An improved technique to more accurately calculate pore pressure of sedimentary rock due to subsurface fluid expansion. The technique is built upon a combination of known force balanced in situ loading limb mineralogical stress/strain relationships with locally variable unloading stress/strain relationships. In stress/strain space, the material properties governed loading limb is an upper limit for the many possible unloading limbs. A method for relating these different natural stress/strain paths and applying the correct path to calculate pore fluid pressure from in situ force balance is disclosed. This method preferably calibrated with in situ stress/strain data which allows for a lithologic sealing caprock to be identified and the locally prevailing in situ unloading limb stress/strain relationship to be estimated. The forced balance loading and unloading calibrations are applied to more accurately determine well casing depths using either wireline or real-time measured while drilling petrophysical data. Solidity (1.0--porsity) is the in situ strain parameter of choice which can be measured petrophysically in the borehole. Pore pressure is the fractions of the total external load which is borne by the fluids in the pore space of a sedimentary rock. The solid framework of a granular sedimentary rock bears the force balance remainder of the external confining load as effective stress. Loading and unloading power law linear stress/strain relationships are determined between effective stress and solidity for common sedimentary rocks.

1. Field of the Invention
The present invention relates to an improved method for determining the pressure of fluid contained in the sedimentary rock. A mineralogically general force balanced stress/strain--loading limb relationship is a starting point. This relationship is defined in U.S. Pat. No. 5,282,384 to Holbrook, assigned to the assignee of the present invention, and which is incorporated herein by reference, which discloses how to calculate sedimentary rock pore pressure when the effective stress load is either constant or increasing and also teaches how the minimum principal stress and fracture pressure also can be calculated from in situ strain data in Normal Fault Regime .about.biaxial basins. Fracture pressure and pore fluid pressure are the safe force balance borehole fluid pressure limits for drilling the uncased (open to the surface) portion of a borehole into the subsurface.
Well after these loading limb open borehole force balance relationships were disclosed in the prior Holbrook patent, an extended set of force balanced Earth in situ stress/strain inter-relationships was discovered. These Earth in situ force balance inter-relationships can be applied to further improve the drilling decision making process. This newly discovered Earth in situ force balance inter-relationship, led to a direct force balance means of determining the physical location and pressure upper limit of fluid expansion generated port fluid pressure. The methods discovered in this invention produce further valuable geological information from in situ petrophysical measurements which is useful in the hydrocarbon recovery industry.
2. Background
Pore fluid pressure and fracture pressure are the most important external geologic factors affecting the safety and cost of drilling of an oil well. Exceeding either in situ force balance limit in an open borehole frequently leads to dangerous and usually costly well control problems. The borehole fluid hydrostatic pressure (Pb) must be greater than the formation pore fluid pressure (Pp) if one is to avoid the risk of a possibly catastrophic blowout. Likewise, the borehole fluid circulating pressure must be less than the fracture propagation pressure (Pf) if one is to avoid the risk of lost circulation.
Several expensive casing strings are usually requires so that an oil well can be drilled within the limits of the open borehole pore fluid pressure and fracture propagation pressure limits. Great savings would be realized during well planning if one or more casing string could be eliminated through better pore pressure and fracture pressure knowledge. The present invention also enhances the safety of oil or gas well drilling operations. Presently, a considerable portion of expensive rig time is spent in a remedial fashion dealing with unexpected pore pressure and fracture pressure problems encountered while drilling. The improved information from this invention should significantly reduce drilling operations costs by reducing the number of these dangerous situations.
Because of the critical relationship to drilling operations, there are numerous techniques for calculating pore fluid pressure. All known petrophysical prior art methods calculate pore fluid pressure indirectly based upon measured rock properties. Most of these methods follow a calibration procedure which is not based on mechanical or physical information. Instead, these calibration procedures are generally based upon the extension of an observed empirical relationship between a measured physical parameter and a "normal" or hydrostatic compaction trend. The empirical "normal" trend line (Pn) is the average value of the measured parameter which changes as a function of depth.
The change in the measured parameter (Pn) as a function of depth according to these prior art techniques is indirectly related to a change in compaction of the sedimentary rock. The measured parameter described in a pressure prediction technique is usually not compactional strain. The method operator in charge of pore pressure prediction must then decide whether the extrapolated "normal" compaction vs. depth trend line being used is correct or not using some non-physical interpretive basis. Direct empirical (i.e. non-physical) relationships have been the only pore pressure prediction techniques used by the oil industry until very recently.
Sedimentary rocks are compacted by the effective stress applied to their grain matrix framework. When fluid pressure is approximately hydrostatic and the overburden is gradually increasing, both depth and effective stress are increasing. Under these conditions, depth behaves as a pseudo-stress variable. However, when the pore pressure is elevated, effective stress and overburden gradients can be either increasing or decreasing and depth is not a pseudo-stress variable.
Most of the prior art methods for determining pore fluid pressure use depth as a pseudo-stress variable in both "normal" and "excess" pressured intervals which results in significant pore pressure calculation errors. The potential for this error when using a non-physical velocity-depth trend line method will be illustrated later in reference to the patents to Kan et al.
Another significant failing of most prior art pore pressure calculation techniques is attributable to their basic formulation. According to prior art depth trend techniques, pore pressure (Pp) is calculated as a sum of "normal" hydrostatic fluid pressure which is inferred from an extended compaction-depth trend; plus a differential or "excess" fluid pressure (.DELTA.P) which is related to a measured difference from the "normal" trend. The (.DELTA.P) calibration or correction term is back calculated after the fact from measured pore pressures in a nearby well or group of wells within a local area. The equation expressing this non-physical local calibration relationship is: EQU Pp=Pn+.DELTA.P (1)
where Pp is the pressure of fluid in the pore space of rock, Pn is the empirical calculation of the normal pressure trend line and .DELTA.P is the difference in pressure from the normal pressure trend line.
Equation (1) is not a physically representative mathematical formulation. Pascal's Principal requires that all of the fluids in a given local pore space or container be at the same pressure. Physically speaking, "excess" pressure cannot and does not exist in a pore space. Since the "excess" pressure term (.DELTA.P) does not exist in nature, "excess" pressure cannot be physically related to any measured parameter. Calibrating a measured physical parameter to a quantity which does not exist, i.e. (.DELTA.P), has been an acceptable engineering shortcut for a long time. The penalty when applying this (Pp=Pn+.DELTA.P) shortcut method is that the results are specific to the calibration area and the fluid pressurization mechanism in that particular field or reservoir. "Normal compaction trend" operators usually do not know the fluid pressurization mechanism, nor can they change their procedure to account for the mechanism. The (.DELTA.P) calibration is fundamentally non-physical and not related to the known loading and unloading stress/strain relationships of sedimentary rocks. As these stress/strain relationships are so different, there is great risk in mis-applying an empirical (Pp=Pn+.DELTA.P) relationship which contain no means of determining stress paths.
U.S. Pat. No. 5,081,612 to Scott et al discloses a method for determining formation pore pressure from remotely sensed seismic data. This particular method depends upon a hydrostatically compacted reference velocity vs. depth (Pn) profile. Referring back to Equation (1), this profile is essentially an observed or inferred curved (Pn) velocity gradient. The Scott et al pore pressure gradient technique applies to shale, which is also common to most of the prior art methods using a (Pp=Pn+.DELTA.P) formulation. Pore pressures are calculated with respect to the reference velocity vs. depth trend line which is an indirect violation of Pascal's Principle.
In U.S. Pat. Nos. 5,130,949 and 5,233,568 to Kan et al, like U.S. Pat. No. 5,081,612 to Scott et al, the basic pore pressure prediction method is also based upon a velocity vs. depth compaction trend line. Kan et al's FIG. 5 demonstrates the historically common but physically incorrect (Pp=Pn+.DELTA.P) methodology. The normal compaction trend line interpreted from the hydrostatic zone is shown in FIGS. 5b and 5d. The lowest hydrostatically compacted data point is slightly above 5,000 feet. The extrapolated (Pn) interval transit time-depth trend line decreases by half continuously every 8,000 feet on the logarithmic transit time scale shown.
The extrapolated empirical (Pn) shale transit time-depth trend line is beyond any possible physical reality at 8,000 feet or essentially 3,000 feet into the overpressured zone. Shales can compact no further than zero porosity which corresponds to a transit time of about 90 microseconds/foot. In regions that are more nearly hydrostatic than the example shown in reproduced FIG. 5, the 90 microseconds/foot shale transit time limit is not reached at depths above 20,000 feet.
The calibration within the (Pn) hydrostatic zone above 5,000 feet is reasonable. The projection to 90 microseconds/foot 3,000 feet below top of overpressure is physically unreasonable. Quartz is the most compaction resistant sedimentary mineral. The extrapolated (Pn) trend passes the zero porosity quartz transit time of 56 microseconds/foot at about 14,000 feet. The transit time of the Mohorovic discontinuity below the base of the Earth's crust is about 37 microseconds/foot. The (Pn) trend line is 37 microseconds/foot at 19,000 feet and continues to increase below. The actual depth of the base of the crust is about 100,000 feet on average, not 19,000 feet which is extrapolated from the interpreted normal shale compaction (Pn) depth trend of FIG. 5 of Kan et al.
The extrapolated (Pn) trend is grossly off compared to known transit time limits below the hydrostatic zone. Applying the (Pp=Pn+.DELTA.P) methodology the known error in the projected (Pn) depth trend is forced into the (.DELTA.P) term which is calculated by difference. Thus, the physically unreasonable (Pn) trend is automatically compensated for by the physically invalid (Pn+.DELTA.P) formulation relied upon for calibration. In fact any combination of (Pn+.DELTA.P) is forced to the correct answer by the measured pore pressure (Pp) in a calibration well. It takes two equal and opposite wrongs; one physically unrealistic (Pn), and one physically invalid (.DELTA.P) to make a right (Pp). Whenever the extrapolated (Pp=Pn+.DELTA.P) trend line methodology is reported to have been successfully applied; it signifies only that a force balance (.DELTA.P) correction has been applied to a frequently erroneous extrapolated (Pn) trend line.
All of the extrapolated (Pp=Pn+.DELTA.P) trend line methods suffer from the same non-physical (Pn) extrapolation which is transparent to the operator after the local calibration is made. The calibrations have only local applicability because you get a different extrapolated (Pn) trend depending upon where the base of the hydrostatically compacted depth interval occurs. In any particular area many other physical factors, for example overburden gradient, that exist affect the empirical calibration at that depth but are not accounted for in the empirical short cut methodology.
There are at least three (3) prior art methods for determining pore fluid pressure from petrophysical measurements which are based upon the effective stress law. A one-dimensional gravitational force balance was elucidated by Terzaghi, in his 1941 article entitled "Undisturbed Clay Samples and Undisturbed Clays", discussing compaction studies of marine sediments. Terzaghi first presented this uniaxial force balance equation; EQU Pp=S.sub.v .sigma..sub.v (2)
This relationship states that the fluid pressure in the pore space (Pp) can be calculated as the difference between the overburden load (Sv) and the vertical load borne by the sediment grain--grain contacts (.sigma..sub.v). In the science of rock and soil mechanics, this (.sigma..sub.v) term is known as the effective vertical stress.
U.S. Pat. No. 5,200,929 to Bowers is based upon in situ empirically determined velocity vs. calculated effective stress relationships. It uses the Terzaghi uniaxial Equation (2) to calculate effective stress. In NFR .about.biaxial basins the uniaxial calibration is coincidentally related to average effective stress force balance which directly causes the observed sediment compaction. This method accounts for both the loading and unloading stress/strain relationships of sedimentary rocks. The method is intended for use only in velocity reversal zones where fluid expansion unloading is the known fluid pressurization mechanism. The method is dependent only on velocity measurements which are indirectly related to strain and lithology.
The Bowers method is a significant technical advance because it uses a uniaxial approximate measure of effective stress and for its recognition of stress/strain hysteresis in sedimentary rocks. However, like the previously described pore pressure methods, the Bowers method also depends upon local empirical--velocity calibration to determine the coefficients for all its calibration and pore pressure predication relationships.
Using in situ velocity vs. effective stress data for shales only, Bowers describes a method for defining the shape of loading and unloading effective stress--shale acoustic velocity curves. His "virgin curve relationship" is portrayed as the solid line on Bower's FIG. 4. This curve corresponds to a loading limb stress/strain relationship with shale velocity being the indirect measure of strain.
At present the shale velocity--strain relationship is still poorly known. The velocity of an individual shale sample varies by up to 25% depending on whether the measurement is made parallel or perpendicular to bedding, as discussed in a 1994 article by Sayers, entitled "The Elastic Anisotrophy of Shales". An in situ measurement of velocity on shales with identical strain would produce very different pore pressure answers depending on the formation dip at the measurement location.
FIG. 4 of the Bowers patent shows how the extension of local empirical velocity loading limb and unloading limb relationships intersect. The position of this intersection point in both depth and effective stress space has a major impact on the value of the unloading limb calculated pore pressure. The data from both loading and unloading limbs must be known and their curving functions determined through interpolation before their intersection point can be determined by extrapolation. No other means for establishing the onset of unloading limb pore pressure is revealed by Bowers. If this method were to be applied with real-time Measurement-While-Drilling data, one would not have a criterion to determine where and when to switch from loading to unloading stress--velocity relationships.
U K Patent No. 2,174,210A to Fitzgerald reveals a common misunderstanding with respect to the interpretation of laboratory vs. in situ stress/stain relationships. Fitzgerald's method is based upon two (2) linear acoustic velocity vs. stress relationships observed in two (2) shales in a laboratory. Virtually all observed laboratory stress/strain relationships occur along the dominantly elastic unloading-reloading stress path of a rock sample. These rock specific stress paths intersect a mineralogy specific loading limb stress path at the point of maximum effective stress loading. There is no clear indication apparent during laboratory experiments on relatively hard rocks when or where the hysteresis join point is reached. The slopes of the initial loading vs. unloading-reloading limbs are very different.
Fitzgerald's patent indicates a lack of awareness of stress/strain hysteresis in sedimentary rocks and makes calculations based only upon the unloading-reloading stress path. In Fitzgerald, the key rock description qualifier "known constitution" is entirely appropriate and correct. For this method to operate as described a huge catalog of "known constituent" sedimentary rocks would have to be provided to appropriately match stress paths. Only two (2) rock stress paths are described. Fitzgerald describes (3) empirical stress path coefficients which would need to be established to have a predictive equation. These coefficients could not be established without the "known constituent" rock sample or in equivalent from a rock sample catalog. The Fitzgerald patent is operative only for the two (2) rocks described and could not be generalized into a general subsurface pore pressure predictive method.
U.S. Pat. No. 5,282,384 to Holbrook applies force balance for pore pressure prediction using a power law effective stress/strain compaction function. The key scientific elements to this methodology and approach are:
1. The use of the uniaxial Terzaghi force balance (Equation 2) in .about.biaxial Normal Fault Regime Basins. PA1 2. The correlation of effective stress to solidity (1.0-.phi., where .phi. is porosity) which is a direct measure of in situ strain for granular solids. One skilled in the art will recognize the substitution of the relationship (.phi./1.0-.phi.). PA1 3. The discovery through this application that both vertical effective stress and the effective horizontal/vertical stress ratio in .about.biaxial Normal Fault Regime basins are directly related to in situ strain in all lithologies and at all depths.
The direct stress/strain relationships are related to sedimentary rock mineralogy and expressed quantitatively as Equations 6, 7 and 8 in the Holbrook U.S. Pat. No. 5,282,384. These equations and empirical coefficients describe a complete three-dimensional grain and fluid force balance. Additionally, the equations in the patent explain why and how the uniaxial Terzaghi force balance works in .about.biaxial Normal Fault Regime basins where horizontal effective stresses are known to increase with depth. Further, lithologic and stress technical support for the patented method are described in articles by Holbrook in 1995, "the Relationship Between Porosity, Mineralogy, and Effective Stress in Granular Sedimentary Rocks", and 1996, "The Use of Petrophysical Date for Well Planning, Drilling Safety and Efficiency" and "A Simple Closed Force Balanced Solution for Pore Pressure, Overburden, and the Principal Effective Stress in the Earth".
There are severe calibration problems with all of the (Pp=Pn+.DELTA.P) prior art empirical pore pressure prediction methodologies described above. Most of the prior art acoustic pore pressure prediction methodologies use the same non-physical relationship (Equation 1) and suffer the same general pore pressure calibration-prediction problems. The calibrations for all these methods, even including Bowers' (Equation 2) empirical effective stress-velocity relationships apply only locally. The fundamental problem with all the other prior art methods is that of the unspecified relationships between stress and strain. Holbrook (Equation 2) is the only prior art pore pressure method which embodies a direct physical in situ stress/strain calibration basis.
Articles by Ward et al in 1994, "The Application of Petrophysical Data to Improved Pore and Fracture Pressure Determination in North Sea Graben HPHT Wells", and 1995, "Evidence for Sedimentary Unloading caused by Fluid Expansion Overpressure-generating Mechanics", point out evidence for fluid expansion generated fluid overpressuring which was directly related to in situ measurable strain (solidity). The unloading limb stress/strain (solidity) data plotted in a very different areas are in general agreement with Bowers' "virgin curve" vs. unloading velocity data. Ward et al's FIG. 2 from their 1994 article illustrates the similarities, differences, advantages and implementation problems associated with applying unloading stress/strain relationships to the problem of pore pressure determination.
The Ward et al FIG. 2 loading and unloading limb relationships are power law linear stress/strain functions. The major significant advantages of this over the Bowers calibration are that: 1) effective stress is directly related to in situ strain; and 2) the power law function is linear, not curved, which makes calibration, interpolation and extrapolation much more simple and reliable. FIG. 4 of Bowers and FIG. 2 of Ward et al are geometrically similar. Bowers' shale velocity curves would approximate Ward et al's power law linear stress/strain functions if the appropriate material properties transformations were made. The interpretation calibration step and the pore pressure prediction step are much easier to accomplish and more accurate when using the force balanced power law linear relationships.
Ward et al points out in their FIG. 3 that there are many possible unloading stress/strain relationships related to the loading limb relationship depending on the last peak effective stress loading. The interpretive definition of this loading limb intersection point is a critical problem here as it was in the Bowers' methodology.
Ward et al, in the 1994 article, made some observations which are illustrated as FIGS. 3 and 4 which are coincidentally related to a physical rock properties means of determining the loading vs. fluid expansion unloading intersection point in the subsurface. The depth range of a low porosity vertical seal is shown on the FIG. 3 geologic cross section. Pore fluid pressure gradient as indicated by the heavy curved lines on the figure increases dramatically somewhere within the low porosity seal zone. The onset of fluid expansion unloading probably occurs somewhere in the low porosity seal zone which can be recognized from petrophysical measurements. This relationship is discerned mainly by inference form the markedly different observed pressure gradients above and below the low porosity seal zone. Low porosity is a property of the seal zone, but it does not capture or qualify the actual pressure seal relationship.
Ward et al's 1994 article FIG. 5 is a generalized pressure profile showing the relationships between disequilibrium compaction fluid pressurization mechanisms and fluid expansion pressurization mechanisms. The low porosity vertical seal within the chalk is also shown in this diagram. Supporting this circumstantial evidence are the calculations of which indicated that a very low permeability seal is needed for the fluid expansion pressurization mechanism to be operative.
Gaarenstroom et al, in a 1993 article entitled "Overpressures in the Central North Sea: Implications for Trap Integrity and Drilling Safety", also demonstrate a reasonable partial understanding of the relationships that govern pore fluid pressure in the subsurface. Gaarenstroom et al relate trap integrity to formation strength. While a certain minimum formation strength is required, it is not strength that is regulating the compartment pressure. Very weak shales, salt, as well as very strong impermeable quartzites have very different strengths. All these different strength lithologies can equally well accomplish the job of sealing a pressure compartment as long as they have sufficiently low intergranular permeability.
FIGS. 3 and 4 of the Ward et al 1994 article show the transition between loading and unloading limb stress/strain relationships is related to a low porosity zone within the North Sea chalk interval. The transition between effective stress loading and unloading occurs in this zone. The zone definition is broad and general and does not specify the sealing mechanism or exactly where the seal is located within the low porosity zone. The difference between Ward et al's description and the present invention is that low porosity is coincident with, but is not equal to high fracture pressure. A low porosity rock will have different fracture pressures which also depend upon vertical effective stress and pore pressure. Fracture pressure is the actual force that holds the in situ Compartment Pressure Limit Valve closed.
Ward et al and Gaarenstroom et al have identified two (2) different factors, strength and low porosity which are coincidentally related to fracture pressure under special circumstances. Methods related to these parameters should work in a relative sense under the particular geologic situation they describe. The distinction made here is that when fracture pressure is used as the discrimination parameter, the method works in general because of force balance regardless of these other circumstances.
The relationships described by Gaarenstroom et al, Bowers and Ward et al indicate that they have a general understanding of the factors coincidentally related to the occurrence of pressure compartments, and loading vs. unloading stress/strain relationships. The caprock seal required for unloading can be recognized as a relative porosity low within a sequence as described by Ward et al. Porosity provides a means for recognizing a compartment pressure seal under the specified average regional conditions. But porosity does not provide the means for quantifying the caprock's pressure sealing capacity which controls the pore pressure below.
Seal pressure capacity is the truly important aspect of pore pressure forecasting ahead of the bit. Gaarenstroom et al describe rock strength relationship is likewise a related seal recognition criteria which lacks the means for seal capacity quantification. The solution to these problems lies in the seal mechanism which is not identified in the prior art.

Method for determining sedimentary rock pore pressure caused by effective stress unloading


The anode for a capacitor has a flat anode conductor with a large-area connection to an anode body. That end of the anode conductor which leads out of the anode body is bent to form a terminal connector. Three different processes for working with a paste, a green film, and a powder are proposed for the production of the anode body.

The present invention relates to an anode for electrolytic capacitors, having an anode body and an anode conductor. The invention also relates to an electrolytic capacitor provided with the anode, a dielectric surrounding the anode, a layered cathode provided on the dielectric, a first terminal connector formed from the anode conductor and a second terminal connector which is connected to the layered cathode. The present invention furthermore relates to processes for producing the anode.
In its preferred implementation, the capacitor is a chip capacitor. However, the present invention can also readily be applied to other capacitors, such as for example, capacitors without housings. A capacitor without a housing is of low structural height and is integrated, for example, in a hybrid circuit. However, the following text assumes that the capacitor according to the invention is a chip capacitor. Chip capacitors, in particular tantalum chip capacitors, are distinguished by a high volume-specific capacitance-voltage product, also known as the xe2x80x9cCV product.xe2x80x9d This means that in these capacitors the value of the volume-related product of capacitance and voltage which can be applied to the capacitor is particularly high. Further advantageous properties of chip capacitors include a stable thermal behavior and frequency response, a low residual current and a small loss factor.
Due to these excellent properties, in particular tantalum chip capacitors are used for numerous applications in a very wide range of fields. New applications, demanding conditions of use and an increasing tendency toward miniaturization in electronics mean that the demands imposed on chip capacitors are becoming ever greater.
A pertinent prior art assembly is illustrated in FIGS. 24-26. FIG. 24 shows a diagrammatic section through the structure of a conventional tantalum chip capacitor. FIG. 25 shows a side view of the anode body of that chip capacitor, and FIG. 26 is a plan view of the anode body.
The prior art chip capacitor comprises an anode body 1, a dielectric 2, and a layered cathode 3, which form an actual capacitor element.
In addition, there is a housing 4 which is responsible for important protective functions for the capacitor element.
A tantalum wire 5, which in the interior of the housing 4 is connected to a first metal connector 6. The wire 5 leads to the capacitor element comprising the anode body 1, the dielectric 2, and the layered cathode 3. By means of a conductive adhesive 8, the layered cathode 3 is connected to a second metal connector 7. The second metal connector 7, similarly to the metal connector 6, leads out of the housing 4.
Chip capacitors of this nature are produced in different sizes of housing 4, usually with standardized basic surface area dimensions and structural heights. Consequently, if a higher CV product is to be achieved, the volume taken up by the capacitor element or the anode body 1 contained therein must be increased.
Owing to the use of the tantalum wire 5 in the anode body 1 (in this respect see, in particular, FIGS. 25 and 26) as the anode-side conductor, the utilization of the housing can scarcely be increased further. This is because the free end of the tantalum wire 5 is welded to the metal connector 6 which, in the finished chip capacitor, is intended to provide electrical connection to an electronic circuit on a printed circuit board, together with the other metal connector. In a design of this nature, the distance between the capacitor element and the housing wall is particularly great especially on the positive side. The distance between the positive metal connector 6 and the capacitor element or the anode body 1, which is formed by the tantalum wire 5, can scarcely be reduced further, for manufacturing reasons. In other words, the volume of the housing is only insufficiently utilized in the prior art chip capacitor.
East German Patent DD 215 420 discloses a tantalum chip capacitor in which an anode conductor is embedded in a two-part anode body produced by extrusion. That anode body and anode conductor preassembly is then sintered. The use of two pre-extruded partial anode bodies has the drawback that it is impossible to achieve an exact form fit between the anode body and the anode conductor, owing to manufacturing tolerances. Consequently, the electrical contact between the anode body and the anode conductor is impaired.
German published patent application DE 36 34 103 A1 discloses a tantalum capacitor in which a tantalum powder is pressed around a wire anode conductor. That capacitor has the drawback of a small contact area between the wire anode conductor and the anode body. The result is an increased resistance in the capacitor which may have an adverse effect on the electrical characteristics of the capacitor. This is an undesirable effect.
U.S. Pat. No. 3,903,589 discloses a tantalum capacitor, the anode of which is produced by immersing the anode conductor in a dispersion containing metal powder. When the anode conductor is pulled out of the dispersion, a drop remains hanging from the anode conductor, which is then dried and sintered. That tantalum capacitor has the drawback that the anode body cannot be produced with a defined geometry. Because of the absence of an optimized anode geometry and the broad tolerances, that prior art capacitor is subject to poor volume utilization.
The object of the invention is to provide an anode which overcomes the above-noted deficiencies and disadvantages of the prior art devices and methods of this kind, and which has a large contact area between the anode conductor and the anode body, the anode body of which is of fixedly predetermined shape, and in which there is good electrical contact between the anode body and the anode conductor.
With the above and other objects in view there is provided, in accordance with the invention, an anode for an electrolytic capacitor, comprising:
a flat anode conductor; and
an anode body of a continuously deformable material molded onto the anode conductor and solidified into a fixedly predetermined shape.
In other words, the anode has an anode body of fixedly predetermined shape and a flat anode conductor. The anode body is molded onto the anode conductor from a continuously deformable material which can be solidified.
There is also provided, in accordance with the invention, a capacitor, comprising:
the anode according to the above summary, wherein a second end segment of the anode conductor is shaped into a first terminal connector;
a dielectric enclosing the anode body; and
a layered cathode disposed on the dielectric and connected to a second terminal connector.
In other words, the anode body of the capacitor is surrounded by a dielectric, and a layered cathode is provided on the dielectric. A further end section of the anode conductor is shaped into a first terminal connector and the layered cathode is connected to a second terminal connector.
The anode according to the invention has the advantage that as a result of the entire anode body being molded onto the anode conductor in the form of a continuously deformable material, it is possible to form a homogeneous anode body which exhibits a good form fit with the anode conductor and good electrical contact with the anode conductor.
Furthermore, the anode according to the invention has the advantage that, as a result of the anode body being shaped with the aid of a continuously deformable material, it is possible to achieve any desired shape with the aid of suitable molds which are removed before or after solidification of the anode body. The material from which the anode body is formed may, for example, be a paste containing metal powder, a green film produced from the paste, or a suitable metal powder itself.
Due to the flat design of the anode conductor which is sintered into the anode body made from sintered tantalum powder, for example, a larger contact area between anode conductor and anode body is achieved compared with a sintered-in tantalum wire of the same cross-sectional area. The number of powder particles which are in contact with the surface of the anode conductor is increased, and consequently the mean length of the current paths between the dielectric and the anode conductor, which comprise tantalum particles which have been sintered together, is reduced. Consequently, it is possible to achieve reduced resistances and an increased capacitance at high frequencies.
Moreover, the use of a flat anode conductor in the anode body reduces the risk of local overheating at the transitions between the anode conductor and a fine network formed by the sintered tantalum particles when current is flowing. This is because higher current densities occur at these transitions than in the adjoining network. Local overheating of this type may be a cause of chip capacitors being suddenly and dramatically eroded.
The primary feature of the capacitor or anode according to the invention is in particular the production of a strong, large-area connection between the anode body, comprising an open-pored sintered body which forms the capacitance, and an anode conductor with a large surface area. For all these components, it is preferable to use tantalum or another suitable metal, such as niobium or a material which allows a layer with a high dielectric constant to be formed.
Furthermore, an anode in which the anode body completely surrounds an end section of the anode conductor is advantageous. In this way, it is possible to achieve optimum utilization or the surface area of the anode conductor for contact with the anode body. Furthermore, high mechanical stability of the anode is ensured in this way.
Furthermore, the invention also encompasses a method of producing an anode for a capacitor. The method comprises the following steps: molding a continuously deformable material onto a flat anode conductor and simultaneously externally shaping the material, and solidifying the material to form an anode body.
In a preferred embodiment of the method, the molding step comprises applying a paste of a binder system and a powder to the flat anode conductor, and the solidifying step comprises subsequently drying and sintering the paste.
In other words, the anode is produced by molding continuously deformable material, which can be solidified, onto a flat anode conductor with simultaneous external shaping, and is then solidified to form an anode body. The simultaneous molding of the material onto the anode conductor and the defining of the external shape of the anode body with the aid of a continuously deformable material obviates the need for complex post-machining processes for shaping the anode body.
A process in which a paste which contains a binder system and a powder is applied to the anode conductor and is then dried and sintered is particularly advantageous. In this process, the paste may be combined with the anode conductor to form an anode by means of various methods. By way of example, it is possible to use a paste which is known from document DE 199 27 909 A1 and which comprises a discrete phase containing a metal powder and a continuous phase containing organic compounds.
The capacitor according to the invention can be used as an SMD (SMD=Surface Mounted Device). The use of a paste simplifies the processing of high capacitance and ultra-high capacitance tantalum powders.
Furthermore, the invention provides a process for producing the anode according to the invention, in which a powder is pressed around a flat anode conductor, with the anode conductor projecting on one side. Then, the compact is sintered. The method according to the invention may advantageously be carried out in such a way that an anode conductor in the form of a strip-like metal sheet is pushed into a bed of the powder which is situated in a press mold, and then the pressing operation takes place.
The material tantalum which is preferably used for the anode conductor is extremely expensive, and consequently the strip used for the process should be as thin as possible. Conversely, the tantalum sheet used must be sufficiently mechanically stable to be able to be pushed into the powder bed and subsequently bent into a mechanically stable connector. Within these boundary conditions, strip-like anode conductors with a width of between 0.3 and 5 mm and a thickness of between 50 and 150 xcexcm have proven suitable. These anode conductors have a width/thickness ratio of between 2 and 100.
The pressing of the powder may particularly advantageously be carried out by transverse pressing, that is to say by pressing transversely with respect to the direction in which the strip-like anode conductor extends.
The further manufacturing steps correspond to the steps used for the conventional manufacture of tantalum chip capacitors. Therefore, in the procedure known as forming, the dielectric is formed from tantalum pentoxide on the inner and outer surfaces of the sintered anode body. After the cathode layers have been applied, cathode terminal and housing are produced. In the configuration according to the invention, the anode connector made from tantalum, which is used as the positive electrical terminal, may undergo further treatment in order to be made suitable for soldering or adhesive bonding, and this statement also applies to the other exemplary embodiments.
As a modification to the above design according to the invention of the tantalum chip capacitor, the tantalum powder is also mixed with an additive which, due to its lubricating action, makes the pressing operation easier and more gentle on the press mold. The flow properties of the powder and the mechanical stability of the compact are also improved by the binding action of the additive. Camphor is a standard additive. Before the compact is sintered, the additive should be removed as far as possible without leaving any residues.
As an alternative to tantalum, it is also possible to use other suitable metals, such as for example niobium, or alloys of suitable metals, or other materials which are capable of forming a dielectric.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in an anode for electrolytic capacitors, electrolytic capacitor, and a process for producing the anode, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

Anode for electrolytic capacitors, electrolytic capacitor, and method of producing the anode


A target detection apparatus that includes a transmission/reception device for generating a transmission signal for detection of a target, and extracting distance information about the target from a received signal; a number of sensors each of which transmits the transmission signal to respective different angle ranges, receives a signal reflected by the target, and transfers the received signal to the transmission/reception device; and a switch device for switching in a time division manner a connection between the transmission/reception device and one of the sensors to a connection between the transmission/reception device and another one of the sensors, where the switch device selects a first of the sensors for transmitting the transmission signal in a time slot and a second of the sensors for receiving the signal reflected by the target in the time slot.

1. Field of the Invention
The present invention relates to an apparatus and a system for detecting a target such as a person, an animal, an object, etc. intruding into a monitor area.
2. Description of the Related Art
There have conventionally been a camera, a laser device, a monopulse radar device, etc. for detecting any number of targets T intruding into a predetermined monitor area as shown in FIG. 1A. The position of a target T is expressed by, for example, (x, y) in the Cartesian coordinate system (orthogonal coordinate system), and (r, θ) in the polar coordinate system.
However, since the detection device of an optical system such as a laser device, etc. has normally a very narrow beam width, a number of detection devices have to be provided as shown in FIG. 1B to detect a plurality of targets although it is capable of pinpointing a target. In the example shown in FIG. 1B, six laser devices 11 through 16 are provided around the monitor area to detect targets T1 and T2 by radiating laser light among the devices.
Although a detection device provided with a scanning mechanism is used, the detecting capability is considerably reduced by the dirty optical parts due to a spider's web, dust, etc. in an exposure environment especially at an intersection, a crossing, etc. Therefore, frequent maintenance is required. Furthermore, a change in the optical characteristic of a peripheral environment depending on the time can be a serious problem in guaranteeing the performance.
On the other hand, the detection device of a radio system such as a radar device, etc. is advantageous in resistance to environment, but there is the problem in performance because a target is to be localized normally as a point in the polar coordinate system. For example, a monopulse radar device has a relatively wide angle measurement range per device, but only obtains the angle of a single target. A radar device having an array antenna can calculate the angles of a plurality of targets, but is a narrow angle measurement range per device, and requires a large signal processing cost.
There is also a method of measuring only the sight line distance information about a target simply using a plurality of radar devices, solving a set of equations of circles according to the obtained information, and calculating the position of a target in the orthogonal coordinate system. When a target is uniquely localized by the triangulation only according to the distance information, it is necessary to mount a detection device having the angle measurement range of π/2 (90°) at three different points around the monitor area as shown in, for example, FIG. 1C when the monitor area is rectangular. Therefore, at least three detection devices are required.
In the example shown in FIG. 1C, detection devices 21 through 23 are mounted at the tree vertexes of the monitor area, and the positions of the targets T1 and T2 are identified by the triangulation. The targets T1 and T2 are located on the following arcs when viewed from each of the detection devices.                1. detection device 21 T1: arc 24 T2: arc 25        2. detection device 22 T1: arc 26 T2: arc 27        3. detection device 23 T1: arc 28 T2: arc 29
However, since the angle measurement range for a current monopulse radar device is at most π/6(30°), it is necessary to constitute each detection device by three radar devices to uniquely localize a plurality of targets with the above-mentioned configuration, thereby requiring a total of nine or more radar devices.
The following patent document 1 relates to a method of detecting an object to be monitored using the radar of a spread-spectrum system.                [Patent Document 1] Japanese Published Patent Application No. H9-257919
However, the above-mentioned conventional target detection apparatus has the following problems.    (1) A detection device of an optical system such as a laser device, etc. is subject to an influence of an ambient environment, and it is difficult to guarantee the performance when it is mounted outdoors. Additionally, it is necessary to mount a number of detection devices to detect a plurality of targets.    (2) There is a rule that one monopulse radar device detects one target. Therefore, to detect a large number of targets and localize each target according to angle information and distance information, it is necessary to mount the number of radar devices equal to the number of targets. In addition, there is a method of arranging each set of three monopulse radar devices at each of the three points around the monitor area, and calculating the position of a target by the triangulation only according to the distance information. However, since the parts constituting a radar device are expensive, it is desired to realize an angle measurement in a wide range using the smallest possible number of devices.
Therefore, to reduce the number of radar devices, for example, as shown in FIG. 1D, the detection devices 31 and 32 each including three radar devices are mounted at two points, and it is checked whether or not targets can be localized with the configuration. The true targets T1 and T2 are located on the following arcs when viewed from each of the detection devices.                1. detection device 31 T1: arc 41 T2: arc 42        2. detection device 32 T1: arc 43 T2: arc 44
Assuming that the distances from the detection device 31 to T1 and T2 are respectively r11 and r12, and the distances from the detection device 32 to T1 and T2 are respectively r21 and r22, the coordinates of each target is determined by the simple simultaneous equations of circles by pairing with correct measured distance such as T1(r11, r21) and T2(r12, r22), etc. However, the coordinates of the virtual images 51 and 52 are calculated by wrong paring.
Assume that the result as shown in FIG. 1E is obtained by measuring the sight line distance of the targets T1 and T2 in this system. In FIG. 1E, the horizontal axis indicates a distance index, and the vertical axis indicates the power of a baseband signal. The baseband signal in the detection device 31 show two peaks 61 and 62, and the baseband signal in the detection device 32 show two peaks 63 and 64. The distance indexes corresponding to the positions of these peaks indicate the distances to the targets T1 and T2.
At this time, since the peak 63 or 64 can be combined with each of the peaks 61 and 62, there can be two combinations, and the coordinates of a total of four points can be obtained in the monitor area. That is, they are the coordinates of the targets T1 and T2, and the virtual images 51 and 52.
The number of solutions of the simultaneous equations of circles increases in proportion to the squared number of targets. Therefore, with an increasing number of targets for the two detection devices, a higher calculating cost is required to remove detection errors, and there immediately occurs a problem if the number of devices is reduced.    (3) When a large number of targets intrude into a monitor area, it is desired to localize the position of each target as a point in the orthogonal coordinate system or the polar coordinate system to correctly discriminate the targets. However, it is very difficult to perform the process of discriminating a number of targets in a predetermined time using only an autonomous position meter in the conventional detection device in an optical system or a radar system.


A communication system has an analog signal broadcasting station for transmitting an analog signal, a digital signal broadcasting station for transmitting a digital signal and a receiving unit for receiving the analog signal from the analog signal broadcasting station and the digital signal from the digital signal broadcasting station. The receiving unit has a recording and reproducing unit for selectively recording one of received analog and digital signals. The recording and reproducing unit has heads for analog signal each having a predetermined azimuth angle and operative to record an analog signal and heads for digital signal each having an azimuth angle larger than that of the analog signal head and operative to record a digital signal, and performs selective recording and reproduction of the analog signal and the digital signal on and from a recording medium.

The present invention relates to a communication system in which communication is carried out through a communication medium such as a coaxial cable, an optical cable, a telephone circuit or satellite broadcasting and an apparatus for recording and reproducing a signal communicated through the communication medium and more particularly, to a communication system for encrypted data and an apparatus for selectively recording and reproducing a received analog signal and a received digital signal.
A technique concerning a system for encryption and decryption of a video signal and an audio signal as well as fee charging is described in, for example, "Transactions The Institute of Television Engineers of Japan", Vol. 46, No. 1, January, 1992, pp. 31-39.
The above paper describes a technique concerning the system for encryption and decryption of a video signal and an audio signal as well as fee charging in satellite communication service. However, that paper fails to disclose method and technique which can store a received signal while protecting a copyright of the signal and can charge fees of decryption and storage of the signal.
A technique of selecting a digital signal or an analog signal and recording it on the same magnetic recording and reproducing apparatus is described in, for example, JP-A-5-207507.
Available for a domestic magnetic recording and reproducing apparatus (hereinafter referred to as VTR) are, for example, VHS, .beta. and 8 millimeter-VTR standards. In any of these standards, an analog television signal is FM modulated and then recorded. It is stipulated that an audio signal can also be FM modulated and recorded in accordance with each standard. An apparatus for multiplexing, recording and reproducing analog video and audio signals in this manner is disclosed in U.S Pat. No. 4,591,924.
When a television signal is FM modulated for analog recording, there arises a problem that the S/N ratio is inevitably deteriorated owing to recording and reproduction. To cope with this problem, the television signal is digitized and then recorded. For example, D-1, D-2 and D-3 standards prescribed by SMPTE are available. These standards are determined by taking the use for broadcasting into account and therefore, a tape cassette different from that used for the aforementioned domestic VTR is used under these standards.
The fact that quality of recording and reproduction is improved by recording and reproducing a digital signal is desirable but when user's merit is taken into consideration, it is preferable that the conventional analog signal be also recorded and reproduced. In other words, exchangeable reproduction of analog and digital signals must be taken into account.
This requires that at least the shape of a cassette to be used be the same for analog and digital signals and the tape transport system be also the same for analog and digital signals. Further, by making the recording and reproducing head or at least the azimuth angle of the head identical for analog and digital signals, exchangeability can be facilitated and cost reduction can be ensured.
But it has been found that the above expedient faces a new problem. For example, when the digitally recorded cassette is inserted by mistake into the conventional analog VTR, the recorded digital signal is mistaken for an FM signal and is FM demodulated inadvertently. Especially when the FM demodulated signal is an audio signal, the demodulated audio signal has a large amplitude and so large a sound that possibly surprises persons involved and damages the apparatus is generated from a loudspeaker.
The aforementioned conventional technique fails to show what problem arises when the digitally recorded cassette is loaded on the conventional analog VTR. Needless to say, the conventional technique does not clarify how to solve the problem.

Apparatus for selectively recording and reproducing received analog and digital signals


A packet routing apparatus has a routing information table comprised of a plurality of sub-tables. Each sub-table includes an entry of a first format indicative of routing information, and at least one of the sub-tables includes, in addition to the entry of the first format, an entry of a second format for designating another sub-table to be referred to. A routing processor of the packet routing apparatus refers to a sub-table designated by an input line interface. As a result, when the entry of the second format is retrieved, the routing processor executes routing of an input packet and header conversion by referring to another sub-table designated by the entry.

(1) Field of the Invention
The present invention relates to a packet routing apparatus. More particularly, the invention relates to a packet routing apparatus suitable for relaying a variable length packet between lines of different communication protocols.
(2) Description of the Related Art
In an IP network using the TCP/IP protocol, various applications of electric mails, WWW (World Wide Web), and the like can be used. The IP network has advantages such as lower communication cost as compared with a conventional telephone-based switching network. Consequently, traffic has been being explosively increased in recent years.
A router disposed in each of nodes of an IP network determines the outgoing route of a received packet on the basis of the IP header of the packet. A software router is in the main stream of the conventional routers and the software router determines the outgoing route of a received packet by a CPU connected to an input/output line interface via a bus. To address an explosive increase in traffic, in recent years, a hardware router which increases the speed of packet transfer by analyzing the header of an IP packet by hardware is in the limelight. An example of the technique of analyzing the header by hardware is disclosed in Japanese Unexamined Patent Application No. 2000-151709.
One of transfer method for transmitting IP packets on an IP network adopts encapsulation of an IP packet with the header of a lower layer. For encapsulation of IP packets, connection-oriented protocols such as an ATM (Asynchronous Transfer Mode) communication, a frame relay of an HDLC, and PPP (Point to Point Protocol) are used. According to an MPLS (Multi-Protocol Label Switching) system examined by the IFTF (Internet Engineering Task Force), an IP packet is encapsulated by using a shim header including a label.
When IP packets are encapsulated with the header of a lower layer, multiplex transfer of IP packets can be realized between nodes. By reducing the number of destination indication bits, the transfer speed can be increased. When a connection-oriented packet transfer is performed in a lower layer, a closed network can be maintained. In this case, by using the function of the lower layer, a virtual private network (VPN) can be realized on an IP network.
As communication services such as frame relay and ATM are improved by major carriers, the configuration of an intracorporate communication network employing the frame relay communication or ATM communication for the lower layer and using the TCP/IP protocol in the upper layer is increasing.
In the case of realizing the VPN on the Internet, a node (hereinbelow, called an edge node) disposed at the entrance of a network (hereinbelow, called a core network) of an Internet service provider (ISP) for providing VPN services encapsulates IP packets. Each of nodes (hereinbelow, called core nodes) in the core network transfers a received packet in accordance with an encapsulation header. An edge node disposed at the exit of the core network removes the encapsulation header.

Packet routing apparatus and routing controller


Elastomeric sheeting materials are described which are formed from the process of (1) creating a membrane comprising a semi-interpenetrating polymer network ("IPN") of polytetrafluoroethylene ("PTFE") and polydimethylsiloxane ("PDMS") by causing a matrix of PDMS to be formed in situ with a matrix of PTFE; (2) causing a surface of substantially pure PDMS to be formed on at least one side thereof; (3) allowing said PDMS compositions to vulcanize; and (4) converting said structure into useful shapes suitable for application to anatomical areas of the body. The product of the process is suitable for the treatment of dermatologic scars, such as those associated with traumatic or surgical injuries of the skin. The pure PDMS layer provides desired therapeutic effects. The semi-IPN membrane provides improved physical integrity, durability, and elastic behavior in comparison to prior art. The combined structure has increased compliancy, a thinner profile, and improved patient comfort features in comparison to existing products.

1. Field of the invention
The present invention relates to the treatment of dermatologic scars, and more particularly concerns scar treatment sheeting and other articles, and a method of manufacture thereof.
2. Description of the Prior Art
Silicone chemistry has evolved since the early 1900's into a wide variety of systems used for industrial as well as medical applications. Medical grade silicones are usually based on thermoset dimethyl systems, whereby the molecular formula may be represented as follows: ##STR1##
A crosslinking agent is used to create bonds between the hydrogen atoms on the methyl groups of adjacent molecules. These silicone formulations are often supplied as a two(2) part system, wherein one part contains a catalyst for vulcanization and the other part contains the base resin and crosslinking agent. By varying the amount of crosslinking agent, the crosslink density may be adjusted to achieve desired bulk or surface qualities of the vulcanized elastomer. Physical strength and durability tend to increase, while softness and coefficient of friction decrease with higher crosslink densities. Materials with a high crosslink density are relatively slick and tough, but have poor compliancy or "drapability". Silicones with low crosslink densities give a soft gel with a more adhesive or "tacky" surface. These materials are more drapable, although they are inherently weak and tend to fragment easily with low levels of stress.
A number of U.S. Patents and other publications relate to the field of the invention, and are as follows:
______________________________________ U.S. PATENT DOCUMENTS ______________________________________ 4,832,009 5/23/89 Dillon 4,945,125 7/31/90 Dillon et al. 5,066,683 11/19/91 Dillon et al. 5,157,058 10/20/92 Dillon et al. ______________________________________

Semi-interpenetrating polymer network scar treatment sheeting, process of manufacture and useful articles thereof


An amplifier circuit includes first (7A) and second (7B) operational amplifiers connected in a parallel configuration. A first terminal (12) of a first input resistor (5) is coupled to one input of both of the first (7A) and second (7B) amplifiers. A first terminal (15) of a second input resistor (6) is coupled to another input of both of the first (7A) and second (7B) amplifiers. A differential input voltage is applied between the second terminals of the first and second input resistors. The output signals of the first (7A) and second (7B) operational amplifiers are combined to produce an output signal (11AB) representative of feedback currents produced in the first (5) and second (6) input resistors. Upper and lower common mode input voltage ranges associated with the differential input voltage extend substantially above and below the upper and lower supply voltages, respectively, of the amplifier circuit.

The present invention relates generally to instrumentation amplifiers, and more particularly to circuitry and techniques for providing accurate instrumentation amplifier operation in both positive and negative portions of a common mode input voltage range.
The closest prior art is believed to be the assignee's INA 168 positive common mode voltage instrumentation amplifier, a simplified diagram of which is shown in FIG. 1. Referring to FIG. 1, prior art instrumentation amplifier 1 has positive common mode voltage operation between a single supply voltage V+ and ground. Amplifier 1 includes an operational amplifier 7A having a (+) input coupled by a conductor 12 to one terminal of a precision input resistor 5, which may, for example, have a resistance Rin equal to 5 kilohms. The other terminal of resistor 5 is coupled by a conductor 2 to receive an input voltage Vin+ and also is connected to one terminal of a "sense" or "shunt" resistor RS, the other terminal of which is connected by a conductor 3 to one terminal of an external load 4, the other terminal of which is connected to ground. Shunt resistor RS has a very low resistance, typically 10 milliohms to 1 ohm, and a current IS flows through shunt resistor RS into load 4 in response to a positive value of Vin+. The current IS develops a small sense voltage across shunt resistor RS. Conductor 3 is connected to one terminal of another precision input resistor 6, which also has the same resistance Rin. The other terminal of resistor 6 is connected to the (−) input of operational amplifier 7A. Resistor 6 is precisely matched to resistor 5.
The output of operational amplifier 7A is connected by a conductor 10A to the base of an NPN transistor Q1, the emitter of which is connected by an output conductor 11A to one terminal of a load resistor RL, the other terminal of which is connected to ground. The collector of transistor Q1 is connected by conductor 12 to provide feedback to the (+) input of operational amplifier 7A. Positive common mode voltage instrumentation amplifier 1 thus precisely measures the voltage across shunt resistor RS and produces an output voltage Vout on output conductor 11A, where Vout=(IS)(RS)(RL)/Rin. Thus, Vout accurately represents the current IS supplied to load 4 by Vin+.
The voltage on either conductor 2 or conductor 3 of FIG. 1 can be considered to be the positive common mode voltage. The supply voltage V+ typically has a value in the range from a few volts up to approximately +18 volts. Vin+ can be any value from roughly 1.4 volts to roughly 60 or more volts. The feedback provided by transistor Q1 keeps the voltage difference between the (+) and (−) inputs of operational amplifier 7A at nearly zero, and the current Iin2 through resistor 6 and hence the resulting voltage drop across it, are essentially zero. Therefore, the voltage across resistor RS is equal to the voltage developed across 5 kilohm resistor 5. This voltage across resistor 5 produces a current Iin1 that flows through transistor Q1 and resistor RL.
The common mode voltage on conductor 3 must be positive, because amplifier 7A will turn transistor Q1 off, causing positive common mode voltage instrumentation amplifier 1 to be inoperative if Vin+ is below ground.
There are various applications of positive common mode voltage instrumentation amplifier 1 of prior art FIG. 1, including automotive applications in which both positive and negative transient voltages may occur. However, in such applications, positive common mode voltage instrumentation amplifier 1 may produce undesirable "glitches" in the output voltage Vout.
Thus, there is an unmet need for an instrumentation amplifier which has a wide common mode input voltage range in order to effectively reject a substantial range of both positive and negative transient input voltage spikes.
There also is an unmet need for an instrumentation amplifier which is operative through a wide common mode input voltage range including large-magnitude negative common mode input voltage values substantially lower than the negative supply voltage, and also including large-magnitude positive common mode input voltage values substantially greater than the positive supply voltage.

Current shunt instrumentation amplifier with extended bipolar input common mode range


Processes for isolating, amplifying, and characterizing DNA from biological materials are provided. DNA is isolated by contacting a biological material on a solid support which is preferably pre-treated with a lysing reagent. The isolation process is simple and efficient and provides a source of purified DNA without the use of harmful organic solvents such as urea and guanidine-based solvents. The purified DNA and remaining fractions of biological material may be characterized or amplified as necessary.

Nucleic acids such as DNA, are used extensively in the field of molecular biology for research and clinical analyses. Common methods for analyzing DNA are Southern blotting, amplification through methods such as polymerase chain reaction (PCR), and sequencing. Using these methods, differences in DNA sequence are determined to aid in gene identification, population screening, pathogen identification and diagnostic testing. All of these analyses require purified DNA samples as the basis for consistent and valid results.
There are numerous nucleic acid purification methods that fall into two general categories, liquid phase and solid phase purification. In liquid phase purification, the DNA remains in the liquid phase while impurities are removed by precipitation and/or centrifugation. In solid phase purification, the DNA is bound to a solid support while impurities are selectively eluted. Both purification strategies utilize conventional methods, which require many steps and often hazardous reagents, as well as more rapid methods, which require fewer steps and usually less hazardous reagents.
Using conventional liquid phase methods, DNA is most commonly isolated using density gradient centrifugation, organic solvent extraction, or salt precipitation. Protocols describing these purification methods are given in Sambrook et al., Molecular Cloning: A Laboratory Manual, 2nd ed., 7.19-7.25, 9.16-9.19, Cold Spring Harbor Press, Cold Spring Harbor, N.Y. (1989) and Ausubel, et al., Current Protocols in Molecular Biology, 4.4.2-4.4.4 (1987). Briefly stated, the liquid phase purification methods of density gradient centrifugation, phenol-chloroform extraction, and salt precipitation generally require four main steps: lysing the cells to release the DNA from cellular and nuclear membranes; removing impurities (such as proteins, lipids and carbohydrates); concentrating by alcohol precipitation; and then rehydrating the DNA in a hydration solution. The major differences among these three methods occur during the second step, where impurities are removed from the DNA by density differentiation, organic-aqueous phase partitioning, or selective salt precipitation.
A conventional liquid phase purification method for purifying blood dried on specimen collection cards (Guthrie cards) is described by McCabe et al., Human Genetics, 75, 213-216 (1987). The method follows closely a procedure for liquid blood described in Sambrook et al., Molecular Cloning: A Laboratory Manual, 2nd ed., 9.16-9.19, Cold Spring Harbor Press, Cold Spring Harbor, N.Y. (1989). In this phenol extraction method, dried white cells are removed from the collection paper by rehydrating with a saline solution. The white cells are incubated in a buffer to lyse the cells. Then, three phenol extractions are performed to remove protein impurities followed by three ether extractions to remove the phenol. The DNA is concentrated by sodium acetate-ethanol precipitation, washed with 70% ethanol and then rehydrated in a standard DNA hydration solution. Several reagents (ten), two of which are hazardous (phenol and ether), are typically required for this method. Although these conventional methods typically yield highly purified DNA preparations, they are laborious and hazardous.
As with liquid phase purification, conventional solid phase methods have been developed to generate highly purified DNA. Generally these methods require four general steps: lysing cells to release DNA from cellular and nuclear membranes; binding the released DNA to a solid support; washing away impurities; and then eluting the purified DNA. The first two steps, lysing the cells and binding the released DNA, usually require hazardous reagents at high concentration.
For solid phase DNA purification, many solid supports have been used including membrane filters, magnetic beads, metal oxides, and latex particles. Probably the most widely used solid supports are silica-based particles (see, e.g., U.S. Pat. No. 5,234,809 (Boom et al.); International Publication No. WO 95/01359 (Colpan et al.); U.S. Pat. No. 5,405,951 (Woodard); International Publication No. WO 95/02049 (Jones); WO 92/07863 (Qiagen GmbH). For example, the method disclosed in U.S. Pat. No. 5,234,809 (Boom et al.) uses a high concentration chaotropic solution to bind DNA to silica particles and requires six centrifugation steps and five reagents to purify DNA from whole blood. Disadvantages of this method are the use of a particulate suspension, the use of many centrifugation steps, and the use of hazardous reagents, such as guanidinium isothiocyanate and acetone.
One means for simplifying the conventional solid phase purification procedures is to eliminate the elution step and use the DNA while it is bound to a solid support for subsequent analyses, such as amplification. Thus, by using immobilized DNA, usually at least one reagent and one step is omitted. For example, U.S. Pat. No. 5,234,809 (Boom et al.) describes such a method for purifying DNA, although it is not present in a complex mixture such as blood. Using the method described above, but omitting the elution step, reduces the number of reagents and steps by one.
In another example, U.S. Pat. No. 5,496,562 (Burgoyne) describes a method of purifying cellulose filter paper containing dried blood that uses four reagents during four phenol washes and five isopropanol washes. After drying, a small piece of the filter paper is cut from the square and used directly as a substrate for PCR amplification. Despite the use of bound DNA for analysis, these methods still require many steps and hazardous reagents.
Recently, there has been a trend toward developing more rapid and simple methods for both liquid and solid phase purification. This has been driven in part by the development of DNA amplification assays which reduce the time necessary for analysis. As the number of DNA-based assays has increased in the field, there is a need for more rapid means of processing the biological samples. Also, using simpler methods reduces the risk of sample cross-contamination by reducing the number of sample handling steps. In addition, the simpler the method, the more readily the process may be automated.
One rapid liquid phase method for DNA purification uses a chelating resin to remove metal impurities from liquid blood or blood stains (Walsh et al., BioTechniques, 10, 506-513 (1991)). Using this method, blood cells are first washed with deionized water and then incubated with a suspension of the chelating resin and deionized water at 56° C. for 15-30 minutes. This incubation is followed by vortexing, incubating at 100° C. for 8 minutes, vortexing again, and removing the impurities by centrifugation. This method is rapid (completed in 45-75 minutes) and simple (requires only two reagents).
Another simple and rapid method for liquid phase DNA purification is described by Nordvag et al., BioTechniques, 12, 490-492 (1992). Starting with whole human blood, the blood cells are washed twice with a solution of 10 mM EDTA and 10 mM NaCl and collected by microcentrifugation after each wash. Then the cells are resuspended in 50 mM Tris(hydroxymethyl)aminomethanehydrochloric acid (Tris-HCl) buffer (pH 8.0) and boiled for 3 minutes prior to PCR amplification. For this purification method, only two reagents are required, both of which are generally nonhazardous. Furthermore, the method requires only approximately 15 minutes.
An even simpler single reagent method is described by Carducci et al., BioTechniques, 13, 735-737 (1992). Using this procedure, a 3 mm diameter blood spot is autoclaved for 3 minutes and then boiled for 5 minutes or sonicated for 10 minutes in a PCR-compatible buffer (10 mM Tris-HCl pH 8.3, 50 mM KCl, 3 mM MgCl2 and 0.001 gelatin). The impurities remain bound to the disk following autoclaving while the DNA is recovered in the buffer.
All three of these liquid phase methods for DNA purification use low concentrations, nonhazardous reagents, and simplified methods. However, these three methods (Walsh et al., Nordvag et al., and Carducci, et al.) could be simplified further by eliminating the use of resins (which must be uniformly suspended prior to use), eliminating the repetitive washing of cells, or eliminating the cumbersome autoclaving of blood spots.
Rapid and simple methods for solid phase DNA purification have also been developed. The procedure of Berlin et al., Human Mutation, 1, 260-261 (1992) describes washing dried blood spots successively with a nonionic detergent-containing buffer. To elute the DNA from the filter paper, each sample is incubated at 65° C. for one hour with another nonionic detergent-containing buffer containing a proteinase K solution. A final incubation at greater than 95° C. for 10 minutes is necessary to inactivate the proteinase K. This method reduces the number of reagents required to three, but has the disadvantages of using an enzyme, a long incubation time, and a high incubation temperature (i.e., greater than 95° C.).
A rapid method using a membrane filter as a means of trapping DNA is disclosed in U.S. Pat. No. 5,234,824 (Mullis). Typically, this method requires a high concentration lysing reagent to lyse cells present in whole blood. Then, the lysate is applied to a filter and washed successively with a second lysing reagent and then either buffer or water to further purify the DNA. The DNA is eluted from the membrane by boiling for 15 minutes in water or in a buffered reagent containing magnesium chloride. Disadvantages of this solid phase purification method include the absence of a chelating agent in the purification and elution reagents, which can increase the probability of DNA damage (e.g., due to nucleases). In addition, there is a requirement for a cumbersome high temperature incubation (i.e., about 100° C.).
In another example, W.O. Pat. No. 96/18731 (Deggerdal) describes a method of purifying DNA from cells by mixing the cells with a detergent and a solid phase made up of magnetic beads. In this method, cells may be pre-lysed by the detergent to release the DNA which is subsequently bound to the solid phase. Alternatively, detergent may be added to a suspension made up of the cells and the solid phase, or the cells, detergent, and solid phase may be suspended together to allow the detergent to lyse the cells in the liquid phase and subsequently bind the DNA to the solid phase. However, this method involves multiple steps of adding or removing the liquid phase (i.e., detergent or the cell debris-detergent suspension) from the solid phase.
A very simple method is presented by Makowski et al., Nucleic Acids Research, 23, 3788-3789 (1995) in which 3 mm diameter disks punched from blood samples dried on cellulose collection paper are washed with deionized water (two 30 minute washes) and used directly for PCR amplification. As discussed in the above analysis of the '824 Patent, a major disadvantage of using deionized water as a purification reagent is that the absence of a chelating agent increases the probability of DNA damage (e.g., due to nucleases). In addition, the absence of a detergent reduces the efficiency with which impurities are solubilized.
Nucleic Acids may be detected and quantitated by several means. Commonly, UV absorbance at a wavelength of 260 nm is used. A wavelength of 320 nm is used to determine background absorbance. Also, fluorimetry in the presence of Hoechst 33258 dye (e.g., Hoefer, DyNA Quant Fluorimeter, Pharmacia Biotech, Piscataway, N.J.), antibody detection strips (DNA Dipstick, Invitrogen, Carlsbad, Calif.), branched signal amplification (Chiron Corporation, Emeryville, Calif.), and quantitative PCR amplification (e.g., Applied Biosystems 7700, Perkin Elmer Applied Biosystems Division, Foster City, Calif.) are used to detect and quantitate nucleic acids.
As generally known and practiced, the purity of the DNA may be ascertained by measuring the absorbance at various wavelengths. The presence of impurities such as proteins, lipids, carbohydrates, cellular debris, etc. can increase the measured absorbance. In contrast, pure nucleic acids, especially DNA used in PCR amplification, have a substantially lower absorbance at established wavelengths.
Currently, there are numerous nucleic acid amplification systems available. While the most commonly used amplification methods are Polymerase Chain Reaction (PCR), other target amplification technologies include Ligase Chain Reaction (LCR), Nucleic Acid Sequence Based Amplification (NASBA), Self-sustained Sequence Replication (SSR or 3SR), Strand Displacement Amplification (SDA), and Transcription Mediated Amplification (TMA).
PCR is used routinely to amplify one or more targeted nucleic acid sequences within a sample or mixture of nucleic acids. This process is disclosed in U.S. Pat. No. 4,965,188 (Mullis). For each target nucleic acid sequence to be amplified in this process, separate complementary strands of nucleic acid are treated with two primers selected to be substantially complementary to portions of the target nucleic acid within the two strands. A thermostable enzyme (a polymerase) is generally used to extend the primers to form complementary primer extension products. When these are separated into their complementary strands, they serve as templates to extend the complementary primer into the target nucleic acid sequence. When separated, these in turn act as templates for synthesis of additional nucleic acid sequences. The PCR amplification process involves a series of simple steps. These include temperature cycling to cause hybridization of primers and templates, polymerase mediated synthesis of the primer extension products, and separation and subsequent annealing of the strands of template strands and the synthesized target nucleic acid sequences. Thus, there is an exponential increase in the amount of targeted nucleic acid sequences synthesized. PCR amplification is a very sensitive process. Therefore, a very high purity of starting sample is necessary.
LCR is another diagnostic technique that is often utilized in conjunction with a primary PCR amplification. LCR employs a thermostable ligase and allows the discrimination of DNA sequences differing in only a single base pair. LCR depends on highly pure NA templates due to its sensitivity.
Purified nucleic acids can be further analyzed by Southern hybridization, or Southern blotting as it is more commonly known. Southern blotting is the capillary transfer of DNA fragments from gels to various types of filter paper. It allows the researcher to detect rare sequences in a complex population of restriction fragments and is useful in gene cloning, reverse genetics, and the analysis of restriction-fragment-length-polymorphisms (RFLP's) for human genetic disease diagnosis. Southern blotting involves the digestion of DNA with one or more restriction enzymes, followed by a size separation by electrophoresis on an agarose gel. The DNA is then denatured in situ and transferred from the gel to a membrane (e.g., nitrocellulose or nylon). The DNA attached to the membrane is then hybridized to radiolabelled DNA or RNA, and autoradiography is used to locate the positions of bands complementary to the probe. Southern blotting is highly sensitive. A sequence of 1000 base pairs (bp) that occurs only once in the mammalian genome (i.e., 1 part in 3 million) can be detected in an overnight exposure if 10 μg of genomic DNA is transferred to the filter and hybridized to a probe several hundred nucleotides in length.
To advance the field of DNA sample preparation there is a need for solid phase DNA purification strategies. There is also a need for reagents and methods that are adaptable to solid phase purification strategies are not only simple and rapid but general in scope to maximize adaptability for automation. There is a need for reagents that are of generally low concentration, stable at room temperature (i.e., 20-25° C.), less hazardous (i.e., less corrosive, flammable or toxic), nonparticulate to eliminate the need for mixing, and protective of DNA quality. There is also a need for methods with few steps that can be performed using a variety of biological starting materials, whether hydrated or dried, especially as applied to routine testing as found in clinical laboratories. The reagents must not inhibit subsequent DNA analysis procedures by interfering with the buffering capacity of PCR buffers, or cause degradation of polymerase, primers or oligonucleotides used in DNA amplification. There is also a need for methods with few steps that can be performed using a variety of biological starting materials, whether hydrated or dried, especially as applied to routine testing as found in clinical laboratories.
The reagents and methods used in the solid phase purification strategy must also not interfere with standard methods for nucleic acid quantification, restriction enzyme digestion, DNA sequencing, hybridization technologies, such as Southern Blotting, etc., and amplification methods such as Polymerase Chain Reaction (PCR), include Ligase Chain Reaction (LCR), Nucleic Acid Sequence Based Amplification (NASBA), Self-sustained Sequence Replication (SSR or 3SR), Strand Displacement Amplification (SDA), and Transcription Mediated Amplification (TMA), or other DNA analysis.

Processes for isolating, amplifying and characterizing DNA


An apparatus includes a protective case for a portable computing device and an integrated alcohol sensor module for measuring the blood alcohol concentration of a user. The apparatus also includes a breath interface, a wireless communication device, an alcohol sensor module and a microcontroller. The protective case houses and protects the portable computing device and the internal electronic components. The breath interface allows the user to provide a breath sample to the alcohol sensor module. The alcohol sensor module measures the alcohol concentration of the breath sample. The microcontroller operates the alcohol sensor module and conveys the alcohol concentration measurements to the portable computing device via the wireless communication device. The microcontroller and the wireless communication device are both mounted within the protective case. The alcohol concentration measurement is used as input for a variety of software application which promote safe drinking and driving habits.

In the United States, on average, a single household owns about 2.28 vehicles. This large amount of cars leads to various problems in a society and community, one of which is driving under the influence of alcohol. Every day, about 28 people die as a result of drunken driving accidents. Accidents caused by driving under the influence of alcohol claim thousands of lives per year and cost the U.S. hundreds of billions of dollars in damages. In recent years, a flux of programs and laws have been implemented, aimed at increasing awareness and reducing the instances of such behaviors. Programs include television advertisements, educational lectures, and social gatherings meant to educate the general public about the consequences of drinking under the influence. While drunk driving is a major problem in the U.S., most states do allow for marginal blood alcohol content while driving and because of this most people still drive under the influence because they believe that they are under the limit and are sober enough to operate a vehicle; this mindset is what leads to accidents, injuries, and deaths. The problem becomes educating the public about safe habits and regulations instead of just abstinence.
The present invention utilizes a fun and novel apparatus which promotes safe drinking and driving habits. The present invention integrates an easy to use and accurate breathalyzer into a protective case, in particular for a mobile device or computer tablet. The present invention allows the user to become aware of their relative sobriety as well as play an educational and fun game that is directly customized to their inebriated state.

Protective case with integrated breathalyzer


Embodiments of the present specification provide a method, an apparatus, a client terminal, and a server for data processing. The method includes: selecting, based on a data attribute of to-be-processed data, a target coordinating server from a plurality of coordinating servers, the plurality of coordinating servers belonging to a plurality of server clusters respectively; and sending a data processing request to the target coordinating server, such that a server cluster to which the target coordinating server belongs processes the data processing request preferentially, the data processing request directing to the to-be-processed data.

With the rapid development of the Internet, various types of data have emerged and grown explosively. At present, blockchain technologies have become the directions of main attention and research in many technical fields due to their own characteristics of decentralization, untamperability, distribution, and the like.
In related technologies, a system for data processing may include a client terminal and a blockchain server. The blockchain server can join a blockchain network as a blockchain node. In actual services, the client terminal needs to perform frequent read and write operations on the blockchain server, such as reading block data from the blockchain server; or writing status data into the blockchain server. The status data can be configured to indicate a status of a member in a blockchain, e.g., an asset balance of a member account. In the above related technologies, the read and write operations of the client terminal for the blockchain server are relatively frequent, which may result in a high access pressure to the blockchain server and reducing the data processing speed of the system for data processing.

Method, apparatus, client terminal, and server for data processing


A warp knitting machine comprises at least one guide bar and one main shaft. The angular position of the main shaft is determined by an absolute transmitter, while the position of the guide bar is determined by an absolute transmitter. Each transmitter can provide a different signal value for each angular position of the main shaft and for each guide bar position. A continuous displacement function is developed for the guide bar. This function relates each measured angular position of the main shaft with a position target value for the guide bar. A position control circuit controls a setting motor that displaces the guide bar. In this way, the danger of collision between elements of the guide bars and other working parts of the machine are practically totally avoided.

1. Field Of The Invention
The present invention is directed to a warp knitting machine including: (a) at least one guide bar which is axially displaceable by an electrical setting motor having a position signal transmitter, (b) a main shaft which is continually rotatable by an electrical main motor and which is provided with a synchronization signal transmitter, and (c) a schedule transmitter which outputs a position target value to a position control circuit controlling the setting motor, according to at least one displacement schedule in dependence upon the synchronization signal.
2. Description Of Related Art
Such a warp knitting machine is known from German DE OS 22 57 224. The displacement sequence to be carried out are read from a schedule carrier, for example, a hole punched or magnetic tape. A synchronizing signal transmitter generates a signal for particular angular positions of the main shaft based on which, the last read displacement step is then executed with the assistance of a position control circuit. By using another schedule carrier, the pattern of the warp knitted fabric can be changed by altering the guide displacement movement. The progress of the displacement movement is not completely controllable. It depends substantially upon the design of the control circuit. A disadvantage of these uncontrolled movements is that collisions can occur between the guides and other working parts, for example, when swinging through the needle bed or by underlaps with knock-over sinkers.
Thus there is a need for a warp knitting machine of the aforementioned type in which the danger of collision is substantially avoided.

Control arrangement comprising synchroneous signal for knitting machine guide bars


There is provided a method of fabricating a semiconductor, including the steps, in sequence, of (a) forming a first interlayer insulating film over a semiconductor substrate, (b) forming an electrically conductive contact hole in the first interlayer insulating film, (c) forming a second interlayer insulating film over the first interlayer insulating film, (d) forming a photosensitive organic film over the second interlayer insulating film, (e) forming a via-hole passing through the photosensitive organic film and the second interlayer insulating film, the via-hole being in vertical alignment with the contact hole, (f) forming a film so that the film covers the photosensitive organic film therewith and fills the via-hole therewith, (g) exposing the film to plasma so that a portion of the film lying over the photosensitive organic film is removed, (h) removing both the photosensitive organic film and the film remaining in the via-hole, and (i) forming a wire above the via-hole. In accordance with the above mentioned method, the cured layer formed on the photosensitive organic film is removed by being exposed to plasma in oxygen atmosphere with the via-hole being filled with the film. Thus, the second interlayer insulating film defining an inner wall of the via-hole is not exposed directly to oxygen plasma, and hence is not etched by the plasma. As a result, it is possible to prevent that the via-hole has a greater side length than a designed side length.

1. Field of the Invention
The invention relates to a method of fabricating a semiconductor device, and more particularly to a method of fabricating a semiconductor device in which a wire is to be formed above a via-hole.
2. Description of the Related Art
One of conventional methods of fabricating a semiconductor device is explained hereinbelow with reference to FIGS. 1A to 1E.
As illustrated in FIG. 1A, there are formed device isolation regions 3 at a surface of a semiconductor substrate 1, and diffusion layers 2 adjacent to the device isolation regions 3. A gate oxide film 21 is formed at a surface of the semiconductor substrate 1 between the diffusion layers 2. There is formed a gate electrode 22 on the gate oxide film 21. The gate electrode 22 and the gate oxide film 21 are covered at their side surfaces with sidewalls 23.
Then, a resultant is covered with a first interlayer insulating film 4. Then, there are formed contact holes 5 by photolithography and etching. The contact holes 5 pass through the first interlayer insulating film 4 and reach the diffusion layers 2. Then, there is formed a barrier metal film 12 on an inner surface of the contact holes 5. The barrier metal film is constituted of an about 30 nm-thick titanium film and an about 100 nm-thick titanium nitride film. Then, a resultant is covered with a tungsten film 13 by chemical vapor deposition (CVD) employing WF.sub.6 and H.sub.2 gases as source gases. Then, the tungsten film 13 is etched back to thereby fill the contact holes 5 with tungsten 13.
Then, a first wiring layer 6 is formed over a resultant by sputtering, and subsequently patterned in a desired pattern by photolithography and reactive ion etching. Before or while the above mentioned steps are carried out, the semiconductor substrate 1 is processed to have a desired impurity profile therein by ion implantation and annealing and all that.
Then, as illustrated in FIG. 1B, a hydrogenated amorphous carbon film 7 is formed by about 0.1 .mu.m over a resultant, and a fluorinated amorphous carbon film 8 is formed by about 1.0 .mu.m over the hydrogenated amorphous carbon film 7.
Then, as illustrated in FIG. 1C, photoresist 9 is formed by about 1.0 .mu.m over the fluorinated amorphous carbon film 8. Then, the photoresist 9 is exposed to light at a portion where via-holes 10 are to be formed, and developed to thereby remove the portion of the photoresist 9. With the photoresist 9 being partially removed, reactive ion etching (RIE) is carried out to thereby etch the fluorinated amorphous carbon 8 and the hydrogenated amorphous carbon 7. As a result, there are formed via-holes 10. Since the photoresist 9 is exposed to plasma during the reactive ion etching, there is formed a cured layer 11 at the top of the photoresist 9, as illustrated in FIG. 1C.
Then, the cured layer 11 formed on the photoresist 9 is exposed to plasma in oxygen atmosphere to thereby remove the cured layer 11. Thereafter, the photoresist 9 is removed by organic release solution, as illustrated in FIG. 1D.
Then, as illustrated in FIG. 1E, a barrier metal film 32 is formed on an inner surface of the via-holes 10. The barrier metal film 32 consists of an about 30 nm-thick titanium film and an about 100 nm-thick titanium nitride film. Then, a tungsten film 33 is deposited over a resultant by CVD employing WF.sub.6 and H.sub.2 gases as source gases. Thereafter, the tungsten film 33 is etched back to thereby fill the via-hole 10 with tungsten 33. Then, an aluminum layer 14 is deposited over a resultant by sputtering, and thereafter is patterned, as illustrated in FIG. 1E.
In the above mentioned conventional method, when the cured layer 11 formed on the photoresist 9 by reactive ion etching is removed by plasma in oxygen atmosphere, an inner wall of the via-hole 10 is also etched, as illustrated in FIG. 1D, thereby posing a problem that the via-holes 10 have a greater side length than a designed side length.
With respect to photoresist removal, processing variables such as photoresist type are discussed in "A Plasma Oxidation Process for Removing Photoresist Films", Stephen M. Irving, Solid State Technology, June 1971, pp. 47-51.

Method of fabricating a semiconductor device