CN112123196B

CN112123196B - Method, system and polishing pad for chemical mechanical polishing

Info

Publication number: CN112123196B
Application number: CN202010973754.0A
Authority: CN
Inventors: H·C·陈; P·D·巴特菲尔德; J·古鲁萨米; J·G·方; S-S·常; J·张; E·刘
Original assignee: Applied Materials Inc
Current assignee: Applied Materials Inc
Priority date: 2014-07-17
Filing date: 2015-07-10
Publication date: 2023-05-30
Anticipated expiration: 2035-07-10
Also published as: KR20170032325A; JP6955592B2; TWI692385B; CN106463383A; JP2020092276A; JP2017522733A; TW201609313A; CN106463383B; KR102399064B1; CN112123196A; WO2016010866A1

Abstract

Chemical mechanical polishing may be used for "dressing polishing" in which polishing is performed on a limited area of the front surface of the substrate. The contact area between the polishing pad and the substrate may be substantially smaller than the radius surface of the substrate. During polishing, the polishing pad can experience an orbital motion. During the orbital motion, the polishing pad may be maintained in a fixed angular orientation. The contact area may be arcuate. The contact area may be provided by one or more lower portions protruding downward from an upper portion of the polishing pad. The peripheral portion of the polishing pad may be vertically fixed to the annular member and the remaining portion of the polishing pad within the peripheral portion may be freely vertical.

Description

Method, system and polishing pad for chemical mechanical polishing

The present application is a divisional application of the invention patent application with the application number of 201580030724.3 and the name of "method, system and polishing pad for chemical mechanical polishing", which is the application number of 2015, 07, 10.

Technical Field

The present disclosure relates to an architecture of a chemical mechanical polishing (chemical mechanical polishing; CMP) system.

Background

Integrated circuits are typically formed on a substrate by continuously depositing conductive, semiconductive or insulating layers on a silicon wafer. One fabrication step involves depositing a filler layer over a non-planar surface and planarizing the 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 over the patterned insulating layer to fill the trenches or holes in the insulating layer. After planarization, the portions of the metal layer remaining between the raised patterns of the insulating layer form vias, plugs, and wires that provide conductive paths between the diaphragm circuits on the substrate. For other applications such as oxide milling, the filler layer is planarized until a predetermined thickness is left on the non-planar surface. In addition, photolithography generally requires planarization of the substrate surface.

Chemical Mechanical Polishing (CMP) is a well-known planarization method. This planarization method typically requires mounting the substrate on a carrier head or polishing head. The exposed surface of the substrate is typically placed against a rotating polishing pad. The carrier head provides a controllable load on the substrate to push the carrier head against the polishing pad. An abrasive slurry is typically supplied to the surface of the polishing pad.

Disclosure of Invention

Systems and apparatus for polishing (e.g., "dressing polishing") of a substrate are provided, wherein polishing is performed on a limited area of a front surface of the substrate.

In one aspect, a chemical mechanical polishing system includes a substrate support, a movable pad support, and a drive system. The substrate support is configured to hold a substrate in a substantially fixed angular orientation during a polishing operation. The movable pad support is configured to hold a polishing pad having a diameter no greater than a radius of the substrate. The drive system is configured to move the pad support and the polishing pad in an orbital motion while the polishing pad is in contact with the upper surface of the substrate. The orbital motion has an orbital radius that is no greater than a diameter of the polishing pad and maintains the polishing pad in a fixed angular orientation relative to the substrate.

Implementations may include one or more of the following features. The polishing pad may have a contact area that contacts the substrate. The diameter of the contact region may be between about 1% and 10% of the diameter of the substrate. The track radius may be between about 5% and 50% of the diameter of the contact area. The drive system may include a recess in the pad support head, a rotatable cam extending into the recess, and a motor connected to the cam. The links may couple the pad support head to a fixed support to prevent rotation of the pad support head. The positioning drive system may move the liner support head laterally across the substrate. The positioning drive system may include two linear actuators configured to move the liner support head in two perpendicular directions.

In another aspect, a chemical mechanical polishing system includes a substrate support, a polishing pad, a movable pad support, and a drive system. The substrate support is configured to hold a substrate in a substantially fixed angular orientation during a polishing operation. The polishing pad has a contact region contacting the substrate, the contact region having a diameter no greater than a radius of the substrate. The movable pad support is configured to hold a polishing pad. The drive system is configured to move the pad support and the polishing pad in an orbital motion while the contact area of the polishing pad is in contact with the upper surface of the substrate. The orbital motion has an orbital radius that is no greater than a diameter of the polishing pad and maintains the polishing pad in a fixed angular orientation relative to the substrate.

Implementations may include one or more of the following features. The polishing pad may include a protrusion from the self-layer, and a bottom surface of the protrusion may provide a contact area. At least one of the pressure sensitive adhesive or the clamp may hold the polishing pad on the pad support. The contact area may be disk-shaped or arc-shaped.

In another aspect, a method of chemical mechanical polishing includes: contacting the polishing pad with the substrate in a contact region, the contact region having a diameter no greater than a radius of the substrate; and generating a relative motion between the polishing pad and the substrate while the contact region of the polishing pad is in contact with the upper surface of the substrate. The relative motion includes an orbital motion having an orbital radius that is no greater than a diameter of the polishing pad. During the orbital motion, the polishing pad is maintained in a substantially fixed angular orientation relative to the substrate.

Implementations may include one or more of the following features. During the orbital motion, the substrate may be held in a fixed lateral position. During the orbital motion, the polishing pad may be swept across the substrate laterally at a speed that is no greater than about 5% of the instantaneous speed of the orbital motion.

In another aspect, a chemical mechanical polishing system comprises: a substrate support configured to hold a substrate during a polishing operation; a polishing pad support; a polishing pad held by the pad support; and a drive system configured to generate relative motion between the substrate support and the polishing pad support. The polishing pad has an upper portion secured to the polishing pad support and a lower portion protruding downwardly from the upper portion. The upper surface of the upper portion adjoins the polishing pad support. The bottom surface of the lower portion provides a contact surface that contacts the top surface of the substrate during polishing. The contact surface is smaller than the top surface of the substrate. The upper portion has a first lateral dimension and the lower portion has a second lateral dimension that is smaller than the first lateral dimension.

Implementations may include one or more of the following features. The polishing pad support may comprise a plate having a surface that spans the polishing pad, and substantially all of the upper surface of the upper portion of the polishing pad may abut the surface of the plate. The adhesive may hold the polishing pad on the pad support. The polishing pad support may include an annular member, a peripheral portion of the upper surface of the upper portion of the polishing pad may abut the annular member, and a remainder of the upper surface within the peripheral portion may not contact the polishing pad support. One or more clamps may hold the peripheral section of the polishing pad on the pad support. The upper portion of the polishing pad may include a flex section that is more flexible than the section of the polishing pad above the contact surface. The upper portion of the polishing pad may comprise a polyethylene terephthalate sheet.

A plurality of grooves for slurry transport may be formed on the contact surface of the lower portion of the polishing pad. The plurality of grooves may have a depth less than the thickness of the lower portion. At least some of the plurality of grooves may extend entirely across a lower portion of the polishing pad. The pressure chamber may be formed by an interior chamber of the polishing pad support, the chamber may have an opening facing the substrate, and the opening may be sealed by coupling the polishing pad to the polishing pad support. A plurality of holes may be formed in an upper surface of the polishing pad, and a plurality of protrusions from the polishing pad support may be fitted into the plurality of holes to align the lower portion with respect to the polishing pad support.

In another aspect, a polishing pad includes an upper portion and one or more lower portions. The upper portion has an upper surface attached to the cushion carrier and a first lateral dimension. One or more lower portions project downwardly from the upper portion. The bottom surface of the one or more lower portions provides a contact surface that contacts the substrate during chemical mechanical polishing. Each lower portion has a second lateral dimension smaller than the first lateral dimension. The total surface area of the contact surfaces from the one or more lower portions is no more than 10% of the surface area of the upper surface.

Implementations may include one or more of the following features. At least the lower portion may include a polymer body having a substantially uniform composition and having a plurality of pores distributed within the body. The polishing pad may include a polishing layer, and a lower portion protruding downward may be formed in the polishing layer. The pad may include a backing layer that is softer than the abrasive layer. A trough for slurry delivery may be formed on the bottom surface of one or more of the lower portions. One or more lower portions may consist of a single protrusion. The abrasive layer may include a flexible transverse section that is thinner than the transverse sections that make up the abrasive region. The lower portion may comprise microcellular polyurethane.

In another aspect, a chemical mechanical polishing system comprises: a substrate support configured to hold a substantially circular substrate during a polishing operation; a polishing pad support; a polishing pad held by the pad support; and a drive system configured to generate relative motion between the substrate support and the polishing pad support. The polishing pad has an arcuate contact region, and a center point of an arc defined by the arcuate contact region is substantially aligned with a center of a substrate held by the substrate support.

Implementations may include one or more of the following features. The width of the arc defined by the arc-shaped contact area may be between 1mm and 3mm, and the length of the arc may be equal to or greater than 30mm. At least one of the pressure sensitive adhesive or the clamp may hold the polishing pad on the pad support head. The relative motion between the substrate support and the polishing pad support may be an orbital motion that maintains the polishing pad support in a fixed angular orientation. The relative motion may rotate about the center of the substrate.

In another aspect, a polishing assembly includes a polishing pad support and a polishing pad held by the pad support. The polishing pad support includes an annular member and a recess having an opening facing the substrate. The polishing pad has a polishing surface that contacts the substrate during polishing. The peripheral portion of the polishing pad is vertically fixed to the annular member and the remaining portion of the polishing pad within the peripheral portion is free to be vertical. An adjustable pressure is provided on the back surface of the polishing pad by the polishing pad sealing an opening of the polishing pad support facing the substrate to define a pressurizable chamber.

Implementations may include one or more of the following features. The adhesive may secure a peripheral portion of the polishing pad to the annular member. One or more clamps may hold the peripheral section of the polishing pad on the annular member. The polishing pad support may include a base and a diaphragm secured to the base, the volume between the base and the diaphragm may define a second pressurizable chamber such that an outer surface of the diaphragm provides a second adjustable pressure on a back surface of the polishing pad. The diaphragm and the second pressurizable chamber may be configured such that pressure in the second pressurizable chamber controls a lateral dimension of the load zone of the polishing surface against the substrate.

In another aspect, a polishing pad includes an upper portion, one or more lower portions, and a plurality of holes. The upper portion has an upper surface attached to the cushion carrier and a first lateral dimension. One or more lower portions project downwardly from the upper portion. The bottom surface of the one or more lower portions provides a contact surface that contacts the substrate during chemical mechanical polishing. Each lower portion has a second lateral dimension smaller than the first lateral dimension such that the upper portion projects past all lateral sides of the lower portion. A plurality of holes are in the upper surface of the upper portion to receive the protrusions from the cushion carrier. Holes are located in the upper section of the lower laterally outer polishing pad.

Implementations may include one or more of the following features. A plurality of holes may be positioned at corners of the polishing pad. The polishing pad may be rectangular. One or more of the lower portions may have an arcuate contact surface. A plurality of grooves for slurry transport may be formed on the contact surface of the lower portion of the polishing pad.

Advantages of the invention may include one or more of the following.

Small pads that undergo orbital motion can be used to compensate for non-concentric polishing uniformity. The orbital motion may provide an acceptable polishing rate while avoiding overlap of the pad with areas that are not desired to be polished, thereby improving substrate uniformity. In addition, the orbital motion, which maintains a fixed orientation of the polishing pad relative to the substrate, may provide a more uniform polishing rate across the area being polished as compared to rotation.

Making the top of the polishing pad secured to the polishing pad support laterally wider than the bottom protrusions in contact with the substrate can increase the usable area of the pad for connection to the support (e.g., by pressure sensitive adhesive). This may make the polishing pad less prone to delamination during polishing operations.

Polishing pads having arcuate contact areas for contacting a substrate can provide improved polishing rates while maintaining satisfactory radial resolution of the polishing areas.

The alignment features may ensure that the limited contact area of the polishing pad is laterally placed in a known position relative to the pad support, thereby reducing the likelihood of polishing undesired areas of the substrate.

Providing a portion of the polishing pad that flexes may reduce flexing of the portion of the polishing pad's contact surface, thereby improving the likelihood that the polished area matches what is expected by the operator.

The grooves in the protrusions of the polishing pad may facilitate the transport of slurry and thus may improve the polishing rate.

The portion of the polishing pad that does not contact the substrate can be formed of a lower cost material, thereby reducing the overall pad cost.

The pad carrier, which allows controlling the size of the portion of the contact area that is loaded against the substrate, allows the loading area to be matched to the size of the spot to be polished, thereby improving the yield while avoiding polishing undesired areas of the substrate.

In general, non-uniform polishing of the substrate can be reduced, and the resulting flatness and finish of the substrate can be improved.

Other aspects, features, and advantages of the invention will be apparent from the description and drawings, and from the claims.

Drawings

FIG. 1 is a schematic cross-sectional side view of an abrasive system;

FIG. 2 is a schematic cross-sectional side view of an embodiment of an abrasive system including a vacuum chuck to hold a substrate;

FIG. 3 is a schematic cross-sectional side view of an embodiment of a polishing system having a polishing pad that does not include a downward lobe;

FIG. 4 is a schematic cross-sectional side view of an embodiment of a polishing system having a polishing pad with an upper layer having a larger diameter than a substrate and a downward protrusion having a smaller diameter than the substrate;

FIG. 5 is a schematic cross-sectional top view illustrating a polishing pad moving in an orbit while maintaining a fixed angular orientation;

FIG. 6 is a schematic cross-sectional top view of a polishing pad support and drive train system of the polishing system;

FIG. 6A is a schematic cross-sectional top view of the system of FIG. 6 in relation to a substrate;

FIG. 6B is a schematic cross-sectional top view of the system of FIG. 6 rotated a quarter turn relative to FIG. 6A;

FIG. 7A is a schematic cross-sectional side view of a movable polishing pad support coupled to a polishing pad having a plurality of clamps;

FIG. 7B is a schematic cross-sectional view of an embodiment of a movable polishing pad support including an internal pressurized space enclosed by an internal membrane;

FIG. 8A is a schematic cross-sectional side view of the movable polishing pad support of FIG. 7B in a low pressure state;

FIG. 8B is a schematic cross-sectional side view of the movable polishing pad support of FIG. 7B in a high pressure state;

FIG. 9 is a schematic bottom view of a contact area of a polishing pad;

FIGS. 10A and 10B are schematic cross-sectional side views of embodiments of polishing pads;

FIG. 11 is a schematic cross-sectional side view of another embodiment of a movable polishing pad support;

FIG. 12 is a schematic top view of an embodiment of a polishing system having a polishing pad with an arcuate tab layer forming a corresponding arcuate load zone; and

fig. 13 is a schematic cross-sectional side view of an embodiment of a polishing system having an arcuate polishing surface undergoing orbital motion.

Fig. 14 is a schematic top view of a polishing pad.

Like reference symbols in the various drawings indicate like elements.

Detailed Description

1. Introduction to the invention

Some polishing processes result in thickness non-uniformities across the surface of the substrate. For example, a bulk polishing process may result in an under-polished area on a substrate. To solve this problem, after bulk polishing, a "dressing" polishing process may be performed, which focuses on the underpolished portion of the substrate.

In a bulk polishing process, polishing occurs over the entire front surface of the substrate, although polishing at different rates may occur in different areas of the front surface. Not all surfaces of the substrate may be subjected to polishing at a given instant in the bulk polishing process. For example, some portion of the substrate surface may not be in contact with the polishing pad due to the presence of grooves in the polishing pad. However, during the bulk polishing process, the entire front surface of the substrate undergoes a certain amount of polishing due to the relative motion between the polishing pad and the substrate, which is not positioned.

In contrast, in a "finishing" polishing process, the polishing pad may contact less than the entire front surface of the substrate. In addition, the range of motion of the polishing pad relative to the substrate is configured such that during the dressing polishing process, the polishing pad contacts only a localized area of the substrate, and a significant portion (e.g., at least 50%, at least 75%, or at least 90%) of the front surface of the substrate never contacts the polishing pad and is therefore not subject to polishing. For example, in a finishing grind, the contact area may be substantially smaller than the radius surface of the substrate.

As noted above, some bulk grinding processes result in non-uniform grinding. In particular, some bulk grinding processes result in localized non-concentric and non-uniform spots of insufficient grinding. In a finishing polishing process, a polishing pad rotating about the center of the substrate can compensate for non-uniformities of the concentric rings, but may not address localized non-concentric and non-uniform spots, such as angular asymmetry in the thickness distribution. However, small pads (e.g., small pads that undergo orbital motion) may be used to compensate for non-concentric polishing uniformity. For some embodiments, during polishing, the polishing pad may experience an orbital motion with a fixed angular orientation.

Referring to fig. 1, a polishing apparatus 100 for polishing a partial region of a substrate includes a substrate support 105 holding a substrate 10 and a movable polishing pad support 300 holding a polishing pad 200. The polishing pad 200 includes a polishing surface 250 having a diameter smaller than the radius of the substrate 10 being polished.

The polishing pad support 300 depends from a polishing drive system 500 that will provide movement of the polishing pad support 300 relative to the substrate 10 during a polishing operation. The grinding drive system 500 may depend from the support structure 550.

In some embodiments, the positioning drive system 560 is coupled to the substrate support 105 and/or the polishing pad support 300. For example, the polishing drive system 500 may provide a connection between the positioning drive system 560 and the polishing pad support 300. The positioning drive system 560 is operable to position the liner support 300 at a desired lateral position above the substrate support 105. For example, the support structure 550 may include two

linear actuators

562 and 564 oriented perpendicular relative to each other above the substrate support 105 to provide a positioning drive system 560. Alternatively, the substrate support 105 may be supported by two linear actuators. Alternatively, the substrate support 105 may be rotatable and the polishing pad support 300 may depend from a single linear actuator that provides movement in a radial direction. Alternatively, the polishing pad support may depend from the rotary actuator 508 and the substrate support 105 may be rotated using the rotary actuator 506.

Optionally, vertical actuators (illustrated by 506 and/or 508) may be connected to the substrate support 105 and/or the polishing pad support 300. For example, the substrate support 105 may be coupled to a vertically drivable piston that can raise or lower the substrate support 105.

The polishing apparatus 100 includes a port 60 to dispense a polishing liquid 65, such as an abrasive slurry, on the surface 12 of the substrate 10 to be polished. The polishing apparatus 100 may also include a polishing pad conditioner to abrade the polishing pad 200 to maintain the polishing pad 200 in a consistently abraded state.

In operation, the substrate 10 is loaded onto the substrate support 105, for example, by a robot. The positioning drive system 500 positions the polishing pad support 300 and polishing pad 200 at a desired location on the substrate 10, and the vertical actuator 506 moves the substrate into contact with the polishing pad 200 (or vice versa with the actuator 508). The polishing drive system 500 generates relative motion between the polishing pad support 300 and the substrate support 105 to induce polishing of the substrate 10.

During the polishing operation, the positioning drive system 560 may substantially fixedly hold the polishing drive system 500 and the substrate 10 relative to one another. For example, the positioning system may hold the polishing drive system 500 stationary relative to the substrate 10, or may sweep the polishing drive system 500 slowly (as compared to the motion provided to the substrate 10 by the polishing drive system 500) across the area to be polished. For example, the instantaneous speed provided by the positioning drive system 500 to the substrate may be less than 5%, e.g., less than 2%, of the instantaneous speed provided by the grinding drive system 500 to the substrate.

The polishing system also includes a controller 90, e.g., a programmable computer. The controller may include a central processing unit 91, a memory 92, and a support circuit 93. The central processing unit 91 of the controller 90 executes instructions loaded from the memory 92 via the support circuit 93 to allow the controller to receive inputs and control various actuators and drive systems based on the environment and desired polishing parameters.

For a "dressing" polishing operation, the controller 90 is programmed to control the positioning drive system 560 such that even though the polishing drive system 500 is being swept slowly, the range of motion of the polishing drive system 500 is limited such that a significant portion (e.g., at least 50%, at least 75%, or at least 90%) of the front surface of the substrate never contacts the polishing pad and is therefore not subject to polishing during the dressing polishing process.

2. Grinding system

A. Substrate support

Referring to fig. 1, the substrate support 105 is a plate-like body located below the polishing pad support. The upper surface 116 of the body provides a load area large enough to accommodate a substrate to be processed. For example, the substrate may be a 200mm to 450mm diameter substrate. The upper surface 116 of the substrate support 105 contacts and maintains the position of the back surface (i.e., the unground surface) of the substrate 10.

The substrate support 105 has a radius about the same as or greater than the substrate 10. In some embodiments, the substrate support 105 is slightly narrower than the substrate (e.g., see fig. 2), such as 1% -2% narrower than the substrate diameter. When placed on the support 105, the edge of the substrate 10 protrudes slightly beyond the edge of the support 105. This may provide clearance for the edge gripping robot to place the substrate on the support. In some embodiments, the substrate support 105 is wider than the substrate. In this case, a robot having an end effector with a vacuum chuck may be used to place the substrate on the support. In either case, the substrate support 105 may be in contact with a majority of the surface on the backside of the substrate.

In some embodiments, as shown in fig. 1, the substrate support 105 maintains the position of the substrate 10 during a polishing operation using the clamping assembly 111. In some embodiments, the clamping assembly 111 may be a single annular clamping ring 112 that contacts an edge of the top surface of the substrate 10. Alternatively, the clamping assembly 111 may include two arcuate clamps 112 that contact edges of the top surface on opposite sides of the substrate 10. The clamp 112 of the clamp assembly 111 may be lowered into contact with the edge of the substrate by one or more actuators 113. The downward force of the clamp inhibits lateral movement of the substrate during the polishing operation. In some embodiments, one or more of the clamps includes a downwardly projecting flange 114 around the outer edge of the base plate.

In some embodiments, as shown in fig. 2, the substrate support 105 is a vacuum chuck 106. The vacuum chuck 106 includes a chamber 122 and a plurality of ports 124 that connect the chamber 122 to the surface 116 supporting the substrate 10. In operation, air may be exhausted from the chamber 122, such as by the pump 129, applying suction through the ports 124 to hold the substrate in place on the substrate support 106.

In some embodiments, as shown in fig. 3, the substrate support 105 includes a retainer 131. The retainer 131 may be attached to the surface 116 of the support substrate 10 and protrude above the surface. Typically, the holder is at least as thick as the substrate 10 (measured perpendicular to the surface 12). In operation, the retainer 131 surrounds the substrate 10. For example, the retainer 131 may be an annular body having a diameter slightly larger than that of the base plate 10. During polishing, friction from the polishing pad 200 may generate lateral forces on the substrate 10. However, the holder 131 restricts lateral movement of the substrate 10.

The various substrate support features described above may optionally be combined with one another. For example, the substrate support may include both a vacuum chuck and a holder.

Additionally, while substrate support configurations are shown in connection with pressure sensitive adhesive movable pad support configurations for ease of illustration, such configurations may be used with any of the pad support head and/or drive system embodiments described below.

B. Polishing pad

Referring to fig. 1, the polishing pad 200 has a polishing surface 250 that makes contact with the substrate 10 in a contact region (also referred to as a load region) during polishing. The polishing surface 250 may have a diameter smaller than the radius of the substrate 10. For example, the diameter of the abrasive surface may be about 5% -10% of the diameter of the substrate. For example, for wafers having diameters ranging from 200mm to 300mm, the diameter of the abrasive surface may be between 10mm and 30mm. Smaller abrasive surfaces provide more precision but lower throughput.

In some embodiments, less than 1% of the substrate surface may be in contact with the abrasive surface at any given time. Generally, while this may be useful for dressing polishing operations, this small area is not acceptable for bulk polishing operations due to low throughput.

In some embodiments, such as shown in fig. 3, the entire polishing pad (e.g., as measured to the outer edge of the pad) has a diameter smaller than the radius of the substrate 10. For example, the polishing pad may have a diameter that is about 5% -10% of the diameter of the substrate.

In the example of fig. 1, the polishing pad 200 is positioned above the upper surface of the substrate 10 and includes an upper portion 270 coupled to the bottom of the movable pad support 300 and a lower portion 260 having a bottom surface 250 that contacts the substrate 10 during a polishing operation. In some cases, as shown in fig. 1, the bottom 260 of the polishing pad 200 is provided by a protrusion from the wider upper portion 270. The bottom surface 250 of the protrusion 260 contacts the substrate during the polishing operation and provides a polishing surface.

In the example of fig. 1, the movable pad support 300 is coupled to the upper portion 270 of the polishing pad 200 using a pressure sensitive adhesive 231. The pressure sensitive adhesive 231 applied between the bottom surface of the polishing pad support 300 and the top surface of the polishing pad 200 maintains the coupling of the polishing pad 200 on the pad support 300 during the polishing operation.

By making the upper portion 270 of the polishing pad 200 wider than the lower portion 260, the usable surface area of the adhesive 231 is increased. Increasing the surface area of the adhesive 231 may improve the bond strength between the pad 200 and the pad support and reduce the risk of delamination of the polishing pad during polishing.

Referring to fig. 3, the lower portion 260 of the polishing pad 203 may have the same radius as the top 273. However, when the pressure sensitive adhesive 231 provides a coupling between the gasket and the movable gasket support 300, it is preferable that the bottom 263 is narrower than the top 273.

Referring to fig. 5, the contact area 5 of the polishing pad may be a dished geometry 5 formed by a dished bottom protrusion of the polishing pad.

Referring to fig. 9, the contact area 901 of the polishing pad 110 in contact with the substrate 10 may be an arc contact area 901 formed by the arc-shaped protrusions 290 of the polishing pad.

Referring to fig. 1, in some embodiments, the upper portion 270 of the polishing pad 200 may have a smaller diameter than the substrate 10.

Referring to fig. 4, in some embodiments, the upper portion 274 of the polishing pad 204 may have a diameter greater than the diameter of the substrate 10.

Referring to fig. 1, the polishing pad 200 may be comprised of a single layer of uniform composition. In this case, the material composition of the upper portion 270 and the lower portion 260 (also referred to as the protrusion 260) is the same.

Referring to fig. 10B, in some embodiments, the polishing pad 200 can include two or more layers of different compositions, such as a polishing layer 1062 and a more compressible backing layer 1052. Optionally, an intermediate pressure sensitive adhesive layer 1032 may be used to secure the abrasive layer 1061 to the backing layer 1061. In this case, the upper portion 1221 may correspond to the backing layer 102 and the lower portion 1222 may correspond to the polishing layer 1062. The polishing pad may be coupled to the polishing pad support via the pressure sensitive adhesive layer 231.

Referring to fig. 10A, in some embodiments, the polishing pad can comprise two or more layers having different compositions, and the upper portion 1221 of the polishing pad 200 can comprise both the backing layer 1052 and the upper section 1064 of the polishing layer 1062. Accordingly, the polishing layer 1062 includes both a lower section 1066 and an upper section 1062 providing the protrusions 1222, wherein the upper section 1064 is wider than the lower section 1066.

The polishing pad may be coupled to a polishing pad support via a pressure sensitive adhesive layer 321.

In either of the embodiments shown in fig. 10A or 10B, the abrasive layer 1062 may be composed of a single layer of uniform composition. For example, in either of the embodiments shown in fig. 10A or 10B, the portion of the liner that contacts the substrate may be of a conventional material, such as a microporous polymer, such as polyurethane.

Referring to fig. 10A, the backing layer 1052 may be relatively soft to allow for better polishing pad flexibility when polishing non-uniform substrate surface sites. The polishing layer 1064 may be a hard polyurethane.

Referring to fig. 10B, the backing layer 1052 may be relatively soft, but may also be made of a material such as polyethylene terephthalate (e.g., mylar ^TM ) A flexible incompressible layer made of a material of (a) is provided. For example, this pad configuration may be used in an embodiment in which the polishing pad of FIG. 10B is coupled to the pressurized chamber polishing pad support of FIG. 11. The polishing layer 1062 may be a hard polyurethane.

Referring to fig. 11, in some embodiments, the polishing pad 205 can include an upper portion 275 and a lower portion 260. The polishing pad 205 has a thicker lateral section 267 that includes a combined lower portion 260 and upper portion 275. The upper portion 275 extends laterally on either side of the thicker section 267 to provide a lateral side section 285. The lateral side sections 285 flex in response to pressure on the thicker sections 267. The thicker section 267 may have a pad thickness of about 2mm in the grinding zone, similar to a large size pad. The thickness of the pad in the deflected transverse section 285 may be about 0.5mm.

In some embodiments, the bottom surface 250 of the lower portion of the polishing pad 200 may include grooves to allow slurry to be delivered during the polishing operation. The slot 299 may be shallower than the depth of the lower portion 260 (e.g., see fig. 11). However, in some embodiments, the lower portion does not include a slot. If the polishing pad includes grooves, the grooves 299 may extend completely across the lateral width of the lower portion 260. In addition, the slots may be shallower than the vertical thickness of the lower portion 260, i.e., the slots pass through the lower portion 260 in a vertical manner partially, rather than completely.

Referring to fig. 9, the bottom surface 1900 of the polishing pad 200 can be an arcuate region. If the polishing pad includes grooves, the grooves 299 may extend completely across the lateral width of the arcuate region. The slots 299 may be spaced at uniform intervals along the length of the arcuate region. Each slot 299 may extend along a radius through the center 1903 of the slot and arcuate region, or each slot 299 may be positioned at an angle (e.g., 45 deg.) relative to the radius.

Referring to fig. 14, in some embodiments, the polishing pad 200 includes alignment features that mate with mating features on the pad support 300 to ensure that the polishing pad 200 and the lower portion 260 providing the contact region 250 are in a known lateral position relative to the pad support 300.

For example, the polishing pad 200 can include a recess 1402 formed in the back surface of the polishing pad 200. The recess 1402 may be machine drilled in a known location in the polishing pad relative to the contact region 250. The recess 1402 may be positioned in a thin flange or outer lateral portion 285 of the upper portion 270 of the polishing pad 200. The recess may extend partially or completely through the polishing pad. The gasket support 300 may include pins 1404 (e.g., protruding downward from the plate) that fit into the recesses 1402.

As another example, after the contact area 250 is defined on the polishing pad 200, at least some of the edges 1406 of the polishing pad 200 may be processed. The spacer support 300 may include a recess machined into the support plate. The edges of the recesses include an alignment surface and the edge 1406 of the polishing pad is positioned to abut the alignment surface of the recesses in the plate.

The lower portion 260 of the polishing pad 200 contacting the substrate may be formed of a high quality material, such as a material meeting high precision specifications of rigidity, porosity, etc. However, other portions of the polishing pad that do not contact the substrate do not have to meet such high precision specifications, and thus can be formed of lower cost materials. This may reduce the overall cost of the liner.

C. Pad driving system and orbital motion

Referring to fig. 1 and 5, a polishing drive system 500 may be configured to move the coupled polishing pad support 300 and polishing pad 200 in an orbital motion over a substrate 10 during a polishing operation. In particular, as shown in fig. 5, the polishing drive system 500 may be configured to maintain the polishing pad in a fixed angular orientation relative to the substrate during a polishing operation.

Referring to fig. 5, the track radius 20 of the polishing pad in contact with the substrate is preferably smaller than the diameter 22 of the contact area. For example, the track radius may be about 5% -50% (e.g., 5% -20%) of the diameter of the contact area. For a 20mm to 30mm diameter contact area, the track radius may be 1mm to 6mm. This achieves a more uniform velocity distribution in the load zone 5. The polishing pad may rotate in the track at a rate of 1000 to 5000 revolutions per minute ("rpm").

Referring to fig. 6, a drive train may include a mechanical system base 910 that utilizes a single actuator 915 to effect orbital motion. A motor output shaft 924 is connectively coupled to the cam 922. The cam 922 extends into a recess 928 in the polishing pad holder 920. During a polishing operation, the motor output shaft 924 rotates about the rotational axis 990, thereby causing the cam 922 to rotate the polishing pad holder 920. A plurality of anti-rotation links 912 extend from the mechanical system base 910 to an upper portion of the polishing pad holder 920 to prevent rotation of the pad holder 920. The anti-rotation link 912 in combination with the movement of the cam 922 effects an orbital movement of the polishing pad support in which the angular orientation of the polishing pad holder 920 is unchanged during the polishing operation.

As depicted in fig. 6A and 6B, the orbital motion may maintain a fixed angular orientation of the polishing pad relative to the substrate during the polishing operation. As the central motor output shaft 620 rotates, the cam 625 in combination with the anti-rotation links 630 that connect the upper mechanical system base to the polishing pad support translate the rotational motion into the orbital motion of the polishing pad 610. This achieves a more uniform velocity profile than a simple rotation.

In some embodiments, the grinding drive system and the positioning drive system are provided by the same component. For example, a single drive system may include two linear actuators configured to move the liner support head in two perpendicular directions. For positioning, the controller may cause the actuator to move the pad support to a desired position on the substrate. For lapping, the controller may cause the actuators to move the pad support in an orbital motion, for example, by applying a phase-shift sinusoidal signal to both actuators.

Referring to fig. 1, in some embodiments, the grinding drive system 500 may include two rotary actuators. For example, the polishing pad support may depend from a rotary actuator 508, which in turn depends from a second rotary actuator 509. During the polishing operation, the second rotary actuator 509 rotates the arm 510, which sweeps the polishing pad support 300 in an orbital motion. The first rotary actuator 508 rotates, for example, in the opposite direction to the second rotary actuator 509 but at the same rotational speed to counter the rotational motion such that the polishing pad assembly orbits while remaining in a substantially fixed angular position relative to the substrate.

D. Pad support

The movable pad support 300 holds a polishing pad and is coupled to a polishing drive system 500.

In some embodiments, for example as shown in fig. 1-4, the cushion support 300 is a simple rigid plate. The lower surface 311 of the plate is large enough to accommodate the upper portion 270 of the polishing pad 200.

However, the pad support 300 may also include an actuator 508 to control the downward pressure of the polishing pad 200 on the substrate 10.

In the example of fig. 7A, a pad support 300 is shown that can exert an adjustable pressure on the polishing pad 200. The pad support 300 includes a pedestal 317 that is coupled to the polishing drive system 500. The bottom of the base 317 includes a recess 327. The pad support 300 includes a clamp 410 that holds the edge of the polishing pad 200 on a pedestal 317. The polishing pad 200 may cover the recess 327 to define a pressurizable chamber 426. By pumping fluid into and out of the chamber 426, the downward pressure of the polishing pad 200 against the substrate 10 may be adjusted.

In some implementations, as shown in fig. 7B, 8A, and 8B, the gasket support 300 may have an internal diaphragm 405 defining a first pressurizable chamber 406 between the diaphragm 405 and the base 317. The membrane is positioned to contact the side 275 of the polishing pad 200 further from the polishing surface 258. The membrane 405 and chamber 406 are configured such that when the pad support 300 holds the polishing pad 200 during a polishing operation, the pressure in the chamber 406 controls the size of the load zone 809 of the polishing pad 200 on the substrate 10. As the pressure inside the chamber increases, the diaphragm radius expands, thereby applying pressure to a larger portion of the bottom tab layer of the gasket and thus increasing the area of the load zone 810. When the pressure is reduced, the result is a smaller sized load region 809.

Referring to fig. 11, in some embodiments, the polishing pad support 315 may include an internal pressurizable chamber 325 formed by a wall 320 of the polishing pad support 315. The chamber 325 may have an opening 327 facing the substrate. The opening 327 may be sealed by securing the polishing pad 200 to the polishing pad support 315, for example, by a clamp 410. During the grinding operation, the pressure in the pressure chamber 425 may be dynamically controlled, such as by a controller and hydraulic pump, to adjust to the non-uniform point being ground.

Referring to fig. 12, in some embodiments, the contact region 1301 of the polishing pad 20 may be an arcuate region. For example, the protrusion may be arc-shaped. The drive system 500 may rotate the arc about the center 1302 of the substrate 10.

Referring to fig. 13, in some embodiments, the polishing pad 200 contact area 901 can be an arcuate area that undergoes orbital motion relative to the substrate 10.

3. Conclusion(s)

The size of the spot of the non-uniformity on the substrate will dictate the desired size of the contact area during polishing of the spot. If the contact area is too large, the under-polish correction to some areas on the substrate may result in over-polish to other areas. On the other hand, if the contact area is too small, the pad will need to be moved across the substrate to cover the under-polished area, thereby reducing yield.

In a substrate processing operation, the substrate may first undergo a bulk polishing process in which polishing is performed over the entire front surface of the substrate. Optionally, after the bulk polishing operation, the non-uniformity of the substrate may be measured, for example, at an in-line or separate metrology station. The substrate may then be transported to the polishing apparatus 100 and subjected to a finishing polishing process. The control of the area to be abraded at the abrading device may be based on identification of the underabraded area of the substrate from historical data (e.g., thickness measurements generated during qualification) or from substrate measurements at an in-line or separate metrology station.

The entire polishing system may be arranged to position the front surface of the substrate vertically or face down (with respect to gravity). However, the advantage of having the front surface of the substrate facing upwards is that this allows for distributing the slurry over the face of the substrate. This may improve slurry retention and thus reduce slurry usage due to the larger size of the substrate relative to the polishing surface of the polishing pad.

Numerous embodiments of the present invention have been described. Nevertheless, 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 actuators that are capable of moving the substrate into position relative to the polishing pad. As another example, although the system described above includes a drive system that moves the polishing pad in the track path while holding the substrate in a substantially fixed position, the polishing pad may be held in a substantially fixed position and the substrate moved in the track. In this case, the polishing drive system may be a similar drive system, but coupled to the substrate support instead of the polishing pad support. Although a generally circular substrate is employed, this is not required and the support and/or polishing pad may be other shapes such as rectangular (in which case the discussion of "radius" or "diameter" will generally apply to the transverse dimension along the spindle).

Accordingly, other embodiments are within the scope of the following claims.

Claims

1. A chemical mechanical polishing system comprising:

a substrate support configured to hold a substrate in a fixed angular orientation during a polishing operation;

a movable pad support configured to hold a polishing pad having an arcuate contact area and having a diameter no greater than a radius of the substrate; and

a drive system configured to move the pad support and polishing pad in an orbital motion while the polishing pad is in contact with an upper surface of the substrate, the orbital motion having an orbital radius no greater than a diameter of the polishing pad and maintaining the polishing pad in a fixed angular orientation relative to the substrate.

2. The chemical mechanical polishing system of claim 1, wherein the drive system is configured to rotate the pad in an orbit at a rate of 1000 to 5000 revolutions per minute.

3. The system of claim 1, wherein the drive system includes a recess in the pad support, a rotatable cam extending into the recess, a motor for rotating the cam, and a link coupling the pad support to a fixed support to prevent rotation of the pad support.

4. The system of claim 1, comprising a positioning drive system to move the liner support laterally across the substrate.

5. The system of claim 4, wherein the positioning drive system comprises two linear actuators configured to move the pad support in two perpendicular directions.

6. The system of claim 5, comprising a controller coupled to the two linear actuators and configured to cause the two linear actuators to move the pad support in an orbital motion.

7. The system of claim 1, wherein the drive system comprises an arm supporting the pad support, a first rotary actuator for rotating the arm, and a second rotary actuator for rotating the pad support to counteract rotational movement relative to the substrate.

8. The system of claim 1, wherein the drive system is configured to sweep the polishing pad across the substrate laterally during the orbital motion at a speed that is no greater than 5% of an instantaneous speed of the orbital motion.

9. The system of claim 1, wherein the arcuate contact region has a diameter between 1% and 10% of the diameter of the substrate.

10. The system of claim 1, wherein the track radius is between 5% and 50% of the diameter of the arcuate contact region.

11. The system of claim 1, wherein the polishing pad comprises a self-layer protrusion, and a bottom surface of the protrusion provides the arcuate contact area.

12. A method of chemical mechanical polishing, the method comprising the steps of:

holding the substrate in a fixed angular orientation during the polishing operation;

bringing a polishing pad into contact with the substrate in an arcuate contact region, the contact region having a diameter no greater than a radius of the substrate;

generating a relative motion between the polishing pad and the substrate while the arcuate contact region of the polishing pad is in contact with an upper surface of the substrate, the relative motion comprising an orbital motion having an orbital radius no greater than a diameter of the polishing pad; a kind of electronic device with high-pressure air-conditioning system

During the orbital motion, the polishing pad is maintained in a fixed angular orientation relative to the substrate.

13. The method of claim 12, comprising the steps of: during the orbital motion, the substrate is held in a fixed lateral position.

14. The method of claim 13, further comprising the step of: during the orbital motion, the polishing pad is swept laterally across the substrate at a speed that is no greater than 5% of an instantaneous speed of the orbital motion.