A magnetron sputter apparatus is disclosed which includes a rotatable generally heart-shaped, closed-loop magnet array behind the target and in front of a pair of separately driven stationary electromagnets. The apparatus is optimized to produce a sputtered film on a planar substrate having desired film characteristics such as uniformity of thickness, good step coverage, and good via filling and efficient utilization of the target. The shape of the generally heart-shaped array includes a flattened tip forming an arc of a circle centered on the axis of rotation and concave cusps in the lobes of the heart-shape. The electromagnets are used to increase target utilization at its center and to compensate for the change in shape of the target and distance from the target to the substrate with depletion.

Physical vapor deposition by sputtering is a well known process that has widespread application in the fabrication of integrated circuit semiconductor devices. In semiconductor device fabrication, a large number of integrated circuit devices are normally formed on a thin, generally circular semiconductor substrate known as a wafer. Integrated circuit device fabrication involves a large number of processing steps, with sputtering typically being used to provide metal layers which serve as interconnects between devices and device layers. Most commonly, sputtered aluminum is the material used for these purposes. Modern semiconductor processing has also seen the increased use of sputtered tungsten, tungsten silicide, titanium, titanium nitride and other films.
Sputter coating is carried out in a vacuum chamber filled with an inert gas in which a target of sputterable material is subjected to an electric potential with respect to the chamber anode. Electrons which are excited in the vicinity of the target strike and ionize the gas ions and the positive ions strike the target causing target atoms to be ejected.
A magnetron sputtering source is capable of high rate sputtering and represents an enormous improvement over devices forming thin films based on diode sputtering or evaporative techniques. In magnetron sputtering a plasma is formed in a low pressure inert gas by the application of a suitable DC or RF electric field. The plasma is confined by a magnetic field to a region near a target which is made of the material to be sputtered and which usually serves as the cathode of the system. The magnetic field, typically having field lines which loop through the sputter target surface, restricts the trajectories of the electrons of the plasma to retard their transport to the anode and confine them in a region so that ions in the plasma bombard the sputter target dislodging atoms of the target material which then become deposited on a substrate, i.e. a semiconductor wafer.
The demand for lower cost circuits implies larger wafer sizes which imposes greater demands on sputtering systems. For example, one requirement of a sputtering system used in semiconductor processing is that it deposit a layer of uniform thickness over the entire wafer surface. (Hereinafter, the term uniformity will be used in connection with the thickness of the deposited film unless the context suggests otherwise.) Lack of uniformity might result in lowered device yield (i.e., the percentage of the devices which meet operating specifications) and/or variations in device performance. Larger wafer sizes make it more difficult for sputter systems to achieve very demanding levels of uniformity and step coverage. Likewise, the trend towards ever smaller integrated circuit device geometries has required that even greater levels of sputtered film uniformity be achieved.
Other sputtered film characteristics are also quite important to integrated circuit device manufacturers. For example, as noted above, sputtered conductive material is frequently used to form interconnects between devices and between the metal layers. Forming interconnects involves uniformly filling small diameter holes, called vias, in the surface of a wafer. As integrated circuit device geometries have shrunk, the difficulty in filling vias with sputtered material has increased appreciably. Step coverage, or the ability of the sputtered film to evenly conform to angular features on the wafer is, likewise, another important film characteristic.
An earlier approach to improving the uniformity and step coverage characteristics of a sputtered system is to sputter from two concentric targets. For an example of this approach see U.S. Pat. No. 4,606,806 which describes a sputtering source sold by the assignee of the subject invention. In this system, each of the sputter targets has a unique shape and its own separate power supply enabling separate control over the sputtering rate from each target. As wafer size increased this system was replaced, primarily due to undesired particles forming on the substrate believed to be caused by areas of net build-up of sputtered material.
A number of commercially available sputtering sources use planar sputtering targets. Early designs of the planar magnetron sputtering device used a stationary magnet which had practical shortcomings, the most serious of which is that the plasma discharge is localized and erodes a narrow groove in the target in the vicinity of the greatest magnetic field strength. This localized erosion generates a non-uniform distribution of sputtered atoms from the target and a film with non-uniform thickness on the semiconductor wafer. The non-uniform erosion of the sputter target leads to inefficient target utilization. Given the high cost of the sputter targets used in semiconductor manufacture, it is important to obtain the greatest possible target utilization that is consistent with the need for sputtered film uniformity and other required sputtered film characteristics.
Numerous attempts, some partially successful, have been made to modify the planar magnetron source to extend the target erosion and to make the distribution of sputtered atoms more uniform. Attempts have been made to spread out the erosion over a larger surface by using extended magnetic fields. The magnets required for such an approach are large and complicated, and it is difficult to assure that the properties of the magnetron plasma do not change as the target erodes. The resulting erosion pattern is thus difficult to predict.
U.S. Pat. No. 4,444,643, which is incorporated herein by reference, describes a sputtering device which includes a mechanically rotated annular permanent magnet assembly. The rotation of the permanent magnet assembly causes erosion over a wide area of the target. A version of the sputtering source according to the '643 patent have been sold commercially by the assignee of the present invention. This source relies on a rotating permanent magnet mounted behind the target for moving the plasma over the face of the target. Rotation of the plasma improved the uniformity and step coverage, as well as improving the uniformity of target erosion so that targets are more efficiently utilized.
The rotating sputtering source, while a significant improvement over planar magnetron sources employing stationary magnets, nonetheless did not produce truly uniform sputtered film nor uniform target utilization. Thus, efforts have been made to develop improved rotating magnet designs for use with planar targets. (The term "planar target" is intended throughout this specification to be descriptive of the sputter target surface before it is eroded. Those skilled in the art will recognize that after the target has been eroded it might no longer have a planar surface.)
One direction that has been taken by those seeking to improve the design of rotating magnets used with planar magnetron sputtering sources has been the use of closed-loop, generally heart-shaped magnet configurations. Such magnet configurations typically employ an array of magnets which are centered along a line defining a heart-shaped, closed loop. The heart-shaped rotating magnet array can produce more uniform target erosion. While uniform erosion is important, the characteristics of the sputtered film, such as uniformity, are of greater importance to integrated circuit device manufacturers. In many instances, as will be described below, a non-uniform target erosion pattern improves the uniformity of the sputtered film.
Another sputtering source having a heart-shaped magnet arrangement is described in Japanese Patent Application Publication (Kokai) No. 62-211,375. That application prescribes the use of a heart-shaped closed-loop magnet having a curve defined by the equation EQU R=L-A+2A.vertline..theta..vertline./.pi. (for-.pi..ltoreq..theta..ltoreq..pi.)
where the center of the sputter target is located at the origin of a polar coordinate system, R is the distance between the origin and a point on the curve defining the magnet centerline, L is the distance between the center of the heart and the cusp of the heart, and A is the distance between the center of the heart and the center of the target. No derivation is given as to how the inventors arrived at this equation. As discussed in the '375 Japanese application, a magnet having the prescribed curve will not produce uniform erosion nor uniform deposition. Moreover, the '375 application does not teach how to obtain any arbitrarily selected erosion profile.
U.S. Pat. No. 4,995,958, also assigned to the assignee of the subject invention, describes another generally heart-shaped, closed-loop magnet array for use in a planar magnetron sputtering source. The '958 patent, which is hereby incorporated by reference, includes a rigorous mathematical analysis to show how to construct a closed-loop rotating magnet to realize a predetermined erosion profile to thereby achieve, for example, highly efficient target material utilization and high deposition rates.
Among other things, the '958 patent describes the shortcomings of the prior art and shows how the prior art fails to provide a teaching which truly enables one to obtain uniform erosion of a planar sputter target. Importantly, FIGS. 12A-12E of the '958 patent, and the related text, clearly show that minor changes in the shape of the heart-shaped magnet might lead to very dramatic differences in the resulting erosion pattern of the sputter target. Given the demonstrated fact that minor perturbations of the shape of the heart-shaped magnet might cause significant changes in the resulting target erosion profile, it becomes quite difficult to optimize the shape empirically. Thus, the mathematical analysis of the '958 patent is a highly significant teaching in making heart-shaped, closed-loop magnets practically useful.
A closed-loop magnet configuration of the type described in the '958 patent has the additional advantage of being adjustable, i.e., the shape of the magnet array, and therefore the characteristics of the sputtering source, can be changed without great difficulty or expense. As prescribed in that patent, a plurality of magnets are held in position by two iron keepers, or pole pieces, which define the shape of the closed-loop. Replacement and/or adjustment of the iron keepers to provide a different closed-loop configuration is a relatively simple matter. In this manner, it is possible to use one source for different purposes, or to adjust the source as needs change.
A prime objective of the closed-loop rotating magnet of the '958 patent was to achieve better target utilization efficiency, normally an important objective given the high cost of sputter targets, and to achieve high deposition rates, another factor due to the demand for ever greater sputtered film "throughput". As noted above, the need for greater sputtered film uniformity generally outweighs the need for efficient target utilization and deposition rate. Accordingly, the '958 patent provides the basis for obtaining any arbitrary target erosion profile. It is noted, however, that the '958 patent provides no instruction as to how to determine what erosion profile to use under a given set of conditions to maximize sputtered film uniformity or other sputtered film characteristics.
As prescribed therein, the mathematical analysis provided in the '958 patent is inapplicable at discontinuities at two areas of the heart, i.e., in the area near the "tip" of the heart and in the area near the "cusp" of the heart. As a result of the inapplicability of the teaching of the '958 patent to the region of the cusp of the heart, the designs they show do not utilize optimally the very center of the target or the target edge. Moreover, the analysis of the '958 patent is based on the assumption that the magnet has uniform strength at all points along the loop. If true, the total quantity of material sputtered per unit length of the magnet would be a constant. It has been observed that this assumption is not correct.
It is noted that all of the heart-shaped designs shown in the '958 patent, and other prior art are symmetrical about a line which passes through the tip, the cusp, and the axis of rotation of the heart. The symmetry of the '958 designs is due to the fact that their method of generating a heart-shaped magnet is by forming a shape over 180.degree. (i.e. over one half of the polar coordinate system) and then mirroring this shape to close the loop over the remaining 180.degree.. However, as used herein, the term heart-shaped does not require that there be two strictly symmetrical halves. As will be described below, there might be circumstances when an asymmetrical heart-shaped magnet is desired. Likewise, as used herein, the term heart-shaped, does not require that the heart have a noticeable "tip". It has been found that there are advantages to using a design wherein the region farthest from the axis of rotation and generally opposite the cusp forms an arc of a circle. As used herein, the term "heart" implies that there is a cusp-like transition between two lobes. The cusp-like transition might be smoothed for design convenience.
Finally, it has been discovered that there are discrepancies between the position" of the plasma adjacent to the sputter target surface as predicted in the '958 patent and as empirically measured for the location of the magnet per the '958 patent. As noted above, even minor changes in the shape of the magnetic field generated by a heart-shaped PG,9 magnet might result in significant variations in the erosion profile obtained.
As taught in U.S. Pat. No. 4,995,958, the centerline of a heart-shaped, closed-loop magnet array lies on a curve defined by the equation ##EQU1## where .xi.(u) is a function defining a preselected erosion profile and C is a selected constant. As described in the '958 patent, each of the magnets is uniformly disposed on a centerline, which lies between spaced apart inner and outer keepers. The spacing between the inner keeper and the outer keeper is uniform at all points except in the vicinity of the tip and the cusp of the heart. Iron keepers are about 1/16" thick. The magnet array is mounted on a plate which is connected to means for rotating it about an axis of rotation.
An erosion profile can be calculated for the magnet array in the teachings of the '958 patent. In other words, the centerline of the magnet array is laid out, per the above equation to produce a theoretical erosion profile. Stated equivalently, the function .xi.(u) is a constant so as to produce uniform erosion between the limits of integration. It is noted, however, that for r.ltoreq.1 the equation is equal to a constant.
Various other heart-shaped, closed-loop magnet shapes designed to theoretically produce different sputter target erosion profiles wherein the function .xi.(u) is not a constant are shown in FIGS. 12A-12E of the aforementioned '958 patent. It will be noted from an inspection of these figures, and the accompanying text, that minor variations in the shape of the heart-shaped magnet will produce significant differences in the shape of the resulting erosion profile. It follows that, while use of a properly configured heart-shaped, closed-loop magnet in connection with a planar magnetron sputtering device can result in improved target erosion uniformity, it is not obvious how to empirically arrive at the proper shape necessary to produce any arbitrary erosion profile.
Each of the heart-shaped magnet arrays shown in the '958 patent, or in any other prior art of which the inventors are aware, is symmetrical about a line which runs through the tip, the cusp and the axis of rotation of the magnet. Moreover, each of the prior-art magnets is "pointed" at its tip. In other words the centerline is not smooth at the point the curve is reflected, i.e., the derivative of the centerline is discontinuous at this point.
EPC Patent Application Serial No. 91-300565.8 (hereinafter the '565 application) also assigned to the assignee of the subject invention, describes magnet configurations based on the teaching of the '958 patent but extended to correct for the limitations of the of the '958 patent so that uniform erosion could be obtained in the center region of the target. Such an improved heart-shaped, closed-loop magnet array for use in a planar magnetron sputtering system, has been sold commercially by the assignee of the subject invention. This magnet array is based on the teachings of the '958 patent as extended by the '565 application. In contrast to the heart-shaped designs of the '958 patent, this includes magnets positioned in the vicinity of the axis of rotation of the magnet array. In this commercial embodiment, the placement of the magnets near the axis of rotation is not strictly restricted to the teachings of the '565 application but also incorporates a combination of designer intuition and empirical results. It is noted that near the lobes and cusp of the heart, the iron keepers are not uniformly spaced, and the departure from uniform spacing of the keepers in the vicinity of the cusp is far greater than the slight departure present in the previous designs. However, the lack of uniform spacing makes the placement of the magnets more difficult in this vicinity. Moreover, as described in the '565 application, the magnets in the central region could be different in strength.
While this magnet design represents an improvement over the design of the prior art insofar as it produces better target utilization near the center of the sputter target, the mathematical analysis that is required is difficult. In addition, it has been determined that neither the earlier nor the improved design precisely results in the erosion profile predicted by the teachings of the '958 patent or of the '565 application.
An improved design for a heart-shaped, closed-loop magnet array for use in a planar magnetron sputtering system has been disclosed in a patent application by D. Harra entitled "Sputtering Apparatus With a Magnet Array Having a Geometry With A Specified Target Erosion Profile", U.S. Ser. No. 07/855,988, filed Mar. 20, 1992, the disclosures of which are hereby incorporated by reference.
Before describing the method used to arrive at the shape of the permanent magnet array, a description of its shape vis-a-vis the prior art is given. Starting at the cusp of the heart, it is noted that the inner keeper crosses the axis of rotation of the magnet array while maintaining nearly even spacing between inner keeper and outer keeper in the vicinity of the cusp. Thus, this portion of the magnet achieves a better performance without the complexities of other embodiments shown in the '565 application.
It will also be noted that, just beyond the lobes of the heart, the shapes of the magnet array has two inward inflections. In other words, while the shape of the prior art heart-shaped magnets are all such that the curve is at all times convex in relation to the interior of the loop, in this improvement, there are two portions of the curve that are concave in relation to the interior of the loop.
Finally, it should be noted that this improvement has no pointed tip. While this improvement is symmetrical about a line running through the cusp and the axis of rotation of the heart, the portion of the curve that lies farthest away from the axis of rotation, and which lies on either side of the axis of symmetry, lies on an arc which is preferably the arc of a circle. Accordingly, the curve at this point is smooth, i.e., the derivative of the curve is continuous at this point. Moreover, a major portion of the heart, perhaps as much as one fourth or more of the curve, lies on this arc.
The method by which the shape of the improved magnet array, and by which other shapes can be constructed to produce a selected erosion profile will now be described. An initial heart-shaped, closed-loop magnet array is first constructed. In the rotatable magnet array included in the preferred embodiment of the subject invention, the initial closed-loop magnet might be constructed either in accordance with the principles described in the '958 patent or the manner used to create the improved magnet, so that a desired erosion profile will be approximated by the initial magnet shape. It is also possible to start with other heart-shaped designs, including those known in the prior art.
This initial magnet array is then placed in a sputtering system and the system is operated while holding the magnet array stationary to generate a static erosion groove in the surface of the sputter target. When performing this step it is preferred that the sputter target be constructed of material which will be used with the magnet array being designed, and that the operating parameters of the system coincide with the actual operating parameters that will be used by the system in production. For reasons that are not fully understood, it has been observed that the static erosion profile produced by a given magnet array will differ slightly depending on the material that is being sputtered.
As is to be expected, the resulting static erosion groove is also heart-shaped and forms a closed loop. Moreover, as expected from the prior art of planar magnetron sputtering using a stationary magnet array, any given cross section of the erosion groove around the loop has a valley like appearance having a bottom region where erosion is greatest. However, for reasons that are not fully understood, the bottom of the erosion groove does not overly the center of the magnet array. This discrepancy between the bottom of the erosion groove and the centerline of the magnet array, if not corrected or compensated for, will produce results that vary from the teachings of the '958 patent.
An important premise of the '958 patent is that the region of greatest target erosion directly overlies the centerline of the magnet array. This premise is based upon the assumption that the magnetic field intensity adjacent to the target surface is greatest directly over the magnetic centerline. It has now been empirically observed that this premise is not fully accurate. As noted above, minor changes in the configuration of the heart-shaped, closed-loop magnet array can result in significant changes in the erosion profile produced by the magnet array. The discrepancy between the shape of the magnet array and the erosion profile it produces during static sputtering can be thought of as meaning that the magnet array being used has a different effective shape than is intended. This problem is not recognized in the '958 patent, nor does the '958 patent teach how to compensate for the discrepancy to produce a magnet with proper effective shape.
After a static erosion groove is made, the shape of the groove is carefully measured at a finite number of points around the groove and a plot is generated showing the mathematical relationship between position and depth of target erosion. These measurements are made in polar coordinates. For example, at a finite number of values of R, (R being the radial distance from the axis of rotation of the magnet array), the depth of target erosion is measured as a function of the angle .theta..
For R=K.sub.i, where K.sub.i is a given value of distance from the center of rotation, it is seen that a typical erosion profile includes two regions of erosion as one rotates from 0.degree. to 360.degree.. A set of similar plots are then created for a finite number of values of K.sub.i, for example twenty such plots might be created, e.g., if the radius of the target is 5 inches, then the plots could be created at each quarter inch interval between the origin and the edge of the target. The values K.sub.i can be thought of as defining a set of concentric circles centered around the axis of rotation. The present technique does not require that the values of K.sub.i be evenly spaced. For example, one might select values of K.sub.i that correspond to the positions of the individual magnets in the array.
Each of the static erosion plots that have been empirically created using this technique is then integrated over a revolution of the magnet to produce a value of erosion depth E(R) for that particular value of K.sub.i. The erosion depth values for each K.sub.i are then plotted to generate an overall erosion profile for the magnet when it is rotated. The integration required by this step can be performed using standard numerical integration techniques that are well-known to those skilled in the art.
It has been found that the calculated erosion profile conforms to the observed erosions profile generated when the magnet is rotated.
The static erosion data plotted to form the graph can be plotted in another manner. Rather than plot the erosion depth at a certain radial distance as a function of angle the erosion depth data can be plotted at a finite number of angles .theta.=.alpha..sub.i, as a function of distance, r. If the target is thought of being a wheel, the data points can be thought of as the erosion profile taken along a "spoke" of the target, where each spoke is again an angle .alpha..sub.i.
It will be apparent to those skilled in the art that the static erosion profile data can be represented equivalently in a three dimensional system or numerical array wherein a finite number of data points on the surface of the sputter target each has a set of values associated with the angular position .theta., the erosion depth E(R,.theta.), and the radial distance R of that point on the surface of the sputter target from the origin, i.e., the axis of rotation.
The curves thus calculated have been conveniently used to adjust the shape of the magnet array to correct for the discrepancy between the predicted erosion profile of the '958 patent and the static erosion profile observed. How this is done will now be explained. This discrepancy between the effective shape of the magnet and the actual shape is readily apparent from the offset between center line and the point of greatest erosion. For convenience, the position of the centerline of the magnet along the x-axis is arbitrarily defined to be at the point x=0. A fifth order polynomial is then derived, using known mathematical techniques, to fit the data points.
It is assumed that a minor perturbation of the centerline of the magnet at a given .alpha..sub.i will not affect the shape or offset of the curve at any other value of .alpha.. These assumptions are quite reasonable if the displacement of each magnet at each .alpha. is small. In order that these assumptions remain valid, it is best to start with an initial magnet shape which is expected to be close to what the final shape will be, so that the perturbations of the positions of the individual magnets remain small. However, if the perturbations grow too large, the technique described herein can be done on an iterative basis.
The effect of making minor adjustments to the position of the magnet centerline at selected values of .alpha..sub.i can be readily translated into a revised, calculated erosion profile that reflects the adjustments that have been made. Thus, it is possible to calculate the perturbations in the position of the magnets at selected points that are needed to produce a preselected erosion profile on the surface of the target.
So long as the perturbations of the magnet positions are small enough that the assumptions described above remain reasonable, the technique that has been described is a very powerful tool for selecting a magnet shape that will produce a selected erosion profile. While based in principle on the techniques of the '958 patent, it will be seen that this technique has several advantages over what is shown in the '958 patent. These advantages include the ability of the present technique to obtain a magnet shape that will result in preselected erosion profile, accounting for the discrepancy between the actual and the effective shape of the magnet array. It is also advantageous to have the ability to predict and adjust the shape of the erosion profile in the vicinity of the cusp of the magnet, and in the vicinity of the magnet closest to the edge of the sputter target. It is also important to have the ability to correct for variations in the erosion intensity over the length of the closed-loop. Finally, it is also an advantage to have the ability to make perturbations in the shape of the magnet to produce an asymmetrical heart-shaped design.
The use of an asymmetrical design allows greater "fine-tuning" of the magnet shape. In a symmetrical design, any magnet centerline adjustment in a region lying on one half of the magnet is doubled because the same adjustment is automatically made to the symmetrical half. Using the present technique, it is possible to adjust one half of the magnet in a predictable way while holding the other half unchanged. This is because the technique uses data taken over the full 360.degree. of the coordinate system.
As noted, by making suitable adjustments to the centerline of the magnet, it is possible to produce a magnet that has an effective shape that is in accordance with the teachings of the '958 patent. In other words, it is possible to configure a magnet that produces a static erosion pattern on the surface of the target a portion of which conforms to the equation ##EQU2## where .xi.(u) defines a preselected erosion profile and where the centerline of the magnet is displaced from the centerline of the static erosion groove to compensate for the discrepancy therebetween.
Having shown how to obtain a magnet having a shape that results in a predetermined erosion profile on the surface of the sputter target, we now turn to a discussion of how to determine what is the optimal erosion profile. While many of the prior art patents emphasize the desirability and importance of uniformly eroding the surface of the sputter target, uniformity of erosion is actually a secondary consideration to most users of sputtering systems. The primary consideration is the need to consistently obtain a sputtered film having desired characteristics, for example, uniformity on the wafers being coated. This is a technique that can be used to calculate the target erosions profile that will result in a film having the desired characteristics of the surface of the wafer.
This technique for predicting the uniformity of film deposition takes into account a number of variables that affect the rate at which sputtered material accumulates at any given point on the surface of the substrate. The important variables that enter into this will now be discussed.
First, it is necessary to know the angular distribution of atoms ejected from the surface of the sputter target. It is frequently assumed, for the sake of simplicity, that sputtered atoms are ejected in a cosine distribution. This assumption is reasonable in the case of aluminum, the most commonly used sputtered film in semiconductor integrated circuit fabrication, where the atomic weight of the material (z=27) is significantly less than the atomic weight of argon (z=40) which is typically used as the sputtering gas,. It is known, however, that when sputtering higher atomic weight materials such as titanium (z=48) or tungsten (z=184), the angular distribution of the sputtered atoms does not conform to a cosine distribution. Moreover, in some cases the crystalline structure of the sputter target material could also affect the angular distribution of sputtered atoms.
The initial step in determining a desired erosion profile is to establish the angular distribution of the atoms being sputtered under the operating conditions that will be used by the system. If the requisite information is not available from the literature, this might be accomplished by empirical measurement using the material to be sputtered in a system operated under similar conditions. After the distribution is empirically determined, the data is then fit to a mathematical function which approximates, to at least the first order, the measured distribution. In the preferred method, it has been found useful to approximate the empirical data by using a distribution function which is a power of the cosine function multiplied by a second function having an adjustable parameter, as set forth in the equation ##EQU3## where K.sub.1 is an adjustable parameter selected to fit the data and K.sub.2 is a scaling factor.
The next parameter which needs to be understood before a calculation of a desired erosion profile can be made is the distance between the substrate and the sputter target. Normally, the distance between the sputter target surface and the wafer will be constant (ignoring the effect of target erosion), in a given system configuration. In most applications, it is desirable to space the substrate as close as possible to the sputter target to maximize the deposition rate and to minimize the loss of target material. (From the foregoing discussion of the angular distribution of sputtered atoms, it should be apparent from the geometry that an atom which leaves the surface of the target at an acute angle has a greater chance of landing on the substrate if the substrate is closely spaced to the target. (If a significant number of atoms do not land on the substrate, both the rate of film deposition will be lowered and the waste of material will be increased.)
On the other hand, close coupling of the target and the substrate makes it more difficult to obtain adequate sputtered film uniformity. It is sometimes preferable to interpose shields, shutters, collimators, etc., to enhance the sputtered film characteristics or to control the sputtering process, and the present magnet designs and methods are applicable where the source to substrate spacing is increased to accommodate such structures. As a practical matter, sputter sources having a wafer-to-target distance of 2 to 10 cm are now in use.
Another geometrical parameter that must be considered in the calculation of the desired erosion profile is the relative sizes of the sputter target and the wafer. If uniformly eroded, a target that is larger than the substrate will result in considerable waste of sputtered material. On the other hand, if the target is similar in size or smaller than the wafer, it will be more difficult to achieve adequate deposited film uniformity. Such a configuration would also make it difficult to achieve adequate "step-coverage" in the deposited film, where step coverage is a well-known measure of the ability of the film to coat angular features on the device depending on which way those features were facing. There would be a low flux of sputtered material arriving at the wafer at angles toward the perimeter and, thus, it is likely that outwardly facing features near the edge of the wafer would not receive an adequate coating of sputtered film. On the other hand, inwardly facing features at the same location would likely receive an adequate coating of sputtered film since the flux of material would be from angles corresponding to the center of the target.
Most modern integrated circuit devices are now being made on eight-inch diameter wafers, and prior-art sputter targets have diameter as large as 11.64 inches, i.e.,the edge of the target extends almost two inches beyond the edge of the wafer.
Yet another parameter that should be considered in calculating the optimum sputter target erosion profile is the operating pressure of the sputter system. While the sputtered atoms might leave the surface with a certain angular distribution, collisions between gas molecules (or plasma ions) and sputtered atoms might alter the trajectories of the sputtered atoms before they reach the wafer surface. The scattering effect of gas collisions on the angular distribution of sputtered atoms reaching the surface of the wafer can be calculated. It has been found, in the context of the operating parameters used here that gas collisions might or might not be a significant factor depending upon the total pressure used during sputtering. The effects of gas scattering can be reduced with close coupling between the target and the substrate and low operating pressure of the sputtering system, i.e., 1 millitor.
Thus, using this method for determining the desired target erosion profile involves first determining the geometry of the system. In particular, knowledge of the target-to-substrate spacing and the diameters of the target and the substrate are required. Next, one defines a mathematical function which approximates, at least to the first order, the distribution of sputtered atoms leaving the surface of the sputter target at the operating conditions of the sputter source. Finally, if necessary, an adjustment is made to the distribution function to account for gas scattering effects.
With the foregoing information in hand, it is then possible to calculate a target erosion profile that will result in the application of a uniformly thick sputtered film on the surface of the wafer. The calculation is based on the fact that the erosion rate at a point on the surface of the target is a measure of the sputtering rate from that point. Such a calculation can be performed using a variety of computer modeling techniques of the type that are well known in the art. It should be noted that there will be more than one erosion profile that will produce uniform sputtered film deposition. It is desirable to select an erosion profile which both produces a uniform film and, to the greatest extent possible, makes the best use of the target material, and low particulation by avoiding target areas of net build up.
Having arrived at a desired erosion profile in the foregoing manner, it is then possible to configure the magnet, in the manner described above, to obtain the desired erosion profile.
This technique has, thus far, been described as two separate procedures, i.e., a procedure for calculating a desired erosion profile and a procedure for configuring a heart-shaped, closed-loop magnet to obtain the desired erosion profile. These two procedures can be combined into a single method in which all the necessary information is entered into a computer model. The effect on sputtered film uniformity due to minor perturbations in the position of the magnet centerline at one or more locations can then be directly calculated. One could use such a combined model to prescribe a suitable magnet configuration for a given set of parameters.
The flow of the process whereby the sputtered film uniformity is directly calculated with changes in the magnet position is as follows. As described above, the first step is to form a static erosion groove on the surface of the sputter target. The depth of target erosion is then measured at a finite number of points as a function of radius, r, and angle, .theta. on the surface of the target. For selected values of .theta., fifth order polynomials are constructed to fit the observed data, and the polynomials are entered into an array. For simplicity, the fifth order polynomial for a particular .theta. is made relative to the centerline of the magnet used to generate the static erosion groove.
The coordinates of the centerline of a new magnet shape to be tested are then entered into an array and the distance from each value of radius, r, and angle, .theta. used in the array to the new magnet centerline is calculated and entered into an array. Preferably, the position of the centerline of the new magnet does not vary significantly at any given location from the position of the centerline of the magnet used to form the static erosion groove. A static erosion depth calculation is them made for each value of radius, r, and angle, .theta. based on the new magnet positions. The calculated static erosion depth information is then integrated over a revolution of the magnet to obtain a calculated erosion profile associated with the new magnet positions.
The uniformity of the sputtered film is then calculated, using the target erosion profile calculated above. As described above, the calculation of film uniformity should take into account the geometry of the sputtering system as well as the characteristics of the material being sputtered and any significant gas scattering effects. The calculation involves a double integration so that the effects of the release of material at a given rate and at a given distribution from each point on the target is assessed for each point on the wafer. The double integration involves calculating, for each point on the surface of the wafer, the amount of material that will be deposited. This, in turn, involves integrating the flux from each point on the target both as a function of angular position and as a function of radial position. After the uniformity information is thus calculated, a judgement is made as whether acceptable uniformity has been achieved, i.e., the calculated uniformity for each of the points of the wafer is compared to determine the variance in film thickness across the wafer surface. If acceptable film uniformity has been achieved, i.e. if the variance has been minimized, the method is complete and the magnet shape is constructed. If the film uniformity is not acceptable, or if it is thought that further improvement might be achieved, the magnet shape is further perturbed and the process is repeated again from that point.
A systematic approach to perturbing the magnet is as follows. Starting with the magnet shape that is used to form the static erosion groove, a new magnet is defined wherein the position of the magnet is changed at only one point, which might be at any selected value of .theta.. After the sputtered film uniformity for this new magnet is calculated, the uniformity obtained is compared with the uniformity obtained by the prior magnet configuration. If the uniformity is improved, the same magnet position is further adjusted in the same direction and another uniformity calculation is made. If the uniformity is degraded, the magnet is moved in the opposite direction and a new uniformity calculation is made. The first magnet position is iteratively adjusted until no further improvement in uniformity is obtained. Thereafter, the next magnet position is adjusted and the same procedure is followed until no further adjustment of the second magnet produces improved uniformity. This process is repeated for all of the magnet positions in sequence, after which the entire process can be repeated as many times starting again at the first magnet position. This systematic approach lends itself quite well to automation, and can be implemented easily by a computer program. Other, equivalent systematic approaches will be apparent to those skilled in the art. For example, one might limit the adjustments of any given magnet position to a set number during each "loop" around the magnet.
Up until now, this method has been described solely in the context to measuring a static erosion groove to determine the "effective" magnet shape. While this is the preferred manner of implementing the method, other methods are possible. For example, it is possible to measure the "effective" magnet position by observing the position and intensity of the plasma created by a starting magnet. Modern techniques allow one to accurately measure the plasma intensity at a finite number of preselected points over the target, and this information could be used as a substitute for the information obtained from a measurement of a static erosion groove. It is believed, however, that the plasma intensity information would not be as accurate and is, therefore, less preferred.
While the flow of the process has been described solely in the context of sputtered film uniformity, other sputtered film characteristics can also be taken into account. For example, a calculation of the step coverage produced by the new magnet configuration or of the via-filling properties could be used. While the present techniques for via-filling involve steps which go beyond simple sputtering, the ability to deposit a suitably thick layer of film at the bottom of the via is an important aspect of the process. It should be apparent from geometrical considerations that the ability to fill the bottom of a narrow via is related to the angular distribution of the atoms of sputtered material striking the surface of the wafer. Thus, sputtered atoms which are incident at the wafer surface in a substantially perpendicular direction are likely to reach the bottom of a via, whereas atoms which are incident at a sharp angle will be intercepted by a wall of the via before reaching the bottom.
Likewise, more than one film characteristic can be calculated, with the goal of optimizing the balance between them. For example, improved uniformity caused by a particular magnet perturbation might be offset by degraded step coverage.
U.S. patent application No. 471,898, which is a continuation-in-part of the '958 patent, and which is also hereby incorporated by reference, extends the teachings of the '958 patent so that magnet arrays can be constructed for use with non-planar sputter target surfaces to produce arbitrarily selected erosion profiles. A condition required by the '898 application is that the sputter target surface be a surface of revolution. The '898 application teaches that the centerline of the closed loop magnet array should lie on a curve defined by ##EQU4## where .xi.(r) is a preselected erosion profile to be generated in the curved target when the magnet is rotated and sputtering is performed, z(r) is a surface of revolution defining the surface of the sputter target, and C is a selected constant.
Like the '958 patent, a premise of the '898 application is that the magnetic field intensity adjacent to the target surface is greatest directly above the centerline of the magnet array so that the shape of a static erosion groove would conform to the shape of the magnet. Again, it will be apparent to those skilled in the art that the methodology of the present invention can be applied to magnets configured in accordance with the '898 application to compensate for discrepancies between the actual and the effective magnet array shapes.
This description of the prior art pertinent to the subject invention clearly indicates the complexity of the art and the difficulty of following the strict dictates of a mathematical analysis. The interaction of a plasma with magnetic and electric field is not a trivial problem even in an idealized environment. In the real environment of complex geometries and non-uniform materials, mathematical analysis and the intuition of those experienced in the art has not been adequate to find solutions to the problems. Indeed, one of the inventors of the '958 patent, was requested by the applicants of this invention to model magnetic fields of the invention claimed here and he indicated that the small changes in magnetic field predicted might not be useful. In fact, tests have proven our invention to be effective. It is clear that the magnetic field models are inadequate for predicating the associated plasma responses and use of empirical methods is still necessary in this complex technology.

Sputtering apparatus having a rotating magnet array and fixed electromagnets


There are disclosed an instrument and method for using near IR to discriminate between healthy and diseased tissue, using, e.g., a catheter and a spectrophotometer. Near IR is passed at certain wavelengths to suspected tissue, and reflected light is analyzed to determine the absorbance, and preferably the second derivative thereof. From identification of the absorption spectra of known diseased and known healthy tissue, a relation has been established to determine the following correlation equation for determining the predictive value of y: EQU y=Co+C.sub.1 A(.lambda..sub.1)+C.sub.2 A(.lambda..sub.2). wherein A(.lambda..sub.1)+A(.lambda..sub.2) are the second derivatives for the absorbance at the two selected wavelengths. For blood cholesterol esters and plaque, .lambda..sub.1 is preferably 1714.5 and .lambda..sub.2 is preferably 1678.5 nm. Solving for the coefficients Co, C.sub.1 and C.sub.2, it has been shown that values of y less than -8.0 represent diseased tissue, which should be treated. Ablation laser treatment is described as one mode of treatment.

As has been noted in several technical journals recently, atherosclerosis is a leading cause of non-accidental death in the United States. Because the two conventional treatments, bypass surgery and balloon angioplasty, have known disadvantages, laser angioplasty is being turned to as a more effective therapeutic technique.
Even laser angioplasty has its problems, however. Chief of these is the inability to quickly distinguish between "friend" and "foe", that is, between healthy vascular tissue and the diseased plaque. Conventionally, transluminal illumination is delivered to and subsequently received from tissues, such as by diffuse reflection or direct transmission, to identify and distinguish plaque from healthy tissue. The same optics are then used to deliver therapeutic laser light to ablate diseased tissue. In the past, illumination has used light in the near UV region, and the detection has been based upon fluorescence. In some cases, the detected fluorescence was of certain fluorophors claimed to exist in the plaque. Still others are said to detect the natural fluorescence of both plaque and healthy tissue, and compare the signal with predetermined values that are said to represent healthy tissue or plaque. Such a system is described in U.S. Pat. No. 4,718,417 and in Lasers in Surgery and Medicine, Vol. 9, page 109-116 (1989). The latter describes the following equation to determine a so-called LIF ratio for the comparison: LIF=Co+C.sub.1 I.sub.F (.lambda..sub.1)+ . . . +C.sub.13 I.sub.F (.lambda..sub.13), using 13 different wavelengths to detect the fluorescence.
In either case, there are disadvantages in such prior systems. First of all, the illumination uses near UV light, which has very low penetration power of slightly less than 100 .mu.m thickness, "Optics of Human Skin", Journal of Investigative Dermatology, Vol. 77, p. 13-19 (1981). To avoid ablating the wrong (healthy) tissue, such detection techniques require the laser to also ablate only on that order. A thin layer of ablation means that the total removal time is prolonged, and more illumination and detection, and thus delay, is required to remove the same amount of diseased tissue. In any event, delays while double-checking the site cannot be easily skipped--failure to identify tissue as healthy before ablating it with laser energy can lead to vessel perforation. The risk of such perforation is considered to be "the major impediment to safe and effective laser angioplasty" in current technology, Applied Optics, Vol. 27, No. 9, p. 1844 (May 1988). The delay just mentioned is further aggravated when using fluorescence for detection--laser ablation light tends to dehydrate remaining plaque, which in turn can quench the fluorophore. To avoid this, an operation may have to wait up to 10-20 minutes for sufficient rehydration to occur. Such a wait is intolerable, when several ablative "blasts" are needed to get through the plaque 100 .mu.m at a time.
Second, the inability to detect deep tissues has a further problem in that it cannot detect, until it is too late, that all of the vascular wall at a particular point has been converted to diseased tissue. That is, even the media tissue may be diseased, leaving only adventitia underneath it. That however can have a thickness of only 100 .mu.m. Since the ablation removal conventionally is up to about 100 .mu.m, the system that can "see" only less than 100 .mu.m may end up seeing 80 .mu.m of plaque and 20 .mu.m of adventitia, identify it as primarily plaque, and undesirably ablate away all but 80 .mu.m of the vascular wall.
Third, another difficulty exists in relying on fluorescence of plaque--not all plaque is homogeneous; nor do all diseased vascular tissues fluoresce. In fact, plaque has been found to contain some or all of the following: lipids, connective tissues, thrombus, necrotic tissues, mineralized deposits, smooth muscle cell tissues which have proliferated from the vessel wall, as well as other constituents. Therefore, it is very difficult to be sure the fluorescence is complete enough and specific enough to permit the simultaneous multicomponent analysis capability that is an essential prerequisite of an effective and safe "smart" laser angioplasty system. That is, many plaque constituents "look like" other healthy body tissues. For example; platelets that deposit onto the surface of an artery (such as in response to a small, naturally occurring injury in the arterial wall) can exude growth factors which will cause the healthy smooth muscle tissues of the vascular wall to grow into the arterial lumen. Such occlusive tissues are likely to look no different from those smooth muscle tissues which make up the media--the thickest element of the vascular wall. Because healthy tissues can appear in "unhealthy" states, such "diseased" tissues are very difficult to identify and discriminate from similar healthy tissues by using fluorescence.
Fourth, there occasionally arise some conditions that produce a thin surface film such as lipid deposits on the healthy tissue that appear to be plaque, but in fact are not because underneath the very thin film (about 50-100 .mu.m) is healthy tissue. A discrimination system using near UV illumination and fluorescence detection can very easily misinterpret such conditions, leading to dangerous attack on healthy tissue. Such attacks can produce acute responses such as a clot. An example of such a condition follows hereinafter.
Examples of prior art patents using the near UV illumination and detection of fluorescence as described above, also include U.S. Pat. No. 4,641,650. Some such prior art techniques rely on the addition of a dye to preferentially "mark" plaque. However, dyes are inherently a systemic foreign agent, subject to risk and governmental regulation. Accordingly, dyes are to be avoided if possible.
Non-UV laser light has been used to examine tissue to identify abnormal conditions. For example, U.S. Pat. No. 4,449,535 teaches the use of a dye laser operating at a wavelength of 805 nm, the region of the very-near-infrared. The difficulty with that kind of detection system is two-fold: i) the wavelength of 805 nm is incapable of detecting two key materials of plaque in blood vessels, namely cholesterol esters and calcification, and ii) dyes for such dye lasers are not suitable for operating in wavelengths determined by the instant invention to be more appropriate for cholesterol esters and calcification.
Yet another example of the use of non-UV light for disease detection is described in U.S. Pat. No. 4,509,522. This describes the use of mid-infrared lasers operating at 5130 nm, to detect the absorption band of carbon monoxide (column 2, line 39). Such radiation is said to be carried over a fiber optic, if the exposure occurs at locations remote from the skin. This technique also suffers two disadvantages: i) the 5130 nm wavelength, although suitable for CO, is not suitable for the detection of the primary plaque components in atherosclerosis (cholesterol esters and calcification); and ii) there is no non-toxic fiber optic known to man that will transmit 5130 nm radiation.
Thus, prior to this invention there has been a need for a quick, yet accurate laser angioplasty instrument that allows for immediate identification of diseased tissue from healthy tissues before firing the laser, particularly such instrument capable of treating atherosclerosis. Such an instrument is desired for its ability to identify and discriminate between all types of diseased and non-diseased tissues, of which atherosclerosis is but one type.

Near infrared diagnostic method and instrument


A method, system, and/or computer program product adjust values of a plurality of conditions. A processor receives a user input, which is a movement across a user interface. A tendency of the movement, which describes a direction and velocity of the movement, is determined. According to the tendency of the movement, a processor adjusts a value of at least one of the plurality of conditions by using a plurality of graphs representing the plurality of conditions, where the plurality of conditions describe search criteria, and where the user input describes the search criteria.

The present invention relates to information processing, and more particularly, to a method and system for adjusting values of a plurality of conditions.
With the exponential growth of information, finding the right information has much challenge than ever. A user expects to find desired information more rapidly and accurately, but some existing solutions are unable to meet the user's expectations. Normally, a user uses interface elements such as checkboxes, radio buttons, pull-down menus, sliders, and through multiple repeated operations, finally filters out information close to what he/she desires. However, when there are a plurality of conditions (i.e., search criteria) that must be met, these operations will be more inefficient and time-consuming. In addition, current solutions are unable to adjust values of a plurality of conditions simultaneously.

This patent is subject to a terminal disclaimer.

Adjusting values of a plurality of conditions

International Business Machines Corporation


The invention relates to a device for cleaning the ink roller of a printing press. There are two embodiments. There is an ink pan and cleaning blade assembly. The cleaning blade is adapted to engage the ink roller to clean the same. There are mounting brackets attached to the press frame.. There are angle brackets which include saddles adapted to receive flanges on the ink pan and cleaning blade assembly. There are locking levers on the angle brackets having use and non-use positions. When in use the locking lever cooperates with the saddles to lock the ink pan and cleaning blade assembly in position on the angle bracket. When not in use the locking lever is maintained in an out-of-the-way position. There are cam means which cause movement of the angle bracket and hence the ink and pan cleaning blade assembly so that the cleaning blade can contact or not contact the ink roller, as desired.. In one embodiment the cam means causes movement of the angle bracket through a plurality of levers which form with the ink pan and cleaning blade assembly a parallelogram-like structureso that the cleaning blade moves linearly into engagement with the ink roller.. In the other embodiment the angle bracket is pivotally attached to mounting plate and the cam directly engages the angle bracket to cause pivotal movement of the cleaning blade into engagement with the ink roller.

This invention relates to a new improved construction for the cleaning of ink rollers, sometimes referred to as press washers, and more particularly to a new and improved mechanism for cleaning the ink roll of a printing press. In lithographic printing presses it is necessary to clean the ink rollers when the press is shutdown since the ink will become dried on the rollers and affect the quality of subsequent printing. Also from time to time it may be necessary to change the color of ink being used; for this reason it is necessary to clean the ink roll so as to prevent contamination of the new color.


A device to assist manual tightening of a rope passed over a load on a vehicle. In use the device is first attached to the rope by passing the rope over ridge (14), through hole (13) and around neck (18); tensioning may then be achieved by pulling on the rope, after it has been looped (by 180 degrees) around a fixed anchorage on the vehicle and then around hook-like tensioner (15). The taut rope is secured by again passing it around a fixed anchorage point and then winding it around neck (19) and under the rope lying between ridge (14) and a hole (13). An alternative device has two tensioners (15) and is used similarly to the above.

Commonly, the payload on trucks is stabilieed by the process of tying one end of a rope to one fixed point of the truck, extending the other end of the rope around the load, looping the rope about a fixed receiving point, then securely tightening the rope around the load by tying a hitch knot back at a point along the length of the rope. However, the jolting motion of the truck causes the load to exert a force against the rope, leading to a loosening of the grip of the knot. The risk of the load moving independently of the truck poses a foreseeable risk of danger. Furthermore, the knot itself may threaten to interfere with vehicles passing nearby. For instance the loop of the hitch knot normally extends some distance from the side of the truck when not properly concealed, and can attach to vehicles passing in close proximity.

Method for securing load using rope tying device


A method of (and apparatus for) applying and adhering an adhesive-backed label to the surface of a material (e.g., the butt end of a board) in the presence of a contaminant (e.g., sap) that neutralizes the adhesive forces of the adhesive. The method includes the serial steps of applying a surface preparation layer or substance (e.g., a hot-melt adhesive) to the material, the layer (or substance) being compatible with the material to be labeled and the adhesive of the label and being further capable of displacing the contaminant in such a way as to restore the adhesive force between the label adhesive and the material to be labeled; and, immediately thereafter, applying the adhesive surface of an adhesive backed label to the surface thus prepared, that is, onto the surface preparation layer.

The present invention relates to an effective way to cause two objects to adhere together in spite of the presence of a third material which tends to neutralize adhesive forces therebetween and, more particularly, to apparatus (and method) to apply gummed labels (e.g., bar-graph labels) to surfaces that have immersed solvents and like contaminants thereon.
The art of labeling and machines to achieve labeling (e.g., bar code or other labels) are discussed in some detail in applications for U.S. Pat. No. 328,286, filed Mar. 24, 1989 (Murphy) (now U.S. Pat. No. 5,013,156) and U.S. Pat. No. 386,214 filed Jul. 28, 1989 (Murphy) (now U.S. Pat. No. 5,000,812). It is noted in the applications that label applicators of IMTEC, INC. of Bellows Falls, Vt., and others are in widespread use, that is, well known in this art. Hence, it is not necessary for present purposes, to explain in exhaustive detail how label applicators work to perform their functions. Thus, later herein, a label applicator is shown as a block marked "LABEL APPLICATOR"; nothing more is needed for, although the applicator so marked is part of the total inventive concept here, details of such applicator are not needed because workers in the art are familiar with such details; the essence of this invention lies elsewhere.


A pocket garb composed of front and back pieces is provided with pockets of large capacity on the front and back pieces, wherein the back piece pocket has two upper and lower openings, available to be separated with a partition in the middle, the said large pocket can be partitioned into two small pockets for use according to requirement, the front piece pockets have a side opening each adjacent to a joint of a left piece and a right piece, with a covering attached on it to cover up pocket openings, shoulder parts of the said pocket garb are fastened with fastenings, the garb can be developed into a flat piece after untieing the fastenings to facilitate putting in or taking out articles. When going out, valuables, bank notes, credentials, etc. can be put into the garb and safety can be guaranteed on wearing it.

The present invention relates to a garb, particularly to a garb with large capacity pockets.
At present, many countries in the world are rampant with robbers and thieves everywhere. Robbers and thieves are known to go after any of various types of valuables including bank notes, checks, remittance bills, credit cards, passports, and important documents carried by persons performing daily routine transactions, such as making purchases, collections, deliveries, tours, etc. On occasions when people go to the bank to draw a large sum of cash, or when owners of stores or restaurants take their daily cash receipts home or to deposit in the bank, they have to carry large sums of cash by themselves; when salesmen are on a trip to promote sale of goods, they also have to carry expensive samples as wrist watches, jewelry, necklaces and designs. Generally, such articles are carried in a portfolio, suitcase or handbag. However, such containers are visible and easily to be stolen, looted or lost. If these valuables are to be held in garb pockets, ordinarily the pockets are too small and inadequate.


A liquid ejecting apparatus includes: a liquid ejecting head that ejects liquid which is supplied from two or more liquid housing portions that house liquid; two or more housing portion side flow paths which are provided to correspond with each of the liquid housing portions and which supply liquid from an upstream side that is a side of the liquid housing portions to a downstream side; and a flow mechanism which is capable of causing liquid to flow in the housing portion flow paths, and the flow mechanism causes liquid to flow in a housing portion side flow path corresponding with a liquid housing portion that does not supply liquid for a predetermined time set in advance among the housing portion side flow paths.

1. Technical Field
The present invention relates to a liquid ejecting apparatus that supplies liquid housed in a liquid housing portion via flow paths to a liquid ejecting head and a liquid supplying method for the liquid ejecting apparatus.
2. Related Art
A printer (liquid ejecting apparatus) which supplies ink (liquid) housed in an exchangeable cartridge (liquid housing portion) to a liquid ejecting head and ejects ink to a target from the liquid ejecting head to perform printing has been known (see JP-A-2004-98365).
In such a printer, even when liquid that has been housed in the cartridge is run out of, it is possible to perform printing by exchanging the cartridge with new one. However, when it is necessary to exchange cartridges during printing, printing must be interrupted. Then, there cause mottled patterns in printing matters and printing quality may be reduced.
Accordingly, a printer is proposed in which a plurality of cartridges are coupled to the liquid ejecting head, and even when ink housed in one cartridge is run out of, it is possible to supply ink from another cartridge and continue printing.
There is a type of ink such as pigment ink which causes precipitation or aggregation as time passes and causes concentration imbalance. Therefore, when such ink is supplied to the liquid ejecting head, there sometimes causes concentration imbalance in ink in a flow path which couples the liquid ejecting head to the cartridge.
That is, when a plurality of cartridges are coupled, ink flows in a flow path which couples the cartridge for supplying ink (supply liquid housing portion) and the liquid ejecting head. Therefore, concentration imbalance in ink in a flow path is not easily caused. However, since in a flow path (housing portion side flow path) corresponding to another cartridge (non-supply liquid housing portion), ink stagnates to be stopped, and concentration imbalance is easy to be caused.
Note that such a problem is not limited to a printer which supplies ink housed in the cartridge to the liquid ejecting head via a flow path. That is, such a problem is generally common to the liquid ejecting apparatus that supplies liquid housed in the liquid housing portion to the liquid ejecting head via flow paths and the liquid supplying method for the liquid ejecting apparatus.

Liquid ejecting apparatus and liquid supplying method for liquid ejecting apparatus


Novel aqueous titanium compositions comprising mixtures of at least two titanium compounds, at least one of which effects cross-linking of hydroxyl-containing materials more rapidly than at least one other titanium compound; the use of such organic titanium compositions in a novel process for hydraulically fracturing oil- and/or gas-containing subterranean formations; and aqueous compositions useful in such a process.

Titanium esters react with high molecular weight hydroxyl-containing compounds so as to cross-link them and produce gels, J. Oil and Colour Chem. Assoc. 31, 405 (1948). As the cross-linking rate of simple alkyl esters of titanium is too fast for some industrial uses, it has been depressed by combining titanium esters with a variety of multifunctional compounds; e.g., the complex condensation products prepared by Shacklett, U.S. Pat. No. 2,870,181, by reacting an organotitanate with an .alpha.-hydroxy carboxylic acid such as lactic acid; the organic titanate chelates obtained by reacting alkyl titanates with 2,4-pentanedione or an acetoacetate, U.S. Pat. No. 2,680,108; also those prepared by reacting alkyl titanates with alkanolamines, U.S. Pat. Nos. 2,950,174 and 3,301,723.
The production of oil and gas can be stimulated by a technique, known as hydraulic fracturing, in which a fluid composition is introduced into an oil- or gas-containing subterranean formation at a flow rate and pressure which create and/or extend a fracture into the formation. The fluid composition usually carries a proppant (e.g., sand, bauxite, etc.) which is forced into the fracture by the fluid composition and prevents closure of the fracture after the fluid pressure is released. For example, Tiner, et al., U.S. Pat. No. 3,888,312, disclose effecting hydraulic fracturing of a subterranean formation by using an aqueous gel prepared from a solvatable polysaccharide which had been cross-linked with an organotitanate chelate prepared by reacting tetraisopropyl titanate with triethanolamine. The rate at which such aqueous gels are cross-linked by such an organotitanate chelate can be retarded further by adding a polyol to the aqueous gel prior to admixing it with such an organotitanate chelate, Hollenbeak et al., U.S. Pat. No. 4,464,270. On the other hand, Conway, U.S. Pat. No. 4,462,917, retarded the cross-linking rate of that same organotitanate chelate by admixing it with a polyol and aging the admixture for 3 to 12 weeks prior to combining the same with the aqueous gel.
The fluid composition used in hydraulic fracturing comprises an aqueous fluid (usually water or aqueous alcohol), a polymeric gelling agent (e.g., a solvatable polysaccharide), and a cross-linking agent. The aqueous fluid is used to solvate the gelling agent, and the solvated gelling agent, which is to be cross-linked, is typically referred to as the "base gel." The pH of the base gel can be adjusted with various buffering agents prior to cross-linking. The rate of cross-linking determines the rate of viscosity development in the fluid composition. It is desirable to control the rate of cross-linking so that the development of viscosity is delayed until the composition is placed in the subterranean formation.
Several factors influence rate of cross-linking. It is directly proportional to the concentration of the polymeric gelling agent and the temperature of the base gel, so that an increase in the gelling agent concentration or the gel temperature causes an increase in the rate of cross-linking. 0n the other hand, as the temperature of the subterranean formation is cooled by injection of the fluid composition, the rate of cross-linking decreases. The pH of the base gel has its effect on cross-linking as well; as the pH of the base gel increases from 7.0 to 8.5, the rate of cross-linking increases. Because more than one batch of base gel is used in any fracturing job, and because conditions such as base gel temperature and formation temperature vary from job to job and with the time of year, it is desirable to use a cross-linking agent or agents which have a variable or adjustable rate of cross-linking to compensate for these changes and provide a reproducible viscosity development time after time.
Cross-linking agents having a high rate of cross-linking may give a cross-linked gel (e.g., from hydroxypropyl guar) which exhibits poor retention of viscosity with time, also with increased temperature. Moreover, use of such high rate cross-linkers may give gels which develop high viscosity while the gel is being pumped down to the subterranean formation, resulting in shear degradation which reduces or destroys the capacity of the base gel to maintain the proppant (e.g., sand) in suspension. As a consequence, the proppant may drop out of suspension (a "screen-out") and may block the bottom of the well tubing. Excessively high viscosities are not encountered in pumping gels cross-linked with low rate cross-linkers, and therefore such cross-linkers avoid shear degradation. But one may none-the-less experience screen-outs with the use of low rate cross-linkers because the gel fails ever to reach a viscosity high enough to keep the proppant in suspension while being pumped down into the formation.

Organic titanium compositions useful as cross-linkers


The free-running operation of a load sheave of a chain lever hoist is assured by an assist mechanism that keeps the relative position between a hub and a spindle of the hoist at a brake inactive position, when the screwing control position of the hub relative to the spindle has been shifted from a winding operation position to a free-running operation position. operator can easily switch the hoist to the free-running operation made by slightly turning a hub knob and a spindle knob by hand. Such an operation eliminates steps such as holding the chain by hand, or turning the spindle while the hoist lever is engaged with the hub. The above operation frees an operator from getting his hands dirty with the chain, and permits an immediate switching to the free-running operation. The use of indicators allows the operator to recognize the free-running operation setting at a glance.

1. Field of the Invention
The present invention relates to a chain lever hoist that raises or lowers a load by means of a manually operated lever action and has a feature to allow its chain to run freely.
2. Description of the Related Art
A chain lever hoist must offer free-running operation of its chain wheel in shave, sometimes called a "load sheave", to allow for the free running of the chain, in addition to raising or lowering operation (hereinafter referred to as upward or downward winding operation), of the load chain by means of a lever action.
FIG. 13 shows one type of conventional chain lever hoist known as a spring chain lever hoist that comprises a mainframe (I), a load sheave (Ro) freely rotatably supported by the mainframe (I), a spindle (Ha) supported by the mainframe (I) in a manner that allows the spindle to integrally rotate with the load sheave (Ro), a fixed friction plate (Ni) secured to the spindle (Ha), a hub (He) into which the spindle (Ha) is screwed and which is rotated by a lever (Ho) that is pivoted around the spindle (Ha), a ratchet gear (To) with two brake linings (Ti, Ti) arranged respectively on each side of the rachet gear (To) between the fixed friction plate (Ni) and the hub (He) in such a manner that the ratchet gear (To) rotates freely around the spindle (Ha), and a ratchet pawl (Ri) that is mounted on the mainframe (I) in such a manner that the ratchet pawl (Ri) engages with the ratchet gear (To) to be allowed to rotate only in the direction of the upward winding operation. The distance between the fixed friction plate (Ni) and the hub (He) can be adjusted or varied by rotating the hub (He) i.e. screwing it more or less onto the spindle (Ha), in such a way as to squeeze or release the ratchet gear (To) and the brake linings (Ti, Ti). Furthermore, as an assist mechanism, a coil spring (Nu) is disposed between the fixed friction plate (Ni) and the hub (He) so that the force of the coil spring (Nu) constantly, urges the hub (He) outwardly (to the right-hand side in FIG. 13), thereby reducing the contact pressure between the brake lining (Ti) and the hub (He), and thus decreasing the braking effect.
A discussion of the operation of the conventional spring chain lever hoist follows. To carry out an upward winding operation, a switch pawl (Ru) first operated to engage with a switch gear (Wo) of the hub (He) in the upward winding direction, whereby the hub (He) is allowed to rotate only in the upward winding direction. The lever (Ho) is pivoted in the upward winding direction, and the torque generated by a suspended load on the chain causes the hub (He) to be screwed inwardly along the spindle (Ha) in such a manner that the hub (He) and the fixed friction plate (Ni) squeeze the ratchet gear (To) and the brake linings (Ti, Ti) therebetween. Thus, the torque of the lever (Ho) is transmitted from the hub (He) to the load sheave (Ro) via one brake lining (Ti), the ratchet gear (To), the other brake lining (Ti), the fixed friction plate (Ni), and the spindle (Ha). The ratchet gear (To) rotates with the ratchet pawl moving or oscillating thereon, causing the load sheave (Ro) to rotate in the upward winding direction. The load is thus lifted up.
To carry out a downward winding operation, the switch pawl (Ru) is operated to engage with the switch gear (Wo) in the downward direction, whereby the hub (He) is allowed to rotate only in the downward winding direction. The torque generated by a suspended load causes the hub (He) to be screwed inwardly along the spindle (Ha) in such a manner that the hub (He) and the fixed friction plate (Ni) squeeze the ratchet gear (To) and the brake linings (Ti) therebetween in the same manner as in the upward winding operation. When the lever (Ho) is pivoted in a downward winding direction, however, the squeezing force is decreased by the torque of the lever (Ho). Thus, the fixed friction plate (Ni) slides against the ratchet gear (To), and the fixed friction plate (Ni), the spindle (Ha) and the load sheave (Ro) rotate in the downward winding direction in accordance with the degree of rotation of the hub (He). Thus, the load is lowered.
To carry out a free running operation, the switch pawl (Ru) is operated to disengage from the switch gear (Wo), whereby the lever (Ho) is disengaged from the hub (He). The hub (He) is rotated to be spaced apart from the fixed friction plate (Ni), and the contact pressure of the hub (He) against the ratchet gear (To) and the brake linings (Ti, Ti) is reduced. The coil spring (Nu) urges the hub (He) outward, rendering the braking action ineffective. Thus, the load sheave (Ro) is allowed to rotate freely.
In lever hoist of this type described above, it is common for a heavy duty hoist with a load capacity of 0.5 tons or more to have its load sheave and spindle linked through a plurality of reduction gears as shown in FIG. 13. However a light hoist with a load capacity of less than 0.5 tons commonly has its load sheave and spindle connected to each other directly.
In the above-described conventional spring lever hoist, the following problems arise. The assist mechanism comprising coil spring (Nu) blocks the screwing control position of the hub from returning to the winding operation position, when the screwing control position of the hub (He) relative to the spindle (Ha) is shifted. To perform the above operation, the hub (He) must be rotated while the chain is held by hand, or the spindle (Ha) must be rotated while the lever (Ho) is engaged with the hub (He) (typically by allowing the switch pawl (Ru) to engage with the switch gear (Wo) of the hub (He)). The first method permits an immediate switching to the free-running operation, but an operator must use both hands and gets his hands dirty in the operation. The second method allows a single-handed operation, but the operation is a two-step sequence because a locking engagement step is involved. In the second method, the rotation of the spindle may be carried out by pulling the chain. This option may be useful when the spindle (Hal is out of reach of the operator's hand. However, the operator is not freed from getting his hands dirty, and the operation remains a two-step sequence. Also, the operator cannot judge the operation position or mode by just looking at the switch pawl, because the appearance of the switch pawl does not show the condition of whether the contact pressure of the hub against the ratchet gear and the brake linings is reduced or not.


This invention relates to a process for preparing a magnetic disk, which comprises (a) subjecting a substrate having an anodized aluminum film to mirror surface-finishing, (b) widening pores of the anodized aluminum film by chemical dissolution treatment so that the total area of pores becomes from 20 to 80% of the entire surface area, thereby retaining crystalline alumina of the anodized aluminum film extruded after the chemical dissolution treatment, and (c) coating the resultant substrate with a magnetic continuous thin film.

The present invention relates to a process for preparing a magnetic disk by forming a magnetic continuous thin film on the surface of a substrate. More particularly, the present invention relates to a process for preparing a magnetic disk improved by dissolving problems concerning the friction coefficient of the surface and the sticking to a magnetic head.
A magnetic recording medium using a magnetic continuous thin film (hereinafter referred to as a "magnetic thin film") as a high density recording material is not widely used because of the problems in respect of mechanical durability and the like.
Namely, a recording medium using a magnetic thin film and having a very smooth surface is likely to lead to sticking when brought in contact with a magnetic head. Further, a liquid lubricant applied to the medium is easily removed by the contact with the magnetic head, whereby the friction coefficient increases, thus leading to head crush.
In order to avoid such problems, a mechanical texture method has been attempted in which scratch marks are mechanically imparted to the surface of the substrate by means of e.g. sand paper. However, it is very difficult to impart such scratch marks while controlling not to increase bit errors and not to cause the sticking to the magnetic head. Further, in the mechanically scratched texture, fine burrs exist on the surface, and they tend to peel off upon collision with the magnetic head and thus lead to head crush.
Japanese Unexamined Patent Publication No. 22220/1984 discloses the invention relating to a process for preparing a substrate for a magnetic disk, the improvements of which are to reduce the friction coefficient of the surface of the magnetic disk having a magnetic thin film formed on the substrate and to reduce a sticking force to a magnetic head.
This process comprises subjecting the surface of an aluminum alloy substrate coated with an Alumite layer to mirror surface-finishing, and etching the mirror surface-finished surface to form concave parts having a surface precision of Ra 70-1,400 .ANG..
The mirror surface-finishing in the cited process can be conducted by abrading, rubbing, polishing or other methods, thereby forming the mirror surface-finished surface having R.sub.max of at most 200 .ANG. and Ra of at most 50 .ANG., but in this state, the sticking of a magnetic head occurs. In order to avoid the sticking of the magnetic head, the surface is etched to form convex parts in such manner as to have a surface precision of Ra 70-1,400 .ANG., but this process still has the following problems.
Firstly, the pore area ratio (ratio of the total area of pores to the entire surface area) is constantly about 10% before forming a magnetic thin film since the pores of the Alumite layer are not widened by the mirror surface-finishing and etching steps. Consequently, the contacting area of a magnetic head is relatively large, and it is therefore necessary to enlarge the surface roughness in such manner as to reduce the friction coefficient.
Secondly, the etching is plasma-ecthing carried out in the atmosphere of O.sub.2, Ar.sub.2 or a mixture thereof, and the plasma-etching abrades particles out of the Alumite layer surface by bumping plasma against the Alumite layer. Accordingly, after etching, the surface becomes rough and the surface roughness remarkably varies due to the presence of the abraded powder (SiO.sub.2, Al.sub.2 O.sub.3) in Alumite pores and the impurities (Fe.sub.3 Si and the like) in the Alumite film, which respectively have different etching rates.
In other words, according to the above process, the plasma-etching is employed to secure the required surface precision taking the small pore area ratio into consideration, but the surface roughness after etching remarkably varies, which consequently leads to large variation in the friction coefficient over the entire surface of the magnetic disk. Thus, it is difficult to prevent the sticking of a magnetic head and the head crush, and it is also difficult to reduce the spacing between the magnetic head and the magnetic disk.


A first arbitration unit determines one demand engine torque of static demand engine torques set in a power train driver model and an ECT torque control system. The demand engine torque determined by the first arbitration unit is converted into dynamic demand engine torque by a conversion unit. A second arbitration unit determines demand engine torque for use in control of an engine from among the dynamic demand engine torque converted from the static demand engine torque by the conversion unit, dynamic demand engine torque set by a VDIM system, and dynamic demand engine torque set by a vibration suppression control system. An engine control system controls the engine according to the demand engine torque determined by the second arbitration unit.

1. Field of the Invention
The present invention relates to a control apparatus for a driving source, and more particularly to a technique of setting a dynamic demand value and a static demand value concerning driving force of a vehicle and controlling a driving source according to the demand value obtained by arbitrating the set demand values.
2. Description of the Background Art
Conventionally, there is a known engine in which a value of output torque or the like is determined by an opening position of a throttle valve (hereinafter, also referred to as a throttle opening position) or the like. In general, the throttle opening position is actuated so as to chiefly correspond to a position of an accelerator pedal (hereinafter, also referred to as an accelerator pedal position). However, when the throttle opening position and the accelerator pedal position always chiefly correspond to each other, driving force of a vehicle or the like is not easily controlled irrespective of an intention of a driver for example in the case where the behavior of the vehicle is disordered. Therefore, there is a vehicle provided with an electronic throttle valve actuated by an actuator in an engine so as to be capable of controlling the output torque and the like not depending on the accelerator pedal position. In the vehicle provided with the electronic throttle value, it is possible to set demand engine torque based on the behavior of the vehicle in addition to the accelerator pedal position and control the engine so that actual engine torque is the set demand engine torque.
Japanese Patent Laying-Open No. 2006-290235. discloses a driving force control apparatus including a driver model and a powertrain manager for tuning a characteristic related to human sense other than a hardware characteristic of a vehicle in a target transient property addition calculating unit included in the driver model, and tuning the hardware characteristic of the vehicle other than the characteristic related to human sense in a characteristic compensator included in the powertrain manager so as to distinguish the human sense and the hardware characteristic of the vehicle. The driver model calculates target driving force based on a map in which the target driving force is determined by a vehicle speed for example taking the accelerator pedal position as a parameter in a target base driving force calculating unit (static characteristic), and calculates final target driving force by giving a transient property to the target driving force in the target transient property addition calculating unit. The powertrain manager calculates demand engine torque in the characteristic compensator based on the target engine torque output from a target engine torque and AT gear calculating unit. In the characteristic compensator, a response property of a vehicle G serving as an acceleration generated in the vehicle, that is, a portion depending on the hardware characteristic of the vehicle is compensated.
In order to set final demand engine torque, there is a need to consider dynamic demand engine torque in consideration of the transient property of the engine or the like and also static demand engine torque for example for realizing torque-down or torque-up at the time of shifting of an automatic transmission. The dynamic demand engine torque indicates engine torque in an engine transition state. Meanwhile, the static demand engine torque indicates engine torque in an engine steady state. Therefore, it is not possible to simply compare the dynamic demand engine torque and the static demand engine torque. However, Japanese Patent Laying-Open No. 2006-290235. does not describe how the final demand engine torque is set from the dynamic demand engine torque and the static demand engine torque. Therefore, it is not possible to set the final demand engine torque in consideration of both the dynamic demand engine torque and the static demand engine torque. Consequently, there is further room for improving control accuracy of the engine serving as a driving source.


An indication that a user wishes to conduct a bank transaction is received. An authentication path to be presented to the individual is pseudo-randomly determined. The authentication path comprises a combination of authentication challenges to be presented to the individual. A determination is made whether the user presented valid responses to the authentication challenges. The user is authenticated to conduct the bank transaction based on whether the user is determined to have presented valid responses to the authentication challenges.

Financial institutions such as banks offer their customers (account holders) access to their accounts to perform transactions in a variety of ways, such as via on-line websites, at branch locations, via call centers, and so on. Authentication challenges may be presented to customers to attempt to confirm that the person that is attempting to perform a transaction is authorized to perform the transaction. Authentication challenges may be presented as authentication tasks, in which the customer is asked to perform a simple task that a fraudulent individual ("fraudster") would be unlikely to be able to perform. For example, the customer may be asked to provide a valid signature on a withdrawal slip prior to being permitted to withdraw money from an account. As another example, the customer may be asked to provide a physical object that can be used to authenticate the customer (e.g., driver's license, ATM card, and so on).
Authentication challenges may also be presented as authentication challenge questions in which the person is requested to provide information that is unlikely to be known by a fraudster. For example, in on-line banking situations, customers may be asked to provide a login ID, password and/or other information. The other information may include information that is obtained by the financial institution as a part of opening/maintaining the customer's account (e.g., the customer's date of birth, social security number, and so). The other information may also include other arbitrary information that is obtained from the customer exclusively for purposes of authenticating the customer (e.g., mother's maiden name, favorite high school sport, and so on). Such information is immaterial to the account, and the correctness of the information provided by the customer does not matter, except that the customer must always answer the question consistently in order for the authentication to be successful. For example, for the arbitrary challenge question "what is your favorite high school sport," if the user answers hockey, it does not matter whether the user's favorite high school sport really was hockey, rather, it only matters that the user answer the question consistently.
To increase the level of security, the path to authentication that the customer is required to take may be made longer by adding more authentication challenges. However, too many authentication challenges would make the experience highly inconvenient for customers. The vast majority of transactions are attempted by actual customers and not fraudsters. Only a relatively small percentage of attempted transactions are fraudulent. A tradeoff typically exists between the number of authentication challenges that are presented and the level of security that is obtained. An ongoing need exists to develop techniques for preventing fraudsters from conducting fraudulent transactions.


The present disclosure relates to a trailer tracking apparatus (2) for monitoring movement of a trailer (3) connected to a vehicle (1). The trailer tracking apparatus (2) has a controller (5) comprising an electronic processor (6) having an electrical input for receiving image data (DAT) from an imaging sensor (10) disposed on the vehicle (1). An electronic memory device (7) having instructions stored therein is electrically coupled to the electronic processor (6). The electronic processor (6) is configured to access the memory device (7) and to execute the instructions stored therein. The electronic processor (6) is operable to select a subset of said image data (DATSUB1). One or more element (16) are detected and monitored within the selected subset (DATSUB1) of said image data (DAT). The electronic processor (6) determines movement of the trailer (3) relative to the vehicle (1) in dependence on evolution of said one or more detected element (16) with respect to time. The present disclosure also relates to a method of tracking a trailer (3); and to a vehicle (1) incorporating the trailer tracking apparatus (2).

It is known to use an imaging sensor to track movements of a trailer connected to a vehicle. In order to accurately to track the trailer, prior art systems require that a target is mounted to the front of the trailer. The target can, for example, take the form of three circles arranged in a triangular configuration. An optical camera mounted to the vehicle identifies the target and tracks its movement relative to the vehicle. There are certain shortcomings associated with these prior art systems, notably the requirement that the target is fitted to the vehicle. The initial setup of the trailer tracking system can be time-consuming. In order to track the trailer, the target must be installed in a specified location on the trailer, but this may not be possible depending on the configuration of the trailer. Furthermore, accuracy of the prior art systems may be affected in the low visibility conditions meaning that certain control functions may not be available.
It is against this background that the present invention has been conceived. At least in certain embodiments, the method and apparatus described herein seek to overcome or ameliorate at least some of the shortcomings associated with prior art systems.