The present invention is a polishing pad that planarizes and cleans a semiconductor wafer in chemical-mechanical planarization processes. The polishing pad has a polishing body and a cleaning element positioned in the polishing body. The polishing body includes a planarizing surface, a basin formed in the body, and an opening at the planarizing surface defined by the basin. The cleaning element is positioned in the basin so that a cleaning surface of the cleaning element is positioned in the opening proximate to a plane defined by the planarizing surface. In operation, the cleaning surface periodically engages the wafer when the wafer is engaged with the pad to remove residual materials from the surface of the wafer.

Chemical-mechanical planarization ("CMP") processes remove material from the surface of a wafer in the production of ultra-high density integrated circuits. In a typical CMP process, a wafer is pressed against a polishing pad in the presence of a slurry under controlled chemical, pressure, velocity, and temperature conditions. The slurry solution generally contains small, abrasive particles that abrade the surface of the wafer, and chemicals that etch and/or oxidize the surface of the wafer. The polishing pad is generally a planar pad made from a relatively soft, porous material such as blown polyurethane. Thus, when the pad and/or the wafer moves with respect to the other, material is removed from the surface of the wafer by the abrasive particles (mechanical removal) and by the chemicals (chemical removal) in the slurry.
FIG. 1 schematically illustrates a conventional CMP machine 10 with a platen 20, a wafer carrier 30, a polishing pad 40, and a slurry 44 on the polishing pad. The platen 20 has a surface 22 upon which the polishing pad 40 is positioned. A drive assembly 26 rotates the platen 20 as indicated by arrow "A" and/or reciprocates the platen 20 back and forth as indicated by arrow "B". The motion of the platen 20 is imparted to the pad because the polishing pad 40 is attached to the surface 22 of the platen 20 with an adhesive. The wafer carrier 30 has a lower surface 32 to which a wafer 60 may be attached, or the wafer 60 may be attached to a resilient pad 34 positioned between the wafer 60 and the lower surface 32. The wafer carrier 30 may be a weighted, free-floating wafer carrier, or an actuator assembly 36 may be attached to the wafer carrier 30 to impart axial and rotational motion, as indicated by arrows "C" and "D", respectively.
In operation of the conventional planarizer 10, the wafer 60 is positioned face-down against the polishing pad 40, and then the platen 20 and the wafer carrier 30 move relative to one another. As the face of the wafer 60 moves across the planarizing surface 42 of the polishing pad 40, the polishing pad 40 and the slurry 44 remove material from the wafer 60.
CMP processes must consistently and accurately produce a uniform, planar surface on the wafer to enable precise circuit and device patterns to be formed with photolithography techniques. As the density of integrated circuits increases, it is often necessary to accurately focus the critical dimensions of the photo-pattern to within a tolerance of approximately 0.1 .mu.m. Focusing the photo-patterns to such small tolerances, however, is very difficult when the distance between the photolithography energy source and the surface of the wafer varies due to non-uniformities on the wafer. Thus, CMP processes must create a highly uniform, planar surface.
The surface of a wafer, however, may not be uniformly planar because the rate at which the thickness of the wafer decreases as it is being planarized (the "polishing rate") often varies from one area of the wafer to another. The polishing rate is a function of several factors, some of which are: (1) the uniformity of the slurry distribution across the surface of the wafer; (2) the surface contact rate between the polishing pad and the wafer; and (3) the extent to which residual materials aggregate near the center of the wafer. The slurry distribution varies across the face of the wafer because the perimeter of the wafer scrapes the slurry off the planarizing surface. Therefore, only a thin layer of slurry remains on the pad at the center of the wafer. The surface contact rate also varies across the face of the wafer because the linear velocity of the pad varies from the center of the pad to its perimeter. Lastly, residual particles of planarized wafer material and pieces of the pad can, for example, aggregate at the center of the wafer and form a barrier between the surface of the wafer and the slurry. The barrier of residual materials accordingly reduces the polishing rate at the center of the wafer. Therefore, in light of the above-listed problems, it would be desirable to enhance the slurry distribution, equalize the contact rate, and reduce the amount of residual materials on the surface of the wafer.
U.S. Pat. Nos. 5,020,283 to Tuttle, 5,293,364 to Tuttle, and 5,232,875 to Tuttle et al. disclose several existing polishing pads that enhance the slurry distribution and equalize the contact rate across the face of the wafer. The above-listed patents disclose polishing pads that have a face shaped by a series of voids to provide a nearly constant surface contact rate between the pad and the wafer. The voids also enhance the slurry distribution across the face of the wafer because they hold a small volume of slurry that is not scraped off the pad by the perimeter of the wafer. The above-listed patents, however, do not significantly reduce the amount of residual materials on the wafer.
Another objective of CMP processes is to minimize the number of defects on the finished planarized surface. The surface of the wafer is often damaged during the planarization process because residual particles from the pad or the wafer scratch the surface of the wafer. Thus, it would be desirable to develop a pad that reduces surface damage caused by residual particles.

Polishing pad for chemical-mechanical planarization of a semiconductor wafer


A cardiac rhythm management system provides for assessment of cardiac mechanical dyssynchrony based on heart sound morphology and optimization of pacing parameters based on the effect of pacing on the cardiac mechanical dyssynchrony assessment. A degree of cardiac mechanical dyssynchrony is measured by the time delay between tricuspid valve closure and mitral valve closure and/or the time delay between pulmonary valve closure and aortic valve closure. A cardiac resynchronization therapy is optimized by determining therapy parameters to provide an approximately minimum degree of cardiac mechanical dyssynchrony by cardiac pacing.

The heart is the center of a person's circulatory system. It includes a complex electromechanical system performing two major pumping functions. The heart includes four chambers: right atrium (RA), right ventricle (RV), left atrium (LA), and left ventricle (LV). The RA draws deoxygenated blood from organs of the body and injects it into the RV through the tricuspid valve. The RV pumps the deoxygenated blood to the lungs through the pulmonary valve. The blood gets oxygenated in the lungs. The LA draws oxygenated blood from the lungs and injects it into the LV through the mitral valve. The LV pumps the oxygenated blood to the organs of the body, through the aortic valve, to provide the organs with their metabolic needs for oxygen. These mechanical pumping functions are accomplished by contractions of the myocardium (heart muscles). In a normal heart, the sinoatrial (SA) node, the heart's natural pacemaker, generates electrical impulses, called action potentials, that propagate through an electrical conduction system to various regions of the heart to excite myocardial tissues in these regions. Coordinated delays in the propagations of the action potentials in a normal electrical conduction system cause the muscles in various regions of the heart to contract in mechanical synchrony such that the pumping functions are performed efficiently.
The normal pumping functions of the heart, indicated by the normal hemodynamic performance, require a normal electrical system to generate the action potentials and deliver them to designated portions of the myocardium with proper timing, a normal myocardium capable of contracting with sufficient strength, and a normal electromechanical association such that all regions of the heart are excitable by the action potentials. A blocked or otherwise abnormal electrical conduction and/or deteriorated myocardial tissue cause dysynchronous contraction of the heart, resulting in poor hemodynamic performance, including a diminished blood supply to the heart and the rest of the body. The condition where the heart fails to pump enough blood to meet the body's metabolic needs is known as heart failure.
Because the pumping functions are mechanical functions, the hemodynamic performance is ultimately determined by the mechanical synchrony of the heart. For this and other reasons, there is a need for a direct assessment of cardiac mechanical dyssynchrony. The assessment serves as a direct measure of efficacy for a cardiac therapy restoring the cardiac mechanical synchrony.

Method and apparatus for optimization of cardiac resynchronization therapy using heart sounds


The invention relates to a tire with radial carcass reinforcement, intended for equipping a heavy vehicle such as a transport vehicle or construction machinery. It refers in particular to a tire having an axial width greater than 37 inches. The tire according to the invention has a working crown reinforcement, composed of at least two continuous working plies and completed on each side of the circumferential center plane by at least two half-plies whereof the metal reinforcing elements form angles greater than the smallest of the angles of the reinforcing elements of the continuous plies with the circumferential direction, with that half-ply extending axially furthest outwards being in contact with the axially widest continuous working crown ply, and the two half-plies radially covering the axially outer end of the said axially widest working ply.

The invention relates to a tire with radial carcass reinforcement, intended for equipping a heavy vehicle such as a transport vehicle or construction machinery. It refers in particular to a tire having an axial width greater than 37 inches.
A tire of this kind, usually intended to bear heavy loads, comprises a radial carcass reinforcement and a crown reinforcement composed of at least two working crown plies which are formed by non-extensible reinforcement elements that cross from one ply to the next, forming equal or unequal angles of between 10° and 45° with the circumferential direction.
Crown reinforcements of radial tires, in particular as regards very large tires, undergo pronounced deformations which give rise to longitudinal and transverse shear stresses between the edges of two crossed plies (the longitudinal shear is greater than the transverse shear when the cords of crossed plies are at small angles with the circumferential direction) at the same time as a delaminating stress, a radial stress tending to separate the edges of two plies radially from one another. The said stresses are primarily due to the inflation pressure of the tire, which has the effect that the so-called belt pressure between the carcass reinforcement and the crown reinforcement tends to cause the said crown reinforcement to expand circumferentially. The said stresses are moreover due to the load borne by the tire during travel, once a contact surface is produced between the ground and the tire. The said stresses are, furthermore, due to the slip angle of the tire during travel. These stresses produce cracks in the rubber mix adjoining the end of the shortest ply, and these cracks are propagated through the said mix, having an adverse effect on the service life of a crown reinforcement and hence of the tire.
A clear improvement to the service life has been achieved by using in the crown reinforcement at least one protective crown ply having an axial width greater than the width of the axially widest working ply.
The term "axial" means a direction parallel to the axis of rotation of the tire, and the term "radial" means a direction intersecting the axis of rotation of the tire and perpendicular thereto. The axis of rotation of the tire is the axis about which it turns in normal use. The circumferential center plane is a plane perpendicular to the axis of rotation of the tire, dividing the tire into two halves. A radial plane is a plane containing the axis of rotation of the tire.
Another solution, as described in the patent FR 2 421 742, consists in more favorable distribution of the stresses which give rise to separation between working crown plies and which result from the slip angle of the tire, by multiplying the number of working plies.
Multiplying the working plies is not without disadvantages, in particular at the center of the crown reinforcement, where the number of plies has a direct influence on the stiffness in flexure of the crown of the tire. When this stiffness increases, the result is that impacts on the crown of the tire, such as in particular on passing over large stones, may lead to irreparable damage to the tire as a result of this increased stiffness.
Patent application WO 00/54992 has moreover proposed, as a way of avoiding this disadvantage, making a working crown reinforcement composed of at least three continuous working plies and at least one half-ply on either side of the circumferential center plane, disposed between the edges of at least two radially adjacent continuous working plies, and whereof the special feature is in particular the fact of forming an angle with the circumferential direction greater than 25° and greater by an amount of between 5° and 15° than the largest of the angles of the continuous working plies. The results obtained with this type of structure have been perfectly satisfactory for the sizes of tire tested.

Heavy vehicle tire with crown reinforcement half-plies


A system and method for altering the appearance of interference in a video signal caused by spurious interference generated by repeated high speed digital memory write operations affecting video processing in analog circuitry in thereceiver. In one particular embodiment, a picture-in-picture television receiver is provided wherein both the main and sub-pictures are processed on a single IC including analog processing circuitry, as well as a small picture memory array to which small picture video samples are repeatedly being written. The visibility of spurious interference in the picture is reduced by periodically altering the clock timing during the repetitive high speed writing operation to redistribute the interference so as to be less noticeable to the television viewer.

Television receivers which feature picture-in-picture processing are known. In such receivers an inset or "small" picture to be displayed within an area of a "main" or "large" picture is subjected to vertical and horizontal compression by means of selective storage and retrieval from a memory and the compressed picture video signal is inserted within an area of the main picture video signal by means of a multiplex switch that is controlled by timing signals provided by the picture in picture compression processor. Examples of picture-in-picture compression processors are described, for example, by D. L. McNeely and R. T. Fling in U.S. Pat. No. 4,890,162 and by E. D. Romesburg in U.S. Pat. No. 4,768,083, those patents incorporated herein by reference.
It has been suggested in the article "PIX-IN-PIX DIGITAL DECODING/ENCODING USING ONLY ONE CLOCK," Rumreich, IEEE Transactions on Consumer Electronics, Vol. 37, No. 3, August 1991, pp. 210-212 to create a single integrated circuit (IC) to receive two composite video inputs and to provide an overlaid composite video output. In that article, it is described that all video decoding and encoding is performed in an IC using digital signal processing and a single clock. In the above-named article to Rumreich, the small picture Y/R-Y/B-Y data is multiplexed and stored in an 8K.times.8 SRAM located external to the IC.
An IC has been developed which includes a line comb filter for the main picture, as well as video processing circuitry for the small or sub-picture, and including a small-picture field memory on chip shares the IC with all the other active circuitry. A single clock is used by all circuitry on the IC. Some of the circuitry on the IC is analog, i.e. analog-to-digital converters, digital-to-analog converters, video switches and buffers. In the processing of a video signal to become a small picture, the signal is decoded, anti-alias lowpass filtered, subsampled and written into a small-picture field memory. The memory writing operation is a relatively high-powered operation and can generate spurious interference with other circuits on the chip. This may result in interference which appears as obvious vertical stripes in the large picture, which is processed through the line comb filter circuit of the IC. This interference also is present in the small picture by being coupled into the small picture digital-to-analog converter, again producing vertical stripes.
Additionally, although this spurious interference has been found to occur in a picture-in-picture type system, it is not limited to such a system. It is believed that the occurrence of such a vertical stripe interference pattern may occur in any video signal processed using analog circuitry (i.e. a D/A converter, etc.) to process video during repetitive high speed digital memory write operations.
What is needed is a means for reducing the interference visibility caused by spurious interference throughout the analog circuitry during repetitive memory write operations.

Reduction of visibility of spurious signals in video