Temperature control for chemical mechanical polishing

Abstract

A chemical mechanical polishing apparatus includes a platen holding a polishing pad, a carrier holding a substrate against a polishing surface of the polishing pad during a polishing process, a dispenser supplying a polishing liquid to the polishing surface, and a temperature control system including a body, the body is configured to contact a polishing surface or a polishing liquid on the polishing surface. The body supports a thermal control module positioned on the polishing pad.

Description

[0001] This application is a divisional application of a patent application for invention, with the application date of June 21, 2019, the application number of "201980006568.5", and the invention title of "Temperature Control for Chemical Mechanical Polishing". Technical Field

[0002] This disclosure relates to chemical mechanical polishing (CMP), and more particularly to temperature control during chemical mechanical polishing. Background Art

[0003] Integrated circuits are typically formed on a substrate by sequentially depositing conductive, semiconductor, or insulating layers on a semiconductor wafer. Various manufacturing processes require planarization of the layers on the substrate. For example, one manufacturing step includes depositing a filler layer on a non-planar surface and planarizing the filler layer. For certain applications, the filler 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 trenches and holes in the insulating layer. After planarization, the remaining portions of the metal in the holes and trenches of 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 can be deposited on a patterned conductive layer and then planarized to allow for subsequent lithography steps.

[0004] Chemical mechanical polishing (CMP) is an accepted planarization method. This planarization method typically requires mounting the substrate on a carrier head. The exposed surface of the substrate is typically placed against a rotating polishing pad. The carrier head provides a controllable load on the substrate to push the load against the polishing pad. A polishing slurry having abrasive particles is typically supplied to the surface of the polishing pad. Summary of the Invention

[0005] In one aspect, a chemical mechanical polishing apparatus includes a platen, a carrier, and a temperature control system. The platen holds a polishing pad, and the carrier holds a substrate against a polishing surface of the polishing pad during a polishing process. The temperature control system includes a plurality of thermal control modules positioned above the polishing pad at a plurality of different radial positions. Each of the plurality of thermal control modules is configured to independently heat or cool a radial region of the polishing pad.

[0006] In another aspect, a chemical mechanical polishing apparatus includes a platen, a carrier, a temperature control system, and a first actuator. The platen holds a polishing pad, the carrier holds a substrate against a polishing surface of the polishing pad during a polishing process, the temperature control system includes a body that includes a thermal control module positioned above the polishing pad, and the first actuator adjusts a vertical position of the body relative to the polishing pad.

[0007] In another aspect, a chemical mechanical polishing apparatus includes a platen, a carrier, a dispenser, and a temperature control system. The platen holds a polishing pad. The carrier holds a substrate against a polishing surface of the polishing pad during a polishing process. The dispenser supplies a polishing liquid to the polishing surface. The temperature control system includes a body configured to contact the polishing surface or the polishing liquid on the polishing surface. The body supports a thermal control module positioned above the polishing pad.

[0008] An implementation of any of the above aspects may include one or more of the following features.

[0009] Each thermal control module may include one or more of the following: an infrared light source, a thermoelectric heat pump, a heat exchanger, a resistive heater, and a fluid dispenser. One or more temperature sensors may measure a plurality of temperature measurements of the polishing surface at a plurality of different radial positions. A controller may be configured to receive the plurality of temperature measurements and control the plurality of thermal control modules to make the temperature distribution of the polishing pad closer to a desired temperature distribution.

[0010] A base may be positioned on one side of the platen, and the body may extend laterally from the base side over the polishing pad. A second actuator may cause the body to sweep laterally over the polishing pad.

[0011] A layer of the body may be positioned between the thermal control module and the body. The thermal control module may directly contact the polishing pad or the polishing liquid. At least a portion of the body in contact with the polishing pad or the polishing liquid may be ceramic. At least a portion of the body in contact with the polishing pad or the polishing liquid may include silicon carbide, silicon nitride, or aluminum nitride.

[0012] An 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 liquid 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 above the thermoelectric heat pump.

[0013] The controller may be configured to control a current to the thermoelectric heat pump to drive heat to or from the polishing pad by the heat pump, and the controller controls a temperature or a flow rate of a fluid passing through the heat exchanger to raise or lower a temperature of a top surface of the thermoelectric heat pump.

[0014] An implementation may include one or more of the following advantages. Temperature variations during a polishing operation may be reduced. This may improve the predictability of the polishing process. Temperature variations from one polishing operation to another may be reduced. This may improve wafer-to-wafer uniformity and improve the repeatability of the polishing process. Temperature variations on a substrate may be reduced. This may improve in-wafer uniformity.

[0015] Details of one or more implementations are described in the accompanying drawings and the following description. Other aspects, features, and advantages will become apparent from the specification, drawings, and claims. Brief Description of the Drawings

[0016] Figure 1 Schematic cross-sectional view showing an example of a polishing apparatus.

[0017] Figure 2 Schematic top view showing an exemplary chemical mechanical polishing apparatus.

[0018] Figure 3 Schematic cross-sectional view showing a part of a temperature control system having a plurality of temperature control modules.

[0019] Figure 4 Schematic view showing a heat exchanger for a temperature control system.

[0020] Figure 5 Schematic top view showing another exemplary chemical mechanical polishing apparatus. Detailed Description

[0021] Chemical mechanical polishing operates by a combination of mechanical abrasion and chemical etching at the interface between a substrate, a polishing liquid, and a polishing pad. During the polishing process, a large amount of heat is generated due to the friction between the surface of the substrate and the polishing pad. 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 surface of the polishing pad. The abrasion of the conditioning process can also generate heat. For example, in a typical one-minute copper CMP process with a nominal downforce of 2 psi and a removal rate of / min, the surface temperature of a polyurethane polishing pad can increase by about 30 °C.

[0022] The chemical-related variables (e.g., as the initiation and rate of participation in the reaction) and mechanical-related variables (e.g., the surface friction coefficient and viscoelasticity of the polishing pad) in the CMP process are all strongly temperature-dependent. Therefore, changes in the surface temperature of the polishing pad result in changes in the removal rate, polishing uniformity, erosion, dishing, and residues. By more strictly controlling the temperature of the surface of the polishing pad during polishing, the temperature change can be reduced, and the polishing performance measured such as within-wafer non-uniformity or wafer-to-wafer non-uniformity can be improved.

[0023] Some techniques for temperature control have been proposed. As an example, coolant can pass through a platen. As another example, the temperature of the polishing fluid delivered to the polishing pad can be controlled. However, these techniques may be insufficient. For example, the platen must supply or draw heat through the body of the polishing pad itself to control the temperature of the polishing surface. The polishing pad is typically a plastic material and a poor heat conductor, making thermal control of the platen difficult. On the other hand, the polishing fluid may not have significant thermal mass.

[0024] One technique that can address these problems is to directly contact a temperature-controlled body with the polishing surface of the polishing pad, or to directly contact a temperature-controlled body with the polishing fluid on the polishing pad. The temperature of this body can vary along its length, thereby providing radial control of the polishing pad temperature.

[0025] Another problem is that the temperature rise along the radius of the rotating polishing pad during the CMP process is often non-uniform. Without being limited by any particular theory, different scan profiles of the carrier head and pad conditioner can sometimes have different dwell times in each radial region of the polishing pad. In addition, the relative linear velocity between the polishing pad and the carrier head and / or pad conditioner also varies along the radius of the polishing pad. These effects can lead to non-uniform heating on the polishing pad surface, which can cause variations in the removal rate within the wafer.

[0026] One technique that can address these problems is to have a plurality of temperature control modules spaced apart along the radius of the polishing pad. Each temperature control module includes a heat transfer element located above the polishing pad, and the heat transfer element can include a cooling element or a heating element or both. Each temperature control module can independently provide a selected amount of cooling or heating to the corresponding radial region on the rotating polishing pad that travels under each module. In this way, the temperature of each radial region on the polishing pad surface can be controlled, which allows for reducing temperature non-uniformity.

[0027] Figure 1 and Figure 2 An example of a polishing station 20 of a chemical mechanical polishing system is shown. The polishing station 20 includes a rotatable disk-shaped platen 24, and a polishing pad 30 is located on the disk-shaped platen 24. 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 dual-layer polishing pad having an outer polishing layer 34 and a softer backing layer 32.

[0028] The polishing station 20 can include a supply port or a combined slurry distribution arm 39 to distribute a polishing fluid 38 (such as a polishing slurry) onto the polishing pad 30. The polishing station 20 can include a pad conditioner device having an adjustment disk 92 (see Figure 2)To maintain the surface roughness of the polishing pad 30. The regulating disk 92 can be positioned at the end of the arm 94, and the arm 94 can swing so that the regulating disk 92 radially sweeps across the polishing pad 30.

[0029] The carrier head 70 is operable to hold the substrate 10 against the polishing pad 30. The carrier head 70 is suspended from a self - supporting structure 72 (e.g., a carousel or a track), and the carrier head 70 is connected to a carrier head rotation motor 76 via a drive shaft 74 such that the carrier head can rotate about the axis 71. Optionally, the carrier head 70 can vibrate laterally, e.g., on a slider on a carousel, by movement along a track, or by rotational oscillation of the carousel itself.

[0030] The carrier head 70 can include a retaining ring 84 to hold the substrate. In some embodiments, the retaining ring 84 can include a highly conductive portion. For example, the carrier ring can include a thin lower plastic portion 86 and a thick upper conductive portion 88, and the thin lower plastic portion 86 contacts the polishing pad. In some embodiments, the highly conductive portion is a metal, e.g., the same metal as the layer being polished, such as copper.

[0031] In operation, the platen rotates about its central axis 25, and the carrier head rotates about its central axis 71 and laterally translates across the top surface of the polishing pad 30. In the case of multiple carrier heads, each carrier head 70 can independently control its polishing parameters. For example, each carrier head can independently control the pressure applied to each individual substrate.

[0032] The carrier head 70 can include a flexible membrane 80 and a plurality of pressurizable chambers 82. The flexible membrane 80 has a substrate mounting surface that contacts the back surface of the substrate 10, and the plurality of pressurizable chambers 82 apply different pressures to different regions on the substrate 10, such as different radial regions. The carrier head can also include a retaining ring 84 to hold the substrate.

[0033] In some embodiments, the polishing station 20 includes a temperature sensor 64 to monitor the temperature in the polishing station or in components within 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 (e.g., an IR camera) that is located above the polishing pad 30 and is configured to measure the temperature of the polishing pad 30 and / or the slurry 38 on the polishing pad. Specifically, the temperature sensor 64 can be configured to measure the temperature at a plurality of points along the radius of the polishing pad 30 to generate a radial temperature distribution. For example, the IR camera can have a field of view that spans the radius of the polishing pad 30.

[0034] In some embodiments, 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 located on or in the platen 24. Additionally, the temperature sensor 64 can be in direct contact with the polishing pad.

[0035] In some implementations, multiple temperature sensors may be spaced at different radial positions on the polishing pad 30 to provide temperature at multiple points along the radius of the polishing pad 30. This technique can be used as an alternative or addition to an IR camera.

[0036] Although shown in Figure 1 to be positioned to monitor the temperature of the polishing pad 30 and / or the slurry 38 on the polishing pad 30, the temperature sensor 64 may be positioned within 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 20, e.g., to measure the temperature of the polishing station or different components within the polishing station.

[0037] The polishing station 20 also includes a temperature control system 100 to control 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 on the polishing pad 30 from the edge of the polishing pad to a location at 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 may be an arm supported by a base 112 to extend over the polishing pad 30. The base 112 may be supported on the same frame 40 as the platen 24. The body 110 is positioned to avoid collision with other hardware components such as the carrier head 70, the conditioning disk 92, and the slurry dispensing arm 39.

[0038] The body 110 may be generally linear and may have a substantially uniform width along its length, although other shapes such as a circular sector (also referred to as a "pie slice"), an 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. Specifically, multiple thermal control modules may be supported by a wedge-shaped arm that is wider at one end away from the axis. For example, Figure 5 the body 110 of the temperature control system 100 shown as a wedge (other elements of the polishing equipment are not shown for simplicity in Figure 1 ).

[0039] Returning to Figure 1 and Figure 2 , the body 110 may be in direct contact with the polishing pad 30. Alternatively, the body may be slightly separated from the polishing pad 30 and still in contact with a layer of polishing fluid (such as slurry) on the surface of 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 the slurry. The base 112 may include an actuator (e.g., a linear actuator) to raise or lower the body 110.

[0040] The lateral position of the body 110 can be fixed or can be controlled by another actuator. For example, the body 110 can be driven by a motor in the base 112 to sweep laterally across the polishing pad. For example, the body 110 can be driven to perform a sweep motion to avoid collisions with other hardware components and / or increase the effective heat transfer area on the surface of the polishing pad.

[0041] The body 110 can include a plurality of heat control modules 120 arranged in a line. For example, the heat control modules 120 can be positioned along the radius of the platen, e.g., spaced apart along the radial direction of the polishing pad. Each heat control module 120 includes a heat transfer element, which can include a cooling element or a heating element or both. When the polishing pad rotates under the module, each heat control module 120 can independently provide a selected amount of cooling or heating to a corresponding radial region on the polishing pad.

[0042] Due to being separated along the radial direction of the polishing pad 30, the temperature control modules apply heating or cooling to regions spaced apart along the radial direction of the polishing pad 30.

[0043] The size and shape of the regions depend on the placement of the heating or cooling elements (such as resistance heaters, coolant channels, etc.) in the heat control module 120.

[0044] The regions can be rectangular, as Figure 2 shown, or can be some other shape, such as trapezoidal (see Figure 5 ), oval, arc-shaped, polygonal, or more complex shapes.

[0045] In addition, the regions can be of the same size and / or shape, as Figure 2 shown, but this is not necessary. The sizes of some regions can be different from those of other regions. For example, the outer regions can be larger than the inner regions (inner and outer are divided with respect to the axis of rotation of the platen). That is, the regions farther from the axis can be larger than the regions closer to the axis. Thus, the regions farther from the axis can have a wider angular spread than the regions closer to the axis. Specifically, moving outward from the axis of rotation of the platen, each successive region can be larger than the previous region (as Figure 5 shown).

[0046] Components of the thermal control module 120 may be included within the body 110 such that the body 110 itself serves to conduct heat between the polishing pad and / or slurry and the thermal control module 120. The material of the bottom surface of the body 110 may be formed of a high thermal conductivity 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 highly chemically resistant 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 this material, or the ceramic material may be coated on a body of another material such as 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 have better wear resistance. The coating may reduce wear of the pad, improve chemical resistance to the polishing fluid, and have higher thermal conductivity.

[0047] Alternatively, components of the thermal control module 120 may be fixed to the body 110 and suspended below the body 110 such that these components are in direct contact with the polishing pad and / or slurry. In this case, the body 110 is not required to conduct heat between the polishing pad and / or slurry and the thermal control module 120.

[0048] For the cooling element, the thermal control module 120 may include a cold plate cooler having a thermoelectric (TE) cooling element. The cooling element may also be a cryogenic heat exchanger that operates by recirculating a cryogenic fluid or gas (i.e., below the temperature of the polishing pad and / or polishing fluid). The cooling element may further include a dispenser configured to deliver a cryogenic gas or liquid or solid onto the surface of the polishing pad 30. For example, the cooling element may be a nozzle configured to produce a jet of cryogenic gas or liquid. The cryogenic gas, liquid, or solid may also undergo an endothermic phase change on the polishing pad surface. Additionally, the cooling element may use a combination of the above techniques. For example, the cooling element may be formed by stacking a cryogenic heat exchanger on top of the thermoelectric cooling element to further enhance the cooling capacity.

[0049] For a heating element, the thermal control module 120 may include a hot plate 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 high-temperature fluid or gas (i.e., above the temperature of the polishing pad and / or the polishing fluid). The heating element may further include a dispenser configured to deliver a high-temperature gas, 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 high-temperature gas or liquid. The high-temperature gas, liquid, or solid may also undergo an exothermic phase change on the polishing pad surface. 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 heat exchanger on top of a thermoelectric heating element to further increase the heating capacity.

[0050] The polishing station 20 may further include a controller 90 to control the operation of various components, such as the temperature control system 100. The controller 90 is configured to receive temperature measurements for each radial region of the polishing pad from the temperature sensor 64. The controller 90 may compare the measured temperature profile with a desired temperature profile and generate a feedback signal to a control mechanism (such as an actuator, a power supply, a pump, a valve, etc.) for 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 through the cooling or heating elements of the temperature control module such that the polishing pad and / or the slurry reaches (or at least gets closer to) the desired temperature profile.

[0051] Examples of control techniques include causing the power supply to adjust the intensity of an infrared light source, causing the power supply to adjust the amount of electric current flowing through a thermoelectric heater or cooler, causing an actuator to move the thermal control module closer to or farther from the polishing pad, causing a pump to increase or decrease the flow rate in a heat exchanger, and causing a valve to adjust the ratio of hot or cold fluid flowing through a heat exchanger.

[0052] Examples of control mechanisms for stacking of TE cooling elements (as cooling elements) and low-temperature heat exchangers or stacking of TE heating elements (as heating elements) and high-temperature heat exchangers may include: (I) controlling the amount of current (or voltage) supplied to the TE element; (II) controlling the relative percentage of the TE element in the on and off modes under pulse width modulation, (III) controlling the relative percentage of the TE element in the cooling and heating modes under bipolar modulation; (IV) controlling the temperature or flow rate of the liquid recirculated within the low-temperature or high-temperature heat exchanger.

[0053] 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 percentage of the resistive heater in the on and off modes under pulse width modulation.

[0054] In some implementations, the thermal control module 120 can provide bidirectional temperature control. Thus, each thermal control module 120 can provide selective heating and selective cooling according to different processing requirements.

[0055] In some implementations, bidirectional temperature control is provided by including both a cooling element and a heating element in each thermal control module 120. By way of example, referring to Figure 3 , each thermal control module 120 can have a heat transfer element that includes a stack of thermoelectric or resistive heating elements 130 and heat exchangers 140. The flow rate through each heat exchanger can be controlled by a valve 142. The heat exchanger 140 can be used as a cooling element, for example by flowing a cryogenic fluid through the heat exchanger. The thermoelectric or resistive heating element 130 can be used as a heating element, for example by passing an electric current through the thermoelectric or resistive heating element 130. Depending on whether cooling or heating is required at each stage during polishing, the heating element and the cooling element can be engaged at different times.

[0056] However, in some implementations, only one heat transfer element is required in each thermal control module 120. For example, the thermoelectric or resistive heating element 130 or the heat exchanger 140 can be used as a heating or cooling element, for example depending on the direction of current flow or the temperature of the fluid flowing through the heat exchanger.

[0057] In some implementations, each thermal control module 120 includes a stack of thermoelectric or resistive heating elements 130 and heat exchangers 140, wherein both the thermoelectric or resistive heating elements 130 and the heat exchangers 140 are configured for bidirectional temperature control. The thermal control module 120 can be used as a cooling element by: (i) selecting the direction of current flow in the thermoelectric or resistive heating element 130 to pump heat out of the polishing pad and (ii) circulating a cryogenic fluid within the heat exchanger 140. The same thermal control module 120 can be used as a heating element by: (i) switching the direction of current flow (reversing the polarity) within the thermoelectric or resistive heating element 130 to pump heat into the pad and (ii) switching from circulating a cryogenic fluid to a hot fluid within the heat exchanger 140.

[0058] For example, referring to Figure 4 , two fluid circulators C1 and C2 can supply fluid at two different temperatures. For example, C1 can pump cold water while C2 can pump hot water. Using valves V1 and V2, the hot fluid or the cold fluid can flow to the thermal control modules 120a and 120b. Exemplary fluids include water and / or ethylene glycol. The fluid can flow simultaneously or at different time points. This fluid is used to cool or heat the non-contact side of the thermoelectric or resistive heating element 130.

[0059] Returning to Figure 2, in some embodiments, the polishing station 20 includes a plurality of temperature control systems 100a, 100b, each temperature control system having its own body 110, and the body 110 having an array 122 of thermal control modules 120. The slurry dispensing arm 39 may be positioned between two arrays 122 of thermal control modules.

[0060] The body of one of the temperature control systems (such as the body 110 (such as Figure 2 the body 110 of system 110b in )) that is in a leading position relative to the carrier head 70 along the rotational direction can be used as a barrier layer for removing the slurry. For example, the body 110 of the temperature control system 100b may be positioned closer to the polishing pad 30 than the body 110 of the temperature control system 100a. In operation, the polishing liquid may be dispensed by the slurry dispensing arm 39, carried by the underlying pad and heated by the array 122 of thermal control modules 120 of the temperature control system 110a, and then carried under the carrier head 70 to dock with the substrate. Then, the used slurry may be carried from the carrier head 70 and deflected by the body 110 of the temperature control system 110b to be transferred outside the pad area. The body 110 of the temperature control system 110a may also be positioned on the polishing pad 30 to radially smear the polishing liquid.

[0061] In some embodiments, the temperature control system 100 may use two-stage heating / cooling. A heat pump may be used as the first stage, while a heat exchanger may be used as the second stage. The first stage is closer to the polishing pad.

[0062] The design specification of the performance of a thermoelectric element is the difference between the cold side and the hot side. This difference has limitations. For example, assume that a thermoelectric element is used to heat a target surface. The bottom surface of the thermoelectric element will be the hot side (and should be hotter than the target) and the top surface will be the cold side. The target will be placed close to the bottom hot side. Heat transfer occurs from the bottom hot side to the target.

[0063] Most thermoelectric elements maintain a set temperature difference between the top side and the bottom side. However, heating the top side of the thermoelectric element allows the bottom side to become hotter, which can result in higher efficiency of heat transfer from the bottom to the target. For example, the top side of the thermoelectric element can be achieved by flowing hot liquid over it. This two-stage cooling phenomenon by using a thermoelectric element in series with a heat exchanger (such as a water circulator) would be advantageous in CMP. This also applies to the reverse cooling phenomenon.

[0064] Water cannot be used as a coolant above 0 degrees Celsius. A mixture of water and ethylene glycol is preferably below 0 degrees Celsius, but often results in a compromise in heat transfer due to ethylene glycol.

[0065] Multiple stacks of thermoelectric elements along the radial direction of the pad (with cumulative or individual fluid inlets and outlets) will enable regional control of the temperature along the CMP pad.

[0066] In some implementations, the body 110 also serves as a slurry wiper or spreader. For example, referring to Figure 2 , the polishing liquid can be dispensed from the slurry dispensing arm 39. Due to the rotation of the platen 24, the slurry will be carried on the polishing pad 30 towards the temperature control system 100a. Specifically, assuming that the body 110 is positioned to contact the polishing pad 30, the bottom edge of the trailing surface (the surface opposite to the rotation direction) will serve as a barrier layer to inhibit the flow of the slurry from the slurry dispensing arm 39. In this way, the slurry that actually passes under the body 110 (such as in the grooves in the polishing pad 30 or through the gap between the body 110 and the polishing pad 30) will be more evenly distributed.

[0067] Possible advantages include the following.

[0068] (I) The device is essentially dedicated and exclusive hardware for controlling the surface temperature of the polishing pad during the CMP process.

[0069] (II) The device does not rely on controlling the pad surface temperature by adjusting CMP process parameters (such as the downward force of the carrier head or the pad conditioner disk). In this way, this temperature control device has less impact on the existing CMP process.

[0070] (III) Through certain selections of the components in the thermal control module, for example, when using a stack of thermoelectric elements and heat exchangers as described above, the temperature control device has less interference with the polishing pad surface compared to, for example, air vortices or deionized water jets for cooling purposes.

[0071] (IV) Through certain selections of the components in the thermal control module, for example, when using a stack of thermoelectric elements and heat exchangers as described above, the temperature control device can achieve two-way temperature control including cooling and heating in the same thermal control module. Therefore, during implementation, the footprint of the new device can be very small. In addition, the two-way temperature control enables the new processing knob to be adjusted at different stages of the entire CMP process to achieve improved CMP results measured in terms of throughput, topography, residues, corrosion, etc.

[0072] (V) Using multiple temperature control modules in the module array can reduce the temperature non-uniformity within the pad during the CMP process. In addition, through certain selections of the components in the thermal control module, for example, when using a stack of thermoelectric elements and heat exchangers as described above, there is a multi-level control mechanism to provide more reliable temperature control in each individual module to achieve the desired temperature or temperature change rate in each radial region and reduce the temperature non-uniformity on the polishing pad surface.

[0073] The above polishing equipment and method can be applied to various polishing systems. One or both of the polishing pad or the carrier head can be moved to provide relative movement 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. Some aspects of the endpoint detection system can be applicable to linear polishing systems, for example, where the polishing pad is a continuously or reel-to-reel belt that moves linearly. The polishing layer can be a standard (e.g., polyurethane with or without fillers) polishing material, a soft material, or a fixed abrasive material. The terms of relative positioning are used to refer to relative positioning within the system or the substrate; it should be understood that during the polishing operation, the polishing surface and the substrate can be held in a vertical orientation or some other orientation.

[0074] The functional operations of the controller 90 can be implemented 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 or control of the operation of a data processing apparatus, such as a programmable processor, a computer, or multiple processors or computers.

[0075] Numerous embodiments of the 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. Accordingly, other embodiments are within the scope of the following claims.

Claims

1. A chemical mechanical polishing apparatus, comprising: A platen that holds a polishing pad; A carrier that holds a substrate against a polishing surface of the polishing pad during a polishing process; A supply arm that laterally extends over the polishing pad and has a nozzle for supplying a polishing liquid to the polishing surface of the polishing pad; A temperature control system that includes a body having a thermal control module located above the polishing pad, wherein the thermal control module includes a heat transfer element that includes a cooling element or a heating element or both, and the cooling element or the heating element includes a dispenser configured to deliver a gas or a liquid onto the polishing pad; And A first actuator that adjusts a vertical position of the body relative to the polishing pad.

2. The apparatus according to claim 1, wherein the cooling element includes a nozzle configured to generate a jet of cold gas or liquid, or the heating element includes a nozzle configured to generate a jet of hot gas or liquid.

3. The apparatus according to claim 1, wherein the platen is rotatable about an axis, and a plurality of thermal control modules are positioned along a radius of the platen, and each thermal control module includes a dispenser configured to deliver a gas or a liquid onto the polishing pad.

4. The apparatus according to claim 3, wherein the plurality of thermal control modules are aligned in a line.

5. The apparatus according to claim 1, wherein each of the plurality of thermal control modules is configured to independently apply heating or cooling over an area.

6. The apparatus according to claim 1, including a base positioned on one side of the platen, and wherein the body laterally extends over the polishing pad from the base.

7. The apparatus according to claim 6, including a second actuator that causes the body to laterally sweep over the polishing pad.

8. The apparatus according to claim 1, including two temperature control systems, each having a body with an array of thermal control modules.

9. The apparatus according to claim 8, wherein each body is an arm that extends over the polishing pad.

10. The apparatus according to claim 9, wherein a slurry distribution arm is positioned between the arrays of thermal control modules.

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