Temperature control of chemical mechanical polishing

Abstract

To provide a technique relating to Chemical Mechanical Polishing (CMP), more specifically, temperature control during Chemical Mechanical Polishing.SOLUTION: A Chemical Mechanical Polishing apparatus includes: a platen to hold a polishing pad; a carrier to hold a substrate against a polishing surface of the polishing pad during a polishing process; a dispenser to supply a polishing liquid to the polishing surface; and a temperature control system including a body configured to contact the polishing surface or the polishing liquid on the polishing surface. The body supports a thermal control module positioned over the polishing pad.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] TECHNICAL FIELD This disclosure relates to chemical mechanical polishing (CMP), and more specifically, 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. Various manufacturing processes require planarization of layers on the substrate. For example, one manufacturing step involves depositing a fill layer on a non-planar surface and planarizing the fill layer. In certain applications, the fill layer is planarized until the top surface of the patterned layer is exposed. For example, a metal layer can be deposited on a patterned insulating layer to fill the trenches and holes in the insulating layer. After planarization, the remaining portions of the metal in the trenches and holes in the patterned layer form vias, plugs, and lines to provide conductive paths between thin film circuits on the substrate. As another example, a dielectric layer is deposited on top of a patterned conductive layer and then planarized to allow for subsequent photolithography steps.

[0003] Chemical mechanical polishing (CMP) is one accepted method of planarization. This planarization method typically requires that the substrate be mounted on a carrier head. The exposed surface of the substrate is typically positioned against a rotating polishing pad. The carrier head provides a controllable load on the substrate to press the substrate against the polishing pad. An abrasive slurry having abrasive particles is typically supplied to the surface of the polishing pad. Summary of the Invention

[0004] In one aspect, a chemical mechanical polishing apparatus includes a platen for holding a polishing pad, a carrier for holding a substrate against a polishing surface of the polishing pad during a polishing process, and a temperature control system, the temperature control system including a plurality of thermal control modules disposed at a plurality of different radial positions above the polishing pad, each thermal control module of the plurality of thermal control modules configured to individually heat or cool a radial region of the polishing pad.

[0005] In another aspect, a chemical mechanical polishing apparatus includes a platen for holding a polishing pad, a carrier for holding a substrate against a polishing surface of the polishing pad during a polishing process, a temperature control system including a body including a thermal control module disposed above the polishing pad, and a first actuator for adjusting a vertical position of the body relative to the polishing pad.

[0006] In another aspect, a chemical mechanical polishing apparatus includes a platen for holding a polishing pad, a carrier for holding a substrate against a polishing surface of the polishing pad during a polishing process, a dispenser for supplying a polishing liquid to the polishing surface, and a temperature control system including a body configured to contact the polishing surface or the polishing liquid on the polishing surface, the body supporting a thermal control module disposed above the polishing pad.

[0007] Implementations of any of the above aspects may include one or more of the following features.

[0008] Each thermal control module may include one or more of an infrared light source, a thermoelectric heat pump, a heat exchanger, a resistive heater, and a fluid dispenser. The one or more temperature sensors may measure a plurality of temperature measurements of the polishing surface at a plurality of different radial positions. The controller may be configured to receive the plurality of temperature measurements and control the plurality of thermal control modules to cause the temperature profile of the polishing pad to approach a desired temperature profile.

[0009] The base can be disposed to a side of the platen and the body can extend laterally from the base across the polishing pad. The second actuator can cause the body to sweep laterally across the polishing pad.

[0010] The layer of the body may be disposed between the thermal control module and the body. The thermal control module may directly contact the polishing pad or the polishing fluid. At least a portion of the body that contacts the polishing pad or the polishing fluid may be ceramic. At least a portion of the body that contacts the polishing pad or the polishing fluid may include silicon carbide, silicon nitride, or aluminum nitride.

[0011] The actuator may adjust a vertical position of the body relative to the polishing pad. A bottom surface of the body may contact the polishing surface. The bottom surface of the body contacts the polishing fluid on the polishing surface. The thermal control module may include a stack having a thermoelectric heat pump and a heat exchanger. The heat exchanger may be on the thermoelectric heat pump.

[0012] The controller may be configured to control the current to the thermoelectric heat pump, causing the heat pump to deliver heat to or remove heat from the polishing pad, and to control the temperature or flow rate of fluid passing through the heat exchanger, causing the heat exchanger to raise or lower the temperature of the top surface of the thermoelectric heat pump.

[0013] Implementations may include one or more of the following advantages: Temperature variation during the polishing step may be reduced, which may improve polishing predictability of the polishing process; Temperature variation from one polishing step to another may be reduced, which may improve wafer-to-wafer uniformity and improve repeatability of the polishing process; Temperature variation across the substrate may be reduced, which may improve within-wafer uniformity.

[0014] 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]

[0015] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of a polishing apparatus. [Diagram 2] 1 is a schematic top view of an exemplary chemical mechanical polishing apparatus. [Diagram 3]1 is a schematic cross-sectional view of a portion of a temperature control system having multiple temperature control modules. [Figure 4] FIG. 2 is a schematic diagram showing a heat exchanger for a temperature control system. [Diagram 5] FIG. 2 is a schematic top view of another exemplary chemical mechanical polishing apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Chemical mechanical polishing is performed by a combination of mechanical wear and chemical etching at the interface between the substrate, the polishing fluid, and the polishing pad. During the polishing process, friction between the substrate surface and the polishing pad generates a significant amount of heat. In addition, some processes also include an in-situ pad conditioning step, in which a conditioning disk, e.g., a disk coated with abrasive diamond particles, is pressed against the rotating polishing pad to condition and texture the polishing pad surface. Wear during the conditioning process can also generate heat. For example, a typical 1-minute copper CMP process with a nominal downforce pressure of 2 psi and a removal rate of 8000 Å / min can cause the surface temperature of a polyurethane polishing pad to increase by about 30°C.

[0017] Both chemically-related variables (e.g., the onset and rate of the reactions involved) and mechanically-related variables (e.g., the surface friction coefficient and viscoelasticity of the polishing pad) of the CMP process are strongly temperature-dependent. As a result, variations in the surface temperature of the polishing pad lead to changes in removal rate, polishing uniformity, erosion, dishing, and residues. By more closely controlling the temperature of the surface of the polishing pad during polishing, temperature variations can be reduced, and polishing performance, as measured, for example, by intra-wafer or inter-wafer non-uniformity, can be improved.

[0018] Several techniques have been proposed for temperature control. As one example, a coolant can be flowed through the platen. As another example, the temperature of the polishing liquid delivered to the polishing pad can be controlled. However, these techniques may be insufficient. For example, the platen must supply or extract heat through the body of the polishing pad itself to control the temperature of the polishing surface. Polishing pads are typically plastic materials with poor thermal conductivity, so heat control from the platen may be difficult. On the other hand, the polishing liquid may not have significant thermal mass.

[0019] A technique that can address these issues is to place a temperature-controlled body in direct contact with the polishing surface of the polishing pad, or with the polishing liquid on the polishing pad. The temperature of this body can be varied over its length, allowing radial control of the temperature of the polishing pad.

[0020] A further problem is that the temperature rise along the radius of the rotating polishing pad during the CMP process is often not uniform. Without being limited to any particular theory, different sweep profiles of the polishing head and pad conditioner can often have different dwell times in each radial zone of the polishing pad. Furthermore, the relative linear velocity between the polishing pad and the polishing head and / or pad conditioner also varies along the radius of the polishing pad. These effects can contribute to non-uniform heat generation on the polishing pad surface, which can result in varying removal rates within the wafer.

[0021] A technique that can address these problems is to have multiple temperature control modules spaced along the radius of the polishing pad. Each temperature control module includes a heat transfer element disposed above the polishing pad, which may include a cooling element or a heating element, or both. Each temperature control module can individually provide a selective amount of cooling or heating to a corresponding radial zone on the rotating polishing pad moving under each module. In this way, the temperature of each radial zone on the surface of the polishing pad can be controlled to reduce temperature non-uniformity.

[0022] 1 and 2 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 may turn a drive shaft 28 to rotate the platen 24. The polishing pad 30 may be a two-layer polishing pad having an outer polishing layer 34 and a softer backing layer 32.

[0023] The polishing station 20 may include a feed port or combined feed and rinse arm 39 for dispensing a polishing fluid 38, such as a polishing slurry, onto the polishing pad 30. The polishing station 20 may include a pad conditioner apparatus 90 having a conditioning disk 92 (see FIG. 2) to maintain the surface roughness of the polishing pad 30. The conditioning disk 90 may be disposed at the end of an arm 94 that may be traversed to sweep the disk 90 radially across the polishing pad 30.

[0024] 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, such that the carrier head can rotate about axis 71, and is connected to a carrier head rotation motor 76 by a drive shaft 74. Optionally, carrier head 70 may be oscillated laterally, e.g., on a slider on the carousel, by movement along the track, or by rotational oscillation of the carousel itself.

[0025] The carrier head 70 may include a retaining ring 84 for holding the substrate. In some implementations, the retaining ring 84 may include a highly conductive portion, e.g., the carrier ring may include a thin lower plastic portion 86 that contacts the polishing pad, and a thicker upper conductive portion 88. In some implementations, the highly conductive portion is metal, e.g., the same metal as the layer being polished, e.g., copper.

[0026] 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 top surface of polishing pad 30. When multiple carrier heads are present, each carrier head 70 may individually control its polishing parameters, e.g., each carrier head may individually control the pressure applied to each substrate.

[0027] 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.

[0028] In some implementations, the polishing station 20 includes a temperature sensor 64 for monitoring the temperature of the polishing station or components of / in the polishing station, such as the temperature of the polishing pad and / or the slurry on the polishing pad. For example, the temperature sensor 64 can be an infrared (IR) sensor, such as an IR camera, disposed on 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.

[0029] 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 disposed on or within the platen 24. Additionally, the temperature sensor 64 can be in direct contact with the polishing pad.

[0030] 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.

[0031] 1 as 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 be in direct contact with the semiconductor wafer of the substrate 10 (i.e., a contact sensor). In some implementations, multiple temperature sensors are included in the polishing station 22, for example, to measure the temperature of different components of / in the polishing station.

[0032] The polishing system 20 also includes a temperature control system 100 for controlling the temperature of the polishing pad 30 and / or the slurry 38 on the polishing pad. The temperature control system 100 includes at least one elongated body 110 that extends over the polishing pad 30 from the edge of the polishing pad to or near the center of the polishing pad 30 (e.g., within 5% of the total radius of the polishing pad). For example, the body 110 can be an arm supported by a base 112 to extend over the polishing pad 30. The base 112 can be supported on the same frame 40 as the platen 24. The body 110 is positioned to avoid collisions with other hardware components, such as the polishing head 70, the pad conditioning disk 90, and the slurry distribution arm 39.

[0033] The body 110 may be generally linear and have a substantially uniform width along its length, although other shapes such as a sector (also known as a "pie slice"), a circular arc, or a triangular wedge (all as a top view of the system) may be used to achieve the desired heat transfer area between the body 110 and the polishing pad surface. In particular, multiple thermal control modules may be supported by wedge-shaped arms that are wider at the ends away from the axis. For example, FIG. 5 illustrates the body 110 of the temperature control system 100 as a wedge (other elements of the polishing apparatus are not shown in FIG. 1 for simplicity).

[0034] 1 and 2, the body 110 may be in direct contact with the polishing pad 30. Alternatively, the body may be in contact with a layer of polishing fluid, e.g., slurry, on the surface of the polishing pad 30 while being slightly separated from the polishing pad 30. In some implementations, e.g., non-contact heaters such as IR lamps, the body is suspended above the polishing pad 30 without contacting the polishing pad or polishing. The base 112 may include an actuator, e.g., a linear actuator, for raising or lowering the body 110.

[0035] The lateral position of the body 110 may be fixed or may be controlled by another actuator. For example, the body 110 may be driven by a motor in the base 112 to sweep laterally across the polishing pad. For example, the body 110 may be driven to perform a sweeping motion to avoid collisions with other hardware components and / or to increase the effective heat transfer area on the polishing pad surface.

[0036] The body 110 may include multiple temperature control modules 120 arranged in a row. For example, the temperature control modules 120 may be spaced apart along a radius of the platen, e.g., along a radial direction of the polishing pad. Each temperature control module 120 includes a heat transfer element, which may include a cooling element or a heating element, or both. Each temperature control module 120 may individually impart a selective amount of cooling or heating to a corresponding radial zone on the polishing pad as the polishing pad rotates beneath the module.

[0037] As spaced apart along the radius of the polishing pad 30, the temperature control modules apply heating or cooling to zones that are spaced apart along the radius of the polishing pad 30.

[0038] The size and shape of the zones depend on the arrangement of heating or cooling elements in the thermal control module 120, such as resistive heaters, passages for coolant, and the like.

[0039] As shown in FIG. 2, the zones may be rectangular, or other shapes such as trapezoidal (see FIG. 5), elliptical, arc-shaped, polygonal, or more complex shapes.

[0040] Further, the zones may be the same size and / or shape, for example, as shown in FIG. 2, but this is not required. Some zones may have a different size than other zones. For example, the outer zones may be larger than the inner zones (inner and outer being relative to the axis of rotation of the platen). That is, the regions further from the axis may be larger than the regions closer to the axis. Thus, the regions further from the axis may have a wider angular spread than the regions closer to the axis. In particular, moving outward from the axis of rotation of the platen, each successive zone may be larger than the previous zone (as shown in FIG. 5).

[0041] The components of the temperature control module 120 may be housed within the body 110 such that the body 110 itself performs a heat transfer function between the polishing pad and / or slurry and the temperature control module 120. The material of the bottom surface of the body 110 may be formed of a highly thermally conductive material that is also resistant to wear from the polishing pad. The material of the body 110 should be chemically compatible with the polishing process and have high chemical resistance to the polishing fluid. For example, at least the bottom of the body 110 may be a ceramic material such as silicon carbide, silicon nitride, or aluminum nitride. The entire body 110 may be formed of the material, or the ceramic material may be coated onto a body of another material, for example, aluminum. Optionally, the thermally conductive material may be coated with a thin CVD diamond coating (similar to diamond or amorphous diamond-like carbon DLC coating) to improve wear resistance. The coating may reduce pad wear, improve chemical resistance to the polishing fluid, and increase thermal conductivity.

[0042] Alternatively, the components of the temperature control module 120 may be secured to and suspended below the body 110 such that the components are in direct contact with the polishing pad and / or slurry. In this case, the body 110 does not need to perform a thermal conduction function between the polishing pad and / or slurry and the temperature control module 120.

[0043] In the case of the cooling element, the temperature control module 120 may include a cold plate style cooling device with a thermoelectric (TE) cooling element. The cooling element may also be a low temperature heat exchanger that operates by recirculating a low temperature (i.e., lower than the temperature of the polishing pad and / or polishing liquid) fluid or gas. The cooling element may also include a dispenser configured to deliver a low temperature gas or liquid or solid onto the surface of the polishing pad 30. For example, the cooling element may be a nozzle configured to generate a jet of low temperature gas or liquid. The low temperature gas, liquid, or solid may also undergo an endothermic phase change at the surface of the polishing pad. Furthermore, the cooling element may use a combination of the above techniques. For example, the cooling element may be formed by stacking a low temperature heat exchanger on top of a thermoelectric cooling element to further increase the cooling capacity.

[0044] In the case of a heating element, the temperature control module 120 may include a hot plate style heater having a thermoelectric (TE) heating element or a resistive heating element therein. The heating element may also be a high temperature heat exchanger that operates by recirculating a hot (i.e., higher than the temperature of the polishing pad and / or polishing liquid) fluid or gas. The heating element may also include a dispenser configured to deliver a hot gas or liquid or solid onto the surface of the polishing pad 30. For example, the heating element may be a nozzle configured to generate a jet of hot gas or liquid. The hot gas or liquid or solid may also undergo an exothermic phase change at the surface of the polishing pad. The heating element may also be in the form of a thermal radiation source, such as an infrared (IR) lamp or a low intensity laser. Additionally, the heating element may use a combination of the above techniques. For example, a heating element may be formed by stacking a high temperature exchanger on top of a thermoelectric heating element to further increase heating capacity.

[0045] The polishing system 20 may also include a controller 90 for controlling 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 the control mechanism (e.g., actuators, power supplies, pumps, valves, etc.) of each temperature control module. 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 by the cooling or heating elements of the temperature control module so that the polishing pad and / or slurry reach (or at least approach) the desired temperature profile.

[0046] Examples of control techniques include having a power source adjust the intensity of an infrared light source, having a power source adjust the amount of current flowing through a thermoelectric heater or cooler, having an actuator move a thermal control module closer to or farther from the polishing pad, having a pump increase or decrease the flow rate through a heat exchanger, and having a valve adjust the ratio of hot or cold fluid flowing through a heat exchanger.

[0047] Examples of control mechanisms for a stack of a TE cooling element and a low temperature heat exchanger as a cooling element, or a stack of a TE heating element and a high temperature heat exchanger as a heating element, may include: (I) controlling the amount of current (or voltage) supplied to the TE element; (II) controlling the relative proportions of the TE element in on and off modes under pulse width modulation; (III) controlling the relative proportions of the TE element in cooling and heating modes under bipolar modulation; (IV) controlling the temperature or flow rate of the liquid recirculating through the low temperature or high temperature heat exchanger.

[0048] Examples of control mechanisms for resistive heater elements may include: (I) controlling the amount of current (or voltage) supplied to the resistive heater, and (II) controlling the relative proportions of the resistive heater in on and off modes under pulse width modulation.

[0049] In some implementations, the temperature control modules 120 may provide bidirectional temperature control, such that each module 120 may provide selective heating and selective cooling in response to different processing requirements.

[0050] In some implementations, bidirectional temperature control is obtained by including both cooling and heating elements in each temperature control module 120. As an example, referring to FIG. 3, each thermal control module 120 may have a heat transfer element including a stack of thermoelectric or resistive heating elements 130 and heat exchangers 140. The flow rate through each heat exchanger may be controlled by a valve 142. The heat exchanger 140 may be used as a cooling element, for example, by flowing a cryogenic fluid through the heat exchanger. The thermoelectric or resistive heating element 130 may be used as a heating element, for example, by passing an electric current through the element 130. The heating and cooling elements may be engaged at different times depending on whether cooling or heating is required at each stage during polishing.

[0051] However, in some implementations, only one heat transfer element is required for each temperature control module 120. For example, the thermoelectric element 130 or the heat exchanger 140 may be used as a heating or cooling element, depending, for example, on the direction of current flow or the temperature of the fluid flowing through the heat exchanger.

[0052] In some implementations, each thermal control module 120 includes a stack of thermoelectric or resistive heating elements 130 and heat exchangers 140, with both the thermoelectric heating elements 130 and the heat exchangers 140 configured for bidirectional temperature control. The temperature control module 120 can be used as a cooling element by (i) selecting the direction of current flow in the thermoelectric elements 130 to pump heat away from the polishing pad and (ii) circulating a cold fluid inside the heat exchanger 140. The same temperature control module 120 can be used as a heating element by (i) switching the direction of current flow (reversing polarity) inside the thermoelectric elements 130 to pump heat to the pad and (ii) switching the circulation inside the heat exchanger 140 from cold fluid to hot fluid.

[0053] For example, referring to FIG. 4, two fluid circulators C1 and C2 may provide fluid at two different temperatures. For example, C1 may pump cold water, while C2 may pump hot water. Valves V1 and V2 may be used to flow hot or cold fluid to temperature control modules 120a and 120b. Examples of fluids include water and / or ethylene glycol. The fluids may be flowed simultaneously or at different times. The fluid is used to cool or heat the non-contact side of the thermoelectric module 130.

[0054] 2, in some implementations, the polishing system 20 includes multiple temperature control systems 100a, 100b, each having its own body 110 with an array 122 of thermal control modules 120. The slurry delivery arm 39 can be disposed between the two arrays 122 of thermal control modules.

[0055] One of the bodies of the temperature control systems, for example the body 110 in the leading position along the rotational direction relative to the carrier head 70 (for example, the body 110 of the system 110b in FIG. 2), may act as a barrier to slurry removal. For example, the body 110 of the system 100b may be positioned closer to the polishing pad 30 than the body 110 of the system 100a. In the process, the polishing liquid may be dispensed by the slurry delivery arm 39, carried by the pad below, heated by the array 122 of the thermal control modules 120 of the temperature control system 110a, and then carried under the carrier head 70 to contact the substrate. The used slurry may then be carried from the carrier head 70 and deflected by the body 110 of the temperature control system 110b to be diverted out of the pad area. The body 110 of the temperature control system 110a may also be positioned to smear the polishing liquid radially across the polishing pad 30.

[0056] In some implementations, the temperature control system 100 may use two stages of heating / cooling. A heat pump may function as the first stage and a heat exchanger may function as the second stage. The first stage is closer to the polishing pad.

[0057] The design specification for the performance of a thermoelectric element is the difference between the cold side and the hot side. There is a limit to how much this difference can be. For example, say a thermoelectric element is used to heat a target surface. The bottom side of the thermoelectric element will be the hot side (it should be hotter than the target) and the top side will be the cold side. The target is placed close to the bottom hot side. Heat transfer occurs from the bottom hot side to the target.

[0058] Most thermoelectric elements maintain a set temperature difference between the top and bottom sides. However, heating the top side of the thermoelectric element can make the bottom side hotter and allow for more efficient heat transfer from the bottom to the target. For example, the top side of the thermoelectric element can be achieved by flowing a hot liquid over it. This two-stage cooling phenomenon by using a thermoelectric element in series with a heat exchanger, e.g. a water circulator, can be advantageous in CMP. This can also be true for reverse cooling.

[0059] Water cannot function as a coolant above 0 degrees Celsius. A mixture of water and ethylene glycol is preferred below 0 degrees Celsius, but the ethylene glycol can reduce heat transfer.

[0060] Multiple stacks of thermoelectric elements along the radial direction of the pad with cumulative or separate fluid inlets and outlets provide zonal control of temperature along the CMP pad.

[0061] In some implementations, the body 110 also functions as a slurry wiper or spreader. For example, referring to FIG. 2, polishing fluid may be dispensed from the arm 39. Rotation of the platen 24 carries the slurry onto the polishing pad 30 toward the temperature control system 100a. In particular, assuming the body 110 is positioned to contact the polishing pad 30, the bottom edge of the rear surface (the surface opposite the direction of rotation) acts as a barrier to inhibit the flow of slurry from the arm 39. As a result, the slurry passing under the body 110, e.g., through the grooves of the polishing pad 30 or through the gap between the body 110 and the polishing pad 30, is more evenly distributed.

[0062] Possible advantages include:

[0063] (I) The apparatus is essentially a self-contained piece of hardware dedicated to controlling the surface temperature of a polishing pad during the CMP process.

[0064] (II) The apparatus does not rely on controlling the pad surface temperature by adjusting CMP processing parameters such as the downforce of the polishing head or pad conditioner disk, thereby reducing the impact of this temperature control device on existing CMP processes.

[0065] (III) The particular selection of elements of the thermal control module, for example when using a stack of thermoelectric elements and heat exchangers as described above, results in less disturbance to the polishing pad surface by the temperature control device compared to, for example, air vortexes or deionized water jets for cooling purposes.

[0066] (IV) The particular selection of elements in the thermal control module, for example when using a stack of thermoelectric elements and heat exchangers as described above, allows the temperature control device to achieve bi-directional temperature control, including both cooling and heating, in the same thermal control module. Thus, the footprint of the new device during implementation is small. Furthermore, bi-directional temperature control allows new process knobs that can be tuned at various stages throughout the CMP process, improving CMP results as measured by throughput, topography, residue, corrosion, etc.

[0067] (V) The use of multiple temperature control modules in a modular array reduces within-pad temperature non-uniformity during the CMP process. Furthermore, with the specific selection of elements in the thermal control modules, for example, when using a stack of thermoelectric elements and heat exchangers as described above, there are multiple levels of control that provide more reliable temperature control in individual modules to reach a desired temperature or rate of temperature change in each radial zone and reduce temperature non-uniformity across the polishing pad surface.

[0068] The above polishing apparatus and method can be applied to various polishing systems. The polishing pad, the carrier head, or both can be moved to provide relative motion between the polishing surface and the substrate. For example, the platen can orbit without rotating. The polishing pad can be a circular (or other shaped) pad fixed to the platen. Some aspects of the endpoint detection system can be applicable to linear polishing systems, for example, where the polishing pad is a continuous belt or a reel-to-reel belt moving linearly. The polishing layer can be a standard (e.g., polyurethane with or without fillers) abrasive material, a soft material, or a fixed abrasive material. The term relative position is used to refer to the relative position within the system or the substrate. It should be understood that the polishing surface and the substrate can be held vertically or in some other orientation during the polishing process.

[0069] The functional operations of the controller 90 may be performed using 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 one or more data processing devices, e.g., a programmable processor, a computer, or multiple processors or computers.

[0070] 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. Accordingly, other embodiments are within the scope of the following claims.

Claims

1. 1. A chemical mechanical polishing apparatus comprising: a platen for holding the polishing pad; a carrier for holding a substrate against the polishing surface of the polishing pad during a polishing process; a temperature control system including a plurality of thermal control modules disposed at a plurality of different radial locations on the polishing pad for heating or cooling a plurality of regions of the polishing pad, each thermal control module of the plurality of thermal control modules configured to individually heat or cool a radial region of the polishing pad; An apparatus comprising:

2. The apparatus of claim 1 , wherein the platen is rotatable about an axis and the plurality of thermal control modules are disposed along a radius of the platen.

3. The apparatus of claim 1 , wherein the regions have different shapes.

4. The apparatus of claim 3 , wherein the platen is rotatable about an axis, the area distal to the axis being larger than the area proximate to the axis.

5. The apparatus of claim 4 , wherein a region away from the axis has a wider angular spread than a region closer to the axis.

6. 1. A chemical mechanical polishing apparatus comprising: a platen for holding the polishing pad; a carrier for holding a substrate against the polishing surface of the polishing pad during a polishing process; a temperature control system including a body including a thermal control module disposed above the polishing pad; a first actuator for adjusting a vertical position of the body relative to the polishing pad; An apparatus comprising:

7. 1. A method of chemical mechanical polishing comprising the steps of: contacting the substrate with a polishing pad; inducing relative motion between the polishing pad and the substrate; using a plurality of thermal control modules disposed above the polishing pad to individually heat or cool a plurality of regions at a plurality of different radial locations on the polishing pad; The method includes:

8. 1. A method of chemical mechanical polishing comprising the steps of: contacting the substrate with a polishing pad; inducing relative motion between the polishing pad and the substrate; Raising or lowering a thermal control module of a main body of a thermal control system away from or toward said polishing pad. The method includes:

9. 1. A chemical mechanical polishing apparatus comprising: a platen for holding the polishing pad; a carrier for holding a substrate against the polishing surface of the polishing pad during a polishing process; a dispenser for supplying a polishing liquid to the polishing surface; a body configured to contact the polishing surface or the polishing liquid on the polishing surface and supporting a thermal control module disposed above the polishing pad; and An apparatus comprising:

10. The apparatus of claim 9 , wherein at least a portion of the body that contacts the polishing pad or the polishing fluid comprises a ceramic.

11. The device of claim 10 , wherein the body is ceramic.

12. The device of claim 10 , wherein a portion of the body comprises a coating of ceramic on another material.

13. 1. A chemical mechanical polishing apparatus comprising: a platen for holding the polishing pad; a carrier for holding a substrate against the polishing surface of the polishing pad during a polishing process; a temperature control system including a plurality of thermal control modules disposed over the polishing pad, each thermal control module including a heat exchanger having a passage for receiving a fluid and exchanging heat between the polishing pad and the fluid, the temperature control system further including a plurality of fluid circulators for supplying fluid at two different temperatures, and a plurality of valves for selectively fluidly coupling each of the plurality of fluid circulators to a respective heat exchanger; An apparatus comprising:

14. The apparatus of claim 13 , wherein the thermal control module comprises a stack including a thermoelectric heat pump and the heat exchanger.

15. The apparatus of claim 14 , wherein the heat exchanger is above the thermoelectric heat pump.

16. 16. The apparatus of claim 15, further comprising a controller configured to control a current to the thermoelectric heat pump to cause the heat pump to deliver heat to or extract heat from the polishing pad and to control a temperature or flow rate of a fluid passing through the heat exchanger to cause the heat exchanger to raise or lower a temperature of a top surface of the thermoelectric heat pump.

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