KR102399064B1 - Method, system and polishing pad for chemical mechancal polishing - Google Patents

Abstract

Chemical mechanical polishing can be used for “touch-up polishing” in which polishing is performed on a limited area of the front surface of a substrate. The area of contact between the polishing pad and the substrate may be substantially smaller than the radial surface of the substrate. During polishing, the polishing pad may undergo orbital motion. The polishing pad may be held in a fixed angular orientation during orbital motion. The contact area may be arc-shaped. The contact area may be provided by one or more lower portions projecting downwardly from an upper portion of the polishing pad. A peripheral portion of the polishing pad may be vertically fixed to the annular member, and the remaining polishing pads in the peripheral portion of the polishing pad may be vertically free.

Description

METHOD, SYSTEM AND POLISHING PAD FOR CHEMICAL MECHANCAL POLISHING

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

Integrated circuits are typically formed on a substrate by sequential deposition of a conductive layer, a semiconductor layer, or an insulating layer on a silicon wafer. One fabrication step involves depositing a filler layer over a non-planar surface, and planarizing the fill layer. For certain applications, the fill layer is planarized until the top surface of the patterned layer is exposed. A conductive fill layer may, for example, be deposited on the patterned insulative layer to fill trenches or holes in the insulative layer. After planarization, portions of the metal layer remaining between the raised pattern of the insulating layer form vias, plugs, and lines that provide conductive paths between thin film circuits on the substrate. For other applications, such as oxide polishing, the fill layer is planarized until a predetermined thickness remains over the non-planar surface. In addition, planarization of the substrate surface is generally required for photolithography.

Chemical mechanical polishing (CMP) is one accepted planarization method. Such planarization methods typically require that the substrate be mounted on a carrier or polishing head. The exposed surface of the substrate is typically positioned against a rotating polishing pad. The carrier head provides a controllable load on the substrate to push the substrate against the polishing pad. An abrasive polishing slurry is typically applied to the surface of the polishing pad.

SUMMARY The present disclosure provides systems and apparatus for polishing substrates, such as “touch-up polishing,” in which polishing is performed on a limited area of a front surface of a 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 the 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 not 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 an upper surface of the substrate. The orbital motion has an orbital radius no greater than the diameter of the polishing pad and maintains the polishing pad in a fixed angular orientation with respect to the substrate.

Implementations may include one or more of the following features. The polishing pad may have a contact area for contacting the substrate. The diameter of the contact area may be about 1 to 10% of the diameter of the substrate. The radius of the orbit may be about 5 to 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 for the cam. Linkages may couple the pad support head to a fixed support and prevent rotation of the pad support head. A positioning drive system may move the pad support head laterally across the substrate. The positioning drive system may include two linear actuators configured to move the pad support head in two vertical 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 the substrate in a substantially fixed angular orientation during a polishing operation. The polishing pad has a contact area for contacting the substrate, the contact area having a diameter no greater than a radius of the substrate. The movable pad support is configured to hold the 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 no greater than the diameter of the polishing pad and maintains the polishing pad in a fixed angular orientation with respect to the substrate.

Implementations may include one or more of the following features. The polishing pad may include a protrusion from the layer, and a bottom surface of the protrusion may provide a contact area. At least one of a pressure sensitive adhesive or a 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 a polishing pad with a substrate at a contact area having a diameter not greater than a radius of the substrate, and contacting the polishing pad with the polishing pad while the contact area of the polishing pad is in contact with an upper surface of the substrate. generating relative motion between the substrates. Relative motion includes orbital motion having an orbital radius that is not greater than a diameter of the polishing pad. The polishing pad is maintained in a substantially fixed angular orientation with respect to the substrate during orbital motion.

Implementations may include one or more of the following features. The substrate may be held in a fixed lateral position during orbital motion. The polishing pad may be swept laterally across the substrate during orbital motion at a rate not greater than about 5% of the instantaneous velocity of the orbital motion.

In another aspect, a chemical mechanical polishing system is configured to create 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 relative motion between the substrate support and the polishing pad support. Includes drive system. The polishing pad has an upper portion that is secured to the polishing pad support and a lower portion that projects downwardly from the upper portion. An upper surface of the upper portion abuts the polishing pad support. The lowermost surface of the lower portion provides a contact surface for contacting the uppermost 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 less than the first lateral dimension.

Implementations may include one or more of the following features. The polishing pad support may include a plate having a surface that spans the polishing pad, and substantially all of the upper surface of an upper portion of the polishing pad may abut the surface of the plate. An adhesive may hold the polishing pad on the pad support. The polishing pad support may include an annular member, and a perimeter portion of an upper surface of an upper portion of the polishing pad may be adjacent the annular member, the remaining upper surface of the upper surface within the peripheral portion being It may not contact the polishing pad support. One or more clamps may hold a peripheral section of the polishing pad on the pad support. The upper portion of the polishing pad may include a flexing section having greater flexibility than a section of the polishing pad above the contact surface. The upper portion of the polishing pad may include a sheet of polyethylene terephthalate.

A plurality of grooves for transporting the slurry may be formed on the contact surface of the lower portion of the polishing pad. The plurality of grooves may have a depth smaller than a thickness of the lower portion. At least some of the plurality of grooves may extend completely to the lower portion of the polishing pad. A pressure chamber may be defined by an interior chamber of the polishing pad support, the chamber may have a substrate-facing opening, the opening sealed by coupling of the polishing pad to the polishing pad support. can be sealed. A plurality of apertures may be formed in an upper surface of the polishing pad, and the plurality of protrusions from the polishing pad support may fit into the plurality of apertures to align the lower portion with respect to the polishing pad support. there is.

In another aspect, a polishing pad includes an upper portion and one or more lower portions. The upper portion has an upper surface for attachment to a pad carrier and has a first lateral dimension. One or more lower portions project downwardly from the upper portion. The lowermost surface of the one or more lower portions provides a contact surface for contacting the substrate during chemical mechanical polishing. Each lower portion has a second lateral dimension that is less than the first lateral dimension. The total surface area of the contact surface from the one or more lower portions is not greater 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 of a substantially uniform composition and having a plurality of pores distributed therein. The polishing pad may include a polishing layer, and the downwardly projecting lower portion may be formed in the polishing layer. The pad may include a backing layer that is softer than the polishing layer. A grooving for transporting the slurry may be formed on the lowermost surface of the one or more lower portions. The one or more lower portions may consist of a single projection. The abrasive layer may include flexible lateral sections that are thinner than the lateral sections constituting the abrasive region. The lower portion may comprise microporous 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 relative motion between the substrate support and the polishing pad support. and a drive system configured to create The polishing pad has an arc-shaped contact region, wherein a center point of the arc defined by the arc-shaped contact region is substantially aligned with the center of the 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 1 mm and 3 mm, and the length of the arc may be greater than or equal to 30 mm. At least one of a pressure sensitive adhesive or a 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 be a rotation around 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 a substrate-facing opening. The polishing pad has a polishing surface for contacting the substrate during polishing. A peripheral portion of the polishing pad is vertically fixed to the annular member, and the remaining polishing pads in the peripheral portion of the polishing pad are vertically free. The substrate-facing opening of the polishing pad support is sealed by the polishing pad to define a pressurizable chamber, thereby providing an adjustable pressure on the back surface of the polishing pad.

Implementations may include one or more of the following features. The adhesive may fix the 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 membrane secured to the base, wherein a volume between the base and the membrane is such that an outer surface of the membrane exerts a second adjustable pressure on a back surface of the polishing pad. to provide a second pressurizable chamber. The membrane and the second pressurizable chamber may be configured such that the pressure in the second pressurizable chamber controls the lateral extent of the loading region of the polishing surface relative to the substrate.

In another aspect, a polishing pad includes an upper portion, one or more lower portions, and a plurality of apertures. The upper portion has an upper surface for attachment to a pad carrier and has a first lateral dimension. One or more lower portions project downwardly from the upper portion. The lowermost surface of the one or more lower portions provides a contact surface for contacting the substrate during chemical mechanical polishing. Each lower portion has a second lateral dimension that is less than the first lateral dimension such that the upper portion projects beyond all lateral sides of the lower portion. A plurality of apertures are present in the upper surface of the upper portion to receive protrusions from the pad carrier. The apertures are positioned in a section of the upper portion of the polishing pad laterally outwardly of the lower portion.

Implementations may include one or more of the following features. A plurality of apertures may be positioned at corners of the polishing pad. The polishing pad may be rectangular. The one or more lower portions may have an arc-shaped contact surface. A plurality of grooves for transporting the slurry may be formed on the contact surface of the lower portion of the polishing pad.

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

A small pad that undergoes orbital motion may be used to compensate for non-concentric polishing uniformity. Orbital motion can provide an acceptable polishing rate while avoiding overlap of the pad with areas not desired to be polished, thereby improving substrate uniformity. Additionally, orbital motion, which maintains a fixed orientation of the polishing pad relative to the substrate, as opposed to rotation, can provide a more uniform polishing rate across the area being polished.

Making the top portion of the polishing pad secured to the polishing pad support laterally wider than the bottom protrusion making contact with the substrate will increase the area available for connection of the pad to the support, such as by a pressure sensitive adhesive. can This may make the polishing pad less susceptible to delamination during polishing operations.

A polishing pad having an arc-shaped contact area for contacting a substrate can provide an improved polishing rate while maintaining sufficient radial resolution for the polishing zone.

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

Providing the polishing pad with a flexing portion may reduce flexing of the portion of the contact surface of the polishing pad, thereby improving the likelihood that the area being polished will match that expected by the operator.

The grooves in the protrusion of the polishing pad may enable transport of the slurry, thus improving 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 total pad cost.

A pad carrier that allows control over the size of the portion of the contact area that is loaded with respect to the substrate can allow the loading area to match the size of the spot to be polished, thereby removing unwanted areas of the substrate. The throughput is improved while grinding is avoided.

Overall, non-uniform polishing to the substrate can be reduced, and the resulting flatness and finish to the substrate can be improved.

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

1 is a schematic side cross-sectional view of a polishing system;
2 is a schematic cross-sectional side view of an implementation of a polishing system including a vacuum chuck for holding a substrate;
3 is a schematic cross-sectional side view of an implementation of a polishing system having a polishing pad that does not include a downward protrusion.
4 is a schematic cross-sectional side view of an implementation of a polishing system having a polishing pad having a top layer having a diameter greater than the substrate and a downward projection having a diameter less than the substrate.
5 is a schematic cross-sectional plan view illustrating a polishing pad moving in orbit while maintaining a fixed angular orientation.
6 is a schematic cross-sectional plan view of a polishing pad support and drive train system of a polishing system.
6A is a schematic cross-sectional plan view of the system of FIG. 6 with respect to a substrate;
FIG. 6B is a schematic cross-sectional plan view of the system of FIG. 6 in a quarter revolution turn with respect to FIG. 6A ;
7A is a schematic cross-sectional side view of a movable polishing pad support connected to the polishing pad with a plurality of clamps.
7B is a schematic cross-sectional view of an implementation of a removable polishing pad support comprising an inner pressurized space enclosed by an inner membrane.
8A is a schematic cross-sectional side view of the movable polishing pad support of FIG. 7B in a low pressure state;
8B is a schematic cross-sectional side view of the movable polishing pad support of FIG. 7B in a high pressure condition;
9 is a schematic bottom view of the contact area of the polishing pad.
10A and 10B are schematic cross-sectional side views of implementations of a polishing pad.
11 is a schematic cross-sectional side view of another implementation of a removable polishing pad support.
12 is a schematic plan view of an implementation of a polishing system having a polishing pad having a layer of arc-shaped protrusions defining a corresponding arc-shaped loading region.
13 is a schematic cross-sectional side view of an implementation of a polishing system having an arc-shaped abrasive surface undergoing orbital motion.
14 is a schematic plan view of a polishing pad.
Like reference signs in the various drawings indicate like elements.

1. Introduction

Some polishing processes result in non-uniformity in thickness across the surface of the substrate. For example, a bulk polishing process can result in under-polished areas on the substrate. To solve this problem, after bulk polishing, it is possible to perform a "touch-up" polishing process focusing on the insufficiently polished portions of the substrate.

In a bulk polishing process, polishing occurs over the entire front surface of the substrate, although potentially at different rates in different regions of the front surface. In a bulk polishing process, not all of the surface of the substrate may be undergoing polishing at any given moment. For example, due to the presence of grooves in the polishing pad, some portions of the substrate surface may not be in contact with the polishing pad. Nevertheless, since these portions are not local due to relative motion between the polishing pad and the substrate during the bulk polishing process, all front surfaces of the substrate undergo some amount of polishing.

In contrast, in a “touch-up” polishing process, the polishing pad may contact less than all of the front surface of the substrate. In addition, the range of motion of the polishing pad relative to the substrate is such that, during the touch-up polishing process, the polishing pad only contacts a localized area of the substrate and a significant portion (eg, at least 50%, at least 75%) of the front surface of the substrate. %, or at least 90%) is configured to never contact the polishing pad and thus not undergo polishing. For example, in touch-up polishing, the contact area may be substantially smaller than the radial surface of the substrate.

As mentioned above, some bulk polishing processes result in non-uniform polishing. In particular, some bulk polishing processes result in localized non-concentric and non-uniform spots that are insufficiently polished. In a touch-up polishing process, a polishing pad rotating about the center of a substrate may be able to compensate for concentric rings with non-uniformities, but localized non-concentric and non-uniform spots, such as thickness profile. Resolving each asymmetry in the profile may not be possible. However, small pads, such as those that undergo orbital motion, may be used to compensate for non-concentric polishing uniformity. For some implementations, during polishing, the polishing pad may undergo orbital motion in a fixed angular orientation.

Referring to FIG. 1 , a polishing apparatus 100 for polishing localized regions of a substrate includes a substrate support 105 for holding a substrate 10 , and a movable polishing pad support for holding a polishing pad 200 . (300). The polishing pad 200 includes a polishing surface 250 having a diameter less than the radius of the substrate 10 being polished.

The polishing pad support 300 is suspended from the polishing drive system 500 which will provide motion of the polishing pad support 300 relative to the substrate 10 during a polishing operation. The abrasive drive system 500 may be suspended from the support structure 550 .

In some implementations, a 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 pad support 300 in a desired lateral position over the substrate support 105 . For example, the support structure 550 may include two linear actuators 562 and 564 , which are above the substrate support 105 perpendicular to each other to provide a positioning drive system 560 . is oriented 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 be suspended from a single linear actuator that provides motion along a radial direction. Alternatively, the polishing pad support may be suspended from a rotary actuator 508 and the substrate support 105 may be rotatable using a rotary actuator 506 .

Optionally, a vertical actuator (shown as 506 and/or 508 ) may be coupled to the substrate support 105 and/or the polishing pad support 300 . For example, the substrate support 105 may be connected to a vertically drivable piston capable of raising or lowering the substrate support 105 .

The polishing apparatus 100 includes a port 60 for dispensing a polishing liquid 65 such as a polishing slurry onto a surface 12 of a substrate 10 to be polished. The 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 polishing condition.

In operation, the substrate 10 is loaded onto the substrate support 105 by, for example, a robot. The positioning drive system 560 positions the polishing pad support 300 and the polishing pad 200 at a desired position on the substrate 10 , and the vertical actuator 506 moves the substrate 10 with the polishing pad 200 . move in contact with (or move the polishing pad 200 into contact with the substrate 10 using the actuator 508 ). The polishing drive system 500 creates relative motion between the polishing pad support 300 and the substrate support 105 to cause polishing of the substrate 10 .

During a polishing operation, positioning drive system 560 may hold polishing drive system 500 and substrate 10 substantially fixed relative to each other. For example, the positioning system may hold the abrasive drive system 500 stationary relative to the substrate 10 , or may hold the abrasive drive system 500 over the area to be polished (abrasive drive system 500 ). ) can sweep slowly (relative to the motion provided to the substrate 10). For example, the instantaneous velocity provided to the substrate by the positioning drive system 560 may be less than 5%, such as less than 2%, of the instantaneous velocity provided to the substrate by the polishing drive system 500 .

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 circuits 93 . The central processing unit 91 of the controller 90 causes the controller to receive input based on the environment and desired polishing parameters and to control the various actuators and drive systems, via support circuits 93 to memory Execute the instructions loaded from (92).

For a “touch-up” polishing operation, the controller 90 controls a significant portion (eg, at least 50%) of the front surface of the substrate during the touch-up polishing process, even if the polishing drive system 500 is being swept slowly. , at least 75%, or at least 90%) are programmed to control the positioning drive system 560 such that the range of motion of the polishing drive system 500 is constrained such that it never contacts the polishing pad and thus undergoes polishing. .

2. Polishing system

A. Substrate support

Referring to FIG. 1 , the substrate support 105 is a plate-shaped body positioned below the polishing pad support. The upper surface 116 of the body provides a loading area large enough to accommodate the substrate to be processed. For example, the substrate may be a 200-450 mm diameter substrate. The top surface 116 of the substrate support 105 contacts and maintains its position with the back surface (ie, the unpolished surface) of the substrate 10 .

The substrate support 105 is approximately the same radius as or larger than the substrate 10 . In some implementations, the substrate support 105 is slightly narrower than the substrate, eg, by 1-2% of the substrate diameter (eg, see FIG. 2 ). When disposed on the support 105 , an edge of the substrate 10 may slightly overhang the edge of the support 105 . This can provide clearance for the edge grip robot to place the substrate on the support. In some implementations, the substrate support 105 is wider than the substrate. In this case, a robot equipped with an end effector with a vacuum chuck can be used to place the substrate on the support. In either case, the substrate support 105 may contact most of the backside surface of the substrate.

In some implementations, as shown in FIG. 1 , the substrate support 105 maintains the substrate 10 position during a polishing operation using the clamp assembly 111 . In some implementations, the clamp assembly 111 may be a single annular clamp ring 112 that contacts a rim of the top surface of the substrate 10 . Alternatively, the clamp assembly 111 may include two arc-shaped clamps 112 that contact the rim of the top surface on opposite sides of the substrate 10 . The clamps 112 of the clamp assembly 111 may be lowered into contact with the rim of the substrate by one or more actuators 113 . The downward force of the clamp restrains the substrate from moving laterally during the polishing operation. In some implementations, the clamp(s) includes a downwardly projecting flange 114 surrounding an outer edge of the substrate.

In some implementations, 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 connecting the chamber 122 to a surface 116 supporting the substrate 10 . In operation, air may be evacuated from the chamber 122 , such as by a pump 129 , such that a suction force is applied through the ports 124 to bring the substrate into position on the substrate support 106 . is held

In some implementations, as shown in FIG. 3 , the substrate support 105 includes a retainer 131 . The retainer 131 may be attached to and project over the surface 116 supporting the substrate 10 . Typically, the retainer is at least as thick as the substrate 10 (thickness measured perpendicular to the surface 12 ). In operation, retainer 131 surrounds substrate 10 . For example, retainer 131 may be an annular body having a diameter slightly larger than that of substrate 10 . During polishing, friction from the polishing pad 200 may create a lateral force against the substrate 10 . However, retainer 131 limits the lateral motion of substrate 10 .

The various substrate support features described above may optionally be coupled to each other. For example, the substrate support may include both a vacuum chuck and a retainer.

Additionally, for ease of illustration the substrate support configurations are shown as removable pad support configurations with a pressure sensitive adhesive, however, these are shown in conjunction with any of the embodiments of the pad support head and/or drive system described below. can be used

B. Polishing Pad

Referring to FIG. 1 , a polishing pad 200 has a polishing surface 250 that comes into contact with a substrate 10 in a contact region (also referred to as a loading region) during polishing. The abrasive surface 250 may have a diameter less than the radius of the substrate 10 . For example, the diameter of the polishing surface may be about 5-10% of the diameter of the substrate. For example, for wafers with a diameter in the range of 200 mm to 300 mm, the polishing surface may be 10 to 30 mm in diameter. Smaller abrasive surfaces provide higher precision but lower yields.

In some implementations, less than 1% of the substrate surface may be contacted by the polishing surface at any given time. In general, this may be useful for touch-up polishing operations, but such a small area will not be acceptable for bulk polishing operations due to low yield.

In some implementations, for example, as shown in FIG. 3 , the entire polishing pad has a radius that is less than the radius of the substrate 10 , for example, as measured relative to the outer edge of the pad. For example, the diameter of the polishing pad may be about 5-10% of the diameter of the substrate.

In the example of FIG. 1 , a polishing pad 200 is located over an upper surface of a substrate 10 , and an upper portion 270 coupled to a lowermost portion of a movable pad support 300 and substrate 10 during a polishing operation. and a lower portion 260 having a contacting lowermost surface 250 . In some examples, as shown in FIG. 1 , the lowermost portion 260 of the polishing pad 200 is provided by a protrusion from the wider upper portion 270 . The lowermost surface 250 of the protrusion 260 contacts the substrate during a polishing operation and provides a polishing surface.

In the example of FIG. 1 , the removable pad support 300 is coupled to the upper portion 270 of the polishing pad 200 using a pressure sensitive adhesive 231 . A 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 to the pad support 300 during the polishing operation. do.

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

Referring to FIG. 3 , the polishing pad 203 may have a radius at its lower portion 260 that is the same as a radius at its uppermost portion 273 . However, where the pressure sensitive adhesive 231 provides coupling between the pad and the removable pad support 300 , it is preferred that the lowermost portion 263 is narrower than the uppermost portion 273 .

Referring to FIG. 5 , the contact area 5 of the polishing pad may have a disk-shaped geometry 5 formed by a disk-shaped lowermost protrusion of the polishing pad.

9A and 9B , the contact area 901 of the polishing pad 110 in contact with the substrate 10 may be an arc-shaped contact area 901 formed by the arc-shaped protrusion 290 of the polishing pad. there is.

Referring to FIG. 1 , in some implementations, the diameter of the upper portion 270 of the polishing pad 200 may be smaller than the diameter of the substrate 10 .

4 , in some implementations, the diameter of the upper portion 274 of the polishing pad 204 may be greater than the diameter of the substrate 10 .

Referring to FIG. 1 , the polishing pad 200 may be formed of a single layer having a 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 , are the same.

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

Referring to FIG. 10A , in some implementations, the polishing pad may include two or more layers of different composition, wherein the upper portion 1221 of the polishing pad 200 is on top of the polishing layer 1062 . It may include both a section 1064 and a backside layer 1052 . Thus, the abrasive layer 1062 includes both a lower section 1066 and an upper section 1064 that provide protrusions 1222 , the upper section 1064 being wider than the lower section 1066 .

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

10A or 10B, the abrasive layer 1062 may consist of a single layer of uniform composition. For example, in either of the implementations shown in FIGS. 10A or 10B , the portion of the pad that contacts the substrate may be made of a conventional material, such as a microporous polymer such as polyurethane.

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

Referring to FIG. 10B , the backside layer 1052 may be relatively soft, but may also be a flexible, incompressible layer made of a material such as polyethylene terephthalate, such as Mylar ^™ . For example, such a pad configuration may be used in implementations where the polishing pad of FIG. 10B is coupled to the pressure chamber polishing pad support of FIG. 11 . The abrasive layer 1062 may be a rigid polyurethane.

Referring to FIG. 11 , in some implementations, 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 joined lower portion 260 and an upper portion 275 . The upper portion 275 extends laterally on either side of the thicker section 267 to provide lateral side sections 285 . The lateral side sections 285 flex in response to pressure on the thicker section 267 . The thicker section 267 may have a pad thickness of about 2 mm in the abrasive area, similar to a larger sized pad. The pad thickness in the flexing lateral sections 285 may be about 0.5 mm.

In some implementations, the bottom surface 250 of the lower portion of the polishing pad 200 may include grooves to allow transport of the slurry during a polishing operation. The grooves 299 may be shallower than the depth of the lower portion 260 (eg, see FIG. 11 ). However, in some implementations, the lower portion does not include grooves. If the polishing pad includes grooves, the grooves 299 may extend completely over the lateral width of the lower portion 260 . In addition, the grooves may be shallower than the vertical thickness of the lower portion 260 , ie, the grooves pass partially vertically but not completely through the lower portion 260 .

Referring to FIG. 9 , the lowermost surface 1900 of the polishing pad 200 may be an arc-shaped region. If the polishing pad includes grooves, the grooves 299 may extend completely over the lateral width of the arc-shaped area. The grooves 299 may be spaced at a uniform pitch along the length of the arc-shaped region. Each of the grooves 299 may extend along a radius through the center 1903 of the groove and arc-shaped area, or may be positioned at an angle to the radius, such as 45°.

Referring to FIG. 14 , in some implementations, the polishing pad 200 is positioned in a known lateral position relative to the pad support 300 , the polishing pad 200 , and the lower portion 260 providing the contact area 250 . alignment features that mate with matching features on the pad support 300 to ensure that it is in

For example, the polishing pad 200 may include recesses 1402 formed in the back surface of the polishing pad 200 . Recesses 1402 may be machine drilled into the polishing pad at a known position with respect to contact area 250 . The recesses 1402 may be positioned in the thin flange or outer lateral portion 285 of the upper portion 270 of the polishing pad 200 . The recesses may extend partially or completely through the polishing pad. The pad support 300 may include pins 1404 that fit into the recesses 1402 , such as projecting downwardly from the plate.

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

The lower portion 260 of the polishing pad 200, which is in contact with the substrate, may be formed of a high-quality material, for example, a material that meets high-precision specifications such as rigidity, porosity, and the like. However, other portions of the polishing pad that are not in contact with the substrate do not need to meet such high precision specifications and, therefore, can be formed of lower cost materials. This can reduce the total pad cost.

C. Orbital motion of drive system and pads

1 and 5 , a polishing drive system 500 may be configured to move a coupled polishing pad support 300 and polishing pad 200 in orbital motion over a substrate 10 during a polishing operation. can 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 with respect to the substrate during a polishing operation.

Referring to FIG. 5 , the radius of the track 20 of the polishing pad in contact with the substrate is preferably less than the diameter 22 of the contact area. For example, the radius of the trajectory may be about 5-50% of the diameter of the contact area, such as 5-20%. For a 20-30 mm diameter contact area, the radius of the orbit may be 1-6 mm. This achieves a more uniform velocity profile in the loading region 5 . The polishing pad is capable of revolving in its orbit at a rate of 1000 to 5000 revolutions per minute (“rpm”).

Referring to FIG. 6 , the drive train may include a mechanical system base 910 that achieves orbital motion with a single actuator 915 . A motor output shaft 924 is connectably coupled to the cam 922 . The cam 922 extends into a recess 928 in the polishing pad holder 920 . During the polishing operation, the motor output shaft 924 rotates about an axis of rotation 990 to cause the cam 922 to revolve 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 links 912 in conjunction with the motion 922 of the cam achieve orbital motion of the polishing pad support, where the angular orientation of the polishing pad holder 920 does not change during the polishing operation.

The orbital motion shown in FIGS. 6A and 6B may maintain a fixed angular orientation of the polishing pad with respect to the substrate during the polishing operation. As the central motor output shaft 620 rotates, the cam 625 engages anti-rotation links 630 that connect the mechanical system base above to the polishing pad support, thereby transferring rotational motion to the polishing pad 610 . ) to an orbital motion. This achieves a more uniform velocity profile than a simple rotation.

In some implementations, the abrasive drive system and positioning drive system are provided by the same components. For example, it may include two linear actuators (a single drive system) configured to move the pad support head in two vertical directions. For positioning, the controller may cause the actuators to move the pad support to a desired position on the substrate. For polishing, the controller may cause the actuators to move the pad support in orbital motion, such as by applying phase offset sinusoidal signals to the two actuators.

Referring to FIG. 1 , in some implementations, abrasive drive system 500 may include two rotary actuators. For example, the polishing pad support may be suspended from a rotary actuator 508 , which in turn is suspended from a second rotary actuator 509 . During the polishing operation, the second rotary actuator 509 rotates an arm 510 sweeping the polishing pad support 300 in orbital motion. The first rotary actuator 508 rotates, for example, at the same rotation rate as the second rotary actuator 509 , but in the opposite direction to cancel the rotational motion, such that the polishing pad assembly is at a substantially fixed angle relative to the substrate. It will orbit while maintaining its position.

D. Pad support

The removable pad support 300 holds the polishing pad and is coupled to the polishing drive system 500 .

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

However, the pad support 300 may also include an actuator 508 for controlling the downward pressure of the polishing pad 200 against the substrate 10 .

In the example of FIG. 7A , a pad support 300 is shown capable of applying an adjustable pressure on the polishing pad 200 . The pad support 300 includes a base 317 coupled to the polishing drive system 500 . The lowermost portion of the base 317 includes a recess 327 . The pad support 300 includes a clamp 410 that holds the rim of the polishing pad 200 on the base 317 . The polishing pad 200 may define a pressurizable chamber 426 by covering the recess 327 . By pumping a fluid into or out of the chamber 426 , the downward pressure of the polishing pad 200 against the substrate 10 may be modulated.

In some implementations, as in FIGS. 7B , 8A, and 8B , the pad support 300 has an inner membrane defining a first pressurizable chamber 406 between the membrane 405 and the base 317 ( 405) may have. The membrane is positioned to contact the face 275 of the polishing pad 200 distal from the polishing surface 258 . Membrane 405 and chamber 406 ensure that when pad support 300 holds polishing pad 200 during a polishing operation, the pressure in chamber 406 causes loading of polishing pad 200 on substrate 10 . configured to control the size of the region 809 . When the pressure inside the chamber increases, the membrane exerts pressure on a larger portion of the lowermost raised layer of the pad by expanding its radius, thereby increasing the area of the loading region 810 . When the pressure is reduced, a smaller sized loading area 809 results.

Referring to FIG. 11 , in some implementations, the polishing pad support 315 can include an internal pressurizable chamber 325 defined by walls 320 of the polishing pad support 315 . Chamber 325 may have a substrate-facing opening 327 . The opening 327 may be sealed, for example, by securing the polishing pad 200 to the polishing pad support 315 by a clamp 410 . The pressure in the pressure chamber 425 may be dynamically controlled during a polishing operation, such as by a controller and a hydrostatic pump, to adjust for non-uniform spots being polished.

Referring to FIG. 12 , in some implementations, the contact area 1301 of the polishing pad 20 may be an arc-shaped area. For example, the protrusion may be arc-shaped. The drive system 500 may rotate the arc around the center 1302 of the substrate 10 .

Referring to FIG. 13 , in some embodiments, the contact area 901 of the polishing pad 200 may be an arc-shaped area that undergoes orbital motion with respect to the substrate 10 .

3. Conclusion

The size of the spot with non-uniformity on the substrate will dictate the ideal size of the contact area while polishing the spot. If the contact area is too large, correction of insufficient polishing for some areas on the substrate may result in excessive polishing for 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 insufficiently polished area, thus reducing the yield.

In a substrate processing operation, a substrate may first be subjected to a bulk polishing process in which polishing is performed over the entire front surface of the substrate. Optionally, after a bulk polishing operation, for example, at an in-line or stand-alone metrology station, the non-uniformity of the substrate can be measured. Thereafter, the substrate may be transported to the polishing apparatus 100 to undergo a touch-up polishing process. Control of the area to be polished in the polishing apparatus can be achieved by controlling the under-polished areas of the substrate, either from historical data, such as thickness measurements made during quality control, or measurements of the substrate at an in-line or stand-alone metrology station. It can be based on identification.

The entire polishing system may be arranged to be positioned so that the front surface of the substrate faces either vertically (with respect to gravity) or downwards. However, an advantage of having the front surface of the substrate facing upward is that it allows the slurry to be distributed over the surface of the substrate. Due to the larger size of the substrate relative to the polishing surface of the polishing pad, slurry retention may be improved, and thus slurry usage may be reduced.

A number of embodiments of the 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, the substrate support may, in some embodiments, include its own actuators capable of moving the substrate into position relative to the polishing pad. As another example, the system described above includes a drive system that moves the polishing pad into an orbital path while the substrate is held in a substantially fixed position, but instead, the polishing pad is held in the substantially fixed position and the substrate is held in the substantially fixed position. It can be moved in an orbital path. In this situation, the polishing drive system may be similar, but coupled to the substrate support rather than the polishing pad support. Although a circular substrate is generally assumed, this is not required, and the support and/or polishing pad may be of other shapes, such as a rectangle (in this case, discussion of "radius" or "diameter" is generally major axis)).

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

Claims (25)

A chemical mechanical polishing system comprising:
a substrate support configured to hold a substrate during a polishing operation;
a polishing pad support, the polishing pad support comprising an annular member and a base having a recess having a substrate-facing opening;
a polishing pad held by the polishing pad support, the polishing pad having an upper portion secured to the polishing pad support and a lower portion projecting downwardly from the upper portion, an upper surface of the portion abuts the polishing pad support, and a bottom surface of the lower portion provides a contact surface for contacting a top surface of the substrate during polishing, the contact surface comprising: less than the top surface of the substrate, the upper portion having a first lateral length, the lower portion having a second lateral length less than the first lateral length, the top portion of the polishing pad being a perimeter portion of the portion is vertically fixed to the annular member, the remainder of the polishing pad in the perimeter portion is vertically free, and the substrate-facing opening of the polishing pad support comprises: 1 sealed by the polishing pad to define a pressurizable chamber to provide a first adjustable pressure on a first portion of a back surface of the polishing pad;
a membrane secured to the base in the recess, the volume between the base and the membrane defining a second pressurizable chamber, the outer surface of the membrane in contact with a second portion of the back surface of the polishing pad and separate from the first portion of the back surface of the polishing pad, the membrane providing a second adjustable pressure on a second portion of the back surface of the polishing pad; and
a drive system configured to create relative motion between the substrate support and the polishing pad support;
Chemical mechanical polishing system. The method of claim 1,
the polishing pad support comprising a plate having a surface spanning the polishing pad, wherein all top surfaces of an upper portion of the polishing pad are adjacent to the surface of the plate;
Chemical mechanical polishing system. The method of claim 1,
a perimeter portion of an upper surface of the upper portion of the polishing pad is adjacent the annular member, and a remainder of the upper surface within the perimeter portion does not contact the polishing pad support;
Chemical mechanical polishing system. 4. The method of claim 3,
one or more clamps holding a peripheral section of the polishing pad on the polishing pad support;
Chemical mechanical polishing system. 4. The method of claim 3,
an upper portion of the polishing pad comprising a flexing section having greater flexibility than a section of the polishing pad above the contact surface;
Chemical mechanical polishing system. The method of claim 1,
a plurality of grooves on the contact surface of the lower portion of the polishing pad for transporting slurry;
at least some of the plurality of grooves extend throughout the lower portion of the polishing pad;
Chemical mechanical polishing system. The method of claim 1,
wherein the membrane and the second pressurizable chamber are configured such that a pressure in the second pressurizable chamber controls a lateral extent of a loading region of the polishing pad relative to the substrate;
Chemical mechanical polishing system. An abrasive assembly comprising:
a polishing pad support, the polishing pad support comprising an annular member and a base having a recess having a substrate-facing opening;
a polishing pad held by the polishing pad support, the polishing pad having a polishing surface for contacting a substrate during polishing, a peripheral portion of the polishing pad fixed perpendicular to the annular member, the polishing pad in the peripheral portion the remaining portion is not vertically fixed, and wherein the substrate-facing opening of the polishing pad support is configured to define a first pressurizable chamber to provide a first adjustable pressure on a first portion of the back surface of the polishing pad. sealed by a polishing pad; and
a membrane secured to the base in the recess, the volume between the base and the membrane defining a second pressurizable chamber, the outer surface of the membrane in contact with a second portion of the back surface of the polishing pad and the polishing pad separated from a first portion of the back surface of the polishing pad, wherein the membrane provides a second adjustable pressure on a second portion of the back surface of the polishing pad;
grinding assembly. 9. The method of claim 8,
wherein the membrane and the second pressurizable chamber are configured such that a pressure within the second pressurizable chamber controls a lateral extent of a loading region of the polishing surface relative to the substrate;
grinding assembly. A chemical mechanical polishing system comprising:
a substrate support configured to hold the substrate in a fixed angular orientation during a polishing operation;
a polishing pad support, the polishing pad support comprising an annular member and a base having a recess having a substrate-facing opening;
a polishing pad held by the polishing pad support, the polishing pad having a contact area for contacting the substrate, the contact area having a diameter no greater than a radius of the substrate, and a perimeter portion of the polishing pad being the annular fixed vertically to the member, wherein the remainder of the polishing pad in the peripheral portion is not vertically fixed, and the substrate-facing opening of the polishing pad support defines a first pressurizable chamber to provide sealed by the polishing pad to provide a first adjustable pressure on a first portion;
a membrane secured to the base in the recess, the volume between the base and the membrane defining a second pressurizable chamber, the outer surface of the membrane in contact with a second portion of the back surface of the polishing pad and the polishing pad separate from the first portion of the back surface of the polishing pad, the membrane providing a second adjustable pressure on a second portion of the back surface of the polishing pad; and
a drive system configured to move the polishing 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;
wherein the orbital motion has an orbital radius no greater than a diameter of the polishing pad and maintains the polishing pad in a fixed angular orientation with respect to the substrate;
Chemical mechanical polishing system. 11. The method of claim 10,
wherein the drive system is configured to revolve the polishing pad at a rate of 1000 to 5000 revolutions per minute (rpm).
Chemical mechanical polishing system. 11. The method of claim 10,
The diameter of the contact area is 1 to 10% of the diameter of the substrate,
Chemical mechanical polishing system. 11. The method of claim 10,
wherein the orbital radius is 5 to 50% of the diameter of the contact area;
Chemical mechanical polishing system. 11. The method of claim 10,
wherein the drive system includes a recess in the polishing pad support, a rotatable cam extending into the recess, and a motor for rotating the cam.
Chemical mechanical polishing system. 15. The method of claim 14,
wherein the drive system further comprises linkages coupling the polishing pad support to a fixed support to prevent rotation of the polishing pad support.
Chemical mechanical polishing system. 11. The method of claim 10,
The drive system includes two linear actuators configured to move the polishing pad support in two vertical directions, and connected to the two linear actuators and configured to move the polishing pad support by the two linear actuators. a controller configured to move in orbital motion;
Chemical mechanical polishing system. 11. The method of claim 10,
wherein the drive system is configured to sweep the polishing pad laterally across the substrate during the orbital motion at a rate not greater than 5% of an instantaneous velocity of the orbital motion.
Chemical mechanical polishing system. 18. A method for chemical mechanical polishing using the system according to any one of claims 10 to 17, comprising:
contacting the polishing pad with the substrate at the contact area having a diameter not greater than a radius of the substrate;
creating relative motion between the polishing pad and the substrate while the contact area of the polishing pad is in contact with the upper surface of the substrate, the relative motion having the orbital radius not greater than a diameter of the polishing pad including said orbital motion; and
maintaining the polishing pad in the fixed angular orientation with respect to the substrate during the orbital motion;
Chemical mechanical polishing method. 19. The method of claim 18,
holding the substrate in a fixed lateral position during the orbital motion;
Chemical mechanical polishing method. 20. The method of claim 19,
sweeping the polishing pad laterally across the substrate during the orbital motion at a rate not greater than 5% of the instantaneous velocity of the orbital motion;
Chemical mechanical polishing method. delete delete delete delete delete

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