Polishing head assembly with recess and cap

Abstract

A polishing head assembly for polishing semiconductor wafers includes a polishing head and a cap. The polishing head has a top portion and a groove along a bottom portion. The groove has a concave surface. A hole extends from the top portion through the concave surface. The cap is positioned within the groove and has an annular wall and a base plate extending across the annular wall. The annular wall has a aperture corresponding to the hole. The base plate is spaced from the concave surface to form a cavity therebetween. The polishing head assembly further includes a strip external to a portion of the annular wall. The hole and the corresponding aperture receive fasteners to removably secure the annular wall to the concave surface.

Description

[0001] Cross-reference of related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 202,827, filed June 25, 2021, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to the polishing of semiconductor wafers, and more specifically, to a polishing head assembly having grooves and a cap. Background Technology

[0004] Semiconductor wafers are commonly used to produce integrated circuit (IC) chips on which printed circuit systems are mounted. The circuit system is first printed onto the surface of the wafer in a miniaturized form. The wafer is then diced into circuit chips. This miniaturized circuit system requires that the front and back surfaces of each wafer be extremely flat and parallel to ensure that the circuit system can be properly printed over the entire surface of the wafer.

[0005] To achieve this, grinding and polishing processes are commonly used to improve the flatness and parallelism of the front and back surfaces of the wafer after it has been cut from the ingot. Particularly good finishing is required when polishing wafers in preparation for printing miniaturized circuits on them via electron beam lithography or photolithography (hereinafter referred to as "lithography"). The wafer surface on which the miniaturized circuits will be printed must be flat.

[0006] Polishing machines typically consist of a circular or annular polishing pad mounted on a turntable or pressure plate and driven to rotate about a vertical axis passing through the center of the pad, and a mechanism for holding the wafer and forcing it into the polishing pad. The wafer is typically mounted to the polishing head using, for example, liquid surface tension or vacuum / suction. A polishing slurry (typically containing chemical polishing agents and abrasive grains) is applied to the pad to create a greater polishing interaction between the polishing pad and the wafer surface. This type of polishing operation is commonly referred to as chemical mechanical polishing (CMP).

[0007] During operation, the pad is rotated, bringing the wafer into contact with the pad and pressing the pad against the polishing head. Polishing heads are typically assembled using epoxy adhesive. However, epoxy adhesive failure during the polishing head's lifespan can cause undesirable effects, including component loosening, air leakage, wafer damage, and poor yield. Repairing these polishing heads is difficult because the head must be heated to release residual epoxy to allow for complete disassembly. After cooling, few of the existing components of the head assembly are recyclable. Therefore, an improved polishing head assembly is needed.

[0008] This "Background Art" section is intended to introduce the reader to various technical aspects that may relate to the various aspects of this disclosure described and / or claimed below. This discussion is intended to help provide the reader with background information to facilitate a better understanding of the various aspects of this disclosure. Therefore, it should be understood that these statements should be interpreted in this light and not as an endorsement of prior art. Summary of the Invention

[0009] In one aspect, a polishing head assembly for polishing semiconductor wafers includes a polishing head and a cap. The polishing head has a top portion and a groove along a bottom portion. The groove has a concave surface. A hole extends from the top portion through the concave surface. The cap is positioned within the groove and has an annular wall and a base plate extending across the annular wall. The cap is made of a structural material. The base plate has a bottom surface and a top surface, and the base plate is spaced from the concave surface to form a cavity between the concave surface and the top surface. The annular wall has a aperture corresponding to the hole. The polishing head assembly further includes a strip extending from the portion of the annular wall. The hole and the corresponding aperture receive fasteners to removably secure the annular wall to the concave surface.

[0010] In another aspect, a polishing head assembly for polishing semiconductor wafers includes a polishing head and a cap. The polishing head has a top portion and a downwardly extending annular portion defining a groove along a bottom portion. The groove has a concave surface. An aperture extends from the top portion through the concave surface. The cap is positioned within the groove and has an annular wall and a base plate extending across the annular wall. The cap is made of a structural material. The base plate is spaced from the concave surface to form a cavity therebetween. The annular wall has a first portion and a second portion. The first portion of the annular wall has an aperture corresponding to the aperture. The second portion of the annular wall extends downward from the first portion. The polishing head assembly also includes an integral one-piece strip external to the second portion of the annular wall. The aperture and the corresponding aperture receive fasteners to removably secure the first portion of the annular wall of the cap to the concave surface of the polishing head. The first portion of the annular wall has a first O-ring that forms a seal when the first portion and the concave surface are secured.

[0011] Various improvements are possible to the features mentioned above. Further features may also be incorporated into the above aspects. These improvements and additional features may exist individually or in any combination. For example, the various features discussed below with respect to any of the illustrative embodiments may be incorporated individually or in any combination into any of the above aspects. Attached Figure Description

[0012] Figure 1 This is a partial schematic front view of the polishing equipment;

[0013] Figure 2 This is a cross-section of the exemplary polishing head assembly of the first embodiment;

[0014] Figure 3 This is a cross-section of the exemplary polishing head assembly of the second embodiment;

[0015] Figure 4 This is a cross-section of the exemplary polishing head assembly of the third embodiment;

[0016] Figure 5 It includes a template and a chip held by the template. Figure 2 A perspective view of the polishing head assembly shown in the image; and

[0017] Figure 6 It does not contain chips. Figure 5 The image shows a partial cross-section of the polishing head assembly.

[0018] The same reference symbol in various diagrams indicates the same element. Detailed Implementation

[0019] Generally, and in embodiments of this disclosure, the suitable substrate “wafer” (which may also be referred to as a “semiconductor wafer” or “silicon wafer”) comprises a single-crystal silicon wafer, for example, a silicon wafer obtained by dicing a single-crystal silicon ingot formed by the Tchaikovsky process or the float-melt process. Each wafer includes a central axis, a front surface, and a rear surface parallel to the front surface. The front and rear surfaces are substantially perpendicular to the central axis. The circumferential edges join the front and rear surfaces. The wafer may be of any diameter suitable for use by those skilled in the art, including, for example, wafers with diameters of 200 mm, 300 mm, greater than 300 mm, or even 450 mm.

[0020] In one embodiment, a wafer that has previously undergone coarse polishing, resulting in rough front and rear surfaces, first undergoes an intermediate polishing operation, where the front surface of the wafer, rather than the rear surface, is polished to improve flatness parameters or to smooth the front surface and remove treatment scratches. To perform this operation, the wafer is placed against a polishing head assembly. In this embodiment, the wafer is held in place by surface tension against the polishing head assembly. The wafer is also placed on the turntable of the polishing machine with its front surface in contact with the polishing surface of the polishing pad.

[0021] The polishing head assembly mounted on the machine can move vertically along an axis that extends through the wafer. As the turntable rotates, the polishing head assembly moves against the wafer to bring it toward the turntable, thereby pressing the front surface of the wafer into polishing engagement with the polishing surface of the polishing pad.

[0022] A conventional polishing slurry containing abrasive particles and chemical etchants is applied to a polishing pad. The polishing pad presses against the surface of the wafer to process the slurry, removing material from the front surface of the wafer to result in a smoother surface. As an example, intermediate polishing operations preferably remove material smaller than about 1 micrometer from the front side of the wafer.

[0023] The wafer then undergoes a fine polishing operation, in which the front surface of the wafer is finely polished to remove the large-size colloidal silica (e.g., from DuPont Air Products Nanomaterials, LLC) that was deposited in the intermediate steps. Intermediate polishing removes fine or “micro” scratches caused by [unspecified] particles and produces a highly reflective, non-destructive front surface of the wafer. Intermediate polishing operations generally remove more wafer material than fine polishing operations. Wafers can be fine polished in the same polishing machine used for intermediate polishing, as described above. However, a separate polishing machine can also be used for fine polishing operations. The fine polishing slurry typically contains ammonia and a reduced concentration of colloidal silica, injected between the polishing pad and the wafer. The polishing pad is pressed against the front surface of the wafer to process the fine polishing slurry to remove any remaining scratches and atomize, resulting in a generally highly reflective and non-destructive front surface of the wafer.

[0024] refer to Figure 1 The image schematically shows and generally indicates a portion of the polishing equipment, marked with 100. Polishing equipment 100 can be used to polish the front surface of a semiconductor wafer W. Other types of polishing equipment are expected to be used.

[0025] Polishing apparatus 100 includes a wafer holding mechanism (e.g., a template including a back film 110 and a retaining ring 120), a polishing head assembly 130, and a turntable 140 having a polishing pad 150. The back film 110 is located between the polishing head assembly 130 and the retaining ring 120, which receives the wafer W. The retaining ring 120 has at least one circular opening therein for receiving the wafer W to be polished.

[0026] In this embodiment, the wafer W is attached to and held against the polishing head assembly 130 by surface tension. To create surface tension, a wet-saturated backing film 110 is attached to the polishing head assembly 130 by a pressure-sensitive adhesive. The backing film 110 and the retaining ring 120 form a template or "wafer holding template". The backing film 110 is generally a soft polymer pad or other suitable material.

[0027] The wafer W is then pressed into a wet-saturated back film 110 to remove or squeeze out most of the water or other suitable liquid. The squeezed-out water causes the wafer to remain on the back film 110 due to surface tension and atmospheric pressure on the exposed surface of the wafer. This squeezed-out water then mounts the wafer onto the polishing head assembly 130.

[0028] A portion of the polishing head assembly 130 is flexible enough to deform in response to changes in pressure applied to it, and rigid enough to remain undeformed when the wafer is pressed into a wet saturated template. Surface tension provides a constant holding force on the surface of the wafer. This constant holding force causes any deformation of the polishing head assembly 130 adjacent to the wafer to be directly translated into proportional deformation of the wafer.

[0029] The surface tension-based wafer holding mechanism differs from other known mechanisms that use flexible diaphragms or vacuum to hold the wafer against the polishing head assembly. Flexible diaphragms known in the art deform to create a space or vacuum cavity between the wafer and the flexible diaphragm when the wafer is pushed toward it. These vacuum cavities allow the diaphragm to pick up the wafer. Other diaphragms have vacuum holes connected to a vacuum to create a low-pressure area for wafer pickup.

[0030] The polishing apparatus 100 applies force to the polishing head assembly 130 to vertically move the polishing head assembly 130, causing it to rise and fall relative to the wafer W and the turntable 140. An upward force raises the polishing head assembly 130, and a downward force lowers it. As discussed above, the downward vertical movement of the polishing head assembly 130 against the wafer W provides polishing pressure to the wafer, causing it to enter the polishing pad 150 of the turntable 140. As the polishing apparatus 100 increases the downward force, the polishing head assembly 130 moves vertically downward to increase the polishing pressure.

[0031] A portion of the polishing head assembly 130, along with the polishing pad 150 and the turntable 140, rotates at a selected rotational speed via a suitable drive mechanism (not shown) known in the art. The rotational speeds of the polishing pad and the turntable may be the same or different. In some embodiments, the polishing apparatus 100 includes a controller (not shown) that allows an operator to select the rotational speed of both the polishing head assembly 130 and the turntable 140, as well as the downward force applied to the polishing head assembly.

[0032] refer to Figure 2 This image illustrates an example polishing head assembly 200 for use in a polishing apparatus 100. The polishing head assembly 200 includes a polishing head 210, a cap 240, and a strip 270. The polishing head assembly 200 may also include a template, which includes a backing film and a retaining ring, such as a backing film 110 and a retaining ring 120. Figure 1 (As shown in the image). The polishing head 210 has a top 212 and a bottom 214 that are substantially parallel to each other. The polishing head 210 has a platform 216 at the top 212 and a hole 218 extending from the platform 216 through the bottom 214.

[0033] The polishing head 210 has an annular member 220 extending downward from the platform 216 to the bottom 214. The annular member 220 has an inner surface 222 and an outer surface 224. The outer surface 224 forms the circumference of the polishing head 210. The annular member 220 defines a groove along the bottom 214, and the groove has a concave surface 226 extending between the annular members 220. In this embodiment, a hole 218 extends from the platform 216 through the concave surface 226. As will be discussed in more detail below, a portion of the annular member 220 at the bottom 214 may have inlets 272, 278 respectively formed on the outer surface 224 and the inner surface 222, which mate with the shape of the strip 270.

[0034] The cap 240 is positioned within a recess defined by the annular member 220. The cap 240 includes a base plate 242 surrounded by an annular wall 250 extending upward therefrom. The base plate 242 has a top surface 244 and a bottom surface 246. In this embodiment, the bottom surface 246 extends outward beyond the annular wall 250 to a lug 248. As will be discussed in more detail below, the lug 248 may be shaped to mate with the strip 270. In other embodiments, the bottom surface 246 may not extend beyond the annular wall 250, such that the annular wall 250 defines the outermost circumference of the cap 240.

[0035] The annular wall 250 has an inner surface 252, an outer surface 254, a top portion 256, and a bottom portion 258. The top portion 256 has a top edge 260 and a aperture 259 formed at the top edge 260. The aperture 259 extends into the top portion 256 and corresponds to a hole 218. The hole 218 and the corresponding aperture 259 receive fasteners 290 (e.g., screws) to removably secure the annular wall 250 to the concave surface 226 and thereby removably secure the cap 240 to the polishing head 210. When the annular wall 250 is secured to the concave surface 226, the top edge 260 of the annular wall 250 contacts the concave surface 226. The top portion 256 may also include an O-ring 262 at the top edge 260, which forms a seal when the annular wall 250 is secured to the concave surface 226.

[0036] like Figure 2 As shown, the thickness of the annular wall 250 is greater at the top portion 256 than at the bottom portion 258. The thinner wall of the bottom portion 258 allows it to act as a hinge, around which the base plate 242 can be temporarily deflected rather than permanently deformed relative to the polishing head 210. For example, the base plate 242 can be temporarily deflected upward toward the polishing head 210 in response to downward vertical movement of the polishing head assembly 200 to cause the cap 240 to contact the wafer (e.g., ...). Figure 1 The wafer W shown in the figure. The inner surface 252 of the annular wall 250 at the top portion 256 may be angled relative to the outer surface 254, such that the thickness of the top portion 256 is thickest at the top edge 260 and tapers downward toward the bottom portion 258.

[0037] When the cap 240 is secured to the polishing head 210, at least a portion of the outer surface 254 abuts the inner surface 222 of the annular member 220. Suitably, the outer surface 254 is substantially parallel to the inner surface 222. In this embodiment, the height of the annular wall 250 is greater than the downward extension of the annular member 220, and the inner surface 222 of the annular member 220 externally aligns with the top portion 256 of the annular wall 250. In other embodiments, the annular member 220 may be more or less externally aligned with the annular wall 250.

[0038] When the cap 240 is secured to the polishing head 210, the base plate 242 is spaced from the concave surface 226. Therefore, when the cap 240 is secured to the polishing head 210, the annular wall 250, the top surface 244 of the base plate 242, and the concave surface 226 define the chamber 205. Because the top edge 260 contacts the concave surface 226 when the annular wall 250 is secured to the concave surface 226, the height of the chamber 205 is determined by the height of the annular wall 250. In some embodiments, the chamber 205 is pressurized by a pressurized medium or fluid. The chamber 205 may be connected to a pressurization source (not shown) to provide pressurized medium or fluid to the chamber 205. As discussed above, the base plate 242 can be temporarily deflected rather than permanently deformed relative to the polishing head 210. For example, adjusting the pressure in the chamber 205 can cause an increase or decrease in the deflection of the base plate 242. In embodiments where an O-ring 262 is used, the seal formed by the O-ring 262 between the top edge 260 and the concave surface 226 prevents pressurized media or fluid from leaking from the chamber 205, thereby maintaining a given pressure in the chamber 205.

[0039] The polishing head 210 and cap 240 may be made of a structural material, such as steel, aluminum, ceramic, or another suitable material. In some embodiments, the polishing head 210 and cap 240 are made of cast aluminum (e.g., from Alcoa). The cap 240 is made of aluminum cast plate. In other embodiments, the cap 240 may be made of ceramic (e.g., alumina) or plastic material. In embodiments using plastic materials, polyetherimide (e.g., ULTEM, available from Saudi Basic Industries Corporation (SABIC)) may be used. TM Resin 1000). Plastic caps 240 are substantially thicker than caps made of metal or ceramic. Caps made of ceramic material have a base plate that is substantially thinner than caps made of metal or plastic.

[0040] Metals used in the polishing head assembly 200 can potentially contaminate the wafer by becoming a source of metal ions through polishing chemicals or slurries. To prevent metal contamination of the slurry and wafer from the polishing head 210, the polishing head 210 is coated with epoxy resin, fluorocarbon, or another suitable non-metallic material to create a barrier and provide metal ion protection.

[0041] To prevent metal contamination of the slurry and wafers used in the polishing head assembly 200 and / or to prevent metal chemical exposure to polishing chemicals or slurry, a portion of the polishing head 210 and / or cap 240 is externally connected by a strip 270. The strip 270 forms a barrier between the slurry and the polishing head 210 and / or cap 240. The strip 270 may be a non-metallic material. In some embodiments, the strip 270 is made of plastic, such as polyetherimide (e.g., ULTEM from Saudi Basic Industries Corporation (SABIC)). TM Resin 1000), polydietherketone, polyphenylene sulfide and polyethylene terephthalate.

[0042] In this embodiment, the strip 270 is externally and sealably connected to a portion of the polishing head 210 at the bottom 214, a portion of the outer surface 254 of the annular wall 250 not externally connected to the polishing head 210, and a lug 248. The annular member 220 has a side inlet 272 extending inwardly from the outer surface 224 at the bottom 214 of the polishing head 210. A side groove 274 is formed between the lug 248 and the bottom of the annular member 220 and extends along a portion of the outer surface 254 of the annular wall 250 not externally connected to the annular member 220. The strip 270 is sized and shaped to externally connect the side inlet 272, the side groove 274, and the lug 248 and form a seal therebetween.

[0043] In some embodiments, the strip 270 is not single and is made of two or more segments. For example, the strip 270 may be made of three, four, five, or six segments. In these embodiments, the strip 270 may be joined at segment joints (e.g., Figure 5 The segmented joint 275 shown is sealed together and sealed to the polishing head 210 and / or cap 240 using an adhesive (e.g., epoxy resin). To prevent the seal between the strip 270 and the polishing head 210 and / or cap 240 from loosening due to adhesive failure, the strip 270 may include an interlocking member 276 to secure the strip 270 to the polishing head assembly 200. For example, the strip 270 may include a dovetail 276, which joins with an inner inlet 278 formed on the inner surface 222 of the annular member 220 and with an inner groove 280 formed by an upwardly extending member of the lug 248. In addition to or as an alternative to adhesive, the dovetail 276 can be used to secure the strip 270 to the polishing head 210 and / or cap 240.

[0044] The polishing head assembly 200 includes a backing film and a retaining ring (e.g. Figure 1In the embodiment of the template (back film 110 and retaining ring 120) shown, the strip 270 may also overlap with at least a portion of the template to prevent metal contamination of the polishing head 210 and / or cap 240 by the slurry or wafer and / or to prevent metal chemical exposure to polishing chemicals or slurry.

[0045] refer to Figure 3 This illustrates another example of a polishing head assembly 300 for use in a polishing apparatus 100. The polishing head assembly 300 includes a polishing head 310, a cap 340, and a strip 370. The polishing head assembly 300 may also include a template, which includes a backing film and a retaining ring, such as a backing film 110 and a retaining ring 120. Figure 1 (As shown in the image). The polishing head 310 has a top 312 and a bottom 314 that are substantially parallel to each other. The polishing head 310 has a platform 316 at the top 312 and a hole 318 extending from the platform 316 through the bottom 314.

[0046] The polishing head 310 has an annular member 320 extending downward from the platform 316 to the bottom 314. The annular member 320 has an inner surface 322 and an outer surface 324. The outer surface 324 forms the circumference of the polishing head 310. The annular member 320 defines a groove along the bottom 314, and the groove has a concave surface 326 extending between the annular members 320. In this embodiment, a hole 318 extends from the platform 316 through the concave surface 326. The annular member 320 has a bottom edge 372 at the bottom 314 that overlaps with and is sealable to the strip 370.

[0047] The cap 340 is positioned within a recess defined by the annular member 320. The cap 340 includes a base plate 342 surrounded by an annular wall 350 extending upward therefrom. The base plate 342 has a top surface 344 and a bottom surface 346. In this embodiment, the bottom surface 346 extends outward beyond the annular wall 350 to a lug 348. In other embodiments, the bottom surface 346 may not extend beyond the annular wall 350, such that the annular wall 350 defines the outermost circumference of the cap 340.

[0048] The annular wall 350 has an inner surface 352, an outer surface 354, a top portion 356, and a bottom portion 358. The top portion 356 has a top edge 360 ​​and a aperture 359 formed at the top edge 360. The aperture 359 extends into the top portion 356 and corresponds to a hole 318. The hole 318 and the corresponding aperture 359 receive fasteners 390 (e.g., screws) to removably secure the annular wall 350 to the concave surface 326 and thereby removably secure the cap 340 to the polishing head 310. When the annular wall 350 is secured to the concave surface 326, the top edge 360 ​​of the annular wall 350 contacts the concave surface 326. The top portion 356 may also include an O-ring 362 at the top edge 360, which forms a seal when the annular wall 350 is secured to the concave surface 326.

[0049] like Figure 3 As shown, the thickness of the annular wall 350 is greater at the top portion 356 than at the bottom portion 358. The thinner wall of the bottom portion 358 allows it to act as a hinge, around which the base plate 342 can be temporarily deflected rather than permanently deformed relative to the polishing head 310. For example, the base plate 342 can be temporarily deflected upward toward the polishing head 310 in response to downward vertical movement of the polishing head assembly 300 to cause the cap 340 to contact the wafer (e.g., ...). Figure 1 The wafer W shown in the figure. The inner surface 352 of the annular wall 350 at the top portion 356 may be angled relative to the outer surface 354, such that the thickness of the top portion 356 is thickest at the top edge 360 ​​and tapers downward toward the bottom portion 358.

[0050] When the cap 340 is secured to the polishing head 310, at least a portion of the outer surface 354 abuts the inner surface 322 of the annular member 320. Suitably, the outer surface 354 is substantially parallel to the inner surface 322. In this embodiment, the height of the annular wall 350 is greater than the downward extension of the annular member 320, and the inner surface 322 of the annular member 320 externally aligns with the top portion 356 of the annular wall 350. In other embodiments, the annular member 320 may be more or less externally aligned with the annular wall 350.

[0051] When the cap 340 is secured to the polishing head 310, the base plate 342 is spaced from the concave surface 326. Therefore, when the cap 340 is secured to the polishing head 310, the annular wall 350, the top surface 344 of the base plate 342, and the concave surface 326 define the chamber 305. Because the top edge 360 ​​contacts the concave surface 326 when the annular wall 350 is secured to the concave surface 326, the height of the chamber 305 is determined by the height of the annular wall 350. In some embodiments, the chamber 305 is pressurized by a pressurized medium or fluid. The chamber 305 may be connected to a pressurization source (not shown) to provide pressurized medium or fluid to the chamber 305. As discussed above, the base plate 342 can be temporarily deflected relative to the polishing head 310 rather than permanently deformed. For example, adjusting the pressure in the chamber 305 can cause an increase or decrease in the deflection of the base plate 342. In embodiments where an O-ring 362 is used, the seal formed between the top edge 360 ​​and the concave surface 326 prevents pressurized media or fluid from leaking from the chamber 305, thereby maintaining a given pressure in the chamber 305.

[0052] The polishing head 310 and cap 340 may be made of a structural material, such as steel, aluminum, ceramic, or another suitable material. In some embodiments, the polishing head 310 and cap 340 are made of cast aluminum (e.g., from Alcoa). The cap 340 is made of aluminum cast plate. In other embodiments, the cap 340 may be made of ceramic (e.g., alumina) or plastic material. In embodiments using plastic materials, polyetherimide (e.g., ULTEM, available from Saudi Basic Industries Corporation (SABIC)) may be used. TM Resin 1000). Plastic caps 340 are substantially thicker than caps made of metal or ceramic. Caps made of ceramic material have a base plate that is substantially thinner than caps made of metal or plastic.

[0053] Metals used in the polishing head assembly 300 can potentially contaminate the wafer by becoming a source of metal ions through polishing chemicals or slurries. To prevent metal contamination of the slurry and wafer from the polishing head 310, the polishing head 310 is coated with epoxy resin, fluorocarbon, or another suitable non-metallic material to create a barrier and provide metal ion protection.

[0054] To prevent metal contamination of the slurry and wafers used in the polishing head assembly 300 and / or to prevent metal chemical exposure to polishing chemicals or slurry, a portion of the polishing head 310 and / or the cap 340 is externally connected by a strip 370 to form a barrier between the slurry and the polishing head 310 and / or the cap 340. The strip 370 may be a non-metallic material. In some embodiments, the strip 370 is made of plastic, such as polyetherimide (e.g., ULTEM, available from Saudi Basic Industries Corporation (SABIC)). TM Resin 1000), polydietherketone, polyphenylene sulfide and polyethylene terephthalate.

[0055] In this embodiment, the strip 370 is externally and sealable to a portion of the outer surface 354 of the annular wall 350 not externally connected to the polishing head 310 and to the lug 348. The strip 370 may also be sealed to the annular component 320 at its bottom edge 372. The strip 370 may be sealed to the polishing head 310 and / or the cap 340 using an adhesive (e.g., epoxy resin). To prevent the seal between the strip 370 and the polishing head 310 and / or the cap 340 from loosening due to adhesive failure, the strip 370 may be a one-piece strip. When the cap 340 is secured to the polishing head 310, the one-piece strip 370 may also be held in place by an interference fit between the strip 370 and the lug 348 and between the strip 370 and the bottom edge 372.

[0056] The polishing head assembly 300 includes a backing film and a retaining ring (e.g. Figure 1In the embodiment of the template (back film 110 and retaining ring 120) shown, the strip 370 may also overlap with at least a portion of the template to prevent metal contamination of the polishing head 310 and / or cap 340 by the slurry or wafer and / or to prevent metal chemical exposure to polishing chemicals or slurry.

[0057] refer to Figure 4 This illustrates another exemplary polishing head assembly 400 for use in polishing apparatus 100. Polishing head assembly 400 includes a polishing head 410, a cap 440, and a strip 470. Polishing head assembly 400 may also include a template comprising a backing film and a retaining ring, such as a backing film 110 and a retaining ring 120. Figure 1 (As shown in the image). The polishing head 410 has a top 412 and a bottom 414 that are substantially parallel to each other. The polishing head 410 has a platform 416 at the top 412 and a hole 418 extending from the platform 416 through the bottom 414.

[0058] The polishing head 410 has an annular member 420 extending downward from the platform 416 to the bottom 414. The annular member 420 has an inner surface 422 and an outer surface 424. The outer surface 424 forms the circumference of the polishing head 410. The annular member 420 defines a groove along the bottom 414, and the groove has a concave surface 426 extending between the annular members 420. In this embodiment, a hole 418 extends from the platform 416 through the concave surface 426. The annular member 420 has a bottom edge 472 at the bottom 414 that overlaps with and is sealable to the strip 470.

[0059] The cap 440 is positioned within a recess defined by the annular member 420. The cap 440 includes a base plate 442 surrounded by an annular wall 450 extending upward therefrom. The base plate 442 has a top surface 444 and a bottom surface 446. In this embodiment, the bottom surface 446 extends outward beyond the annular wall 450 to a lug 448. In other embodiments, the bottom surface 446 may not extend beyond the annular wall 450, such that the annular wall 450 defines the outermost circumference of the cap 440.

[0060] The annular wall 450 has an inner surface 452, an outer surface 454, a top portion 456, and a bottom portion 458. The top portion 456 has a top edge 460 and a aperture 459 formed at the top edge 460. The aperture 459 extends into the top portion 456 at the top edge 460 and corresponds to a hole 418. The hole 418 and the corresponding aperture receive a fastener 490 (e.g., a screw) to removably secure the annular wall 450 to the concave surface 426 and thereby removably secure the cap 440 to the polishing head 410. When the annular wall 450 is secured to the concave surface 426, the top edge 460 of the annular wall 450 contacts the concave surface 426. The top portion 456 may also include an O-ring 462 at the top edge 460, which forms a seal when the annular wall 450 is secured to the concave surface 426.

[0061] like Figure 4 As shown, the thickness of the annular wall 450 is greater at the top portion 456 than at the bottom portion 458. The thinner wall of the bottom portion 458 allows it to act as a hinge, around which the base plate 442 can be temporarily deflected rather than permanently deformed relative to the polishing head 410. For example, the base plate 442 can be temporarily deflected upward toward the polishing head 410 in response to downward vertical movement of the polishing head assembly 400 to cause the cap 440 to contact the wafer (e.g., ...). Figure 1 The wafer W shown in the figure. The inner surface 452 of the annular wall 450 at the top portion 456 may be angled relative to the outer surface 454, such that the thickness of the top portion 456 is thickest at the top edge 460 and tapers downward toward the bottom portion 458.

[0062] When the cap 440 is secured to the polishing head 410, at least a portion of the outer surface 454 abuts the inner surface 422 of the annular member 420. Suitably, the outer surface 454 is substantially parallel to the inner surface 422. In this embodiment, the height of the annular wall 450 is greater than the downward extension of the annular member 420, and the inner surface 422 of the annular member 420 externally aligns with the top portion 456 of the annular wall 450. In other embodiments, the annular member 420 may be more or less externally aligned with the annular wall 450.

[0063] When the cap 440 is secured to the polishing head 410, the base plate 442 is spaced from the concave surface 426. Therefore, when the cap 440 is secured to the polishing head 410, the annular wall 450, the top surface 444 of the base plate 442, and the concave surface 426 define the chamber 405. Because the top edge 460 contacts the concave surface 426 when the annular wall 450 is secured to the concave surface 426, the height of the chamber 405 is determined by the height of the annular wall 450. In some embodiments, the chamber 405 is pressurized by a pressurized medium or fluid. The chamber 405 may be connected to a pressurization source (not shown) to provide pressurized medium or fluid to the chamber 405. As discussed above, the base plate 442 can be temporarily deflected rather than permanently deformed relative to the polishing head 410. For example, adjusting the pressure in the chamber 405 can cause an increase or decrease in the deflection of the base plate 442. In embodiments where an O-ring 462 is used, the seal formed between the top edge 460 and the concave surface 426 prevents pressurized media or fluid from leaking from the chamber 405, thereby maintaining a given pressure in the chamber 405.

[0064] The polishing head 410 and cap 440 may be made of a structural material, such as steel, aluminum, ceramic, or another suitable material. In some embodiments, the polishing head 410 and cap 440 are made of cast aluminum (e.g., from Alcoa). The cap 440 is made of aluminum cast plate. In other embodiments, the cap 440 may be made of ceramic (e.g., alumina) or plastic material. In embodiments using plastic materials, polyetherimide (e.g., ULTEM, available from Saudi Basic Industries Corporation (SABIC)) may be used. TM Resin 1000). Plastic caps 440 are substantially thicker than caps made of metal or ceramic. Caps made of ceramic material have a base plate that is substantially thinner than caps made of metal or plastic.

[0065] Metals used in the polishing head assembly 400 can potentially contaminate the wafer by becoming a source of metal ions through polishing chemicals or slurries. To prevent metal contamination of the slurry and wafer from the polishing head 410, the polishing head 410 is coated with epoxy resin, fluorocarbon, or another suitable non-metallic material to create a barrier and provide metal ion protection.

[0066] To prevent metal contamination of the slurry and wafers used in the polishing head assembly 400 and / or to prevent metal chemical exposure to polishing chemicals or slurry, a portion of the polishing head 410 and / or the cap 440 is externally connected by a strip 470 to form a barrier between the slurry and the polishing head 410 and / or the cap 440. The strip 470 may be a non-metallic material. In some embodiments, the strip 470 is made of plastic, such as polyetherimide (e.g., ULTEM, available from Saudi Basic Industries Corporation (SABIC)). TM Resin 1000), polydietherketone, polyphenylene sulfide and polyethylene terephthalate.

[0067] In this embodiment, the strip 470 is externally and sealable to a portion of the outer surface 454 of the annular wall 450 not externally connected to the polishing head 410 and to the lug 448. The strip 470 may also be sealed to the annular component 420 at its bottom edge 472. The strip 470 may be secured to the polishing head 410 and / or the cap 440 using an adhesive (e.g., epoxy resin). To prevent the seal between the strip 470 and the polishing head assembly 400 from loosening due to adhesive failure, the strip 470 may be a one-piece strip. When the cap 440 is secured to the polishing head 410, the one-piece strip 470 may also be held in place by an interference fit between the strip 470 and the lug 448 and between the strip 470 and the bottom edge 472. In this embodiment, the lug 448 has an O-ring 474 forming a seal between the lug 448 and the strip 470. O-ring 474 can add an additional seal to prevent chemical exposure inside the joint between strip 470 and polishing head assembly 400. O-ring 474 can also compensate for any undesirable clearance due to tolerance overlap.

[0068] The polishing head assembly 400 includes a backing film and a retaining ring (e.g. Figure 1 In the embodiment of the template (back film 110 and retaining ring 120) shown, the strip 470 may also overlap with at least a portion of the template to prevent metal contamination of the polishing head 410 and / or cap 440 by the slurry or wafer and / or to prevent metal chemical exposure to polishing chemicals or slurry.

[0069] The features of the above embodiments have several advantages. For example, by using fasteners instead of epoxy resin to attach the polishing head assembly, problems associated with epoxy resin joint failure, a major cause of failure during the service life of the polishing head assembly, can be reduced or eliminated. When the polishing head assembly requires repair, the fasteners allow for disassembly of the polishing head assembly without the use of heating or other destructive actions, reducing maintenance time and aiding in component salvage. If a coating is used, the reassembly of the polishing head assembly can occur without applying a new material coating to the polishing head assembly. Indexing pins can be used to ensure that components are placed together in their original orientation, avoiding the need for repeated polishing of components. Indexing pins thus prevent flatness problems associated with reassembling conventional polishing head assemblies using fasteners (e.g., screws). Additionally, by securing the top edge of the cap's annular wall to the concave surface of the polishing head, leakage of pressurized media or fluid from the chamber of the polishing head assembly can be prevented. This seal can be improved by using an O-ring at this connection. Furthermore, non-metallic strips prevent polishing chemicals or slurries from contacting the polishing head assembly, thus maintaining the service life of the polishing head and cap.

[0070] refer to Figure 5 and 6 Show each Figure 2 A perspective view and partial cross-section of the polishing head assembly 200. As discussed above, the polishing head assembly 200 includes a polishing head 210, a cap 240, and a strip 270. The cap 240 has a base plate 242 with a bottom surface 246 extending outwardly to a lug 248. Figure 5 and 6 As shown, the polishing head assembly 200 also includes a template 295. The template 295 includes a back film 296 and a retaining ring 298. The retaining ring 298 extends downward along the periphery of the back film 296 to form a receiving wafer W. Figure 5 The circular opening is shown in the figure. In some embodiments, the height of the retaining ring 298 is less than the height of the wafer W, which facilitates reducing or eliminating contact between the retaining ring 298 and the polishing pad (e.g., polishing pad 150). Figure 1 (As shown in the diagram) During operation, the wafer W in this embodiment is kept against the back film 296 by surface tension.

[0071] To prevent metal contamination of the slurry and wafer W in the cap 240, a pressure-sensitive adhesive is used to seal the back film 296 of the template 295 to the bottom surface 246 of the cap 240. The back film 296 is typically a thin, soft polymer pad or other suitable material. The back film 296 appropriately comprises two or more material layers (not shown). For example, the back film 296 may have an adhesive layer, a thin plastic film layer, and a thin polyurethane foam or other nonwoven material (e.g., felt) layer. The adhesive layer seals the back film 296 to the bottom surface 246 of the cap 240. The thin plastic film layer provides a protective barrier between the cap 240 and the slurry and / or wafer W. The layer comprising the polyurethane foam or nonwoven material (e.g., felt) contacts the wafer W and provides a similar effect to a polishing pad (e.g., a polishing pad). Figure 1 The surface of the polishing pad 150 shown is shown. A retaining ring 298 extends downward from the back film 296 and is generally made of plastic. The wafer W is received by the retaining ring 298 and held against the back film 296 by surface tension. Therefore, the wafer W does not directly contact the cap 240.

[0072] In this embodiment, the template 295 has a circumference larger than that of the cap 240 and extends outward from the lug 248. The cap 240 is externally attached by a strip 270, which overlaps with the outer portion of the template 295 at the overlapping surface 299. The backing film 296 of the template 295 is sealed to the bottom surface 246 using a pressure-sensitive adhesive and to the strip 270 at the overlapping surface 299. The strip 270 and the template 295 together form a protective seal between the slurry and wafer W and the polishing pad 210 and the cap 240 to prevent the slurry and wafer W from directly contacting the polishing head 210 and the cap 240.

[0073] The embodiments described herein provide the ability to disassemble the polishing head assembly without using heating or other destructive actions, and enable efficient and economical repair of the polishing head assembly. The embodiments described herein also provide the ability to attach the polishing head assembly using fasteners while maintaining the desired flatness and other specifications of the polished wafer.

[0074] Another advantage of using the embodiments described herein is the reduction or elimination of problems associated with epoxy joint failure during the service life of the polishing head assembly. Additionally, leakage from the pressurized chamber is prevented by a seal formed between the cap and the concave surface. The strip and template provide further protection for the metal of the wafer and polishing head assembly and reduce the amount of epoxy required to attach the polishing head assembly and / or the chance of epoxy joint failure due to chemical exposure.

[0075] When elements of this disclosure or embodiments thereof are introduced, the articles “a / an” and “the / said” are intended to mean that one or more elements are present. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that additional elements may be present in addition to those listed. The use of terms indicating a particular orientation (e.g., “top,” “bottom,” “side,” “down,” “up,” etc.) is for convenience of description and does not require any particular orientation of the described article.

[0076] Since various changes can be made to the above construction and methods without departing from the scope of this disclosure, all matters contained in the above description and shown in the accompanying drawings are intended to be illustrative rather than limiting.

Claims

1. A polishing head assembly for polishing semiconductor wafers, the polishing head assembly comprising: A polishing head having a top portion and a downwardly extending annular member defining a groove along a bottom portion, the groove having a concave surface and a hole extending from the top portion through the concave surface; A cap, positioned within the recess, the cap having an annular wall and a base plate extending across the annular wall, the base plate having a bottom surface and a top surface and spaced from the recess to form a cavity between the recess and the top surface, wherein the annular wall has pores corresponding to the hole, and wherein the cap is made of a metallic material; and A strip, which is external to a first portion of the annular wall, wherein the strip is made of a non-metallic material; The annular component is externally connected to the second portion of the annular wall; and The hole and the corresponding aperture receive fasteners to removably secure the annular wall of the cap to the concave surface of the polishing head, such that when the annular wall and the concave surface are secured, the height of the chamber is determined by the height of the annular wall.

2. The polishing head assembly of claim 1, wherein the strip is external to a portion of the annular component.

3. The polishing head assembly according to claim 1, wherein the strip is not single and has at least two segments.

4. The polishing head assembly of claim 3, wherein the strip has an interlocking component for securing the strip to the annular wall.

5. The polishing head assembly according to claim 1, wherein the strip is an integral, single-piece strip.

6. The polishing head assembly according to claim 1, wherein the non-metallic material is selected from the group consisting of polyetherimide, polydietherketone, polyphenylene sulfide and polyethylene terephthalate.

7. The polishing head assembly of claim 1, wherein the annular wall has a top edge that contacts the concave surface when the annular wall and the concave surface are secured.

8. The polishing head assembly of claim 7, wherein the top edge includes a sealing O-ring formed when the annular wall and the concave surface are fixed.

9. The polishing head assembly of claim 1, further comprising a template attached to the bottom surface of the base plate, the template comprising a backing film.

10. The polishing head assembly of claim 9, wherein the template is attached to the bottom surface using a pressure-sensitive adhesive.

11. The polishing head assembly of claim 9, wherein the template extends outward beyond the outer surface of the annular wall such that the strip partially overlaps with the template.

12. The polishing head assembly of claim 11, wherein the pressure-sensitive adhesive forms a seal at the portion of the template overlapping the strip.

13. The polishing head assembly of claim 9, wherein the template further includes a retaining ring extending downward from the back film.

14. The polishing head assembly of claim 13, wherein the retaining ring forms an opening to receive a semiconductor wafer, and wherein the height of the wafer is greater than the height of the retaining ring.

15. The polishing head assembly of claim 14, wherein the template, together with the liquid, is used to hold the wafer on the polishing head assembly by surface tension.

16. The polishing head assembly according to claim 1, wherein said first portion of said annular wall has an aperture corresponding to said aperture of said hole, said second portion of said annular wall extending downwardly from said first portion; and The strip is a single, integral strip, which is externally connected to the second part of the annular wall; The fastener removably secures the first portion of the annular wall of the cap to the concave surface of the polishing head; and The first portion of the annular wall has a first O-ring that forms a seal when the first portion and the concave surface are fixed.

17. The polishing head assembly of claim 16, wherein the cap has a lug extending outward from the second portion of the annular wall and a second O-ring forming a seal between the lug and the strip.

18. The polishing head assembly of claim 16, wherein the non-metallic material is selected from the group consisting of polyetherimide, polydietherketone, polyphenylene sulfide, and polyethylene terephthalate.

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