TW440497B - Method and apparatus for automatically adjusting the contour of a wafer carrier surface - Google Patents

Abstract

A method and apparatus is provided for holding a workpiece in a carrier parallel to a polishing pad while pressing the workpiece against the polishing pad during a planarization process. The carrier's pressure plate and/or backing film are comprised of materials that allow the carrier to adjust its local contours based on the removal rate of material from the workpiece during the planarization process without the need for complicated mechanical devices. In addition, or alternatively, the retaining ring may be comprised of materials that allow the retaining ring to adjust its local contours due to the friction between the retaining ring and the polishing pad during the planarization process, thereby pre-loading and stretching the polishing pad in an even and uniform manner resulting in a superior planarization process.

Description

^ 4〇4 V. Description of the invention (l) Technical aspects | The present invention generally relates to semiconductor wafers, etc .; ^ The leveling technology of parts, especially to improve the workpiece carrier; 'the profile can be adjusted automatically during the leveling process; A flat dish or "wafer" is a substrate in the semiconductor industry for manufacturing integrated circuits. Β Semiconductor wafers are typically shirt-shaped cylindrical monocrystalline silicon, and individual wafers are cut from the cylinder to obtain β.

The front face of the wafer to form the integrated circuit must be extremely flat to facilitate reliable confluence of the semiconductor with the subsequent layers of material applied to the wafer. The layer of material applied to the wafer in order to establish an integrated circuit connection must also be of uniform thickness. The removal of protrusions and other imperfections to produce a flat surface ' and the removal of material to produce a uniform thickness of the thin film layer deposited on the wafer are technically referred to as leveling. To this end, chemical mechanical leveling (CMP) machines have been developed that are well known in the art to provide leveling under the control of semiconductor wafers and deposited layers. Q CMP machines typically include one or more wafer carriers or "chucks" ", Hold and carry the wafer to be leveled, and press the front of the wafer tightly against the surface of the polishing pad. Polishing pads are most commonly used on rotating polishing plates, see U.S. Patent No. 5,498,196 'can also be used for linear belt systems, see U.S. Patent No. 5,692,947 ", or rotating barrel systems, see U.S. Patent No. I7. 7 No. 74 or 5, 643, 056, or any other machine that can cause relative motion between the wafer and the polishing pad. The conventional wafer body typically has a cover assembly, and a hard pressure plate is formed on the bottom surface with a flexible backing. A buckle is typically attached to the periphery of the rigid pressure plate ' to form a pouch. These components cooperate together and remain in the flattening process. Page 5 44〇497 V. Description of the invention (2) Restraint wafer. Conventional carriers have generally yielded satisfactory results in the past. As crystals gradually require tighter tolerances when flattening, their current flaws must be overcome. This is particularly difficult, as the nature of the problems encountered with conventional crystal® plants used in the Gein levelling process has not been fully understood in the past. The conventional carrier has a problem. When its pressure plate, back membrane and / or buckle is compressed, the material of the back membrane and / or buckle is included in the pressure plate. As a result, conventional materials are more robust under load, thereby reducing their ability to adjust in local areas). Another problem with conventional carriers is that the pressure plate, back film and buckle are made of positive thermal expansion material (PTEJO). When heated, the material expands as follows:

AV / V0 = rAT where Δν is the capacity change'V. Is the initial capacity, τ 'is the capacity expansion coefficient, and ΔΤ is the temperature change. Similar analogous equations are related to both area and linear expansion, with coefficients of 5 and α, respectively. The capacity expansion coefficient r of the materials used in the conventional carrier is different, which is greatly related to the materials used, usually between 10e-5 / ° C for metals and plastics and 10e-6 / ° C for ceramics. During the leveling process, the heat is outstanding due to the friction between the wafer and the polishing pad. Despite efforts to level the wafer evenly ', some areas are polished faster than others' and thus generate a higher degree of heat in that area. During the leveling process, a high degree of heat is generated by the friction between the wafer and the polishing pad, which causes the roof plate and / or the back film to have a high thermal expansion due to the heat transmitted to these areas through the wafer. Uneven thermal expansion 'can cause warping of the abrasive plates and / or backing film used to hold the wafer. Areas that experience large thermal expansion

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V. Description of the invention (3) 圊 generates greater pressure, and thus increases the plate and / or back kinking to restrict the crystal gj process. Uneven loading allows the crystal plane to be carried from the carrier. Heat is added to these areas. This destructive ′ causes the wafer to be flattened and pre-loaded with polishing pads ”thus causing non-uniform thermal bulging and causing the polishing pad polishing or material removal rate to cycle, further compressing the process. The buckle will also undergo bulging, causing the buckle of the buckle to be subjected to uneven pre-stressing. It looks like another carrier such as the United States can form a concave or convex curved bottom. It is the temperature of the external machine. Can't control the emperor! The shell that is pressed on the wafer always knows that the carrier has the same problem & the process has a negative impact. Β National Patent No. 5,036,630 "This surface is used to press the wafer down. . The concave or convex structure is made of different materials having different properties for adjusting the thermal expansion properties of Ip, and laminated on top and bottom to form the bottom surface of the carrier. However, the local curvature 'requires an external device to control the bottom surface shape. This carrier device also has the above-mentioned uncontrollable local curvature. For flat S 733 and 1,82 types / ships such as US patents 5,486,129; 5,720, 845 and Qiu Tan Fang Mu, said that they are pressed down on The local shape of the wafer's surface shape: all the carriers disclosed in these patents require external mechanical farming, which is difficult to control and manufacture, and is extremely expensive. At the same time, there is an urgent need for a simplified self-adjusting carrier to improve the leveling process, with a simple structure and operation. Summary of the Invention 1 The present invention provides a workpiece carrier that is an object of the present invention. Is to provide a workpiece carrier

Page 7440043 'V. Description of the invention (4) The whole process is carried out, and the present invention is produced at a glance @ fast workpiece area, which reduces the workpiece area and increases the workpiece. Another object of the invention is the flatness rate of different areas of the invention. The purpose is to adjust its contour to ensure loading.

"Generating localized contours" is to provide a workpiece carrier that is flattening the material removal rate of the workpiece 'and flattening the material removal rate too slowly. It is to provide a workpiece carrier that can control different external measurement devices or controls. 'It is to provide a workpiece carrier, the buckle can hold the average pressure of the polishing pad, and uniformly pre-load the workpiece according to the present invention and other flat workpieces, including the shell assembly area; the buckle is used to restrain the pad ; And back as needed to support the artifact. Localized pressure on the pressure plate and / or dynamically adjusted workpiece The removal rate is inversely proportional to β In addition, to maintain uniform pre-loading of the polished cymbal or the carrier of the workpiece or other desired properties of the workpiece carrier. Purpose, to provide a workpiece carrier to be held, with a dust plate, to substantially flatten the movement of the workpiece 'and pre-loaded on the polishing film' located between the workpiece and the pressure plate, or the back film dare to include the materials, which can be self-zoned 'The material buckle that is level with the workpiece is preferably made of a material whose contour can be adjusted automatically. Any component can be coated to improve the corrosion resistance. A workpiece flattening method is also provided. The workpiece has a front and a back, held in the workpiece carrier, and against the polished surface moving relative to the workpiece. This method includes the steps of flattening the front side of the workpiece. And automatically adjust the local pressure zone on the back of the workpiece, which is inversely related to the local removal rate of the workpiece from the workpiece

44 〇4 9 V. Description of the invention (5) The above and other aspects of the present invention and the drawings. For details, please refer to the following description 'Patent application paradigm where the same numbers refer to the same elements using a hard pressure plate to directly press the invention. as follows. In the drawings: Figure 1 is a section of the workpiece carrier to hold the workpiece; Figure 2 is a section of the workpiece carrier to directly hold the workpiece. The detailed description of the use of back media as needed The present invention is generally related to semi-conducting Zhao However, it should be noted that the present invention is not limited to special, research, polishing, or polishing environment. Rotating, trajectory, linear belt, or roller trains are used to smear or level workpieces such as wafers under pressure under the required control. Workpiece type or special manufacturing and leveling. The present invention can operate in a wide range of systems (such as systems), Fig. 1 shows the workpiece carrier 100 «in the process. Typically, the implant 100 is mounted on the distal end of the mandrel 116. The mandrel can rotate, move vertically and reciprocally across the polishing pad 112. The carrier 100 is typically a body component of a chemical-mechanical planer or a workpiece-like polishing device, as taught in U.S. Patent No. 5,3 2 9,7 3 2. The wafer carrier 100 is typically rotated around its own sleeve line to prevent excessive polishing of the leading edge of the wafer (if the wafer "dives" into the cymbal), or insufficient polishing (if the leading edge of the wafer is sliding on the pad) . In any case, the 'crystal round carrier 100 must rotate' to make the uneven polishing effect on the wafer 111 ΗΒΓΊΗΒί 04 9 7 V. Description of the invention (6) Average. In addition, the carrier 100 reciprocates across the surface of the polishing pad 112, allowing the polishing pad 112 to wear evenly. Furthermore, a downward force is also applied to the carrier 100 to increase the material removal rate from the front surface where the wafer 111 contacts the polishing pad 112. In addition, 'also causes the polishing pad 112 to move relative to the wafer Η 1 and preferably rotates about its own axis. A polishing slurry (not shown on the circle) such as colloidal silica slurry is often introduced at the interface between the polishing pad 112 and the wafer 111 to expand the leveling process. In addition, the slurry can be designed to chemically etch or mechanically remove certain materials faster than other materials on the wafer 1 1 1. Housing Assembly The housing assembly 101 helps keep the wafer Π1 side substantially parallel to the polishing pad 112. The cover assembly 101 can be firmly fixed in position, creating a parallel state between the wafer 111 and the polishing pad 112 ', but it is preferable to have a self-alignment mechanism so as to maintain the parallel state during the flattening process. A preferred self-aligning mechanism includes a gimbal, such as shown in U.S. Patent No. 5,571,044. However, other self-aligning mechanisms of the housing assembly 101 may be used and include ball bearing joints, diaphragms, and / or other well-known biasing members. The cover assembly 101 can also be designed to allow: (i) pressurizing various chambers in the carrier 100 (not shown in the figure) with fluid, (ii) holding the wafer Π1 in the carrier 100 by vacuum extraction, Or (iii) the wafer 111 is blown off or discharged from the carrier 100 with a pressurized fluid. Pressure plate The casing assembly 101 includes a pressure plate 102. »The pressure plate 102 can be made into a casing. The assembly is one of the bottom surface of the assembly.

Page 10 440497 V. Description of the invention (7) Assembly 101 'forms the bottom surface of the cover assembly 101, and presses the wafer 111 ° pressure plate 102 during flattening, which may be less than, equal to, or as shown in Figures 1 and 2 It is shown that it is larger than the size of the wafer 111. The pressure plate 102 is preferably made of a hard material, and allows any force applied to the wafer 111 to be distributed in a controlled and comprehensive manner. As shown in FIG. 2 'as required, the back film 103 can be attached to the pressure plate i 02' to help distribute the force on the wafer. The pressure plate 102 can be shaped as concave or convex Φ, but it is best to use a flat surface. According to the present invention, the 'pressure plate 102' is preferably composed of a material which can automatically adjust the surface wheel and the corridor of the pressure plate 102 during the leveling process to compensate for the uneven material removal rate of the workpiece. For automatic adjustment, the pressure plate 102 can be directly contacted to the wafer 111 as shown in FIG. 1, or the back film 103 can be placed between the pressure plate 102 and the wafer 111 as shown in FIG. 2. According to an example, the pressure plate 102 may be composed of glass or carbon woven laminates. The carbon fiber laminates preferably contain uniaxially oriented fibers. More preferably, the pressure plate 102 is composed of a porous membrane and contains cells in the porous weave. The microscopic crossbow of the hole can be reversed and depends on the temperature. Because some areas of the wafer lu are polished faster than other areas of the wafer 111, the faster polishing area generates a larger track due to friction between the polishing pad 112 and the wafer 111. The increased hot water level caused by friction on the wafer nl's faster polishing area is transmitted to a specific area on the pressure plate 102, resulting in these areas becoming softer and more compressible. Due to the heated area of the pressure plate 102, it is shown that the compression is increased compared to other areas of the pressure plate 102, so the M area of the pressure plate 102 will warp, resulting in a decrease in the downward force applied by 2 wafers. Decreasing the downward force on the crystal circle within the compression area of the pressure plate 102 will slow down the rate of throwing and cause these faces of the wafer

Page 11 4 * 4 〇4 9 7 V. Description of the invention (8) The product polishing rate is more uniform with the remaining area of the wafer 111. In the preferred embodiment of the carrier device of the present invention, the pressure plate 102 is made of a material with a negative thermal expansion coefficient (NTE material), such as LiAlSi04 (cold-spodumene), LiAlSi2oe (ling-spodumene), and some Plastic or certain rare earth ceramics are preferred. For a detailed description of materials with negative thermal expansion characteristics and structure, see US Patent Nos. 3,969,123 of Hoi combe et al., US Patent Nos. 5,322,559 and 5,433,778 of Sleight, the relevant parts of which are incorporated herein by reference. In another specific example, the pressure plate 102 does not need to be entirely composed of NTE materials, because various patterns or concentrations of NTE materials can be added to the pressure plate 102 to perform the same function and achieve similar results. In addition, other materials with additional required qualities such as special temperature response (smaller or larger thermal expansion coefficient): uniaxial, biaxial, or triaxial response; increase strength; reduce the amount; increase corrosion resistance, and easily For example, the pressure plate 102 may be used for manufacturing. However, the most preferable specific example of the carrier 100 device of the present invention includes the force plate 102 'entirely composed of a negative thermal expansion material such as a rare earth ceramic. Back Film Fig. 2 shows another specific example of a wafer carrier-µ has a back film 103 located next to the pressure plate 102. The back side of wafer 1 11 is often rough (shown in the figure), due to the initial process of wafer 111 or the back side of wafer 111 in other processing steps. The back film 103 is made of a soft material and can be deformed locally, thereby preventing the roughness of the back side of the wafer from increasing pressure; and the polishing rate of the front side of the wafer 111. For further explanation of the purpose of the back pad, please refer to U.S. Patent No. 5,791,975, which is incorporated herein by reference.

44 049? V. Description of the invention (9) ---- The back film 103 can be attached to the pressure plate 102 by any different method known in the art. The back surface 103 can be concave or convex (not shown on the top) to adjust the polishing process, but it is best to flatten the surface. As shown in Figure 2, the β back film 10 can be smaller than the wafer 111. Wafer 111 is the same, or preferably as shown in FIG. 2, larger than wafer 1 1 1. During the polishing process, some areas of the wafer lu are polished faster than other areas of the wafer 111. A common problem seen during wafer polishing is that the polishing rate that occurs at the edge of the wafer is greater than the polishing rate that occurs at the center of the wafer. In addition, common r hot spots ", that is, the special area polishing on the wafer will be faster than the remaining area of the wafer 111. The faster polishing position on the wafer will generate more heat, due to the wafer and polishing pad The friction between them is increased. The back film 103 may be made of any compliant material, but is preferably made of a material whose surface profile can be adjusted to compensate for uneven polishing rates. If the back film 103 is completely or partially made of the NTE material of the present invention, heat will cause it to thin automatically. During the polishing process, the thickness of the back film can be automatically reduced without external or mechanical control. The contours (outside of flat, free or concave) presented by the pressure plate 102 and the back film 103 can be used in the flattening process. Medium fine-tuning to the local problem area ° The area on the back film 103 that has been compressed or is thinner will put lower pressure on the back side of the wafer 111. The lower pressure on the back side of the wafer u 丨 will automatically reduce the polishing rate of that area of the wafer, so that other areas of the wafer ^ 丨 丨 can catch up during the prison light process, which can provide excellent polishing results. In another specific example of the wafer carrier 100 of the present invention, the 'back film 103 is preferably composed of a polymer such as a fluoropolymer, amidine, amidine, imine, or a thermoplastic as ^^ ΠΠΒΗΓ Page 13 440497 V. Invention Note (10) is good, and it is better to use porous polyvinyl acetate (PVA) material. During the leveling process, the 'back film 103 is operated under pressure' so that the compressibility of the back film 103 is reduced 'because it has been compressed. However, even under pressure, the heat can increase the compressibility of the aforementioned polymer material, so that the back film 103 can be further shrunk (become softer) in areas that are overheated (areas that are polished too quickly), or in areas with less heat. The surface fineness (area that is polished too slowly) is still hard (becomes harder). The contour of the backing film 103 is automatically optimized because of different local areas that automatically soften or harden, without outside control of the leveling process. A common problem when wafer 111 is flattened is that material removal at the edge of wafer 111 is faster than the center of wafer 111. The increase in the material removal rate near the edge of the wafer 111 is called the fast edge effect. Making the back film 103 smaller in size than the crystal garden 1 ′ can adjust the fast edge effect. The size of the back film 10 03 is reduced, causing a gap between the edge of the crystal gj 1 1 1 and the pressure plate 102 (not shown in the figure). The gap reduces the force at the edge of the wafer 111 ', thereby slowing the material removal rate at the edge of the wafer 111. A slower removal rate occurs at the edge of the crystal plane 1 and balances the removal rate at the center of the wafer 1, thereby improving the leveling process. The better solution to overcome the rapid edge effect is to manufacture the back film 103. The part of the back film 103 that touches the edge of the wafer 111 is made of a material with higher compressibility than the back film 103 located near the center of the wafer 111. . Materials with higher compressibility will preferably show greater compressibility when heated. The deployment of materials with higher compression performance can be reversed during the flattening process, so that the center has a rapid effect, that is, the polishing occurring at the center of the wafer U 1 is faster than the wafer π 1 edge polishing. In addition, the deployment of materials with increased compressive properties is optimal for any given process because it exhibits more compressibility when heated.

Chapter 14 440497 V. Description of the Invention (il) Buckle The military casing assembly 101 should be connected to the flange or buckle 105 to prevent the wafer 111 from escaping from the carrier 100 during the polishing process. The buckle 105 can be firmly connected to the casing assembly 101 as shown in Figs. 1 and 2 'or allowed to move independently relative to the casing assembly (see U.S. Patent No. 5,795 21 5, hereby). Included in politics). The buckle 105 can perform at least two functions. The first function of the buckle ι05 is to work in combination with the pressure plate 102 to form a pouch to maintain and control the movement of the wafer 1 11 during the polishing process. Β buckle 1 〇 The second function of 5 is to preload and stretch the polishing pad I12. When the wafer 111 is pressed against the polishing pad 112, the entire polishing piece 112 and the backing film 103 (if used) are compressed, and the buckle is allowed. 5 in contact with the polished cymbal 112 (not shown). This contact can pre-load and extend the buckle 105 to the polishing pad 112, thereby flattening the wafer m and improving the workable surface. The retaining ring 105 and the polishing pad 112 rub against each other, and thus generate heat during the flattening process. As described above with respect to the shapes of the pressure plate 102 and the back 103, the buckle 105 may experience uneven thermal expansion, which may cause loss of wafers or uneven stretching of the M-ray diaphragm. The uneven thermal expansion of the buckle 105 can be corrected by the invention including the buckle of the self-adjusting material. The buckle 105 is preferably made of NTE material, and is preferably made of rare earth ceramics. For a detailed description of the negative thermal expansion characteristics and structure as described above for the pressure plate 102, see US Patent Nos. 3 9 6 9 1 23 of Holcombe et al. And US Patent Nos. 5, 322, 559 and 5, 433 of Sleight. No. 778, the relevant part of which is included here. Although the foregoing is a preferred specific example of the present invention, the scope of the present invention is not limited to

• page 15 ^ 4 04 9 7 V. Description of the invention (12) These special specific examples. The special type and design of the present invention can be modified without departing from the spirit and scope expressed by the scope of the following patent applications. Page 16 44 04 9 7 The diagram is briefly explained. Figure 1 is a cross-sectional view of the workpiece carrier. The hard pressure plate is used to directly press the workpiece. Figure 2 is a cross-sectional view of the workpiece carrier. Squeeze the workpiece. III · Page 17

Claims (1)

44 〇4 9 7 VI. Application for Patent Scope 1, a workpiece carrier 'for keeping the workpiece parallel to the polishing pad, and at the same time pressing the workpiece against the polishing pad during the polishing process, including: the cover "forming; and the grinding force The 'plate' forms the bottom surface of the military shell assembly, wherein the pressure plate can automatically adjust its profile according to the removal rate of the material from the workpiece. 2. For a carrier as claimed in item 1 of the patent scope, wherein the pressure plate includes a negative thermal expansion The material of the coefficient. 3. If the carrier of the scope of patent application No. 2, wherein the pressure plate includes rare earth ceramics. 4. If the carrier of the scope of patent application No. 1, wherein the pressure plate includes a porous membrane, including the porous The shape of the sacral cells is slightly curved, which can be reversed and depends on the temperature. 5.-A kind of workpiece carrier to keep the workpiece parallel to the polishing pad, while pressing the workpiece against the polishing pad during the polishing process Including: cover and shell assembly; pressure plate forming the bottom surface of the cover and shell assembly; and a back film attached to the pressure plate, wherein the back film can be automatically adjusted according to the material removal rate from the workpiece Outliner. 6. If the carrier of item 5 of the patent application, where the back film includes a polymer. 7. If carrier of the patent application, item 6 where the back film includes polyvinyl acetate. 8.- Workpiece carrier 'to keep the workpiece parallel to the polishing pad while pressing the workpiece against the polishing pad during polishing, including: Page 18 44〇497 6. Scope of patent application Cover assembly; pressure plate, which forms the bottom surface of the cover assembly; back film, attached to the pressure plate, the compression ratio of the back film near the periphery is increased compared to the center of the back film. 9. A workpiece carrier for holding a workpiece parallel to a polishing pad, and simultaneously pressing the workpiece against the polishing pad during polishing, comprising: a cover assembly; a pressure plate forming a bottom surface of the cover assembly; a buckle The ring is functionally connected to the cover assembly, wherein the buckle can automatically adjust its profile according to the amount of friction with respect to the polishing pad. 10. If the carrier of item 9 of the patent application, the buckle The ring includes a material having a negative thermal expansion coefficient. 11. The carrier as claimed in claim 10, wherein the buckle includes rare earth ceramics. 12. The carrier as claimed in claim 9 wherein the retaining ring includes a polymer. 13_ —A method of flattening a workpiece. The workpiece has a front and a back surface “held on a carrier” to withstand a polished surface moving relative to the workpiece. This method includes flattening the front side of the workpiece; and automatically adjusting the local pressure area on the back surface of the workpiece. In flattening, the material removal rate from the workpiece is inversely related. Page 19 ·