve, until a property of fuel has been detected and determined. Furthermore, the detection and determination of the property of fuel is performed with high precision, thus ensuring good vehicle running performance.
However, if deterioration of the combustion occurs, for example, the property of fuel is inferior, then restriction of the closing action of the intake control valve can occur, which results in a reduction or elimination of the combustion performance improving effect. Accordingly, this reduction or elimination can degrade the state of the operation of the engine, thus discomforting an occupant in the vehicle. Furthermore, when the restriction of the closing action of the intake control valve is prevented, or when an opening action of the valve is caused, the state of the combustion in the engine changes which can cause produced torque to fluctuate depending on conditions, and therefore an occupant may be discomforted.
Accordingly, it is an object of the invention to provide an intake control apparatus and methods of an internal combustion engine that reduce the discomfort caused to a vehicle occupant by the changes in the combustion in the engine, even during the opening and closing actions of an intake control valve.
In accordance with a first aspect of the invention, an intake control apparatus of an internal combustion engine includes an intake control valve disposed in an intake pipe downstream of a throttle valve. The control apparatus and methods control an opening and closing of the intake control valve based on a stability of the combustion in the internal combustion engine during a period from a start-up to a warm-up of the internal combustion engine.
Therefore, by controlling the intake control valve based on the stability of the combustion, deterioration in the operation of the engine can be reduced or prevented, thus also reducing the discomfort caused to a vehicle occupant.
In accordance with a second aspect of the invention, an intake control apparatus and methods of an internal combustion engine includes an intake control valve disposed in an intake pipe downstream of a throttle valve. The control apparatus and methods change an open-closed state of the intake control valve during a period from a start-up to a warm-up of the internal combustion engine, and determine a property of a fuel based on a change in the operation of the internal combustion engine that is caused by the changing of the open-closed state of the intake control valve.
Since the state of the combustion can be changed by the open-close control of the intake control valve, it becomes possible to determine the property of the fuel with high precision by actively performing the open-close control to intentionally change the combustion, and by measuring changes in the operation of the engine that occur in association with the changes in the combustion.
In accordance with a third aspect of the invention, an intake control apparatus and methods of an internal combustion engine include an intake control valve disposed in an intake pipe downstream of a throttle valve. The control apparatus and methods control an opening and closing of the intake control valve synchronously with a change in a load on the internal combustion engine.
Therefore, if the open-close control of the intake control valve changes the combustion so that the state of output of the internal combustion engine fluctuates, such fluctuations are absorbed or offset by fluctuations in the load. Since fluctuations in the load can be anticipated by vehicle occupants, fluctuations in the load will not considerably dismay or discomfort vehicle occupants.
In accordance with a fourth aspect of the invention, an intake control apparatus and methods of an internal combustion engine includes an intake control valve disposed in an intake pipe downstream of a throttle valve. The control apparatus and methods control the intake control valve to close the intake control valve upon determining that the property of the fuel being used is inferior.
Therefore, if it is determined that the property of the fuel is inferior, that is, if it is determined that the property of the fuel will prevent a certain stability of combustion from being maintained if the intake control valve is opened, the intake control valve is maintained closed in order to improve combustion, and maintain a predetermined stability of combustion.
The invention is not limited to the intake control apparatuses and methods of the first to fourth aspects, but is also applicable to vehicles equipped with an intake control apparatus as described above, and to a control method thereof.

Internal combustion engine intake control apparatus and methods


The boosting voltage generating circuit of example embodiments may include a boosting level detection unit, a first boosting pump, and a second boosting pump. The boosting level detection unit may be configured to generate a target level detection signal and a margin level detection signal. The target level detection signal may have a logic state according to a level of a boosting voltage compared with a target voltage level, and the margin level detection signal may have a logic state according to a level of the boosting voltage compared with a margin voltage level, the margin voltage level being higher than the target voltage level. The first boosting pump may be controlled based on a target voltage level. The second boosting pump may be controlled based on a margin voltage level. According to the boosting voltage generating circuit of example embodiments, overshoot of the boosting voltage by the second boosting pump may remarkably decrease. Accordingly, the boosting voltage generating circuit of example embodiments may generate a stable boosting voltage under a wider range of supply voltage.

1. Field
Example Embodiments relate to an internal circuit of semiconductor memory device and, for example, to a boosting voltage generating circuit of a semiconductor memory device.
2. Description of Related Art
In a semiconductor memory device, a boosting voltage VPP may be used for preventing a voltage drop of a transferred signal. The boosting voltage VPP may be higher than an external supply voltage VCC. The supply voltage VCC may be used as an operation voltage in the semiconductor memory device. The boosting voltage VPP may be generated by pumping the supply voltage VCC. The boosting voltage generating circuit may be complemented in the semiconductor memory device. For example, the range of the supply voltage VCC may have a relatively wide scope, for example a scope of 1.5V to 3.8V. Accordingly, the boosting voltage generating circuit may be required to generate a stable boosting voltage VPP under a wider range of supply voltage VCC.
FIG. 1 is a drawing illustrating a conventional boosting voltage generating circuit 10. In the boosting voltage generating circuit 10, a boosting level detection unit 11 may compare the boosting voltage VPP with a target voltage level Vtag(for example 3.6V) and may generate a target level detection signal VDTG. A first boosting pump 13 may pump the supply voltage VCC to increase the boosting voltage VPP depending on the logic state of the target level detection signal VDTG, for example, depending on the level of the boosting voltage VPP. A second boosting pump 15 may be controlled by an active control signal XACT that may be provided from an active response unit 17. The active control signal XACT may be activated in response to an active command ACMD. When the active command ACMD is generated, the semiconductor memory device may be operated in an active mode.
A bus including a modeling parasitic capacitor 19 may transfer the boosting voltage VPP.
The second boosting pump 15 may pump the supply voltage VCC to increase the boosting voltage VPP, regardless of the level of the pumping voltage in active operation. Accordingly, it may be very difficult to make the boosting voltage VPP stable.
For example, if the second boosting pump 15 is designed with lower pumping capacity, the supply capacity of the boosting voltage VPP may be lower when the supply voltage VCC is lower. Accordingly, when a semiconductor memory device is in the active mode, the level of the boosting voltage VPP may be decreased.
If the second boosting pump 15 is designed with higher pumping capacity, the boosting voltage VPP may be stable, if the supply voltage VCC is lower. However, there may be a problem that the boosting voltage VPP may overshoot a target voltage level when the supply voltage VCC is higher.
Accordingly, in the conventional boosting voltage generating circuit 10, it may be difficult to make the boosting voltage VPP stable.

Boosting voltage generating circuit for generating a stable boosting voltage under a wider range of supply voltage and semiconductor memory device having the same


A device which can prevent a pull rod of suitcase from being automatically ejected out includes a counter weight which is installed in an inner lining of the pull rod. The counter weight is emplaced in a middle section of a frame slot of sliding rod. If the suitcase is fallen on a ground when a push button on a handle bar of pull rod is not pressed down, a blocking rod at one end of the counter weight will be automatically extended out of a concaved hole of an outer cover to retain a positioning block, so as to prevent the pull rod from being automatically ejected out due to an inadvertent condition.

a) Field of the Invention
The present invention relates to a device which can prevent a pull rod of suitcase from being automatically ejected out, and more particularly to a device that if a suitcase is thrown on a ground when its push button on a handle bar of pull rod is not pressed down, the pull rod can be prevented from being automatically ejected out, by using a counter weight in an interior of the pull rod.
b) Description of the Prior Art
A conventional suitcase is provided with a retractable pull rod, such that when the pull rod is extended up, the suitcase can be dragged to move with a user. As a handle bar of pull rod is provided with a push button, the user has to press down the push button to unlock a locking device in an interior of the pull rod before extending the pull rod. During a process of transporting and throwing the suitcase, the pull rod will be still ejected out automatically, even without pressing down the push button, which will cause trouble to a working staff and will also break the pull rod.

Device which can prevent a pull rod of suitcase from being automatically ejected out


The device has a voice and/or manual user interface for accessing its functions. The functions are accessible through a hierarchy of menus in which the branches can be short-circuited by voice instructions referred to as voice short-cuts.

1. Field of the Invention
The present invention relates to a device having a voice and/or manual user interface and to a process for aiding with learning the voice instructions of such a device. It relates in particular to the field of devices designed to be controlled using a remote control that can be operated by voice or alternatively using buttons.
2. Description of the Related Art
In general, the various functions of a device are accessed through a hierarchy of menus through which the user navigates using buttons on his or her remote control, using voice instructions or optionally buttons fitted to the device itself.
One problem which arises for the users is to know the voice instructions, that is to say the keywords which need to be spoken in order to use them. This is because, even if these keywords are chosen so as to be memorized with ease, if the user does not use them often, he runs the risk of forgetting them and therefore not using the voice instructions.
One first way of aiding users to know the voice instructions consists in implementing the principle of xe2x80x9cWYSIWYCSxe2x80x9d, standing for xe2x80x9cWhat You See Is What You Can Sayxe2x80x9d. That is to say, when a menu contains headings (a heading being a submenu or a function) is displayed on the screen, the user can reach or activate one of the headings by saying the keyword displayed on the screen which corresponds to this heading.
However, the main benefit of voice instruction of the devices over manual instruction involves the use of short-cuts for:
either directly accessing certain menus or certain functions of the devices by saying a keyword corresponding to the said menu or the said function, without having to perform multiple operations of navigating through the menu, in which case the term navigation voice short-cuts is used;
or directly activating certain functions, also by saying a keyword corresponding to the said function, without having to enter into any menu, in which case the term activation voice short-cuts is used;
it being possible for these two possibilities to be combined with voice short-cuts which make it possible both to access a function and activate it.
In this case, the xe2x80x9cWYSIWYCSxe2x80x9d approach cannot be applied since the user will not necessarily see on screen the keywords which he can say to reach a menu or activate a given function.
One object of the invention is to solve the problem explained above by making it easier for users to learn and know the voice instructions.
For this purpose, the invention provides a device having a voice and/or manual user interface for accessing its functions, the functions being accessible through a hierarchy of menus in which the branches can be short-circuited by certain voice instructions referred to as voice short-cuts. According to the invention, the device has:
means for storing a sequence of interactions by the user;
means for detecting the existence of a voice short-cut corresponding to the stored sequence of interactions; and
means for delivering, in the event that the existence of a voice short-cut is detected, a message to the user in order to inform him or her of the existence of the voice short-cut.
The invention also relates to a process for aiding the learning of voice instructions of a device as mentioned above. This process comprises the steps consisting in:
a) storing a sequence of interactions by the user;
b) testing whether a voice short-cut corresponding to said sequence of interactions exists; and
c) in the event that the existence of a voice short-cut is detected, providing means for informing the user of the existence of the voice short-cut.
Thus, as soon as the user uses a complex sequence of interactions to reach a menu or a function of the device even though he could have reached this menu or this function using a voice short-cut, he will be reminded of the use of this voice short-cut. By virtue of the invention, the user will find it very easy to remember the voice short-cuts corresponding to the menus or functions which he accesses most often.
According to a particular embodiment of the invention, step a) comprises:
i) storage of the initial state of the user interface;
ii) detection of an action performed by the user;
iii) storage of the current state of the user interface following this action;
steps ii) and iii) being repeated until one of the following conditions for the end of a sequence of interactions is fulfilled:
the action detected corresponds to the activation of a function; or
no action is detected for a period longer than a predetermined limit duration.
It is thus possible to detect both sequences of interactions leading to the activation of a function and those consisting in accessing a menu or a particular function without activating it.
According to a particular embodiment, the user interface has a remote control equipped with buttons and a microphone, and the action detected in step ii) belongs to the set consisting of:
a button on the remote control being pressed; and
the microphone picking up a keyword corresponding to a voice instruction.
Advantageously, the process of the invention furthermore comprises the steps consisting in:
iv) providing a use counter associated with each voice instruction of the device;
v) testing whether the action detected in step ii) is a voice instruction which corresponds to a voice short-cut; and
vi) incrementing the use counter associated with said voice instruction when the answer to the test above is positive.
According to a preferred aspect of the invention, the storage means of the device include an interaction register comprising:
an xe2x80x9cinitial statexe2x80x9d field in which the initial state of the user interface is stored during step i);
a xe2x80x9ccurrent statexe2x80x9d field in which the current state of the user interface is stored during step iii).
According to a particular embodiment, step a) furthermore includes:
vii) storage of the use of each voice short-cut detected in step v); and step c) furthermore includes
viii) checking that the voice short-cut corresponding to the stored sequence of interactions has not already been used during said sequence of interactions.
According to a preferred aspect of the invention, if in step viii) it is detected that the voice short-cut corresponding to the stored sequence of interactions has not yet been used during said sequence of interactions, then the steps consisting in:
ix) comprise the use counter of the voice instruction corresponding to said voice short-cut with a predetermined threshold, and
if the use counter is greater than or equal to the threshold, then
x) decrementing the use counter;
else,
xi) sending a message to the user informing him or her of the existence of the voice short-cut detected in step b)
are carried out.
Thus, if the user is in the habit of using a voice short-cut but sometimes forgets to employ it, the system reacts xe2x80x9cintelligentlyxe2x80x9d by not reminding him or her of the existence of the voice short-cut.
According to another aspect of the invention, means are provided for disabling the process described above for the case when the user does not in general wish to be disturbed by the messages reminding him or her of the voice instructions.

Device having a voice or manual user interface and process for aiding with learning the voice instructions

Abstract: According to the invention, means are provided for storing the sequences of interactions performed by the user and for detecting the cases in which a voice short-cut could have been used instead of the sequence of interactions. In this case, a message is sent to the user in order to inform him or her of the existence of the detected voice short-cut.

Abstract: The invention also relates to a process for aiding with learning the voice instructions of the device using the means above.


A photo-polymerizable composition is disclosed, which comprises. a thermoplastic polymeric binder; PA0 a non-gaseous ethylenically unsaturated compound; PA0 a photo-polymerization initiator system composed of 4,4'-bis(dialkylamino)benzophenone, aromatic ketone and lophine dimer; PA0 an organic halogen compound; and a leuco dye.

Recently in the electronics industry there has been a demand for an increase in integration thus requiring a photo resist having a higher resolving power. In addition, a higher sensitivity is demanded so as to shorten the time required for production steps.
Studies for enhancing sensitivity of a photo-polymerizable composition have conventionally been conducted and, as a result, many photo-polymerization initiators (systems) have been proposed. For example, U.S. Pat. No. 2,448,828 describes benzoin ethers, U.S. Pat. No. 3,046,127 describes anthraquinones, JP-B-49-11936 (the term "JP-B" as used herein means an "examined Japanese patent publication") (corresponding to U.S. Pat. No. 3,661,588) describes aminophenylketone and an active methylene or amino compound, U.S. Pat. No. 3,682,641 describes Michler's ketones and benzophenone, JP-B-48-38403 describes benzophenone and 4-N,N-diethylaminobenzophenone, JP-B-45-37377 and JP-B-48-38403 describe Michler's ketones and lophine dimers, JP-A-56-35134 (the term "JP-A" as used herein means an "unexamined published Japanese patent application") describes lophine dimers and photo-polymerizable unsaturated monomers, JP-A-59-78339 describes a ternary system of 4-N,N-dialkylaminobenzophenones, benzophenone and an organic halogen compound, and the like.
It is true that the use of these photo-polymerization initiator systems serves to improve sensitivity and resolving power to some extent, but the degree of improvement is still insufficient for satisfying the recent requirements. In addition, when used as dry film resists to be used upon preparation of printed circuit boards, they provide a tenting film with only an insufficient strength upon formation of through-holes according to the tenting process, and hence a film-breaking trouble has been liable to take place during a development or etching step. It is well known that breakage of a film during the development or etching step can cause a serious problem of conduction failure as a result of dissolution with an etching solution of the copper-plated portion inside the through-hole conducting the surface side and the back side to each other.


A direct positive photographic material comprising a support having provided thereon one or more hydrophilic colloid containing layers, wherein at least one of said hydrophilic colloid containing layers is an internal latent image type silver halide emulsion which has not been previously fogged and at least one of said emulsion layer or other hydrophilic colloid containing layer contains a colloidal metal or a colloidal water-insoluble metallic sulfide, selenide or telluride, and a method for forming a direct positive from the direct positive photographic material in which a light-sensitive material contains at least two layers containing colloidal silver.

Photography by directly obtaining a positive image (a direct positive) without requiring a reversal process and a negative film is well known in the art.
Taking practical utility into consideration, conventional techniques for obtaining a positive from a direct positive silver halide photographic material, exclusive of special materials, are divided chiefly into the following two types.
One type employs a previously fogged silver halide emulsion whose fog centers (latent image) in exposed areas are destroyed making use of the solarization or Herschell effect to obtain a direct positive.
The other type uses an internal latent image type silver halide emulsion not having been fogged, which is imagewise exposed to light and then subjected to surface development either after fogging or while fogging to obtain a direct positive. The internal latent image type silver halide emulsion used herein is such an emulsion in which silver halide grains have sensitivity specs predominantly in the inside thereof and form a latent image predominantly in the inside upon exposure to light.
The methods belonging to the latter type generally enjoy higher sensitivity and are suitable for uses requiring high sensitivity as compared with the methods of the former type. The present invention belongs to the latter type.
Various techniques of this type have been proposed, such as those disclosed in U.S. Pat. Nos. 2,592,250, 2,466,957, 2,497,875, 2,588,982, 3,317,322, 3,761,266, 2,761,276, and 3,796,577, and British Patents 1,151,363, 1,140,553, and 1,011,062. According to these conventional techniques, photographic materials providing a direct positive with relatively high sensitivity can be produced.
For the details of the direct positive formation mechanism, reference can be made to it, e.g., in T. H. James, The Theory of the Photographic Process, 4th Ed., Ch. 7, pp. 182-193 and U.S. Pat. No. 3,761,276.
It is believed that a direct positive is formed through the following mechanism: First, imagewise exposure results in the formation of an internal latent image (a so-called positive hole) in the inside of silver halide grains, which leads to the formation of fog centers selectively on the surface of the unexposed silver halide grains by surface desensitization ascribed to the positive hole, and subsequent surface development results in formation of a direct positive on the unexposed area.
Selective formation of fog centers can be effected by a so-called light fog method in which the entire surface of a light-sensitive layer is secondarily exposed to light as described in British Patent 1,151,363 or a chemical fog method using a nucleating agent as described in Research Disclosure, Vol. 151, No. 15162 (November, 1976), pp. 76-78.
In the formation of a direct positive, the internal latent image type silver halide light-sensitive material is subjected to surface color development either after or simultaneously with fogging and then subjected to bleach and fixation (or blix). After the bleach-fixation, the material is usually washed with water and/or stabilized.
The direct positive formation by the above-described chemical fog method is disadvantageous in that the resulting image is apt to have poor graininess as compared with ordinary negatively working photographic materials. In particular, this disadvantage becomes conspicuous in cases where a color developing solution is fatigued with running the development process due to oxidation of the developing agent, reduction in pH, increase of bromine ions, etc., or in cases where the light-sensitive materials are preserved under severe conditions for a long time. Moreover, deterioration of graininess is accelerated as the pH of a developing solution is decreased. From the standpoint of graininess, therefore, it has conventionally been effective to carry out development processing at a pH of 12 or higher.
On the other hand, the rate of development is less, requiring a longer development time in the formation of a direct positive as compared with the formation of general negative images. Hence, the pH of a developing solution used in the formation of a direct positive has been increased to thereby reduce development time.
However, use of a developing solution having a higher pH value generally causes an increase in the minimum image density of the resulting direct positive. Further, under a high pH, the developing agent is more susceptible to deterioration due to air oxidation, so that development activity becomes subject to great variation.
The aforesaid light fog method does not require a high pH and, therefore, enjoys a relative practical advantage. Nevertheless, this method encounters various technical problems when applied to a broad photographic field for various purposes. That is, since this method is based on the formation of fog centers by photolysis of silver halide, the optimum illumination or exposure varies depending on the kind and characteristics of the silver halide used. It is, therefore, difficult to assure predictable performance. In addition, the development apparatus required is complicated and expensive. The rate of development is also unsatisfactory.
According to the direct positive formation by the above-described light fog method or chemical fog method, the rate of development is lower, requiring a longer development time as compared with general negatively working photographic materials. Hence, the pH and/or temperature of a development solution used in these methods may be increased to thereby reduce the development time. However, the use of a developing solution having a higher pH value, as mentioned above, generally causes an increase in the minimum image density of the resulting direct positive and the developing is more susceptible to deterioration due to air oxidation under a high pH, so that development activity becomes seriously reduced.
In addition to increasing the pH value of the developing solution, other known means for increasing the rate of development in the direct positive formation system include use of hydroquinone derivatives as disclosed in U.S. Pat. No. 3,227,552 and the use of mercapto compounds having a carboxyl group or sulfo group as disclosed in Japanese Patent Application (OPI) No. 170843/85. However, these compounds produce only small effects. Therefore, there has not yet been established an effective technique for increasing the maximum density of a direct positive without increasing the minimum density. In particular, there has been a demand for a technique for obtaining a sufficient maximum image density even when a low pH developing solution is employed.
On the other hand, the known direct positive light-sensitive materials have the disadvantage, mentioned above, that the resulting image is apt to have poor graininess as compared with ordinary negatively working photographic materials. In particular, this disadvantage becomes conspicuous in cases where a developing solution is fatigued during continuous processing due to oxidation of the developing agent, reduction in pH, increase of bromine ions, etc., or in cases where the light-sensitive materials are preserved under severe conditions for a long time. Therefore, it has been especially desired to develop a technique for obtaining sufficient graininess even when processing is carried out with a low pH developing solution.


A silicon wafer includes BMDs with a diagonal length of from 10 nm to 50 nm, and has a density of BMD which exists at a depth of 50 μm and deeper from the surface of the silicon wafer which is greater than or equal to 1×1011/cm3, and a ratio of the {111} plane of the BMD to the total planes surrounding the BMD, as an indication of the morphology of the BMD, is less than or equal to 0.3.

1. Field of the Invention
The present invention relates to a silicon wafer and production technology therefor which is capable of suppressing generation of both slip dislocations and warpage, in a field of production technology of semiconductor wafers, in particular, device production processes.
2. Background Art
Silicon wafers to be used as a substrate for producing semiconductor devices are produced by slicing a single crystal silicon ingot, and performing heat treatment or mirror finishing or the like. Due to the ease of obtaining single crystal ingots having a large diameter, or in controlling defects, most single crystal silicon ingots are produced by a Czochralski ("CZ") method. A silicon single crystal silicon grown by such a CZ method ("CZ-Si") has internal "Grown-in defects," in particular, supersaturated oxygen taken into the silicon lattice in a supersaturated state, which causes formation of micro defects known as Bulk Micro Defects ("BMD"), during a subsequent heat treatment (anneal).
In general, BMDs existing inside a crystal just after single crystal silicon growth (Grown-in defect, an oxygen deposit, dislocation, lamination defect or the like induced in a device production process) deteriorates device characteristics, and therefore it is required that there are no crystal defects in a formation region of a semiconductor device. However, on the other hand, it has also been revealed that BMDs can be utilized effectively as a gettering site for heavy metals or to increase the mechanical strength of the substrate, and thus at present, generation of a suitable amount of BMDs inside a silicon wafer is required.
In order to satisfy such requirements, there is generally used at present a method for forming an Intrinsic Gettering layer (hereafter referred to as "an" IG layer") by annealing the silicon wafer at high temperature and inducing BMD formation inside the silicon wafer, as well as forming a Denuded Zone layer (hereafter referred to as a "DZ layer") having extremely low crystal defects by eliminating grown-in defects near the surface of the silicon wafer.
However, the DZ layer formed on the front and rear surfaces of the silicon wafer by the annealing process at high temperature decreases the number of BMDs or dislocations, which together with oxygen or oxygen impurities or the like, results in an extreme decrease of oxygen concentration by outward diffusion of oxygen during heat treatment, and in turn extremely decreases suppression of the extension of dislocation defects at the front and rear surfaces of the silicon wafer. Therefore, dislocation defects (hereafter referred to as "slip") easily extend into the bulk from minute flaws on the front and rear surfaces, introduced in the annealing step, creating the problem that the strength of the silicon wafer decreases due to extension of such slip dislocations. Furthermore, such decrease of silicon wafer strength can result in wafer damage or wafer destruction during production steps. However, the DZ layer is indispensible in semiconductor device formation, therefore, silicon wafers which have a DZ layer and yet exhibit excellent strength properties are desired. In particular, when annealing is performed on a wafer supported by a heat treatment susceptor or the like, a slip dislocation often extends from the part supported by the susceptor, because of a dislocation generated at the contact point of the silicon wafer and the susceptor. In addition, a slip dislocation may extend from the edge part of the silicon wafer.
In addition, in order to produce a device such as once having a thermally oxidized film, or activation of a dopant injected into a source or drain region, heat treatment of the silicon wafer is essential. In general, heat treatment is classified as: batch heat treatment, where one treatment is performed by assembling longitudinally several tens to hundreds or more of wafers held horizontally; and single wafer heat treatment, where heat treatment is performed wafer by wafer. In heat treatment, generation of a temperature gradient on the silicon wafer surface causes thermal stress on the surface in proportion to the gradient, and a thermal stress of over a certain value raises a problem of not only minute level differences on the wafer surface, or the slip previously mentioned, but also causes warpage of the silicon wafer.
Technologies to suppress and prevent the generation of such slip dislocation or warpage are known. For example, in JP-A-2008-166721, there is disclosed a technology to produce a silicon wafer, in which a predetermined amount of plate-like BMDs are formed and an inter-lattice oxygen concentration is less than or equal to 5×1017 atoms/cm3, by performing heat treatment at a temperature range of 600 to 750° C. for 10 minutes to 10 hours, and then increasing the temperature up to 1000° C. at a rate of 0.1° C./minute to 1° C./minute for 5 to 50 hours, and further subjecting the silicon wafer to heat treatment at a temperature range of 1000 to 1250° C. so that the diffusion length of inter-lattice oxygen is below 20 to 30 μm.
In addition, in JP-A-2008-160069, there is disclosed a technology to produce a silicon wafer, in which a predetermined amount of octahedral BMDs are formed and an inter-lattice oxygen concentration is less than or equal to 5×1017 atoms/cm3, by performing heat treatment at a temperature range of 600 to 750° C. for 30 minutes to 10 hours, and then the increasing the temperature up to 1000° C. at a rate of 0.1 to 1° C./minute for 5 hours to 50 hours, and by further subjecting the silicon wafer to heat treatment at a temperature range of 1000 to 1250° C. so that the diffusion length of inter-lattice oxygen is 30 μm to 50 μm.
Further, in JP-A-2009-164155, there has been disclosed a technology to control the change of substitution-type carbon concentration and inter-lattice oxygen concentration inside a silicon wafer to be within a predetermined range before and after heat treatment in a heat treatment furnace by a low temperature heat treatment of 650 to 800° C., thereafter setting a maximal temperature at 700 to 1000° C. and increasing the temperature at a rate of 0.1 to 2° C./minute; removing the silicon wafer at 600° C. to 800° C.; further inserting the silicon substrate inside a heat treatment furnace at a furnace temperature of 600 to 800° C.; increasing the temperature of the heat treatment furnace at a rate of 5 to 10° C./minute in a temperature range from the insertion temperature up to below 1100° C.; increasing the temperature of the heat treatment furnace at a rate of 1 to 2° C./minute in a temperature range of 1100 to 1250° C.; and keeping the temperature of the heat treatment furnace constant within the range of 1000° C. to 1250° C.; thus performing a heat treatment at a high temperature of 1100 to 1250° C.
FIG. 1 shows a schematic diagram of a typical example of slip and warpage introduced by heat treatment. The slip is introduced from a contact point of the rear surface of the wafer and a wafer holding member or from the edge of the wafer. The introduced slip extends in a 110 direction and incurs wafer damage or destruction depending on the case. The warpage is a phenomenon that the wafer deforms due to thermal strain in heat treatment. For example, a wafer of the 100 plane, as shown in FIG. 1, may exhibit concave-type warpage. Usually, warpage of the silicon wafer, before heat treatment is performed to bring desired characteristics, is less than or equal to 10 μm. However, the heat applied by heat treatment may generate a concave-convex height difference of the silicon wafer that reaches several tens of μm. Increased warpage disturbs correct exposure of a semiconductor device pattern on the wafer surface, and causes decreased yield of the semiconductor device.
The warpage problem tends to be significant when the wafer diameter is greater than or equal to 200 mm, and is also significant when the heat treatment step of the device is performed at high temperature over a long time. On the other hand slip dislocation decreases when the BMD concentration increases, and warpage increases when the BMD concentration increases. Thus, it is known that slip and warpage are in a trade-off relationship. Accordingly, there still is a problem that generation of slip and warpage, in particular, generation of warpage, cannot be suppressed and prevented effectively. The total density of BMDs inside the silicon wafer can only be increased to a high concentration by the technology as disclosed in JP-A-2008-166721 and JP-A-2008-160069, in which the concentration of relatively large BMDs is decreased to suppress and prevent generation of warpage, the density of relatively small BMDs is increased to suppress and prevent generation of slip or slip length, and further, BMD shape is controlled to a predetermined morphology such as plate or octahedron to suppress and prevent generation of slip or slip length, so as to adjust inter-lattice oxygen concentration and then to secure oxygen adhered to BMD to the predetermined amount.
In addition, there is a problem that warpage cannot be suppressed and prevented effectively by the method as disclosed in JP-A-2009-164155, by the number of oxygen or carbon atoms adhered to BMDs by performing heat treatment so as to maintain carbon concentration and oxygen concentration in the silicon wafer as much as possible before and after heat treatment to the predetermined amount, although generation of slip or slip length can be suppressed to some extent.

Silicon wafer and production method therefor


A new class of logic gates are presented that use non-linear polar material. The logic gates include multi-input majority gates and threshold gates. Input signals in the form of analog, digital, or combination of them are driven to first terminals of non-ferroelectric capacitors. The second terminals of the non-ferroelectric capacitors are coupled to form a majority node. Majority function of the input signals occurs on this node. The majority node is then coupled to a first terminal of a capacitor comprising non-linear polar material. The second terminal of the capacitor provides the output of the logic gate, which can be driven by any suitable logic gate such as a buffer, inverter, NAND gate, NOR gate, etc. Any suitable logic or analog circuit can drive the output and inputs of the majority logic gate. As such, the majority gate of various embodiments can be combined with existing transistor technologies.

Typical logic gates such as AND gate, OR gate, or a logic gate that receives three or more inputs may consist of nine more transistors per logic gate and many interconnects to connect the various transistors. As the number of transistors increases, power consumption also increases. As devices are pushing down the power envelope to save battery power, existing circuit architecture for multi-input logic gates present challenges to the goal of lower power consumption.
The background description provided here is for the purpose of generally presenting the context of the disclosure. Unless otherwise indicated here, the material described in this section is not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.

This patent is subject to a terminal disclaimer.

Majority logic gate with input paraelectric capacitors


A method for inspecting a portion of a tire surface involves comparison with an image of a three-dimensional (“3D”) reference surface. The method includes: extracting contours of graphic elements of an image of a 3D profile of a surface to be inspected; transforming the reference surface by establishing a correspondence between the contours of the graphic elements of the surface to be inspected and contours of identical graphic elements of the reference surface using a series of transformations; associating a B-spline surface, which includes control points, with the graphic elements of the transformed reference surface; and deforming the contours of the graphic elements of the reference surface by modifying positions of the control points of the B- spline surface so as to minimize distances between the contours of the graphic elements of the reference surface and the contours of the graphic elements of the surface to be inspected corresponding thereto.

The methods employed for carrying out these processings usually consist in comparing a two- or three-dimensional image of the surface of the tyre to be inspected with a reference image in two or three dimensions of the surface of the said tyre. The general principle of these methods consists in establishing a correspondence between the image or the surface of the tyre to be inspected and the image or the reference surface, for example by superposing them, in order to determine the moulding anomalies by analyzing the differences between the two images or the two surfaces.
In the case of the tyre, the reference image of the surface may come for example from the digital data originating from the design of the tyre or, more commonly, from the digital data used to describe and to manufacture the curing mould, the said mould itself being designed to give its definitive shape to the said tyre.
The three-dimensional image of the surface of the tyre may be obtained, in a known manner, with the aid of an acquisition system capable of determining the three-dimensional relief of the tyre surface.
Matching the reference surface and the surface of the tyre to be evaluated uses methods which must be adapted to the particular case of this type of object.
Therefore, as an example, publication U.S. Pat. No. 5,715,166 describes the transformations to be made to match a reference surface with a three-dimensional image of a given object by using transformation functions such as rotations or slidings. This method is applied with good results when it is sought to match non-deformable solid objects such as metal parts, in this instance considered to be infinitely rigid. It does not apply to the tyre situation because of the deformable nature of this product.
Publication EP 1 750 089, which relates more specifically to an application designed for the inspection of tyres, proposes to divide the surface to be inspected and the reference surface into surface portions of reduced dimensions, corresponding substantially to the surface of a marking element such as a letter or a set of letters, and then sliding the said surface portions of the reference surface and of the surface to be inspected one over the other, so as to determine the optimum match between the contours of the reliefs of the two surface portions. After having carried out this local reset, the two surface portions are compared with one another in order to determine, in the zone corresponding to the surface portion, the degree of conformity of the tyre to be inspected relative to a reference.
Although the algorithms described in this publication have the advantage of dispensing, to a certain degree, with the positional differences between the model and the real tyre to be evaluated, and with the differences in fitting and inflation from one casing to another, they are close to those described in publication U.S. Pat. No. 5,715,166 in that they still assimilate the surface portions with rigid elements.
Specifically, it is observed that the tyre coming out of the mould does not exactly match the negative image of the mould in which the moulding and curing operation has been carried out, because of the elastic nature of the materials that make it up. The tyre deforms as soon as it comes out of the curing press under the action of the thermal retractions of the materials when cooling. Moreover, when fitted and inflated, the reinforcing plies take their final position and the curve of equilibrium of the inflated tyre does not necessarily match the curvature of the curing mould.
Also, it is found to be necessary to make a very precise prior adjustment of the image of the reference surface and of the acquired image of the surface of the tyre to be inspected in order to match the two surfaces for the purpose of obtaining therefrom pertinent information on the conformity of the tyre resulting from the production.
The method described in publication WO2009077539 proposes, in order to achieve this objective, to make affine transformations of the reference surface, of which the coefficient is different from 1, so as to have it coincide with the surface to be inspected, which is the equivalent of carrying out a variable elastic deformation in a particular direction of the said surface, and thereby distinct from a simple variation of scale.
It is however observed that this method does not make it possible to make the fine adjustments necessary to the perfect superposition of the surfaces and may induce incorrect judgements during the comparison of the surface to be inspected and the reference surface.

Method for the pre-processing of a three-dimensional image of the surface of a tyre for use in the inspection of said surface

COMPAGNIE GENERALE DES ESTABLISSEMENTS MICHELIN


A vibration generation device is provided with a housing, a vibration target component provided to be movable relatively to the housing, an actuator which has a metal base portion, a metal movable portion, a beltlike shape memory alloy disposed between the base portion and the movable portion and in which, when the shape memory alloy receives current application to be changed so that the outer shape becomes small, the movable portion is pushed out in one direction of separating from the base portion in a state where the base portion abuts on a first wall surface of the housing, a resin holder component fixed to the vibration target component and abutting on a pushing surface facing the one direction of the movable portion, and an elastic member elastically energizing the movable portion in a direction opposite to the one direction.

In electronic apparatuses, such as a Laptop PC and a tablet PC, a reduction in thickness has been strongly demanded. Therefore, input operation portions, such as a touchpad which can be input by clicking and a push button, have been demanded to eliminate a mechanical up and down movement thereof. Then, the electronic apparatus of this type has been mounted with a feedback technology (HAPTICS technology) of transmitting a click feeling to a user without the mechanical up and down movement by driving an actuator according to a touch input operation of a user in some cases. For example, Japanese Patent No. 5950139 discloses a configuration of using an actuator containing a shape memory alloy (SIA: Shape memory alloy Impact Actuator) as a vibration generation device of a touch panel.

Vibration generation device and electronic apparatus


A display device includes a generally annular display (10) and a light source (3a) disposed to oppose a rear surface of the display (10). The display (10) is indicated by a rotatable pointer (4) and includes an indicator portion (12) disposed along a trace of displacement of a tip end portion (4a) of the pointer (4), and a transparent member (20) having a light incidence surface (a light incidence portion) (21) on which light from the light source (3a) is incident. The transparent member (20) is disposed on a front side of the indicator portion (12) and spaced from a front surface of the indicator portion (12) with a clearance (K) therebetween, and extends toward a center axis of the pointer (4).

A vehicular display device is conventionally known, which includes a display having an indicator portion which is disposed along an arcuate trace of displacement of a tip end portion of a rotatable pointer (for instance, see Patent Literature 1).
The conventional vehicular display device includes a ring-shaped recessed portion which is formed along an outer circumference of the indicator portion. The recessed portion is configured such that an inclined side surface thereof is illuminated with light.    Patent Literature 1: Japanese Patent Application Unexamined Publication No. 2007-17166.


A mechanism and method for seaming and joining overlaid sheets such as to form seams on adjacent bags by applying heated pressure sealing jaws to opposite sides of the overlaid sheets with the pressure being applied decreasingly inwardly away from the edges of the seam and cutting the seaming areas between them to separate the seamed portions so as to form edges of adjacent bags with the bags preferably having rib and groove upper fasteners extending outwardly to the edge of the seam.

The present invention relates to improvements in apparatus and methods for forming reclosable plastic bags, and more particularly to an improved method and mechanism for forming edge seams on adjacent bags which are cut to separate the bags.
In the manufacture of plastic bags, one form of manufacture employs material that is sealed by the application of heat and pressure opposed overlaid sheets of plastic from the front and back walls of a bag with a reclosable interlocking rib and groove plastic zipper along the top. Such sheets are continuous and separate bags are formed by sealing jaws which apply heat and pressure at the edges of the bag and cut the continuous length of film to separate adjacent bags.
In one well known form of the manufacture which is frequently referred to as a form, fill and seal process, thermoplastic material is fed forwardly and wrapped over a filling tube. At the edges of the plastic material, is an interlocking zipper. The material is fed downwardly over the filling tube and contents are dropped through the tube to fill individual bags. Individual bags are cut from the continuous length by heated sealing jaws being pressed at bag intervals and the resultant seam is cut intermediate its sides to separate individual bags which have seams running along their sides. As a seam is formed and the finished bag is cut, the contents are dropped into the bag and it is pulled downwardly whereupon a new seam is formed above the contents. Examples of this type of bag manufacture are illustrated in U.S. Pat. Nos. 4,709,533, Ausnit, and 4,617,683, Christoff and Ausnit. This arrangement of bag manufacture employs relatively high speed operation with the tubular material being incrementally pulled down over the filling tube and cut and cross-sealed. The integrity of the seam formed by the cross-seal depends upon the amount of heat transmitted to the plastic. It is essential that a complete integral seal be formed by supplying sufficient heat to the plastic to cause the overlaid sheets to melt at the seam edge but the heat must not be at a level so that melt holes are formed adjacent the seam in the bag plastic. Yet, the heat which is transmitted to the plastic must be sufficient to cause complete sealing. Difficulties are encountered in high speed operation varying from incomplete joining of the layers to form the seam to openings inadvertently caused in the plastic by the heated sealing jaws.
It is accordingly an object of the present invention to provide an improved method and apparatus for cross-seaming plastic bags such as in a form, fill and seal operation wherein the seams are of improved integrity and strength.
A further object of the present invention is to provide an improved cross-seaming apparatus and method for the formation of edge seams for bags wherein an improved appearing seam is formed and one which eliminates perforations and insures a more secure seam.
A further object of the invention is to provide an improved seaming apparatus and method wherein variances can be accommodated in the speed of seaming and operation without adversely affecting the integrity of the seams which are formed.
Another further object of the invention is to provide a cross-seaming apparatus and method for forming side seams in bags wherein a thicker amount of plastic occurs at the top of the bag due to the presence of an interlocking rib and groove fastener and wherein the seaming apparatus and method accommodates this thicker plastic without adversely affecting the integrity of the seam.

Sealing jaw for heat sealable film with zippered section


A method for diagnosis and treatment of arteriosclerotic lesions is provided wherein the method is characterized by introducing a chemical compound to the patient, the compound being a complex of a photosensitive portion, and a radioactive portion. Cells which exhibit an affinity for the porphyrin element indicate sites of plaque buildup. The radioactive portion within the compound allows tomographic scanning as well as simultaneous radiation treatment. The complexed compound can be introduced to the patient a desired number of times to provide the necessary radiation treatment and ongoing monitoring of plaque removal. Further observation or treatment may be conducted through a fluorescence guided endoscopic procedure.

This invention relates to use of radiopharmaceuticals in the treatment of arteriosclerotic lesions in blood vessels, and more particularly, to the use of metaloporphyrins wherein a porphyrin is complexed with a radioactive metal for targeted delivery of radiation to arteriosclerotic lesions.
It is known that certain types of obstructions in arteries may be due, in part, to arteriosclerotic plaques. These plaques typically result from the proliferation of smooth muscle cells and associated fibrous tissue which invades the wall and lining cells (intima) of the artery. While the reasons for the smooth muscle and fibrous cell proliferation in the arterial walls is not completely understood, this proliferation is not generally considered to be neoplastic in origin, in spite of the fact that regeneration of plaque can take place very rapidly, sometimes within a few months of total removal by coronary endarterectomy.
Management of arteriosclerotic stenosis by balloon angioplasty is a common treatment method; however, the effectiveness of such treatment is limited by restenosis. Restenosis occurs in about 30% to 50% of patients having undergone angioplasty. Fibrocellular intimal hyperplasia is a main cause of such restenosis which arises from proliferation of smooth muscle cells in the intimal layer.
Porphyrins are a large class of typically red or purple fluorescent crystalline pigments, with natural or synthetic origin, having in common a substituted aromatic macrocyclic ring consisting of four pyrrole-type residues, linked together by four methine bridging groups. It is recognized that smooth muscle cells which proliferate in arteries have a distinct affinity for various porphyrin compounds such as HPD, photofrin, photofrin II, and a long list of other porphyrin compounds. A proliferating smooth muscle cell will take up such porphyrin compounds much in the same manner as cells which are either dysplastic or overtly malignant. Because these cells become sensitized by these porphyrin compounds, they are capable of responding to both photo-detection and photo-destruction when proper frequencies of light are administered. Use of this xe2x80x9cphoto-dynamicxe2x80x9d therapy in the management of angioplasty restenosis in patients is described in Photodynamic Therapy of Normal and Balloon Injured Rat Carotid Arteries Using 5-Amino-Levulinic Acid, Circulation, 91(2):417-25 (1995), incorporated herein by this reference in its entirety for disclosing basic procedures for photodynamic therapy of arteriosclerotic abnormalities.
Although many physicians and researchers are familiar with photodynamic therapy and many have used such procedures in the laboratory, few have become advocates of the therapy because of the severe limitations imposed by the use of porphyrins which utilize light frequencies that do not penetrate, and are therefore impossible to deliver to any significant depth in tissue. The light frequencies required for photo detection generally range between 380-420 nm, and the resulting fluorescence is typically in the range of 635 nm. Because of these wavelengths, penetration of the light source is restricted to tissue of minimal depth in the body. Accordingly, without surgical intervention, phototherapy is not capable of effectively reaching arteriosclerotic lesions.
As also understood by those skilled in the art, photodynamic therapy has been used for treatment of various cancers. Examples of references which disclose use of photodynamic therapy for treatment of cancer include the U.S. Pat. Nos. 5,087,636 and 5,211,938.
Another significant, well known method for treatment of arteriosclerotic abnormalities includes localized intercoronary radiation therapy. This therapy is reviewed in Localized Intercoronary Gamma Radiation Therapy to Inhibit the Recurrence of Restenosis after Stenting, and Endoluminal Beta Radiation Therapy for the Prevention of Coronary Restenosis after Balloon Angioplasty, The New England Journal of Medicine, 344(4)243-56 (2001). The studies reported therein indicate significantly lowered rates of clinical and angiographic restenosis following radiation therapy.
There are also a number of references which further disclose radiation therapy for arteriosclerotic abnormalities including U.S. Pat. Nos. 6,422,989; 6,422,988; 6,395,016; 6,387,350; 6,358,989; and 6,235,767.
Finally, there is a known treatment for cancer which utilizes metaloporphyrins to deliver site selective radiation therapy. More specifically, U.S. Pat. No. 5,391,547 discloses a method for using porphyrins to detect lung cancer by the use of tetra-aryl porphyrins. The porphyrins are used as fluorescent tracers for cancers of the lung. The porphyrins are complexed with 64Cu or 67Cu. Thus, the complex can be used as radiotracers as well. The 67Cu provides a source of beta radiation for selective destruction of lung malignancies as well as gamma radiation useful for image analysis, as by a single photon emission computed tomography (SPECT). The 64Cu as a positron emitter, may be used for radiotracing wherein positron emission tomography (PET) techniques can be used to locate the malignant tissue.
While the aforementioned radiation treatments for arteriosclerotic abnormalities have shown some promise, one significant drawback to known procedures is the inability to effectively localize the radio compounds in the targeted tissue. Furthermore, such radiation treatment is typically done after there has already been an interventional procedure conducted, such as balloon angioplasty or stent emplacement. Thus, such radiation is primarily used as a follow-up treatment and not an initial treatment of arteriosclerotic abnormalities.
While photodynamic therapy also has been proven to be effective in prevention of arteriosclerosis, photodynamic therapy in practice is extremely difficult to incorporate because an illuminating catheter must be delivered to the damaged arterial locations and even after the catheter has reached the site to be treated, normal blood flow through the arteries further complicates the ability to deliver an effective intensity of light to the targeted tissue.
Therefore, while photodynamic therapy and radiation treatment can potentially be effective, there is still a need for a non-interventional procedure for treatment of arteriosclerotic abnormalities which provides not only an initial screening or diagnosis, but also may be simultaneously used for actual treatment of the affected blood vessels to reduce and destroy plaque and prevent or eliminate restenosis.
The present invention provides a method for diagnosis, visualization and treatment for arteriosclerotic abnormalities. The method is non-invasive and can be utilized to remove arteriosclerotic plaque at any inter-arterial site in the body. This new modality of treatment can be directed at arteries which have had no previous surgical intervention, as well as those sites which have been previously treated such as by balloon angioplasty or stent emplacement.
The present invention makes use of porphyrin compounds complexed with various metals such as silver (Ag), aluminum (Al), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), gadolinium (Gd), indium (In), lutetium (Lu), magnesium (Mg), manganese (Mn), nickel (Ni), palladium (Pd), platinum (Pt), rhodium (Rh), ruthenium (Ru), scandium (Sc), silicon (Si), tin (Sn), titanium oxide (TiO), vanadium oxide (VO), ytterbium (Yb) and zinc (Zn). These complexes are generally categorized as metaloporphyrins meaning a porphyrin moiety having a chelated radioactive isotope of a metal atom. These metaloporphyrins are further processed so that the metal is in the form of a radioactive isotope. The resulting radioactive metaloporphyrins thereby constitute radiopharmaceuticals that can be intravenously introduced to the patient. The affinity of the smooth muscle cells and fibrous tissue (plaque) for porphyrins results in selective uptake of the radioactive metaloporphyrin, thereby effecting targeted delivery of therapeutic radiopharmaceuticals to plaque lesions. In the instance of elemental copper chelated by the porphyrin, the copper can be transformed to radioactive 67Cu. In this way, introduction of the metaloporphyrin radiopharmacuetical to the patient is an effective means of targeted or site-selective deliver of measured radiation therapy to the targeted arteriosclerotic tissue. Additionally, these metaloporphyrin complexes still provide the ability to simultaneously conduct fluorescence detection and phototherapy if desired. Also, the metaloporphyrins provide the ability for observation of the areas of plaque buildup through PET scanning (for example, through use of 64Cu) or SPECT scanning (for example, through use of 67Cu). Metaloporphyrins complexed with 67Cu, also provide a source of beta radiation for the selective destruction of plaque sites.
Accordingly, the method of the invention provides a non-invasive (non-surgical) procedure, and also provides various options for initial diagnosis and treatment of plaque buildup. The natural affinity of the proliferating tissues for the porphyrin compounds provides an effective means for delivering radiation to the affected tissue.

Method of using metaloporphyrins for treatment of arteriosclerotic lesions