Carrier for small pads for chemical mechanical polishing

Abstract

A chemical mechanical polishing system includes a substrate support configured to hold a substrate during a polishing operation, a polishing pad assembly including a membrane and a polishing pad portion, and a drive system configured to cause relative motion between the substrate support and a polishing pad carrier. The polishing pad carrier includes a casing having a cavity and an aperture connecting the cavity to an exterior of the casing. The polishing pad assembly is positioned in the casing such that the membrane divides the cavity into a first chamber and a second chamber, and the aperture extends from the second chamber. The polishing pad carrier and the polishing pad assembly are positioned and configured such that, at least during a time when sufficient pressure is applied to the first chamber, the polishing pad portion protrudes through the aperture.

Description

[0001] This application is a divisional application of Chinese patent application (PCT application number PCT / US2016 / 064541) filed on December 2, 2016, with application number 201680078495.7 and entitled "Carrier for a small pad for chemical mechanical polishing". Technical Field

[0002] This disclosure relates to chemical mechanical polishing (CMP). Background Technology

[0003] Integrated circuits are typically formed on a substrate by continuously depositing conductors, semiconductors, or insulating layers onto a silicon wafer. One fabrication step includes depositing a filler layer on a non-planar surface and planarizing that filler layer. For some applications, the filler layer is planarized until the top surface of the patterned layer is exposed. For example, a conductive filler layer may be deposited on a patterned insulating layer to fill trenches or holes in the insulating layer. After planarization, portions of the metal layer remaining between the raised patterns in the insulating layer form vias, plugs, and wiring that provide conductive paths between thin-film circuits on the substrate. For other applications (such as oxide polishing), the filler layer is planarized until a predetermined thickness remains on the non-planar surface. Furthermore, photolithography often requires planarization of the substrate surface.

[0004] Chemical mechanical polishing (CMP) is a widely accepted planarization method. This planarization method typically requires mounting the substrate on a carrier or polishing head. The exposed surface of the substrate is usually positioned against a rotating polishing pad. The carrier head provides a controlled load on the substrate to push it against the polishing pad. Abrasive polishing slurry is typically supplied to the surface of the polishing pad. Summary of the Invention

[0005] This disclosure provides an apparatus for polishing a substrate, wherein the contact area of ​​the polishing pad against the substrate is smaller than the radius of the substrate.

[0006] In one aspect, a chemical mechanical polishing (CMP) system includes a substrate support, a polishing pad assembly, a polishing pad carrier, and a drive system. The substrate support is configured to hold a substrate during polishing operations. The polishing pad assembly includes a membrane and a polishing pad portion. The drive system is configured to cause relative movement between the substrate support and the polishing pad carrier. The polishing pad portion has a polishing surface for contacting the substrate during polishing operations, and the polishing pad portion is bonded to the membrane on one side opposite the polishing surface. The polishing pad carrier includes a housing having a cavity and an aperture connecting the cavity to the outside of the housing. The polishing pad assembly is positioned within the housing such that the membrane divides the cavity into a first chamber and a second chamber, and the aperture extends from the second chamber. The polishing pad carrier and the polishing pad assembly are positioned and configured such that, at least during periods when sufficient pressure is applied to the first chamber, the polishing pad portion protrudes through the aperture.

[0007] Implementation may include one or more of the following features.

[0008] The membrane and polishing pad portion are a single unit. The polishing pad portion can be fixed to the membrane using an adhesive. The membrane may include a first portion surrounded by a less flexible second portion, and the polishing pad portion is bonded to the first portion. The outer surface of the polishing pad carrier surrounding the pores may be substantially parallel to the polishing surface.

[0009] The polishing pad carrier and polishing pad assembly can be configured such that, when the first chamber is under atmospheric pressure, the polishing pad portion extends at least partially through the pores. Alternatively, the polishing pad carrier and polishing pad assembly can be configured such that, when the first chamber is under atmospheric pressure, the polishing pad portion extends completely through the pores. Or, the polishing pad carrier and polishing pad assembly can be configured such that, when the first chamber is under atmospheric pressure, the polishing pad portion extends only partially through the pores.

[0010] A controllable pressure source is fluidly coupled to the first chamber. A reservoir for polishing fluid is fluidly coupled to the second chamber. The system can be configured such that during polishing operations, the polishing fluid flows into the second chamber and out through an orifice. A cleaning fluid source is fluidly coupled to the second chamber. The system can be configured such that between polishing operations, cleaning fluid flows into the two chambers and out through an orifice.

[0011] The housing may include a lower portion that substantially extends across the entire membrane except at the pores. The housing may include an upper portion, with the edge of the membrane held between the upper and lower portions of the housing. The membrane may be substantially parallel to the polishing surface. The drive system may be configured to move the polishing pad carrier in a tracked motion, during which the polishing pad portion contacts the exposed surface of the substrate and maintains the polishing pad in a fixed angular orientation relative to the substrate.

[0012] In another aspect, the polishing pad assembly may include a membrane and a polishing pad portion having a kidney-bean shaped perimeter, and the polishing pad portion having a polishing surface for contacting a substrate during a polishing operation. On the side opposite the polishing surface, the polishing pad portion may be bonded to the membrane.

[0013] Implementation may include one or more of the following features.

[0014] The polishing pad portion can be positioned near the midline of the membrane and substantially equidistant from the opposite edges of the membrane. The membrane can have bilateral symmetry across the midline of the membrane.

[0015] The advantages of this invention may include one or more of the following: The pressure of the polishing pad against the substrate can be controlled, thus allowing adjustment of the polishing rate via the polishing pad. The film holding the polishing pad can be protected from polishing debris, thereby increasing the lifespan of the pad portion. The slurry can be provided near the portion of the polishing pad that contacts the substrate. This allows for a smaller amount of slurry to be supplied, thus reducing costs. The small pad undergoing orbital motion can be used to compensate for non-concentric polishing uniformity. This orbital motion can provide an acceptable polishing rate while avoiding overlap of the pad with areas that are not desired to be polished, thereby improving substrate uniformity. Non-uniform polishing of the substrate can be reduced, and the resulting substrate flatness and finish can be improved.

[0016] Other aspects, features, and advantages of the invention will become apparent from the description, drawings, and claims. Attached Figure Description

[0017] Figure 1 This is a side view of a cross-section of the polishing system.

[0018] Figure 2 This is a top-view view showing the loading area of ​​the polishing pad portion on the substrate.

[0019] Figures 3A to 3E This is a schematic cross-sectional view of the polishing pad assembly.

[0020] Figures 4A to 4C This is a bottom view of the polished surface of the polishing pad assembly.

[0021] Figures 5A to 5B This is a bottom view of the polishing pad assembly.

[0022] Figure 6 This is a schematic cross-sectional view of the polishing pad carrier.

[0023] Figure 7 This is a top-view outline of a cross-section showing a portion of a polishing pad that moves along a track while maintaining a fixed angular orientation.

[0024] Figure 8 This is a side view of the outline cross-section of the polishing pad carrier and the transmission system of the polishing system;

[0025] Figure 9 These are a schematic cross-sectional view and a top view showing the orbital movement of the polishing pad portion relative to the substrate.

[0026] Figure 10 These are a schematic cross-sectional view and a top view showing the rotational movement of the polishing pad portion relative to the substrate.

[0027] The same reference numerals in different figures represent the same elements. Detailed Implementation

[0028] 1. Introduction

[0029] Some chemical mechanical polishing processes can lead to thickness non-uniformity across the substrate surface. For example, bulk polishing may create under-polished areas on the substrate. To address this issue, a "touch-up" polishing process may be performed after bulk polishing, focusing on the under-polished substrate areas.

[0030] Some batch polishing processes produce localized, non-concentric, and non-uniform spots due to insufficient polishing. Polishing pads rotating around the center of the substrate can compensate for concentric rings of non-uniformity, but may not be able to resolve localized non-concentric and non-uniform spots. However, small pads undergoing orbital motion can be used to compensate for non-concentric polishing non-uniformity.

[0031] Reference Figure 1 A polishing apparatus 100 for polishing localized areas of a substrate includes a substrate support 105 and a movable polishing pad carrier 300. The substrate support 105 holds the substrate 10, and the movable polishing pad carrier 300 holds a polishing pad portion 200. The polishing pad portion 200 includes a polishing surface 220, which has a diameter smaller than the radius of the substrate 10 being polished.

[0032] The polishing pad carrier 300 is suspended from the polishing drive system 500, which provides movement of the polishing pad carrier 300 relative to the substrate 10 during the polishing operation. The polishing drive system 500 may be suspended from the support structure 550.

[0033] In some implementations, the positioning drive system 560 is connected to the substrate support 105 and / or the polishing pad carrier 300. For example, the polishing drive system 500 can provide a connection between the positioning drive system 560 and the polishing pad carrier 300. The positioning drive system 560 can be operated to position the pad carrier 300 at a desired lateral position above the substrate support 105.

[0034] For example, the support structure 550 may include two linear actuators 562 and 564 to provide a positioning drive system 560, the two linear actuators 562 and 564 being oriented to provide movement in two perpendicular directions on the substrate support 105. Alternatively, the substrate support 105 may be supported by two linear actuators. Alternatively, the substrate support 105 may be supported by one linear actuator, while the polishing pad carrier 300 may be supported by other linear actuators. Alternatively, the substrate support 105 may be rotatable, and the polishing pad carrier 300 may be suspended by a single linear actuator that provides movement in a radial direction. Alternatively, the polishing pad carrier 300 may be suspended by a rotary actuator, and the substrate support 105 may rotate with the rotary actuator. Alternatively, the support structure 550 may be an arm pivotally attached to a base positioned offset from one side of the substrate 105, and the substrate support 105 may be supported by either a linear or rotary actuator.

[0035] A vertical actuator can be selectively connected to the substrate support 105 and / or the polishing pad carrier 300. For example, the substrate support 105 can be connected to a vertically driven piston 506, which can lift or lower the substrate support 105. Alternatively or supplementarily, the vertically driven piston can be included in the positioning system 500 to lift or lower the entire polishing pad carrier 300.

[0036] Polishing apparatus 100 may optionally include a reservoir 60 containing polishing fluid 62, such as an abrasive slurry. As discussed below, in some embodiments, the slurry is dispensed onto the surface 12 of the substrate 10 to be polished via a polishing pad carrier 300. A conduit 64 (such as a flexible tube) may be used to transport polishing fluid from the reservoir 60 to the polishing pad carrier 300. Alternatively or supplementally, the polishing apparatus may include a separate port 66 for dispensing polishing fluid. Polishing apparatus 100 may also include a polishing pad conditioner for abrading the polishing pad 200 to maintain the polishing pad 200 in a consistent abrasive state. The reservoir 60 may include a pump for supplying polishing fluid at a controllable rate through the conduit 64.

[0037] Polishing apparatus 100 may include a cleaning fluid source 70, such as a reservoir or supply line. The cleaning fluid may be deionized water. A conduit 72 (such as a flexible tube) may be used to transport the polishing fluid from the reservoir 70 to the polishing pad carrier 300.

[0038] The polishing apparatus 100 includes a controllable pressure source 80 (such as a pump) to apply controllable pressure to the interior of the polishing pad carrier 300. The pressure source 80 can be connected to the polishing pad carrier 300 via a conduit 82 (such as a flexible tube).

[0039] Each of the storage tank 60, the cleaning fluid source 70, and the controllable pressure source 80 can be mounted on the support structure 555 or on a separate frame for holding various components of the polishing equipment 100.

[0040] During operation, substrate 10 is loaded onto substrate support 105 by means of a robot. In some embodiments, positioning drive system 560 moves polishing pad carrier 500 such that when substrate 10 is loaded, polishing pad carrier 500 is not directly above substrate support 105. For example, if support structure 550 is a pivotable arm, the arm can swing such that polishing pad carrier 300 is offset to one side of substrate support 105 during substrate loading.

[0041] Next, the positioning drive system 560 positions the polishing pad support 300 and the polishing pad 200 at desired locations on the substrate 10. The polishing pad 200 contacts the substrate 10. For example, the polishing pad carrier 300 can actuate the polishing pad 200 to press it down onto the substrate 10. Alternatively or supplementarily, one or more vertical actuators can lower the entire polishing pad carrier 300 and / or raise the substrate support to contact the substrate 10. The polishing drive system 500 generates relative movement between the polishing pad support 300 and the substrate support 105, thereby polishing the substrate 10.

[0042] During the polishing operation, the positioning drive system 560 can substantially fix the polishing drive system 500 relative to the substrate 10. For example, the positioning system can fix the polishing drive system 500 relative to the substrate 10, or slowly sweep the polishing drive system 500 across the entire area to be polished (compared to the motion provided to the substrate 10 by the polishing drive system 500). For example, the instantaneous speed provided to the substrate 10 by the positioning drive system 560 may be less than 5% (e.g., less than 2%) of the instantaneous speed provided to the substrate 10 by the polishing drive system 500.

[0043] The polishing system also includes a controller 90, such as a programmable computer. The controller may include a central processing unit 91, a memory 92, and support circuitry 93. The central processing unit 91 of the controller 90 executes instructions loaded from the memory 92 via the support circuitry 93 to allow the controller to receive environment-based inputs and desired polishing parameters and to control the various actuators and drive systems.

[0044] 2. Substrate support

[0045] Reference Figure 1The substrate support 105 is a disc-shaped body located below the polishing pad carrier 300. The upper surface 128 of this body provides a loading area large enough to accommodate the substrate to be processed. For example, the substrate may be a substrate with a diameter of 200 to 450 mm. The upper surface 128 of the substrate support 105 contacts the back surface (i.e., the unpolished surface) of the substrate 10 and holds it in position.

[0046] The radius of the substrate support 105 is approximately the same as, or larger than, the radius of the substrate 10. In some embodiments, the substrate support 105 is slightly narrower than the substrate, such as 1-2% narrower than the substrate diameter. In this case, when the substrate is placed on the support 105, the edge of the substrate 10 slightly protrudes from the edge of the support 105. This provides clearance for an edge-gripping robot to place the substrate on the support. In some embodiments, the substrate support 105 is wider than the substrate, for example, 1-10% wider than the substrate diameter. In both cases, the substrate support 105 can contact most of the back surface of the substrate.

[0047] In some embodiments, during the polishing operation, the substrate support 105 holds the substrate 10 in position using a clamping assembly 111. For example, the clamping assembly 111 may be located where the substrate support 105 is wider than the substrate 10. In some embodiments, the clamping assembly 111 may be a single annular clamping ring 112 contacting the edge of the top surface of the substrate 10. Alternatively, the clamping assembly 111 may include two arcuate clamps 112 contacting the edges of the top surfaces on opposite sides of the substrate 10. The clamps 112 of the clamping assembly 111 may be lowered to contact the edge of the substrate by one or more actuators 113. During the polishing operation, the downward force of the clamps restricts lateral movement of the substrate. In some embodiments, the clamps include a downwardly projecting flange 114 surrounding the outer edge of the substrate.

[0048] As an alternative or supplement, the substrate support 105 is a vacuum chuck. In this case, the top surface 128 of the support 105 in contact with the substrate 10 includes a plurality of ports 122, which are connected to a vacuum source 126 (such as a pump) via one or more channels 126 in the support 105. In operation, air can be exhausted from the vacuum source 126 through the channels 126, thereby applying suction through the ports 122 to hold the substrate 10 in the proper position on the substrate support 105. A vacuum chuck can be used regardless of whether the substrate support 105 is wider or narrower than the substrate 10.

[0049] In some implementations, the substrate support 105 includes a holder to circumferentially surround the substrate 10 during polishing. The various substrate support features described above can optionally be combined with each other. For example, the substrate support may include both a vacuum chuck and a holder.

[0050] 3. Polishing pad

[0051] Reference Figure 1 and 2 The polishing pad portion 200 has a polishing surface 220 that contacts the substrate 10 in a contact area (also called a loading area) during polishing. The polishing surface 220 can have a maximum lateral dimension D, where D is a diameter smaller than the radius of the substrate 10. For example, the maximum lateral diameter of the polishing pad can be approximately 5-10% of the substrate diameter. For example, for wafers with diameters ranging from 200 mm to 300 mm, the polishing pad surface 220 can have a maximum lateral dimension of 2-30 mm, such as 3-10 mm, or even 3-5 mm. Smaller pads offer greater precision but are slower to use.

[0052] The cross-sectional shape of the polishing pad portion 200 (and the polishing surface 220) in the lateral direction (i.e., the cross-section parallel to the polishing surface 220) can be almost any shape, such as a circle, square, ellipse, or arc.

[0053] Reference Figure 1 and Figures 3A to 3D The polishing pad portion 200 is bonded to the membrane 250 to provide the polishing pad assembly 240. As discussed below, the membrane 250 is configured to be curved such that the central region 252 of the membrane 250 to which the polishing pad portion 200 is bonded can undergo vertical deflection, while the edges 254 of the membrane 250 remain vertically fixed.

[0054] The membrane 250 has a lateral dimension L, which is larger than the maximum lateral dimension D of the polishing pad portion 200. The membrane 250 may be thinner than the polishing pad portion 200. The sidewalls 202 of the polishing pad portion 200 may extend substantially perpendicular to the membrane 250.

[0055] In some implementations, such as Figure 3A As shown, the top of the polishing pad portion 200 is secured to the bottom of the film 250 by an adhesive 260. The adhesive can be an epoxy resin, such as a UV-curable epoxy resin. In this case, the polishing pad portion 200 and the film 250 can be manufactured separately and then bonded together.

[0056] In some implementations, for example, Figure 3B As shown, the polishing pad assembly (including the film 250 and the polishing pad portion 200) is a single entity composed of similar materials. For example, the entire polishing pad assembly 250 can be formed by injection molding in a mold with complementary shapes. Alternatively, the polishing pad assembly 240 can be formed in a block and then processed to thin the portion corresponding to the film 250.

[0057] The polishing pad portion 200 can be a material suitable for contacting the substrate during chemical mechanical polishing. For example, the polishing pad material can include polyurethane, such as microporous polyurethane, for example, IC-1000 material.

[0058] When the film 250 and the polishing pad portion 200 are formed separately, the film 250 can be softer than the polishing pad material. For example, the film 250 can have a hardness of about 60-70 Shore D, while the polishing pad portion 200 can have a hardness of about 80-85 Shore D.

[0059] Alternatively, membrane 250 can be more flexible than polishing pad portion 200, but less compressible. For example, the membrane can be a flexible polymer such as polyethylene terephthalate (PET).

[0060] The membrane 250 may be formed of a material different from that of the polishing pad portion 200, or it may be formed of a material that is substantially the same but has a different degree of crosslinking or polymerization. For example, both the membrane 250 and the polishing pad portion 200 may be polyurethane, but the membrane 250 may be less cured than the polishing pad portion 200, making the membrane 250 softer.

[0061] In some implementations, for example, Figure 3C As shown, the polishing pad portion 200 may include two or more layers with different compositions, such as a polishing layer 210 having a polishing surface 220 and a more compressible backing layer 212 between the film 250 and the polishing layer 210. An intermediate adhesive layer 26 (such as a pressure-sensitive adhesive layer) may be selectively used to secure the polishing layer 210 to the backing layer 212.

[0062] Polishing pads with multiple layers of different compositions can also be used. Figure 3B The implementation shown. In this case, the membrane 250 and the backing layer 212 can be, for example, a single entity of homogeneous composition. Therefore, the membrane 250 is part of the backing layer 212.

[0063] In some implementations, such as Figure 3D As shown (but also applies to) Figure 3B and 3C In the embodiment shown, the bottom surface of the polishing pad portion 200 may include a groove 224 to allow slurry to be delivered during the polishing operation. The groove 224 may be shallower than the depth of the polishing pad portion 200 (e.g., shallower than the polishing layer 210).

[0064] In some implementations, for example, Figure 3E As shown (but also applies to) Figures 3B to 3E In the embodiment shown, membrane 250 includes a thinned portion 256 surrounding a central portion 252. The thinned portion 256 is thinner than the surrounding portion 258. This increases the flexibility of membrane 200 to allow for greater vertical deflection under applied pressure.

[0065] The perimeter 254 of the membrane 250 may include thickened edges or other features to improve the seal against the polishing pad carrier 300.

[0066] Various geometries may be used for the transverse cross-sectional shape of the polished surface 220. (Refer to...) Figure 4A The polishing surface 220 of the polishing pad portion 200 can be a circular area.

[0067] Reference Figure 4B The polishing surface 220 of the polishing pad portion 200 can be an arcuate region. If such a polishing pad includes grooves, the grooves can extend fully through the width of the arcuate region. This width is measured along the thinner dimension of the arcuate region. The grooves can be spaced at uniform intervals along the length of the arcuate region. Each groove can extend along a radius passing through the center of the groove and the arcuate region, or it can be positioned at an angle (e.g., 45°) relative to that radius.

[0068] Reference Figure 4C The polishing surface 220 of the polishing pad portion 200 is basically rectangular, but is shown to be divided by grooves 224. As shown, grooves can be present in the vertical direction of the entire polishing surface 220, but in some implementations, for example, if the polishing surface 220 is narrow enough, all grooves can be in only one direction.

[0069] Reference Figure 1 The maximum lateral dimension of the membrane 250 is smaller than the minimum lateral dimension of the substrate support 105. Similarly, the maximum lateral dimension of the membrane 250 is smaller than the minimum lateral dimension of the substrate 10.

[0070] Reference Figure 5A and 5B The film 250 extends beyond the outer sidewall 202 of the polishing pad portion 200 on all sides of the polishing pad portion 200. The polishing pad portion 200 may be equidistant from the two nearest opposing edges of the film 250. The polishing pad portion 200 may be located at the center of the film 250.

[0071] The minimum lateral dimension of membrane 250 can be approximately five to fifty times larger than the corresponding lateral dimension of the polishing pad portion. The minimum (lateral) circumference of membrane 250 can be approximately 260 mm to 300 mm. Generally, the size of membrane 250 depends on its flexibility; this size can be selected such that the center of the membrane experiences a desired amount of vertical deflection under the desired pressure.

[0072] The pad portion 200 may have a thickness of approximately 0.5 to 7 mm (e.g., approximately 2 mm). The membrane 250 may have a thickness of approximately 0.125 to 1.5 mm (e.g., approximately 0.5 mm).

[0073] The perimeter 259 of the film 250 can typically mimic the perimeter of a polishing pad portion. For example, as... Figure 5B As shown, if the polishing pad portion 200 is circular, then the film 250 can also be circular. However, the perimeter 259 of the film 250 can be smoothly curved so that it does not include sharp corners. For example, if the polishing pad portion 200 is square, then the film 250 can be a square with rounded corners or a squarish-round shape. In some embodiments, the perimeter 259 of the film 250 has a uniform distance from the perimeter of the polishing pad portion 200. That is, the distance between each point on the perimeter 259 of the film 250 and the nearest point on the perimeter of the polishing pad portion 200 is constant.

[0074] Reference Figure 5A In some implementations, the membrane 250 has a "bean" shape. That is, the membrane 250 can be an elongated ellipse with a concavity 290 extending inward along the long side of the shape, but without concavity along the opposite sides of the shape. The membrane 250 can be biaxially symmetric about the minor axis of the shape. At the center line M, the polishing pad portion 200 can be equidistant from the two opposite edges of the membrane 250.

[0075] The "bean" shape can be used in conjunction with the curved polishing pad portion 200. This improves the pressure uniformity of the polishing surface 250 on the substrate. However, the "bean" shape can also be used with polishing pad portions 200 of other shapes, such as square or rectangular.

[0076] 4. Polishing pad carrier

[0077] Reference Figure 6 The polishing pad assembly 240 is held in place by the polishing pad carrier 300, which is configured to provide controllable downward pressure on the polishing pad portion 200.

[0078] The polishing pad carrier includes a housing 310. The housing 310 may generally surround the polishing pad assembly 240. For example, the housing 310 may include an inner cavity in which at least the membrane 250 of the polishing pad assembly 250 is positioned.

[0079] The housing 310 also includes an aperture 312 into which the polishing pad portion 200 extends. The sidewall 202 of the polishing pad 200 can be separated from the sidewall 314 of the aperture 312 by a gap having a width W (e.g., about 0.5 to 2 mm). The sidewall 202 of the polishing pad 200 can be parallel to the sidewall 314 of the aperture 312.

[0080] Membrane 250 extends across cavity 320 and divides cavity 320 into upper chamber 322 and lower chamber 324. Aperture 312 connects lower chamber 324 to the external environment. Membrane 254 can seal upper chamber 320, allowing upper chamber 320 to be pressurized. For example, assuming membrane 250 is impermeable to fluid, the edge 254 of membrane 250 can be clamped to housing 310.

[0081] In some implementations, the housing 310 includes an upper portion 330 and a lower portion 340. The upper portion 330 may include a downwardly extending edge 332 surrounding the upper chamber 322, while the lower portion 340 may include an upwardly extending edge 342 surrounding the lower chamber 342.

[0082] The upper portion 330 can be detachably secured to the lower portion 340 by means of, for example, screws that extend through a hole in the upper portion 330 and into a threaded receiving hole in the lower portion 340. This detachable securing of the portions allows for the removal and replacement of the polishing pad assembly 240 when the polishing pad portion 200 wears out.

[0083] The edge 254 of the membrane 250 can be held between the upper portion 330 and the lower portion 340 of the housing 310. For example, the edge 254 of the membrane 250 is compressed between the bottom surface 334 of the edge 332 of the upper portion 330 and the top surface 342 of the edge 342 of the lower portion 340. In some embodiments, the upper portion 330 or the lower portion 332 may include a recessed region formed to receive the edge 254 of the membrane 250.

[0084] The lower portion 340 of the housing 310 includes a horizontally extending flange portion 350 from the edge 324. The lower portion 340 (such as the flange 350) can extend across the entire membrane 250 except for the area of ​​the aperture 312. This protects the membrane 250 from polishing debris and thus extends the service life of the membrane 250.

[0085] The first channel 360 in the housing 310 connects the conduit 82 to the upper chamber 322. This allows the pressure source 80 to control the pressure in the chamber 322, and thus control the downward pressure on the membrane 250 and the deflection of the membrane 250, and thus control the pressure of the polishing pad portion 200 on the substrate 10.

[0086] In some embodiments, when the upper chamber 322 is under normal atmospheric pressure, the polishing pad portion 200 extends fully through the orifice 312 and protrudes beyond the lower surface 352 of the housing 310. In some embodiments, when the upper chamber 322 is under normal atmospheric pressure, the polishing pad portion 200 extends only partially into the orifice 312 and does not protrude beyond the lower surface 352 of the housing 310. However, in the latter case, appropriate pressure applied to the upper chamber 322 can cause the membrane 250 to flex, causing the polishing pad portion 200 to protrude beyond the lower surface 352 of the housing 310.

[0087] An optional second channel 362 in the housing 310 connects the conduit 64 to the lower chamber 324. During polishing operations, slurry 62 can flow from the reservoir 60 into the lower chamber 324 and out of the chamber 324 through the gap between the polishing pad portion 200 and the lower portion of the housing 310. This allows the slurry to be supplied near the portion of the polishing pad that contacts the substrate. Therefore, a low volume of slurry can be supplied, thereby reducing operating costs.

[0088] An optional third channel 364 in the housing 310 connects the conduit 72 to the lower chamber 324. During operation, such as after a polishing operation, cleaning fluid can flow from the source 70 into the lower chamber 324. This allows polishing fluid to be removed from the lower chamber 324 between polishing operations. This prevents the slurry from solidifying in the lower chamber 324, thereby increasing the service life of the polishing pad assembly 240 and reducing defects.

[0089] The lower surface 352 of the housing 310 (such as the lower surface of the flange 350) may extend substantially parallel to the top surface 12 of the substrate 10 during operation. The upper surface 354 of the flange 344 may include a sloped region 356 that slopes away from the outer upper portion 330 when measured inward. This sloped region 356 may help ensure that the membrane 250 does not contact the inner surface 354 when the upper chamber 322 is pressurized, and thus may help ensure that the membrane 250 does not obstruct the flow of slurry 62 through the orifice 312 during polishing operations. Alternatively or supplementally, the upper surface 354 of the flange 354 may include a channel or groove. If the membrane 250 contacts the upper surface 354, the slurry may continue to flow through the channel or groove.

[0090] Although Figure 3 depicts channels 362 and 364 appearing in the sidewall of the flange 342 of the lower portion 340, other configurations are possible. For example, one or both of channels 362 and 364 may appear in the inner surface 354 of the flange 354 or even in the sidewall 314 of the aperture 312.

[0091] 5. The drive system and track movement of the mat.

[0092] Reference Figure 1 ,7 And 8, the polishing drive system 500 can be configured to move the coupled polishing pad carrier 300 and polishing pad portion 200 in a track-like motion during polishing operations. Specifically, as Figure 7 As shown, the polishing drive system 500 can be configured to maintain the polishing pad in a fixed angular orientation relative to the substrate during the polishing operation.

[0093] Figure 7 The initial position P1 of the polishing pad portion 200 is depicted. The additional positions P2, P3, and P4, where the polishing pad portion 200 travels through one-quarter, one-half, and three-quarters of the track, are indicated by dashed lines in the figure. As shown by the position marked by edge E, the polishing pad maintains a relatively fixed angular orientation during its travel through the track.

[0094] Still refer to Figure 7 The radius R of the track of the polishing pad portion 200 in contact with the substrate can be smaller than the maximum lateral dimension D of the polishing pad portion 200. In some embodiments, the radius R of the track of the polishing pad portion 200 is smaller than the minimum lateral dimension of the contact area. In the case of a circular polishing area, the maximum lateral dimension D of the polishing pad portion 200 is... For example, the radius of the track can be about 5-50% of the maximum lateral dimension of the polishing pad portion 200, such as 5-20%. For a polishing pad portion with a maximum size of 20 to 30 mm, the radius of the track can be 1-6 mm. This achieves a more uniform speed distribution in the contact area where the polishing pad portion 200 abuts against the substrate. The polishing pad should preferably move along the track at a rate of 1000 to 5000 revolutions per minute (“rpm”).

[0095] Reference Figure 1 , 6 In the polishing drive system 500, the drive system can achieve track motion using a single actuator 540 (such as a rotary actuator). A circular groove 334 can be formed in the upper surface 336 of the housing 310, for example, in the top surface of the upper portion 330. A circular rotor 510 with a diameter equal to or smaller than the diameter of the groove 334 is mounted within the groove 334, but the circular rotor rotates freely relative to the polishing pad carrier 300. The rotor 510 is connected to a motor 530 via an offset drive shaft 520. The motor 530 can be suspended from a support structure 355 and can be attached to the positioning drive system 560 and can move together with the moving portion of the positioning drive system 560.

[0096] The offset drive shaft 520 may include an upper drive shaft portion 522 connected to a motor 540, which rotates about an axis 524. The drive shaft 520 also includes a lower drive shaft portion 526 connected to the upper drive shaft 522, but the lower drive shaft portion 526 is laterally offset from the upper drive shaft 522, for example, by a horizontally extending portion 528.

[0097] During operation, the rotation of the upper drive shaft 522 causes both the lower drive shaft 526 and the rotor 510 to move along tracks and rotate. The contact between the rotor 510 and the inner surface of the groove 334 of the housing 310 forces the polishing pad carrier 300 to undergo a similar track movement.

[0098] Assuming the lower drive shaft 520 is connected to the center of the rotor 510, the lower drive shaft 520 can be offset from the upper drive shaft 522 by a distance S, where distance S provides the desired radius R of the track. Specifically, if this offset causes the lower drive shaft 522 to rotate in a circle with radius S, the diameter of the groove 344 is T, and the diameter of the rotor is U, then...

[0099]

[0100] Multiple anti-rotation links 550 (such as four links) extend from the positioning drive system 560 to the polishing pad carrier 300 to prevent rotation of the polishing pad carrier 300. The anti-rotation links 550 can be rods mounted into receiving holes in the polishing pad carrier 300 and the support structure 500. These rods can be formed of a flexible but generally non-elongating material, such as nylon. In this way, these rods can flex slightly to allow orbital movement of the polishing pad carrier 300 but prevent rotation. Thus, the anti-rotation links 550 (in conjunction with the movement of the rotor 510) achieve orbital movement of the polishing pad carrier 300 and the polishing pad portion 200, wherein the angular orientation of the polishing pad carrier 300 and the polishing pad portion 200 does not change during the polishing operation. The advantage of orbital movement is a more uniform speed distribution, resulting in more uniform polishing compared to simple rotation. In some implementations, the anti-rotation links 550 may be spaced at equal angular intervals around the center of the polishing pad carrier 300.

[0101] In some implementations, the polishing drive system and the positioning drive system are provided by the same components. For example, a single drive system may include two linear actuators configured to move the pad support head in two perpendicular directions. For positioning, the controller may cause the actuators to move the pad support to the desired position on the substrate. For polishing, the controller may cause the actuators to move the pad support in an orbital motion, for example by applying a phase-off sinusoidal signal to the two actuators.

[0102] In some implementations, the polishing drive system may include two rotary actuators. For example, a polishing pad support may be suspended from a first rotary actuator, which in turn is suspended from a second rotary actuator. During polishing operations, the second rotary actuator rotates an arm that sweeps the polishing pad carrier in an orbital motion. The first rotary actuator rotates (e.g., in the opposite direction but at the same rotational rate as the second rotary actuator) to counteract this rotational motion, causing the polishing pad assembly to orbit while maintaining a substantially fixed angular position relative to the substrate.

[0103] 6. Conclusion

[0104] The size of the non-uniformity point on the substrate will determine the ideal size of the loading area during polishing of that point. If the loading area is too large, correcting underpolishing in some areas of the substrate may lead to overpolishing in other areas. On the other hand, if the loading area is too small, the pad will need to move across the substrate to cover the underpolished areas, thus reducing yield. Therefore, this implementation allows the loading area to match the size of the point.

[0105] Reference Figure 9 The polishing surface 250 of the polishing pad portion 200 can undergo orbital movement relative to the substrate 10. Compared with rotation, maintaining the fixed orientation of the polishing pad relative to the substrate provides a more uniform polishing rate across the area being polished.

[0106] While orbital motion is as described above, rotational motion is desired in some implementations. For example, as Figure 10 As shown, the drive system 500 can rotate the polishing pad portion 200 about the center 18 of the substrate 10. This implementation is advantageous if the non-uniformity on the substrate is radially symmetrical. The polishing pad portion 200 can have Figure 4B The arc-shaped geometry shown is such that the radial center of the polishing pad portion 200 corresponds to the center of the substrate 10. The advantage of this configuration is that the polishing pad portion 200 can be further stretched around the area to be polished, thus achieving a higher polishing rate without sacrificing radial accuracy.

[0107] As used in this specification, the term substrate may include product substrates (such as product substrates comprising multiple memory or processor chips), test substrates, bare substrates, and gate control substrates. The substrate may be at different stages of integrated circuit manufacturing; for example, the substrate may be a bare wafer, or the substrate may include one or more deposited and / or patterned layers.

[0108] Several embodiments of the invention have been described. However, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, in some embodiments, the substrate support may include its own actuator capable of moving the substrate relative to the polishing pad in the appropriate position. As another example, while the system described above includes a drive system that moves the polishing pad along a track path while holding the substrate in a substantially fixed position, the reverse could also be possible, where the polishing pad is held in a substantially fixed position while the substrate moves along a track path. In this case, the polishing drive system could be similar, but coupled to the substrate support instead of the polishing pad support.

[0109] While a circular substrate is generally assumed, this is not required, and the support and / or polishing pad can be other shapes, such as rectangles (in which case the discussion of "radius" or "diameter" will generally apply to the lateral dimension along the main axis).

[0110] The term relative positioning is used to describe the positioning of components of a system relative to each other, and not necessarily relative to gravity; it should be understood that polished surfaces and substrates can be held in a vertical orientation or some other orientation. However, a gravity-relative arrangement with pores at the bottom of the housing can be particularly advantageous, as gravity can help the slurry flow out of the housing.

[0111] Therefore, other embodiments are within the scope of the following claims.

Claims

1. A chemical mechanical polishing system, comprising: A substrate support configured to hold the substrate during a polishing operation; Polishing pad carrier; A polishing pad assembly held by a polishing pad carrier, the polishing pad assembly having a film and a polishing pad portion, the film being fixed to the polishing pad carrier, the polishing pad portion protruding downward from the film, wherein the bottom surface of the polishing pad portion is an arcuate polishing surface, the arcuate polishing surface providing an arcuate contact area to contact the top surface of the substrate during polishing; A drive system configured to generate rotational motion between the substrate support and the polishing pad carrier, such that the arcuate contact area rotates around the center of the substrate; Storage tank, the storage tank being used to contain polishing fluid; as well as A conduit for conveying the polishing fluid from the reservoir to the polishing pad carrier.

2. The polishing system of claim 1, further comprising a clamping assembly for holding the substrate in proper position on the substrate support during polishing.

3. The polishing system of claim 1, further comprising a holder for circumferentially surrounding the substrate on the substrate support during polishing.

4. The polishing system of claim 1, wherein the substrate support is a vacuum chuck.

5. The polishing system of claim 1 or 4, comprising a vertical actuator connected to the substrate support.

6. The polishing system of claim 5, further comprising a controllable pressure source for applying controllable pressure to the internal chamber of the polishing pad carrier.

7. The polishing system of claim 1 or 4, comprising a controllable pressure source for applying controllable pressure to the internal chamber of the polishing pad carrier.

8. The polishing system of claim 1, wherein the polishing surface provided by the bottom surface of the polishing pad portion of the polishing pad assembly has a maximum lateral dimension smaller than the radius of the substrate.

9. The polishing system of claim 1, wherein the substrate support is rotatable and the polishing pad carrier is suspended by a linear actuator that provides movement in the radial direction.

10. A chemical mechanical polishing system, comprising: A substrate support configured to hold the substrate during a polishing operation; Polishing pad carrier; A polishing pad assembly held by a polishing pad carrier, the polishing pad assembly having a film and a polishing pad portion, the film being fixed to the polishing pad carrier, the polishing pad portion protruding downward from the film, wherein the bottom surface of the polishing pad portion is an arcuate polishing surface, the arcuate polishing surface providing an arcuate contact area to contact the top surface of the substrate during polishing; A drive system configured to generate rotational motion between the substrate support and the polishing pad carrier, such that the arcuate contact area rotates around the center of the substrate; Storage tank, the storage tank being used to contain cleaning fluid; as well as A conduit for conveying the cleaning fluid from the reservoir to the polishing pad carrier.

11. The polishing system of claim 10, further comprising a clamping assembly for holding the substrate in proper position on the substrate support during polishing.

12. The polishing system of claim 10, further comprising a holder for circumferentially surrounding the substrate on the substrate support during polishing.

13. The polishing system of claim 10, wherein the substrate support is a vacuum chuck.

14. The polishing system of claim 10 or 13, comprising a vertical actuator connected to the substrate support.

15. The polishing system of claim 14, further comprising a controllable pressure source for applying controllable pressure to the internal chamber of the polishing pad carrier.

16. The polishing system of claim 10 or 13, further comprising a controllable pressure source for applying controllable pressure to the internal chamber of the polishing pad carrier.

17. The polishing system of claim 10, wherein the polishing surface provided by the bottom surface of the polishing pad portion of the polishing pad assembly has a maximum lateral dimension smaller than the radius of the substrate.

18. The polishing system of claim 10, wherein the substrate support is rotatable and the polishing pad carrier is suspended by a linear actuator that provides movement in the radial direction.

19. A chemical mechanical polishing system, comprising: A substrate support configured to hold the substrate during a polishing operation; Polishing pad carrier; The polishing pad portion is held by the polishing pad carrier, wherein the bottom surface of the polishing pad portion is an arc-shaped polishing surface, and the arc-shaped polishing surface provides an arc-shaped contact area to contact the top surface of the substrate during polishing; A drive system configured to generate rotational motion between the substrate support and the polishing pad carrier, such that the arcuate contact area rotates around the center of the substrate; An actuator for moving the polishing pad carrier to position the polishing pad carrier at a desired lateral position above the substrate support; Storage tank, the storage tank being used to contain polishing fluid; as well as A conduit for conveying the polishing fluid from the reservoir to the polishing pad carrier.

20. The polishing system of claim 19, wherein the substrate support is rotatable.

21. The polishing system of claim 20, wherein the polishing pad carrier is suspended by a linear actuator that provides movement in the radial direction.

22. The polishing system of claim 20, wherein the actuator includes an arm pivotally attached to a base positioned offset from the side of the substrate support.

23. The polishing system of any one of claims 19 to 22, further comprising a clamping assembly for holding the substrate in proper position on the substrate support during polishing.

24. The polishing system of any one of claims 19 to 22, comprising a holder for circumferentially surrounding the substrate on the substrate support during polishing.

25. The polishing system of any one of claims 19 to 22, wherein the substrate support is a vacuum chuck.

26. The polishing system of any one of claims 19 to 22, comprising a vertical actuator connected to the substrate support.

27. The polishing system of claim 19, further comprising a controllable pressure source for applying controllable pressure to the internal chamber of the polishing pad carrier.

28. The polishing system of claim 19, wherein the polishing surface provided by the bottom surface of the polishing pad portion has a maximum lateral dimension smaller than the radius of the substrate.

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