JP6955592B2 - Methods, systems, and polishing pads for chemical mechanical polishing - Google Patents

Description

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

An integrated circuit is usually formed on a substrate by continuously depositing a conductive layer, a semi-conductive layer, or an insulating layer on a silicon wafer. One manufacturing step involves depositing a packed bed on a non-planar surface to flatten the packed bed. In certain applications, the packed bed is flattened until the top surface of the pattern layer is exposed. For example, a conductive packing layer can be deposited on the patterned insulating layer to fill trenches or holes in the insulating layer. After flattening, the portion of the metal layer that remains between the elevated patterns of insulation forms vias, plugs, and lines that serve as conductive paths between the thin film circuits on the substrate. In other applications, such as oxide polishing, the packed bed is flattened until a predetermined thickness remains on a non-planar surface. In addition, substrate surface flattening is typically required for photolithography.

Chemical mechanical polishing (CMP) is one of the recognized methods of flattening. This flattening method typically requires the substrate to be attached to a carrier or polishing head. The exposed surface of the substrate is usually applied to a rotary polishing pad. The carrier head applies a controllable load to the substrate and presses the substrate against the polishing pad. A polishing slurry for polishing is usually supplied to the surface of the polishing pad.

The present disclosure provides a system and apparatus for polishing a substrate, for example, "touch-up polishing" in which polishing is performed in a limited area on the front surface of the substrate.

In one aspect, the 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 the polishing operation. The movable pad support is configured to hold a polishing pad having a diameter equal to or less than the radius of the substrate. The drive system is configured to move the pad support and the polishing pad in orbit while the polishing pad is in contact with the top surface of the substrate. The orbital motion has an orbital radius less than or equal to the diameter of the polishing pad and maintains the polishing pad in a fixed angular orientation with respect to the substrate.

Implementation embodiments may include one or more of the following features: The polishing pad may have a contact area in contact with the substrate. The diameter of the contact area may be between about 1 and 10% of the diameter of the substrate. The radius of the orbit 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 for the cam. The linkage may connect the pad support head to a fixed support to prevent rotation of the pad support head. The positioning drive system can 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, the 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 the polishing operation. The polishing pad has a contact area for contact with the substrate, and the contact area has a diameter equal to or less than the radius of the substrate. The movable pad support is configured to hold the polishing pad. The drive system is configured to orbitally move the pad support and the polishing pad while the contact area of the polishing pad is in contact with the top surface of the substrate. The orbital motion has an orbital radius less than or equal to the diameter of the polishing pad and maintains the polishing pad in a fixed angular orientation with respect to the substrate.

Implementation embodiments may include one or more of the following features: The polishing pad may include protrusions from the layer, and the bottom surface of the protrusions may provide a contact area. At least one of the pressure sensitive adhesives or clamps may hold the polishing pad on the pad support. The contact area may be disk-shaped or arc-shaped.

In another aspect, the method of chemical mechanical polishing involves contacting the polishing pad with the substrate within a contact area having a diameter less than or equal to the radius of the substrate and while the contact area of the polishing pad is in contact with the top surface of the substrate. Includes generating relative motion between the polishing pad and the substrate. Relative movements include orbital movements with orbital radii less than or equal to the diameter of the polishing pad. The polishing pad is maintained in a substantially fixed angular orientation with respect to the substrate during orbital motion.

Implementation embodiments may include one or more of the following features: The substrate can be held in a fixed lateral position during orbital motion. The polishing pad can be sweeped laterally across the substrate during orbital motion at a speed of about 5% or less of the instantaneous velocity of orbital motion.

In another aspect, the chemical mechanical polishing system comprises a substrate support configured to hold the substrate during the polishing operation, a polishing pad support, a polishing pad held by the pad support, and a substrate support. Includes a drive system configured to generate relative motion between the polishing pad supports. The polishing pad has an upper portion fixed to the polishing pad support and a lower portion protruding downward from the upper portion. The upper surface of the upper part abuts on the polishing pad support. The bottom surface of the lower part provides a contact surface that contacts the upper surface of the substrate during polishing. The contact surface is smaller than the top surface of the substrate. The upper part has a first horizontal dimension, and the lower part has a second horizontal dimension smaller than the first horizontal dimension.

Implementation embodiments may include one or more of the following features: The polishing pad support may include a plate having a surface that extends over the polishing pad, and almost the entire upper surface of the upper surface of the polishing pad may abut on the surface of the plate. The adhesive can hold the polishing pad on the pad support. The polishing pad support may include an annular member, the peripheral edge of the upper surface of the polishing pad may abut on the annular member, and the rest of the upper surface in the periphery does not contact the polishing pad support. There is. One or more clamps may hold the peripheral section of the polishing pad on the pad support. The top of the polishing pad may include a bending section that has greater flexibility than the section of the polishing pad above the contact surface. The upper part of the polishing pad may include a polyethylene terephthalate sheet.

Multiple grooves for slurry transfer may be formed on the contact surface at the bottom of the polishing pad. The grooves can have a depth less than the thickness of the bottom. At least some of the grooves may extend over the entire lower part of the polishing pad. The pressure chamber can be formed by the internal chamber of the polishing pad support. The chamber may have an opening facing the substrate, which can be sealed by connecting the polishing pad to the polishing pad support. A plurality of openings may be formed on the upper surface of the polishing pad, and the plurality of protrusions from the polishing pad support may be adapted to the plurality of openings so that the lower portion is aligned with the polishing pad support. Can be done.

In another aspect, the polishing pad comprises an upper part and one or more lower parts. The upper part has an upper surface for attachment to the pad carrier and a first lateral dimension. One or more lower parts project downward from the upper part. One or more lower bottom surfaces provide a contact surface that comes into contact with the substrate during chemical mechanical polishing. Each lower portion has a second lateral dimension that is smaller than the first lateral dimension. The total surface area of the contact surface from one or more lower parts is 10% or less of the surface area of the upper surface.

Implementation embodiments may include one or more of the following features: At least the lower part has a substantially uniform composition and may contain a polymer having a plurality of pores distributed therein. The polishing pad may include a polishing layer, and a 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. Grooving for slurry transport can be formed on the bottom surface of one or more lower parts. One or more lower parts may consist of a single protrusion. The polishing layer may include a flexible lateral section that is thinner than the lateral section forming the polished area. The lower part may contain microporous polyurethane.

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

Implementation embodiments may include one or more of the following features: The width of the arc defined by the arc-shaped contact region may be between 1 mm and 3 mm, and the length of the arc may be 30 mm or more. At least one of the pressure sensitive adhesives or clamps may hold the polishing pad on the pad support head. The relative motion between the substrate support and the polishing pad support may be a trajectory motion that maintains the polishing pad support in a fixed angular orientation. This relative motion can be a rotation around the center of the substrate.

In another aspect, the 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 comes into contact with the substrate during polishing. The peripheral edge of the polishing pad is vertically fixed to the annular member, and the rest of the polishing pad within the peripheral edge is vertically free. The opening of the polishing pad support facing the substrate is sealed by the polishing pad to define a pressurizing chamber for supplying adjustable pressure to the back of the polishing pad.

Implementation embodiments may include one or more of the following features: The adhesive may secure the peripheral edge 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 film fixed to the base, so that the space between the base and the film is such that the outer surface of the film provides a second adjustable pressure on the back of the polishing pad. A second pressurable chamber can be defined. The membrane and the second pressurable chamber may be configured such that the pressure in the second pressurable chamber controls the lateral magnitude of the loading region of the polished surface with respect to the substrate.

In another aspect, the polishing pad comprises an upper part, one or more lower parts, and a plurality of openings. The upper part has an upper surface for attachment to the pad carrier and a first lateral dimension. One or more lower parts project downward from the upper part. One or more lower bottom surfaces provide a contact surface that comes into contact with the substrate during chemical mechanical polishing. Each lower portion has a second lateral dimension that is smaller than the first lateral dimension so that the upper portion projects beyond all sides of the lower portion. Multiple openings are on the top surface of the top to accommodate protrusions from the pad carrier. The perforations are positioned laterally outward in the lower part, within the upper section of the polishing pad.

Implementation embodiments may include one or more of the following features: Multiple openings can be positioned at the corners of the polishing pad. The polishing pad may be rectangular. One or more lower portions may have an arcuate contact surface. Multiple grooves for slurry transfer may be formed on the contact surface at the bottom of the polishing pad.

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

Small pads with orbital motion may be used to correct the non-concentric polishing uniformity. The orbital motion can provide an acceptable polishing rate while avoiding the pad overlapping with areas where polishing is not desirable, thus improving substrate uniformity. In addition, unlike rotation, orbital motion can maintain a fixed orientation of the polishing pad with respect to the substrate, resulting in a more uniform polishing rate over the polishing area.

The top of the polishing pad secured to the polishing pad support extends laterally beyond the bottom protrusion in contact with the substrate to provide an available area for connecting the pad to the support, for example with a pressure sensitive adhesive. Can be increased. This makes it difficult for the polishing pad to peel off during the polishing operation.

A polishing pad having an arcuate contact area in contact with the substrate can provide an improved polishing rate while maintaining sufficient radial resolution of the polishing area.

The alignment feature ensures that the limited contact area of the polishing pad is placed in a well-known position laterally with respect to the pad support, thereby reducing the possibility of polishing unwanted areas of the substrate.

By providing the bent portion of the polishing pad, the bending of a part of the contact surface of the polishing pad can be reduced, and the possibility that the polishing area matches what the operator expected is improved.

Grooves in the protrusions of the polishing pad can facilitate the transfer of the slurry and thus improve the polishing rate.

The portion of the polishing pad that does not contact the substrate may be formed from a low cost material, thereby reducing the total cost of the pad.

The pad carrier, which allows control of the size of a portion of the contact area loaded onto the substrate, allows the loading area to be adapted to the size of the polishing spot. Therefore, throughput is improved while avoiding polishing unwanted areas of the substrate.

Overall, 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 present invention will become apparent from the description and drawings, as well as from the claims.

It is a schematic cross-sectional side view of a polishing system. It is a schematic cross-sectional side view of the mounting form of the polishing system including the vacuum chuck for holding a substrate. It is a schematic cross-sectional side view of the mounting form of the polishing system provided with the polishing pad which does not include a downward protrusion. FIG. 5 is a schematic cross-sectional side view of a mounting embodiment of a polishing system including a polishing pad having an upper layer having a diameter larger than that of a substrate and a downward protrusion having a diameter smaller than that of a substrate. FIG. 5 is a schematic cross-sectional top view illustrating a polishing pad that moves in a trajectory while maintaining a fixed angular orientation. It is a schematic cross-sectional top view of a polishing pad support of a polishing system and a drive train system. FIG. 6 is a schematic cross-sectional top view of the system of FIG. 6 with respect to a substrate. FIG. 6 is a schematic cross-sectional top view of the system of FIG. 6 rotated by a quarter with respect to FIG. 6A. It is a schematic cross-sectional side view of the movable polishing pad support connected to the polishing pad having a plurality of clamps. It is schematic cross-sectional view of the mounting form of the movable polishing pad support including the internal pressure space surrounded by the internal film. It is a schematic cross-sectional side view of the movable polishing pad support of FIG. 7B in a low pressure state. It is a schematic cross-sectional side view of the movable polishing pad support of FIG. 7B in a high pressure state. It is a schematic bottom view of the contact area of a polishing pad. It is a schematic cross-sectional side view of the mounting form of a polishing pad. It is a schematic cross-sectional side view of another mounting form of a movable polishing pad support. It is a schematic top view of the mounting form of the polishing system provided with the polishing pad which has the arc-shaped protruding layer. The arcuate protruding layer forms the corresponding arcuate loading area. It is a schematic cross-sectional side view of the mounting form of the polishing system which has the arc-shaped polishing surface which performs an orbital motion. It is a schematic top view of the polishing pad. The same reference numerals in different drawings indicate the same elements.

1. 1. Introduction Some polishing treatments result in non-uniform thickness over the surface of the substrate. For example, in the bulk polishing process, there may be a region on the substrate where polishing is insufficient. To address this issue, it is possible to perform a "touch-up" polishing process that focuses on the portion of the substrate that is under-polished after bulk polishing.

In the bulk polishing process, polishing is performed over the entire front surface of the substrate, but potentially at different speeds in different regions of the front surface. At a given point in the bulk polishing process, not all surfaces of the substrate are polished. For example, since there is a groove in the polishing pad, a certain part of the substrate surface may not come into contact with the polishing pad. Nevertheless, through the bulk polishing process, due to the relative movement between the polishing pad and the substrate, this portion is not localized and the entire front surface of the substrate is subject to some amount of polishing.

In contrast, in a "touch-up" polishing process, the polishing pad can contact less than the entire front surface of the substrate. Further, the range of motion of the polishing pad with respect to the substrate is such that during the touch-up polishing process, the polishing pad contacts only the local area of the substrate and most of the front surface of the substrate (eg, at least 50%, at least 75%, or At least 90%) are configured so that they never come into contact with the polishing pad and are therefore not subject to polishing. For example, in touch-up polishing, the contact area may be substantially smaller than the radial surface of the substrate.

As described above, some bulk polishing treatments result in non-uniform polishing. In particular, some bulk polishing treatments result in localized, non-concentric, non-uniform, under-polished spots. In a touch-up polishing process, a polishing pad that rotates around the center of the substrate may be able to correct for non-uniform concentric rings, but localized non-concentric and non-uniform spots, such as It may not be possible to deal with angular irregularities in the thickness profile. However, in order to correct the non-concentric polishing uniformity, for example, a small pad with orbital motion may be used. In some implementations, during polishing, the polishing pad undergoes orbital motion in a fixed angular orientation.

Referring to FIG. 1, the polishing apparatus 100 for polishing a local region of a substrate includes a substrate support 105 for holding the substrate 10 and a movable polishing pad support 300 for holding the 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 is suspended from the polishing drive system 500. The polishing drive system 500 causes the polishing pad support 300 to move with respect to the substrate 10 during the polishing operation. The polishing drive system 500 may be suspended from the support structure 550.

In some implementations, the positioning drive system 560 is connected 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 can operate to position the pad support 300 in a desired lateral position on the substrate support 105. For example, the support structure 550 may include two linear actuators 562 and 564. The two linear actuators 562 and 564 are oriented at right angles to each other on the substrate support 105 to provide the 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 be suspended from a single linear actuator that provides movement along the radial direction. Alternatively, the polishing pad support may be suspended from the rotary actuator 508, and the substrate support 105 may be rotatable by the rotary actuator 506.

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

The polishing apparatus 100 includes a port 60 for applying a polishing liquid 65 such as a polishing slurry to the surface 12 of the substrate 10 to be polished. The polishing apparatus 100 may further include a polishing pad conditioner that polishes the polishing pad 200 in order to keep the polishing pad 200 in a constant polishing state.

During the work, the substrate 10 is loaded onto the substrate support 105 by, for example, a robot. The positioning drive system 500 positions the polishing pad support 300 and the polishing pad 200 at desired positions on the substrate 10, and the vertical actuator 506 moves the substrate 10 into contact with the polishing pad 200 (or moves the actuator 508). The reverse movement is performed using). The polishing drive system 500 generates a relative motion between the polishing pad support 300 and the substrate support 105, causing the substrate 10 to be polished.

During the polishing operation, the positioning drive system 560 may hold the polishing drive system 500 and the substrate 10 so as to be substantially fixed to each other. For example, the positioning system can hold the polishing drive system 500 stationary with respect to the substrate 10 or slowly bring the polishing drive system 500 over the area to be polished (the polishing drive system 500 brings to the substrate 10). Can be swept (compared to exercise). For example, the instantaneous speed provided to the substrate by the positioning drive system 500 may be less than 5%, eg, less than 2%, of the instantaneous speed provided to the substrate by the polishing drive system 500.

The polishing system further includes a controller 90, for example 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 an instruction read from the memory 92 via the support circuit 93, and the controller receives input values based on the environment and desired polishing parameters to implement various actuators and drive systems. Allows control.

For "touch-up" polishing operations, the controller 90 is programmed to control the positioning drive system 560, limiting the range of motion of the polishing drive system 500 even if the polishing drive system 500 is slowly swept. During the touch-up polishing process, most of the front surface of the substrate (eg, at least 50%, at least 75%, or at least 90%) never comes into contact with the polishing pad and is therefore not subject to polishing.

2. Polishing system A. Substrate Support With reference to FIG. 1, the substrate support 105 is a plate-shaped body arranged below the polishing pad support. The top surface 116 of the body provides a loading area large enough to accommodate the substrate to be processed. For example, the substrate can be a substrate with a diameter of 200 to 450 mm. The upper surface 116 of the substrate support 105 contacts the back surface of the substrate 10 (ie, the unpolished surface) and maintains its position.

The substrate support 105 has a radius approximately the same as or larger than that of the substrate 10. In some mounting embodiments, the substrate support 105 is slightly shorter than the substrate, for example by about 1-2% of the substrate diameter (see, eg, FIG. 2). When placed on the support 105, the end of the substrate 10 slightly protrudes from the end of the support 105. This makes it possible to provide a clearance for placing the substrate on the support for the edge grip robot. In some implementations, the substrate support 105 is wider than the substrate. In this case, a robot equipped with an end effector having a vacuum chuck may be used to place the substrate on the support. In either case, the substrate support 105 can come into contact with the main surface of the back surface of the substrate.

In some implementations, as shown in FIG. 1, the substrate support 105 uses the clamp assembly 111 to maintain the position of the substrate 10 during the polishing operation. In some implementations, the clamp assembly 111 may be a single annular clamp ring 112 that contacts the rim on the top surface of the substrate 10. Alternatively, the clamp assembly 111 may include two arcuate clamps 112 that contact the top rims on both sides of the substrate 10. The clamp 112 of the clamp assembly 111 can be lowered by one or more actuators 113 to contact the rim of the substrate. The downward force of the clamp constrains the substrate from lateral movement during the polishing operation. In some implementations, one or more clamps include a downwardly projecting flange 114 that surrounds the outer edge of the substrate.

In some implementations, the substrate support 105 is a vacuum chuck 106, as shown in FIG. The vacuum chuck 106 includes a chamber 122 and a plurality of ports 124 that connect the chamber 122 to a surface 116 that supports the substrate 10. In the work, for example, the pump 129 allows air to be exhausted from the chamber 122 and therefore a suction force acts through the port 124 to hold the substrate in place on the substrate support 106.

In some implementations, the substrate support 105 includes a retainer 131, as shown in FIG. The retainer 131 can be attached to and project from a surface 116 that supports the substrate 10. Typically, the retainer is at least as thick as the substrate 10 (measured perpendicular to the surface 12). During the work, the retainer 131 surrounds the substrate 10. For example, the retainer 131 can be an annular body having a diameter slightly larger than the diameter of the substrate 10. During polishing, friction from the polishing pad 200 can create lateral pressure on the substrate 10. However, the retainer 131 constrains the lateral movement of the substrate 10.

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

Further, the substrate support configuration is shown with a movable pad support configuration using a pressure sensitive adhesive for the sake of simplicity, but with any embodiment of the pad support head and / or drive system described below. You may use it.

B. Polishing Pad With reference to FIG. 1, the polishing pad 200 has a polishing surface 250 that comes into contact with the substrate 10 in a contact region (also referred to as a loading region) during polishing. The polished surface 250 may have a diameter smaller than the radius of the substrate 10. For example, the diameter of the polished surface may be about 5-10% of the diameter of the substrate. For example, for wafers in the diameter range of 200 mm to 300 mm, the polished surface may have a diameter between 10 and 30 mm. More accurate, but less throughput than a smaller polished surface.

In some implementations, less than 1% of the substrate surface can be contacted by the polished surface at any given time point. This can usually be useful in touch-up polishing operations, but due to the low throughput, such small areas are unacceptable in bulk polishing operations.

In some implementations, for example, as shown in FIG. 3, the entire polishing pad measured, for example, to the outer edge of the pad has a diameter smaller than the radius of the substrate 10. 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, the polishing pad 200 is positioned on the upper surface 10 of the substrate 10, the upper portion 270 connected to the bottom of the movable pad support 300, and the bottom surface 250 that comes into contact with the substrate 10 during the polishing operation. Includes a lower 260 with. In some examples, as shown in FIG. 1, the bottom 260 of the polishing pad 200 is provided by a protrusion from the wider top 270. The bottom surface 250 of the protrusion 260 contacts the substrate during the polishing operation to provide a polished surface.

In the example of FIG. 1, the movable pad support 300 is connected 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 connected state of the polishing pad 200 on the pad support 300 during the polishing operation.

Making the upper 270 of the polishing pad 200 wider than the lower 260 increases the available surface area of the adhesive 231. By increasing the surface area of the adhesive 231 it is possible to improve the bonding strength between the pad 200 and the pad support and reduce the risk of the polishing pad peeling off during polishing.

Referring to FIG. 3, the polishing pad 203 may have the same radius as the upper 273 at the lower 260. However, it is preferred that the bottom 263 be narrower than the top 273 when the pressure sensitive adhesive 231 provides a connection between the pad and the movable pad support 300.

Referring to FIG. 5, the contact region 5 of the polishing pad may be a disk-shaped dimension 5 formed by the disk-shaped bottom protrusion of the polishing pad.

With reference to FIGS. 9A and 9B, the contact area 901 of the polishing pad 110 in contact with the substrate 10 may be the arc-shaped contact area 901 formed by the arc-shaped protrusion 290 of the polishing pad.

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

Referring to FIG. 4, in some implementations, the diameter of the upper 274 of the polishing pad 204 may be larger than the diameter of the substrate 10.

With reference to FIG. 1, the polishing pad 200 may be composed of a single layer of uniform composition. In this case, the material composition of the upper part 270 and the lower part 260 (also referred to as the protrusion 260) is the same.

With reference 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 backing layer 1052. Optionally, an intermediate pressure sensitive adhesive layer 1032 can be used to secure the polishing layer 1061 to the backing layer 1061. In this case, the upper 1221 can correspond to the backing layer 102 and the lower 1222 can correspond to the polishing layer 1062. The polishing pad may be connected to the polishing pad support via the pressure sensitive adhesive layer 231.

With reference to FIG. 10A, in some implementations the polishing pad may include two or more layers of different composition, the upper 1221 of the polishing pad 200 being the backing layer 1052 and the upper section 1064 of the polishing layer 1062. Both may be included. Therefore, the polishing layer 1062 includes both a lower section 1066 that provides the protrusion 1222 and an upper section 1062, which is wider than the lower section 1066.

The polishing pad can be connected to the polishing pad support via the pressure sensitive adhesive layer 321.

In both implementations shown in FIGS. 10A or 10B, the polishing layer 1062 may consist of a single layer of uniform composition. For example, in both implementations shown in FIGS. 10A or 10B, the portion of the pad in contact with the substrate may be a conventional material, eg, a microporous polymer such as polyurethane.

With reference to FIG. 10A, the backing layer 1052 can be relatively soft so as to allow better polishing pad flexibility when polishing non-uniform substrate surface spots. The polishing layer 1064 can be a rigid polyurethane.

Referring to FIG. 10B, the backing layer 1052 may be relatively soft, but is further a flexible incompressible layer made of a material such as polyethylene terephthalate (eg, Mylar®). There may be. For example, such a pad configuration can be used in a mounting embodiment in which the polishing pad of FIG. 10B is coupled to the pressure chamber polishing pad support of FIG. The polishing layer 1062 can be a rigid polyurethane.

With reference to FIG. 11, in some implementations, the polishing pad 205 may include an upper 275 and a lower 260. The polishing pad 205 has a thicker lateral section 267 that includes a combination of lower 260 and upper 275. The top 275 extends laterally on both sides of the thicker section 267 to provide lateral sections 285. The lateral section 285 bends in response to pressure applied to the thicker section 267. The thicker section 267 may have a pad thickness of about 2 mm in the polished area. This is similar to a large size pad. The pad thickness of the bent lateral section 285 can be about 0.5 mm.

In some implementations, the bottom surface 250 at the bottom of the polishing pad 200 may include a groove that allows the transfer of slurry during the polishing operation. The groove 299 may be shallower than the depth of the lower 260 (see, for example, FIG. 11). However, in some implementations, the bottom does not include grooves. If the polishing pad includes grooves, the grooves 299 may extend over the entire width of the lower 260. Further, the groove may be shallower than the vertical thickness of the lower 260, i.e., the groove partially passes vertically through the lower 260 and does not pass through the entire.

Referring to FIG. 9, the bottom surface 1900 of the polishing pad 200 may be an arcuate region. If such a polishing pad includes grooves, the grooves 299 may extend over the entire width of the arcuate region. The grooves 299 can be separated at a uniform pitch along the length of the arcuate region. Each groove 299 may extend along a radius passing through the center 1903 of the groove and the arcuate region, or may be positioned at an angle of, for example, 45 ° to the radius.

Referring to FIG. 14, in some implementations, the polishing pad 200 includes alignment features that match the fitting features on the pad support 300, thereby providing the polishing pad 200 and a lower portion that provides the contact area 250. The 260 is reliably placed in a known lateral position associated with the pad support 300.

For example, the polishing pad 200 may include a recess 1402 formed on the back surface of the polishing pad 200. The recess 1402 may be mechanically drilled in the polishing pad at a known position relative to the contact area 250. The recess 1402 may be positioned on the thin flange or outer portion 285 of the upper 270 of the polishing pad 200. The recesses can extend partially or entirely through the polishing pad. The pad support 300 may include, for example, a pin 1404 protruding downward from the plate that fits in the recess 1402.

As another example, at least some end 1406 of the polishing pad 200 may be machined after the contact area 250 has been defined on the polishing pad 200. The pad support 300 may include a machined recess in the support plate. The edges of the recesses include the alignment surface, and the end 1406 of the polishing pad is aligned so as to abut the alignment surface of the recesses in the plate.

The lower 260 of the polishing pad 200 in contact with the substrate can be formed from a high quality material that meets high precision specifications such as rigidity, porosity and the like. However, other parts of the polishing pad that do not contact the substrate need not meet such precision specifications and can therefore be formed from low cost materials. This can reduce the total cost of the pad.

C. Pad Drive System and Orbital Motion With reference to FIGS. 1 and 5, the polishing drive system 500 orbitally moves the connected polishing pad support 300 and the polishing pad 200 on the substrate 10 during the polishing operation. Can be configured as 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 the polishing operation.

Referring to FIG. 5, the radius of the orbit 20 of the polishing pad in contact with the substrate is preferably smaller than the diameter 22 of the contact area. For example, the radius of the orbit may be about 5 to 50% of the diameter of the contact area, for example 5 to 20%. For contact areas with a diameter of 20 to 30 mm, the radius of the orbit may be 1 to 6 mm. This achieves a more uniform velocity profile in the loading region 5. The polishing pad can rotate in its orbit at a speed of 1000 to 5000 revolutions (RMM) per minute.

With reference to FIG. 6, the drive train may include a mechanical system base 910 that achieves orbital motion with a single actuator 915. The motor output shaft 924 is connected to the cam 922 in a connective manner. The cam 922 extends into the recess 928 in the polishing pad holder 920. During the polishing operation, the motor output shaft 924 rotates around the rotating shaft 990, whereby the cam 922 swivels the polishing pad holder 920. A plurality of anti-rotation links 912 extend from the mechanical system base 910 to the top of the polishing pad holder 920 to prevent the pad holder 920 from rotating. The anti-rotation link 912 realizes the orbital motion of the polishing pad support along with the motion of the cam 922, and 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 can 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 transforms the rotational motion into the orbital motion of the polishing pad 610 in combination with the anti-rotation link 630 that connects the mechanical system base onto the polishing pad support. This achieves a more uniform velocity profile than a simple rotation.

In some implementations, the polishing drive system and the positioning drive system are provided by the same components. For example, a single drive system may include two linear actuators configured to move the pad support head in two vertical directions. For positioning, the controller can allow the actuator to move the pad support to the desired position on the substrate. For polishing, the controller can allow the actuators to move the pad support in orbit, for example, by applying a phase offset sinusoidal signal to the two actuators.

With reference to FIG. 1, in some implementations, the polishing drive system 500 may include two rotary actuators. For example, the polishing pad support may be suspended from the rotary actuator 508, and then the rotary actuator 508 is suspended from the second rotary actuator 509. During the polishing operation, the second rotary actuator 509 rotates the arm 510 that sweeps the polishing pad support 300 in an orbital motion. The first rotary actuator 508 rotates at the same rotational speed in the opposite direction to the second rotary actuator 509, for example, to cancel the rotational motion. Thereby, the board pad assembly traverses while remaining at a substantially fixed angular position with respect to the board.

D. Pad Support The movable pad support 300 holds the polishing pad and is connected to the polishing drive system 500.

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

However, the pad support 300 may further include an actuator 508 that controls the downward pressure of the polishing pad 200 on the substrate 10.

In the example of FIG. 7A, a pad support 300 is shown in which an adjustable pressure can be applied onto the polishing pad 200. The pad support 300 includes a base 317 connected to a 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 rim of the polishing pad 200 on the base 317. The polishing pad 200 can cover the recess 327 to define the pressurizing chamber 426. The downward pressure of the polishing pad 200 on the substrate 10 can be adjusted by pumping the fluid in or out of the chamber 426.

In some implementations, as in FIGS. 7B, 8A, and 8B, the pad support 300 may have an internal membrane 405 and a first pressurizing chamber 406 between the membrane 405 and the base 317. Is defined. The film is positioned closer to the polishing surface 258 and in contact with the side portion 275 of the polishing pad 200. The membrane 405 and chamber 406 are such that the pressure in the chamber 406 controls the size of the loading region 809 of the polishing pad 200 on the substrate 10 as the pad support 300 holds the polishing pad 200 during the polishing operation. It is composed. As the pressure in the chamber increases, the radius of the membrane increases and the pressure is applied to a larger portion of the pad bottom protrusion layer, expanding the area of the loading region 810. As the pressure drops, a smaller loading region 809 is created.

With reference to FIG. 11, in some implementations, the polishing pad support 315 may include an internal pressurable chamber 325 formed by the walls 320 of the polishing pad support 315. Chamber 325 may have an opening 327 facing the substrate. The opening 327 can be sealed, for example, by fixing the polishing pad 200 to the polishing pad support 315 with a clamp 410. The pressure in the pressure chamber 425 can be dynamically controlled during the polishing operation, for example by a controller and a hydrostatic pump, thereby adjusting the uneven spots being polished.

Referring to FIG. 12, in some implementations, the contact region 1301 of the polishing pad 20 may be an arcuate region. For example, the protruding portion may have an arc shape. The drive system 500 can rotate the arc around the center 1302 of the substrate 10.

Referring to FIG. 13, in some embodiments, the contact region 901 of the polishing pad 200 may be an arcuate region that draws orbital motion with respect to the substrate 10.

3. 3. Conclusion The size of the non-uniform spots on the substrate determines the ideal size of the contact area when polishing the spots. If the contact area is too large, correcting the lack of polishing in some areas on the substrate may result in excessive polishing of other areas. On the other hand, if the contact area is too small, the pad must be moved across the substrate to cover the area of underpolishing, resulting in reduced throughput.

In the substrate processing work, the substrate may be subjected to a bulk polishing treatment in which the entire front surface of the substrate is first polished. Optionally, after the bulk polishing operation, the non-uniformity of the substrate can be measured in-line or at a stand-alone weighing station. Next, the substrate may be conveyed to the polishing apparatus 100 and subjected to a touch-up polishing process. The control of the area to be polished by the device recognizes the area where the substrate is not polished from the historical data (for example, the thickness measurement performed during the certification operation or the measurement of the substrate in the in-line or a single weighing station). Can be based on.

The entire polishing system may be positioned such that the front surface of the substrate is positioned vertically or downward (with respect to gravity). However, the advantage of having the front surface of the substrate facing upwards is that it allows the slurry to be distributed to the surface of the substrate. The larger size of the substrate than the polished surface of the polishing pad improves the holding power of the slurry and reduces the use of the slurry.

Many embodiments of the present invention have been described. However, it should be understood that various modifications can be made without departing from the spirit and scope of the invention. For example, the substrate support may include, in some embodiments, a unique actuator capable of moving the substrate to a position relative to the polishing pad. As another example, the system described above includes a drive system that moves the polishing pad in orbital path while the substrate is held in a substantially fixed position, but instead the polishing pad is substantially fixed. The substrate may be moved in orbital path while being held in place. In this case, the polishing drive system may be a similar system, but is connected to a substrate support rather than a polishing pad support. A circular substrate is generally assumed, but this is not a requirement and the support and / or polishing pad may have other shapes such as a rectangle (in this case a "radius" or "diameter"). The description about applies to the lateral dimension along the spindle in general).

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

Claims (11)

A chemical mechanical polishing system
With a substrate support configured to hold the substrate in a substantially fixed angular orientation during the polishing operation,
A polishing pad having a contact area in contact with the substrate, wherein the contact area has a diameter equal to or less than the radius of the substrate.
A movable pad support configured to hold the polishing pad and
A drive system 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, wherein the orbital motion is the said. It is provided with a drive system having a track radius equal to or less than the diameter of the polishing pad and maintaining the polishing pad in a fixed angular orientation with respect to the substrate.
The pad support comprises a pressure chamber formed by an internal chamber of the pad support, the chamber having an opening facing the substrate, the opening being the pad support of the polishing pad. It is sealed by connecting to the body and
The polishing pad has an upper portion fixed to the pad support and a lower portion protruding downward from the upper portion, the upper surface of the upper portion abuts on the pad support, and the bottom surface of the lower portion is formed. A chemical that provides a contact surface that contacts the top surface of the substrate during polishing, the upper portion having a first lateral dimension and the lower portion having a second lateral dimension smaller than the first lateral dimension. Mechanical polishing system. The system according to claim 1, wherein the drive system is configured to rotate the polishing pad in an orbit at a speed of 1000 to 5000 revolutions / minute. The system of claim 1, wherein the diameter of the contact area is between about 1 and 10% of the diameter of the substrate. The system of claim 1, wherein the orbital radius is between about 5 and 50% of the diameter of the contact area. The system according to claim 1, wherein the drive system includes a recess in the pad support, a rotatable cam extending into the recess, and a motor for rotating the cam. The system of claim 5, wherein the drive system further comprises a linkage that connects the pad support to a fixed support to prevent rotation of the pad support. The drive system is connected to two linear actuators configured to move the pad support in two vertical directions and the two linear actuators, and the pad support is moved in the orbit by the two linear actuators. The system according to claim 1, comprising a controller configured to operate in. The system according to claim 1, wherein the drive system is configured to sweep the polishing pad laterally across the substrate during the orbital motion at a speed of about 5% or less of the instantaneous velocity of the orbital motion. .. A method of chemical mechanical polishing using the system according to any one of claims 1-8.
Bringing the polishing pad into contact with the substrate within a contact area having a diameter less than or equal to the radius of the substrate.
While the contact area of the polishing pad is in contact with the top surface of the substrate, the relative movement between the polishing pad and the substrate is generated, and the relative movement is the polishing. To generate and generate, including orbital motion with orbital radius less than or equal to the diameter of the pad.
A method comprising maintaining the polishing pad in a substantially fixed angular orientation with respect to the substrate during the orbital motion. 9. The method of claim 9 , comprising holding the substrate in a fixed lateral position during the orbital motion. 10. The method of claim 10 , further comprising sweeping the polishing pad laterally across the substrate during the orbital motion at a speed of about 5% or less of the instantaneous velocity of the orbital motion.

Images