In-situ edge asymmetry correction during temperature-based CMP

Abstract

The chemical mechanical polishing apparatus includes a platen that holds a polishing pad, a carrier that can be moved laterally across the polishing pad by an actuator to hold a substrate against the polishing surface of the polishing pad during the polishing process, a thermal control system that includes multiple independently controllable heaters and coolers for independently controlling the temperatures of multiple zones on the polishing pad, and a controller configured to cause the thermal control system to generate a first zone having a first temperature and a second zone having a different second temperature on the polishing pad.

Description

[Technical field]

[0001] TECHNICAL FIELD This disclosure relates to chemical mechanical polishing (CMP), and more particularly to temperature control during chemical mechanical polishing. [Background technology]

[0002] Integrated circuits are typically formed on a substrate by sequentially depositing conductive, semiconducting, or insulating layers on a semiconductor wafer. Planarization of layers on a substrate is required in various manufacturing processes. For example, one manufacturing step involves depositing a filler layer on a non-planar surface and planarizing the filler layer. In certain applications, the filler layer is planarized until the top surface of a patterned layer is exposed. For example, a metal layer may be deposited on a patterned insulating layer to fill trenches and holes in the insulating layer. After planarization, portions of the metal remaining in the trenches and holes in the patterned layer form vias, plugs, and lines that provide conductive paths between thin film circuits on the substrate. As another example, a dielectric layer may be deposited on top of a patterned conductive layer and then planarized to allow for subsequent photolithography steps.

[0003] Chemical mechanical polishing (CMP) is an accepted method of planarization. This planarization method typically requires that the substrate be mounted on a carrier head. Typically, the exposed surface of the substrate is applied to a rotating polishing pad. The carrier head provides a controllable load on the substrate, pressing it against the polishing pad. A polishing slurry containing abrasive particles is typically applied to the surface of the polishing pad. Summary of the Invention

[0004] In one aspect, a chemical mechanical polishing apparatus includes a platen that holds a polishing pad, a rotatable carrier that holds a substrate against a polishing surface of the polishing pad during a polishing process, a thermal control system including multiple independently controllable heaters and / or coolers for independently controlling the temperature of multiple zones on the polishing pad, and a controller. The carrier is movable laterally across the polishing pad by a first actuator and rotatable by a second actuator. The controller is configured to cause the thermal control system to generate a first zone having a first temperature and a second zone having a different second temperature, and is configured to control the first actuator and the second actuator to synchronize lateral oscillation of the carrier head with rotation of the carrier head such that, over multiple successive oscillations of the carrier head, a first angular swath of the edge portion of the substrate overlaps the first zone when the first angular swath is in an azimuthal position about the rotation axis of the carrier head, and a second swath of the edge portion of the substrate overlaps the second zone when the second angular swath is in an azimuthal position.

[0005] Implementations may include one or more of the following features.

[0006] The platen can be rotatable. The first and second zones can be concentric circles about an axis of rotation of the platen. The actuator can be configured to oscillate the carrier along a radius of the platen. The azimuthal position can be an outermost position of the substrate relative to the axis of rotation of the platen.

[0007] The controller can be configured to control the first actuator and the second actuator to synchronize lateral oscillation of the carrier head with rotation of the carrier head so that, over multiple consecutive oscillations of the carrier head, a third angular swath of an edge portion of the substrate overlaps with a third zone when the third angular swath is in an azimuthal position.

[0008] The thermal control system may include a nozzle that sprays a medium onto the zone to regulate the temperature of the zone. The thermal control system may include a heater and the medium may be a gas. The thermal control system may include a cooler and the medium may be a liquid.

[0009] In another aspect, a chemical mechanical polishing apparatus includes a platen rotatable by a motor that holds a polishing pad, a carrier that holds a substrate against a polishing surface of the polishing pad during the polishing process, a thermal control system including multiple independently controllable heaters and coolers for independently controlling the temperature of zones on the polishing pad, and a controller. The controller is configured to cause the thermal control system to alternately heat and cool the zones of the polishing pad as they rotate beneath the heater and cooler to generate first and second regions of alternating different temperatures, and the controller is further configured to control the motor and thermal control system to synchronize the heating and cooling of the zones of the polishing pad with rotation of the carrier head such that, over multiple successive rotations of the carrier head, a first angular swath of the edge portion of the substrate overlaps the first region when the first angular swath is at an azimuth angle about the rotation axis of the carrier head, and a second swath of the edge portion of the substrate overlaps the second region when the second angular swath is at an azimuth angle about the rotation axis of the carrier head.

[0010] Implementations may include one or more of the following features.

[0011] The zones can be circles concentric with the axis of rotation of the platen. The alternating first and second regions can be arcuate segments along a circle. The actuator can be configured to hold the carrier stationary while heating and cooling of the zones of the polishing pad are synchronized with rotation of the carrier head. The azimuthal position can be an outermost position of the substrate relative to the axis of rotation of the platen.

[0012] The controller can be configured to control the motor and thermal control system to synchronize heating and cooling of a zone of the polishing pad with rotation of the carrier head so that a third angular swath of the edge portion of the substrate overlaps a third region of the zone when the third angular swath of the edge portion of the substrate is in an azimuthal position over multiple successive oscillations of the carrier head.

[0013] The thermal control system may include a nozzle that sprays a medium onto the zone to regulate the temperature of the zone. The thermal control system may include a heater and the medium may be a gas. The thermal control system may include a cooler and the medium may be a liquid.

[0014] In another aspect, a chemical mechanical polishing apparatus includes a platen that holds a polishing pad, a carrier that is movable laterally across the polishing pad by an actuator to hold a substrate against a polishing surface of the polishing pad during a polishing process, a thermal control system including a plurality of independently controllable heaters and coolers for independently controlling temperatures of a plurality of zones on the polishing pad, and a controller configured to cause the thermal control system to generate a first zone having a first temperature and a second zone having a different second temperature on the polishing pad.

[0015] In another aspect, a chemical mechanical polishing apparatus includes a platen that holds a polishing pad, a rotatable carrier that holds a substrate against the polishing surface of the polishing pad during the polishing process, a polishing fluid supply port that supplies a polishing fluid to the polishing surface, a thermal control system including a movable nozzle that sprays a medium onto the polishing surface to adjust the temperature of a zone on the polishing surface, an actuator that moves the nozzle radially relative to the axis of rotation of the platen, and a controller configured to coordinate the dispensing of the medium from the nozzle and the movement of the nozzle across the polishing surface.

[0016] Implementations may include one or more of the following features.

[0017] The controller may be configured to adjust the dispensing of the medium to reduce asymmetric polishing of the substrate. The thermal control system may include a heater and the medium may be a heated gas and / or the thermal control system may include a cooler and the medium may be a cooled liquid. The nozzle may be suspended from an arm, which may be supported by a rotatable base to pivot the arm over the polishing surface, or the arm may be extendable and retractable by an actuator, or the nozzle may be linearly moveable along the arm.

[0018] In another aspect, a chemical mechanical polishing apparatus includes a platen that holds a polishing pad, a rotatable carrier that holds a substrate against a polishing surface of the polishing pad during a polishing process, a thermal control system including one or more independently controllable heaters and / or coolers for independently controlling a temperature of at least one of a plurality of zones on the polishing pad relative to another of the plurality of zones, and a controller configured to coordinate media dispensing and movement of the substrate relative to the polishing pad to reduce asymmetric polishing of the substrate.

[0019] Implementations may include one or more of the following features.

[0020] The thermal control system may include multiple heaters disposed at different radial locations from the axis of rotation of the platen. The multiple heaters may be suspended from a first arm that extends laterally above the polishing pad. The thermal control system may include multiple coolers disposed at different radial locations from the axis of rotation of the platen. The multiple coolers may be suspended from an arm, such as a separate second arm, that extends laterally above the polishing pad. The thermal control system may include a movable nozzle that sprays a medium onto the polishing surface. The thermal control system may include a heater and the medium may be a heated gas and / or the thermal control system may include a cooler and the medium may be a cooled liquid.

[0021] Possible advantages may include, but are not limited to, one or more of the following: The polishing profile of the polishing pad can be controlled by quickly and efficiently raising and lowering the temperature of different zones of the polishing pad. The temperature change over the polishing process can be controlled to obtain a polishing profile that results in a desired wafer profile. This can improve wafer-to-wafer uniformity and improve the repeatability of the polishing process. Additionally, temperature changes can be used to provide an in-situ method of compensation for wafer edge asymmetry during the polishing process, thereby improving within-wafer uniformity.

[0022] The details of one or more implementations are set forth in the accompanying drawings and the description below. Other aspects, features, and advantages will become apparent from the description and drawings, and from the claims. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of a chemical mechanical polishing apparatus. [Figure 2A] 1 is a schematic top view of an exemplary chemical mechanical polishing apparatus. [Figure 2B] 1 is a schematic top view of an exemplary chemical mechanical polishing apparatus. [Figure 3A] 1 is a schematic top view of an exemplary chemical mechanical polishing apparatus. [Figure 3B] 1 is a schematic top view of an exemplary chemical mechanical polishing apparatus. [Figure 4] FIG. 2 is a schematic top view of another exemplary chemical mechanical polishing apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] In chemical mechanical polishing, the removal rate at the edge of the substrate may be different from the removal rate at the center of the substrate. Furthermore, the polishing rate along the circumference of the substrate need not be uniform, an effect that may be referred to as "edge asymmetry". To address the non-uniformity of the substrate thickness, the substrate may be transported to a dedicated polishing "touch-up" tool that can polish localized areas of the substrate. Such tools can be used to correct the asymmetry of the substrate edge. For example, after the polishing process is completed, the thicker areas at the edge of the substrate may be locally polished to obtain a substrate of uniform thickness. However, the throughput of such tools is low.

[0025] A technique to solve this problem is to have a dedicated temperature control system that can provide in situ correction of the edge asymmetry of the substrate during the chemical mechanical polishing process. The temperature control system can create zones with different temperatures that provide different polishing rates because the polishing rate of the polishing pad can be temperature dependent.

[0026] 1, 2A, and 2B show an example of a polishing station 20 of a chemical mechanical polishing system. The polishing station 20 includes a rotatable, disk-shaped platen 24 on which a polishing pad 30 is positioned. The platen 24 is operable to rotate about an axis 25. For example, a motor 22 can rotate a drive shaft 28 to rotate the platen 24. The polishing pad 30 can be a two-layer polishing pad having an outer polishing layer 34 and a softer backing layer 32.

[0027] The polishing station 20 may include a supply port, for example at the end of a slurry supply arm 39, for dispensing a polishing fluid 38, e.g., a polishing slurry, onto the polishing pad 30. The polishing station 20 may include a pad conditioner having a conditioning disk for maintaining the surface roughness of the polishing pad 30. The conditioning disk may be positioned at the end of an arm that can swing to sweep the disk radially across the polishing pad 30.

[0028] Carrier head 70 is operable to hold substrate 10 against polishing pad 30. Carrier head 70 is suspended from a support structure 72, e.g., a carousel or track, and connected to a carrier head rotation motor 76 by a drive shaft 74 such that the carrier head can rotate about axis 71. Optionally, carrier head 70 may be oscillated laterally, e.g., by movement along the track on a slider of the carousel, or by rotational oscillation of the carousel itself.

[0029] The carrier head 70 may include a retaining ring 84 that holds the substrate. In some implementations, the retaining ring 84 may include a lower plastic portion 86 that contacts the polishing pad and an upper portion 88 of a harder material.

[0030] In the process, the platen rotates about its central axis 25 and the carrier head rotates about its central axis 71 and translates laterally across the upper surface of the polishing pad 30 .

[0031] Carrier head 70 may include a flexible membrane 80 having a substrate mounting surface that contacts the backside of substrate 10, and a number of pressurizable chambers 82 for applying different pressures to different zones, e.g., different radial zones, on substrate 10. The carrier head may also include a retaining ring 84 for holding the substrate.

[0032] In some implementations, the polishing station 20 includes a temperature sensor 64 for monitoring the temperature within the polishing station or a component of the polishing station, such as the temperature of the polishing pad and / or the temperature of the slurry on the polishing pad. For example, the temperature sensor 64 can be an infrared (IR) sensor, such as an IR camera, positioned above the polishing pad 30 and configured to measure the temperature of the polishing pad 30 and / or the slurry 38 on the polishing pad. In particular, the temperature sensor 64 can be configured to measure the temperature at multiple points along the radius of the polishing pad 30 to generate a radial temperature profile. For example, the IR camera can have a field of view that spans the radius of the polishing pad 30.

[0033] In some implementations, the temperature sensor is a contact sensor rather than a non-contact sensor. For example, the temperature sensor 64 can be a thermocouple or an IR thermometer positioned on or within the platen 24. Additionally, the temperature sensor 64 can be in direct contact with the polishing pad.

[0034] In some implementations, multiple temperature sensors may be spaced at different radial locations across the polishing pad 30 to obtain the temperature at multiple points along the radius of the polishing pad 30. This technique may be used in place of or in addition to an IR camera.

[0035] 1 as being positioned to monitor the temperature of the polishing pad 30 and / or the slurry 38 on the pad 30, the temperature sensor 64 may be positioned inside the carrier head 70 to measure the temperature of the substrate 10. The temperature sensor 64 may directly contact the semiconductor wafer of the substrate 10 (i.e., a contact sensor). In some implementations, multiple temperature sensors are included in the polishing station, for example, to measure the temperature of different components of / within the polishing station.

[0036] The polishing system 20 also includes a temperature control system 100 that controls the temperature of the polishing pad 30 and / or the slurry 38 on the polishing pad. The temperature control system 100 operates by delivering a temperature controlled medium, such as a liquid, vapor, or spray, onto the polishing surface 36 of the polishing pad 30 (or onto the polishing fluid already present on the polishing pad).

[0037] 1 and 2, the temperature control system 120 includes an arm 110 that extends over the platen 24 and polishing pad 30 from the edge of the polishing pad to or near the center of the polishing pad 30. The arm 110 may be supported by a base 112, which may be supported on the same frame 40 as the platen 24. The base 112 may include one or more actuators, such as a linear actuator that raises and lowers the arm 110 and / or a rotational actuator that swings the arm 110 laterally over the platen 24. The arm 110 is positioned to avoid collisions with other hardware components, such as the polishing head 70 and the slurry dispensing arm 39.

[0038] The exemplary cooling system 120 includes a plurality of nozzles, e.g., a linear array of nozzles (e.g., nozzle 128 and nozzle 148) suspended by arm 110. Each nozzle is configured to spray a medium, e.g., a gas or a liquid, onto polishing pad 30 to modify the temperature of a radial zone, e.g., radial zones 129 and 149. In some implementations, the medium can be water, such as substantially pure deionized water, or water with additives or chemicals. For example, nozzle 128 can be configured to direct aerosolized water in spray 114 toward polishing pad 30 and onto zone 129 as polishing pad 30 rotates about axis 25. Zone 129 is concentric with the axis of rotation of polishing pad 30 and can be 0.5 to 20 cm wide, e.g., 3 to 10 cm wide.

[0039] The arm 110 may be supported by the base 112 such that the nozzle 128 is separated from the polishing pad 30 by a gap 116. The gap 116 may increase or decrease as the base 112 is raised or lowered. For example, the gap between the nozzle 128 and the polishing pad 30 may be 0.5 to 100 mm, e.g., 0.5 to 5 mm for a nozzle 128 dispensing a heated fluid, or 5 to 10 cm for a nozzle 128 dispensing a cooled fluid. 0.5 mm to 100 mm. That is, the nozzle for the heating medium may be closer to the pad than the nozzle for the cooling fluid. Similarly, the nozzle 148 may be configured to direct the spray 114 to a zone 149.

[0040] The temperature of the media flowing through each nozzle 128, 148 may be independently controlled. For example, there may be separate sources of cooling and heating media 122, 124 and 142, 144, respectively, and the ratio of fluid flow to the nozzles may control the temperature of the media, for example, by the use of valves. Alternatively, the temperature of the media may be controlled by a heat exchanger prior to the nozzles.

[0041] Additionally, the temperature control system 120 may include gaseous medium sources 122, 142 and liquid medium sources 124, 1 (see FIG. 2A). The gas from sources 122, 142 and the liquid from sources 124, 144 may be mixed, for example, in a mixing chamber 126 (see FIG. 1) in or on the arm 110 before being directed through a nozzle 128 to form the spray 114.

[0042] The gaseous medium 122 and the liquid medium 124 may be used for cooling. In cooling, the medium may be a gas, e.g., air, or a liquid, e.g., water. In some implementations, the nozzles eject an aerosolized spray of water that is cooled below room temperature. The gaseous medium 142 and the liquid medium 144 may be used for heating. In heating, the medium may be a gas, e.g., steam or heated air, or a liquid, e.g., heated water, or a combination of gas and liquid. In some implementations, the nozzles eject a spray of steam to heat a zone of the polishing pad 30.

[0043] In some implementations, a solid material may be mixed with the gas and / or liquid. The solid material may be a cooled material, such as ice, or a material that absorbs heat when dissolved in water, such as by a chemical reaction.

[0044] In some implementations, process parameters (eg, flow rate, pressure, and / or liquid to gas mixture ratio) may be controlled independently for each nozzle 128.

[0045] 1 and 2A-2B show two nozzles 128, 148, there can be more or less nozzles, for example 1 to 10 nozzles forming 1 to 10 zones. The nozzles can be uniformly or non-uniformly distributed, radially and / or angularly.

[0046] Although FIG. 2 shows one arm for the temperature control system 100, the heating and cooling functions can be split into a cooling system 120 and a separate heating system 140. In some implementations, the various subsystems can be included in separate assemblies supported by separate arms. For example, a first assembly can include a cooling module and a second assembly can include a heating module. Each module can include a body, e.g., a linear or arcuate body, that can be secured to a common mounting plate (e.g., frame 40), which can be secured to the end of the arm such that the assembly is positioned above the polishing pad 30. Various fluid delivery components, e.g., tubes, passages, etc., can extend inside each body. In some implementations, the modules are separately removable from the mounting plate. Each module can have similar components to perform the functions of the arm of the associated system described above.

[0047] 1 and 2 show two zones (zone 129 and zone 149), there may be fewer zones (e.g., one zone that either heats or cools) or there may be more than one zone with an independently controlled temperature. For example, there may be multiple temperature zones where each zone may be incrementally cooler or hotter than the next (e.g., the outermost zone is the coldest and the innermost zone is the hottest, with each zone in between gradually heating from the outermost zone to the innermost zone).

[0048] The polishing system 20 may also include a controller 90 that controls the operation of various components, such as the temperature control system 100. The controller 90 is configured to receive temperature measurements from the temperature sensors 64 for each radial zone of the polishing pad. The controller 90 may compare the measured temperature profile to a desired temperature profile and generate a feedback signal to a control mechanism (e.g., actuator, power source, pump, valve, etc.) of each nozzle. The feedback signal is calculated by the controller 90, for example, based on an internal feedback algorithm, to cause the control mechanism to adjust the amount of cooling or heating of each zone so that the polishing pad and / or slurry reaches (or at least approaches) the desired temperature profile.

[0049] The controller 90 may direct the nozzle 128 to spray a liquid and / or gaseous medium into the outer radial concentric zone 129 to bring the zone 129 to a desired temperature (e.g., a cooling zone) as the polishing pad 30 rotates about the axis 25. Similarly, the controller 90 may direct the nozzle 148 to spray a liquid and / or gaseous medium into the inner radial concentric zone 149 (e.g., a heating zone) to bring the zone 149 to a desired temperature as the polishing pad 30 rotates about the axis 25. The temperature sensor 64 may continue to measure the temperature of the polishing pad 30, for example, by measuring portions of the pad 30 corresponding to the cooling zone 129 and / or the heating zone 149, until a desired temperature profile throughout the polishing pad 30 is achieved.

[0050] A decrease in the temperature of the bonding surface between the pad 30 and the substrate 10 has the effect of decreasing the polishing rate. Conversely, an increase in the temperature of the bonding surface between the pad 30 and the substrate 10 has the effect of increasing the polishing rate.

[0051] For example, decreasing the temperature of the interface between the pad 30 and the substrate 10 in zone 129 decreases the polishing rate in zone 129. Increasing the temperature of the interface between the pad 30 and the substrate 10 in zone 149 increases the polishing rate in zone 149. Reducing and / or increasing the polishing rate in different zones creates a non-uniform polishing profile. Creating temperature non-uniformity in the polishing profile results in different polishing rates that can produce a desired profile for the substrate 10. The non-uniform polishing profile can be used to address and compensate for non-uniformities that would occur if the substrate 10 were polished without the temperature control system 100.

[0052] In some implementations, a non-uniform polishing profile can be used to address and correct for a substrate 10 having a non-uniform profile prior to polishing. For example, a non-uniform substrate 10 having an edge portion that is thinner than the remainder of the substrate 10 can be positioned above zone 129 to reduce removal of the thinner edge portion of the substrate 10 (e.g., by being positioned above zone 129 where the polishing rate is reduced). Alternatively, a non-uniform substrate 10 having an edge portion that is thicker than the remainder of the substrate 10 can be positioned above zone 149 to increase removal of the thicker edge of the substrate 10 (e.g., by being positioned above zone 149 where the polishing rate is increased). This results in a more uniform substrate 10 profile.

[0053] In some implementations, a non-uniform profile of the substrate 10 is desired, so the substrate 10 can be polished over different zones (e.g., zone 129 and / or zone 149) to reduce and / or increase removal of portions of the substrate 10 that overlap the different zones at different temperatures to achieve the desired non-uniform substrate 10.

[0054] In some implementations, even when there is temperature uniformity across the polishing pad 30, chemical mechanical polishing of the substrate 10 may result in a non-uniform substrate 10. For example, even assuming a uniform temperature profile of the polishing pad 30, the edge portion of the substrate 10 may be polished at a higher rate than the center portion of the substrate 10. To correct for the non-uniform polishing, the temperature of different zones of the polishing pad 30 (e.g., zone 129 and / or zone 149) may be reduced or increased to obtain a desired substrate 10 profile. For example, if the edge portion of the substrate 10 is polished at a higher rate than the center portion of the substrate 10, the edge portion of the substrate 10 may be positioned above zone 129, which may be at a reduced temperature relative to the remainder of the polishing pad 30. This reduces the polishing rate at the edge portion of the substrate 10, resulting in a more uniform substrate 10 profile.

[0055] In some implementations, the substrate 10 has an asymmetric thickness non-uniformity, where different angular portions of the substrate 10 have different thicknesses. For example, a first edge portion of the substrate 10 may be thinner than a second edge portion of the substrate 10. If a uniform substrate 10 is desired, simply positioning the edge portion of the substrate 10 over a zone (e.g., zone 129, zone 149) may not be sufficient.

[0056] To correct for edge asymmetries in the substrate 10, the controller 90 can direct the movement of the carrier head 70 to bring different edge portions onto different temperature zones of the polishing pad 30. This can be done by synchronizing the oscillation of the carrier head 70 with the rotation of the carrier head 70 or by synchronizing the rotation of the carrier head 70 with the rotation of the platen 24.

[0057] The substrate 10 may have a first angular swath 127 and a second angular swath 147, each having a different thickness. When the first angular swath 127 of the substrate 10 is at a predetermined azimuthal position 12 about the rotation axis 71 of the carrier head 70, the carrier head 70 may position the first angular swath 127 to overlap a first zone (e.g., zone 129). As the carrier head rotates, the second angular swath 147 moves toward the predetermined azimuthal position. When the second angular swath 147 of the substrate 10 is at a predetermined azimuthal position 12 about the rotation axis 71 of the carrier head 70, the carrier head 70 may position the second angular swath 147 to overlap a second zone (e.g., zone 149). The azimuthal position 12 may be the farthest position from the rotation axis 25 of the polishing pad. Similarly, the azimuthal position 12 may be on a line passing through the axis of rotation 25 of the polishing pad 30 and the axis of rotation 71 of the carrier head 70 .

[0058] For example, as shown in FIG. 2A, if a first angular swath 127 of the substrate 10 is thinner than the rest of the substrate 10, the controller 90 can synchronize the lateral movement of the carrier head 70 (indicated by arrow A) and the rotation of the carrier head 70 (indicated by arrow B) such that the first angular swath 127 overlaps with a zone 129, which is at a first temperature that reduces the polishing rate. As a result, the first angular swath 127 is polished at a lower rate. This can result in a more uniform substrate 10. Similarly, as shown in FIG. 2B, if a second angular swath 147 at an edge portion of the substrate 10 is thicker than the rest of the substrate 10, the controller 90 can synchronize the lateral movement of the carrier head 70 and the rotation of the carrier head 70 such that the second angular swath 147 overlaps with a zone 149, which is at a second temperature that increases the polishing rate. As a result, the second angular swath 147 is polished at a higher rate, resulting in a more uniform substrate 10 .

[0059] Although two angular swaths 127, 147 are illustrated in Figures 2A and 2B, the technique can be scaled up to handle many more angular swaths having different thicknesses.

[0060] 3A and 3B, polishing station 20 can include polishing pad 30 with a controlled temperature in mixed temperature zone 339. Mixed temperature zone 339 includes regions 329 and 349 that can be set to different temperatures. For example, zone 339 can include both a first temperature region 329 and a second temperature region 349.

[0061] The mixed temperature zone 339 may alternate between arcuate segments 330 of a region 329 at a first temperature and arcuate segments 330 of a region 349 at a different second temperature. Briefly, the region 329, 429 may be created by the temperature control system 100 alternating between heating and cooling the zone 339 (or by alternating between two different heating rates or two different cooling rates) as the polishing pad 30 rotates. There may be between 2 and 10 segments 330 within the mixed temperature zone 339.

[0062] The temperature of the segment 330, including the mixed temperature zone 339, may be independently controlled. For example, the nozzles 138 may be directed to spray various cooling and heating media (e.g., coolants from the gaseous media source 122 and / or the liquid media source 124, and heating media from the gaseous media source 142 and / or the liquid media source 144) to achieve a desired temperature profile in the mixed temperature zone 339.

[0063] In some implementations, the nozzles 138 may spray different segments 330 of the mixed temperature zone 339 to have two alternating temperatures. As shown in Figures 3A and 3B, the mixed temperature zone 339 may have alternating segments 330 with regions 329 at a first temperature and regions 349 at a second temperature. For example, regions 329 may be sprayed with a cooling medium and regions 349 may be sprayed with a heating medium to create an alternating pattern of cooling regions 329 and heating regions 349.

[0064] Although one arm 110 is illustrated, additional arms can be used to maintain a desired temperature profile on the polishing pad 30. Additionally, although one mixed temperature zone 339 is illustrated, additional nozzles 138 can form additional mixed temperature zones on the polishing pad 30.

[0065] The controller 90 can cause movement of the carrier head 70 to bring different edge portions of the substrate 10 over different segments 330 of the mixed temperature zone 339 of the polishing pad 30, with the regions 329 and 349 of each segment 330 being set to different temperatures. This can be done by synchronizing the rotation of the carrier head 70 with the rotation of the platen 24, with timing of the application of heating or cooling by the temperature control system 100.

[0066] The substrate 10 may have a first angular swath 127 and a second angular swath 147, each having a different thickness. When the first angular swath 127 of the substrate 10 is at a predetermined azimuthal position 12 about the axis of rotation 71 of the carrier head 70, the carrier head 70 may position the first angular swath 127 to overlap a first region (e.g., region 329). As the carrier head rotates, the second angular swath 147 moves toward the predetermined azimuthal position. When the second angular swath 147 of the substrate 10 is at a predetermined azimuthal position 12 about the axis of rotation 71 of the carrier head 70, the carrier head 70 may position the second angular swath 147 to overlap a second region (e.g., region 349). The azimuthal position 12 may be the furthest position from the axis of rotation 25 of the polishing pad. Similarly, the azimuthal position 12 may be on a line passing through the axis of rotation 25 of the polishing pad 30 and the axis of rotation 71 of the carrier head 70 .

[0067] For example, as shown in FIG. 3A, if a first angular swath 127 of the substrate 10 is thinner than the rest of the substrate 10, the controller 90 can synchronize the rotation of the carrier head 70 (indicated by arrow B) with the rotation of the platen 24 and the polishing pad 30 (indicated by arrow C) such that the first angular swath 127 overlaps with a region 329, which is at a first temperature that reduces the polishing rate. As a result, the first angular swath 127 is polished at a lower rate. This can result in a more uniform substrate 10. Similarly, as shown in FIG. 3B, if a second angular swath 147 at an edge portion of the substrate 10 is thicker than the rest of the substrate 10, the controller 90 can synchronize the rotation of the carrier head 70 with the rotation of the polishing pad 30 such that the second angular swath 147 overlaps with a region 349, which is at a second temperature that increases the polishing rate. As a result, the second angular swath 147 may be polished at a higher rate resulting in a more uniform substrate 10. With this technique, the carrier head does not need to sweep laterally, which allows for simpler calculations to accommodate regions of different temperatures and swaths of the substrate.

[0068] Although two angular swaths 127, 147 are illustrated in Figures 3A and 3B, the technique can be scaled up to handle many more angular swaths having different thicknesses.

[0069] The embodiments described above include an arm with multiple nozzles to deliver heating or cooling fluid to different zones on the polishing pad, such that each nozzle can have a dedicated zone on the polishing pad.

[0070] In contrast, as shown in FIG. 4, the nozzle may be movable across the polishing pad. For example, the arm 110 may have a single nozzle 128, and the arm 110 may be moved to position the nozzle radially relative to the axis of rotation of the platen to provide heating or cooling at selectable locations. For example, the arm 110 may extend from a rotatable base 120 such that the end of the arm 110 may sweep radially (as indicated by arrow C) relative to the axis of rotation 25 of the platen. As another example, the arm 110 may have a linear actuator such that the arm can extend and retract. As another example, the arm 110 may be fixed in place and the nozzle 128 may be movable on the arm, for example, by a linear actuator. For example, the nozzle 128 may be suspended from a rack and pinion arrangement. In any of these cases, by appropriate timing of the dispense of heating or cooling fluid onto the polishing pad, one of the temperature profiles described above may be established.

[0071] Additionally, while the above embodiments describe multiple zones on the polishing pad that are heated and cooled, it is possible that there are only heated zones or only heated zones (with the remainder of the polishing pad, e.g., other zones on the polishing pad, having temperatures controlled by other ambient or environmental influences). Additionally, while the above embodiments describe multiple zones on the polishing pad, there may be only a single zone that is heated or cooled.

[0072] The polishing apparatus and method described above can be applied to a variety of polishing systems. Either the polishing pad or the carrier head, or both, can move to provide relative motion between the polishing surface and the substrate. For example, the platen can orbit rather than rotate. The polishing pad can be a circular (or some other shape) pad fixed to the platen. The polishing layer can be a standard (e.g., polyurethane with or without fillers) abrasive material, a soft material, or a fixed abrasive material.

[0073] The term relative orientation is used to refer to the relative orientation within the system or the substrate. It should be understood that during the polishing process, the polishing surface and the substrate may be held in a vertical orientation or in other orientations.

[0074] The functional operations of the controller 90 may be implemented by means of one or more computer program products, i.e., one or more computer programs tangibly embodied in a non-transitory computer-readable storage medium for execution by or to control the operation of a data processing apparatus, e.g., a programmable processor, a computer, or multiple processors or computers.

[0075] Although several embodiments of the invention have been described, it will be understood that various modifications can be made without departing from the spirit and scope of the invention.

[0076] For example, while the above description focuses on providing a heating and / or cooling medium on the polishing pad, it is also possible to provide a heating and / or cooling medium to other components to control the temperature of those components. For example, a heating and / or cooling medium can be sprayed onto the substrate while the substrate is positioned in the transfer station, e.g., the load cup. As another example, the load cup itself can be sprayed with a heating and / or cooling medium. As yet another example, a conditioning disk can be sprayed with a heating and / or cooling medium.

[0077] Accordingly, other embodiments are within the scope of the following claims.

Claims

1. 1. A chemical mechanical polishing apparatus comprising: a platen for holding a polishing pad; a rotatable carrier head for holding a substrate against a polishing surface of the polishing pad during a polishing process, the carrier head being movable laterally across the polishing pad by a first actuator and rotatable by a second actuator; a thermal control system including one or more independently controllable heaters and / or coolers for controlling a temperature of at least one of a plurality of zones on the polishing pad independently of another of the plurality of zones; a controller configured to cause the thermal control system to generate a first zone having a first temperature and a second zone having a different second temperature, the controller being further configured to control the first actuator and the second actuator to synchronize lateral reciprocating movement of the carrier head by the first actuator with rotation of the carrier head by the second actuator such that, over multiple successive reciprocating movements of the carrier head by the first actuator, a first angular swath of a first edge portion of the substrate overlaps the first zone when the first angular swath is oriented in azimuth about a rotation axis of the carrier head and a second angular swath of a second edge portion of the substrate overlaps the second zone when the second angular swath is oriented in azimuth. An apparatus comprising:

2. The apparatus of claim 1 , wherein the platen is rotatable.

3. The apparatus of claim 2 , wherein the first zone and the second zone are concentric circles about an axis of rotation of the platen.

4. The apparatus of claim 2 , wherein the first actuator is configured to reciprocate the carrier head along a radius of the platen.

5. 2. The apparatus of claim 1, wherein the controller is configured to control the first actuator and the second actuator to synchronize lateral reciprocating movement of the carrier head by the first actuator with rotation of the carrier head by the second actuator so that, over multiple consecutive reciprocating movements of the carrier head by the first actuator, a third angular swath of a third edge portion of the substrate overlaps a third zone when the third angular swath is oriented at the azimuth angle.

6. 1. A chemical mechanical polishing apparatus comprising: a platen rotatable by a motor for holding a polishing pad; a carrier head for holding a substrate against a polishing surface of the polishing pad during a polishing process, the carrier head being movable laterally across the polishing pad by a first actuator and rotatable by a second actuator; a thermal control system including one or more independently controllable heaters and / or coolers for independently controlling the temperature of zones on the polishing pad; a controller configured to cause the thermal control system to intermittently apply heat or cooling to the zone of the polishing pad as it rotates beneath the one or more heaters or coolers to create an annular area having first and second regions of alternating different temperatures at a common radial distance from an axis of rotation of the platen, the controller further configured to control the motor and the thermal control system to synchronize heating and cooling of the zone of the polishing pad with rotation of the carrier head such that, over multiple successive rotations of the carrier head, a first angular swath of a first edge portion of the substrate overlaps the first region when the first angular swath is oriented at an azimuth angle about the axis of rotation of the carrier head and a second angular swath of a second edge portion of the substrate overlaps the second region when the second angular swath is oriented at the azimuth angle about the axis of rotation of the carrier head. An apparatus comprising:

7. The apparatus of claim 6 , wherein the zones are concentric circles about an axis of rotation of the platen.

8. The apparatus of claim 7 , wherein the alternating first and second regions are arcuate segments along the circle.

9. The apparatus of claim 6, wherein the first actuator is configured to hold the carrier head stationary while heating and cooling of a zone of the polishing pad is synchronized with rotation of the carrier head during the polishing process.

10. 7. The apparatus of claim 6, wherein the controller is configured to control the motor and the thermal control system to synchronize heating and cooling of a zone of the polishing pad with rotation of the carrier head so that a third angular swath of a third edge portion of the substrate overlaps a third region of the zone when the third angular swath of the edge portion of the substrate is oriented at the azimuth angle over multiple successive reciprocating movements of the carrier head by the first actuator.

11. 1. A chemical mechanical polishing apparatus comprising: a rotatable platen for holding a polishing pad; a rotatable carrier head for holding a substrate against a polishing surface of the polishing pad during a polishing process, the carrier head being movable laterally across the polishing pad by a first actuator and rotatable by a second actuator; a polishing liquid supply port for supplying a polishing liquid to the polishing surface; a thermal control system including a movable nozzle that sprays a medium onto the polishing surface to regulate a temperature of a zone on the polishing surface; an actuator for moving the nozzle radially relative to an axis of rotation of the platen; a controller configured to coordinate the dispensing of the medium from the nozzle and the movement of the nozzle across the polishing surface; An apparatus comprising:

12. 1. A chemical mechanical polishing apparatus comprising: a platen for holding a polishing pad; a rotatable carrier head that holds the substrate against the polishing surface of the polishing pad during the polishing process; a thermal control system including one or more independently controllable heaters and movable nozzles for spraying a medium onto the polishing surface for controlling a temperature of at least one of a plurality of zones on the polishing pad independently of another of the plurality of zones; an actuator for moving the nozzle radially relative to an axis of rotation of the platen; a controller configured to coordinate dispensing of medium from the nozzle, movement of the nozzle across the polishing surface, and movement of the substrate relative to the polishing pad to reduce asymmetric polishing of the substrate; An apparatus comprising:

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