Temperature-controlled removal rates in CMP.

Abstract

A method for removing material from a substrate includes dispensing an abrasive slurry onto a polishing pad, storing an indication of the relative charge on the abrasive, contacting a surface of the substrate with the polishing pad with the slurry present, generating relative motion between the substrate and the polishing pad, measuring a removal rate for the substrate, comparing the measured removal rate to a target removal rate and determining whether to increase or decrease the removal rate based on the comparison, determining whether to increase or decrease a temperature of an interface between the polishing pad and the substrate based on the indication of the relative charge of the abrasive and whether to increase or decrease the removal rate, and controlling the temperature of the interface as determined to modify the removal rate.

Description

[Technical Field]

[0001] This specification relates to chemical mechanical polishing applications using cerium oxide slurries. [Background technology]

[0002] Integrated circuits are typically formed on silicon wafers by sequentially depositing conductive, semiconductive, or insulating layers. One manufacturing step involves depositing a layer on a non-planar surface and planarizing that layer. In some applications, a layer is planarized until the top surface of a patterned underlying layer is exposed. In other applications, a layer is planarized until a predetermined thickness remains above the underlying layer.

[0003] Chemical-mechanical polishing (CMP) is one accepted planarization method. In this planarization method, a substrate is mounted on a carrier head and the surface of the substrate is positioned against the surface of a rotating polishing pad. A polishing liquid, such as an abrasive slurry, is dispensed onto the rotating polishing pad to polish layers on the substrate by mechanical and chemical means. The abrasive particles in the slurry can be silicon oxide and cerium oxide. Summary of the Invention

[0004] In one embodiment, a polishing method includes dispensing a polishing slurry containing negatively charged ceria oxide onto a polishing pad, contacting a surface of a substrate with the polishing pad containing the slurry, generating relative motion between the substrate and the polishing pad to polish the surface of the substrate, measuring a removal rate for the substrate, determining whether the measured removal rate is below a target removal rate, and reducing the temperature of the interface between the polishing pad and the substrate in response to determining that the measured removal rate is below the target removal rate.

[0005] In another aspect, a polishing method includes dispensing a polishing slurry containing negatively charged ceria oxide onto a polishing pad, contacting a surface of a substrate with the polishing pad containing the slurry, generating relative motion between the substrate and the polishing pad to polish the surface of the substrate, measuring a removal rate for the substrate, determining whether the measured removal rate exceeds a target removal rate, and increasing the temperature of the interface between the polishing pad and the substrate in response to determining that the measured removal rate exceeds the target removal rate. The abrasive can include cerium oxide particles.

[0006] In another aspect, a method for removing material from a substrate includes dispensing a slurry including a carrier liquid and an abrasive onto a surface of a polishing pad, storing an indication of the relative charge on the abrasive, contacting the surface of the substrate with the polishing pad containing the slurry, generating relative motion between the substrate and the polishing pad to polish the surface of the substrate, measuring a removal rate for the substrate, comparing the measured removal rate to a target removal rate and determining whether to increase or decrease the removal rate based on the comparison, determining whether to increase or decrease the temperature of the interface between the polishing pad and the substrate based on the indication of the relative charge of the abrasive and whether to increase or decrease the removal rate, and controlling the temperature of the interface as determined to modify the removal rate.

[0007] In another aspect, a polishing method includes polishing a layer on a substrate by dispensing a polishing slurry onto a polishing pad, contacting the surface of the layer on the substrate with the polishing pad on which the slurry is present, and generating relative motion between the substrate and the polishing pad; controlling the polishing temperature to be within a first temperature range for a first polished portion of the layer; obtaining a temperature transition time before an endpoint time; and, upon determining that the temperature transition time has been reached, lowering the polishing temperature to be within a second temperature range that is lower than the first temperature range; and controlling the polishing temperature to be within the second temperature range for a subsequent polished portion of the same layer until an estimated endpoint time.

[0008] In another aspect, a polishing method includes polishing a layer on a substrate by dispensing a polishing slurry onto a polishing pad, contacting the surface of the layer on the substrate with the polishing pad on which the slurry is present, and generating relative motion between the substrate and the polishing pad; controlling the polishing temperature to be within a first temperature range for a first polished portion of the layer; determining whether a temperature transition time is before an endpoint time; and, upon determining that the temperature transition time has been reached, increasing the pressure on the substrate while increasing the coolant flow rate to continue maintaining the polishing temperature to be within the first temperature range; and maintaining the increased pressure for subsequent polished portions of the same layer and controlling the polishing temperature to be within the first temperature range until the estimated endpoint time.

[0009] Embodiments may include one or more of the following features: Dispensing the cooling fluid may include spraying the cooling fluid through a convergent-divergent nozzle; Measuring the removal rate may include monitoring the substrate during polishing with an in-situ optical monitoring system; The surface of the substrate may include an oxide layer, e.g., silicon oxide; Controlling the temperature of the interface may include increasing the polishing rate by increasing the temperature if the indicator is positively charged, increasing the polishing rate by decreasing the temperature if the indicator is negatively charged, decreasing the polishing rate by decreasing the temperature if the indicator is positively charged, or decreasing the polishing rate by increasing the temperature if the indicator is negatively charged.

[0010] Benefits may include, but are not limited to, one or more of the following: The CMP system can achieve high polishing rates to meet customer production demands. The methods described herein further improve system throughput by reducing the time required to polish each substrate, which increases substrate output and reduces consumable material costs per substrate. Optimizing the CMP process temperature in conjunction with applying charged ceria allows for longer polishing pad life and lower costs to customers.

[0011] The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages will become apparent from the description, drawings, and claims. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic cross-sectional view of a chemical mechanical polishing system. [Figure 2] 1 is a flowchart of a polishing method. [Figure 3] 10 is a flowchart of another implementation of a polishing method. [Figure 4] 10 is a flowchart of yet another implementation of a polishing method. DETAILED DESCRIPTION OF THE INVENTION

[0013] Like reference numbers and designations in the various drawings indicate like elements.

[0014] The material removal rate of a CMP process depends on the selection of abrasives and other components of the polishing fluid, the pressure applied to the substrate, the relative velocity between the polishing pad and the substrate, and the temperature at the interface between the substrate and the polishing pad. Conventionally, in chemical reaction processes, such as polishing processes, the temperature is increased. Therefore, increasing the temperature can be a technique for increasing the removal rate.

[0015] However, the actual dependence of the polishing rate on temperature may be more complex due to the effect of temperature on the polishing pad, for example, the interaction between the elastic modulus of the polishing pad and the temperature-determined reaction rate. Moreover, in some polishing processes, the electrostatic potential of the abrasive particles is a component in this interaction.

[0016] Cerium oxide (e.g., ceria) is an abrasive material in polishing fluids for some polishing processes. In the polishing fluid, the surfaces of the abrasive ceria particles can have a positive electrostatic potential, a negative electrostatic potential, or a negligible electrostatic potential on the surface of the abrasive particle. This potential can depend on the synthesis technique. Polishing processes using polishing fluids with ceria particles exhibit polishing rates that respond differently to temperature depending on the positive or negative potential at the surfaces of the particles in the slurry.

[0017] This application describes a technique for temperature control based on the charge characteristics of abrasive particles. CMP systems include heaters or coolers to control the temperature at the interface between the substrate and the polishing pad. By changing the temperature of the polishing process, the material removal rate can increase or decrease depending on the surface charge of the ceria suspended in the slurry. For negatively charged ceria slurries, cooling can increase the polishing rate and improve topography. Without being limited to any particular theory, cooling using negatively charged ceria can improve the material removal rate by increasing hardness and modifying the topography of the pad's upper surface. For some positively charged ceria slurries, a combination of heating and cooling can improve the polishing rate by heating at the beginning of the polishing process, and cooling near the end of polishing can improve the topography. For other positively charged ceria slurries, a combination of cooling and increased pressure can be used to improve the polishing rate, with increased pressure increasing the polishing rate and cooling preventing overheating of the pad and maintaining the topography.

[0018] 1 shows an example of a polishing system 20. The polishing system 20 can include a rotatable, disk-shaped platen 22 on which a polishing pad 30 is positioned. The platen is operable to rotate about an axis 23. For example, a motor 24 can rotate a drive shaft 26 to rotate the platen 22. The polishing pad 30 is removably fastened to the platen 22 by, for example, an adhesive layer. The polishing pad 30 can be a two-layer polishing pad having an outer polishing layer 32 and a softer backing layer 34.

[0019] The polishing system 20 may include a polishing fluid supply port 40 for dispensing a polishing fluid 42, such as an abrasive slurry, onto the polishing pad 30. The polishing system 20 may also include a polishing pad conditioner for polishing the polishing pad 30 to maintain the polishing pad 30 in a consistently polished condition.

[0020] The carrier heads 50 are operable to hold the substrate 10 against the polishing pad 30. Each carrier head 50 also includes multiple independently controllable pressurizable chambers, e.g., three chambers 52a-52c, that can apply independently controllable pressures to associated zones on the substrate 10. The chambers 52a-52c may be defined by a flexible membrane 54 having a bottom surface to which the substrate 10 is attached. The carrier head 50 may also include a retaining ring 56 for retaining the substrate 10 below the flexible membrane 54. While only three chambers are shown in FIGS. 1 and 2 for ease of illustration, there could be two chambers, or four or more chambers, e.g., five chambers. Additionally, other mechanisms for adjusting the pressure applied to the substrate, e.g., piezoelectric actuators, could be used in the carrier heads 50.

[0021] Each carrier head 50 is suspended from a support structure 60, such as a carousel or track, and is connected by a drive shaft 62 to a carrier head rotation motor 64 so that the carrier head can rotate about axis 51. Optionally, each carrier head 50 may oscillate laterally, for example, on a slider on the carousel, by movement along the track, or by rotational oscillation of the carousel itself. In operation, platen 22 rotates about its central axis 23, and carrier head 50 rotates about its central axis 51 and translates laterally across the top surface of polishing pad 30.

[0022] The polishing system also includes an in-situ monitoring system 70 that can be used to control polishing parameters, such as the applied pressure in one or more of the chambers 52a-52c. The in-situ monitoring system 70 can be an optical monitoring system, such as a spectroscopic monitoring system, for polishing oxide layers on the substrates, among other things. Alternatively, the in-situ monitoring system 70 can be an eddy current monitoring system for polishing metal layers on the substrates, among other things.

[0023] As an optical monitoring system, the in-situ monitoring system 70 can include a light source 72, a photodetector 74, a controller 90, e.g., a computer, and circuitry 76 for transmitting signals between the light source 72 and the photodetector 74. One or more optical fibers 78 can be used to transmit light from the light source 72 to the window 36 in the polishing pad 30 and to transmit light reflected from the substrate 10 to the detector 74. As a spectroscopic system, the light source 72 can be operable to emit white light, and the detector 74 can be a spectrometer. The measured spectrum can be converted into a characteristic value indicative of the thickness of the layer being polished in each of the zones.

[0024] The output of circuitry 76 may be a digital electronic signal that passes through rotary coupler 28, e.g., a slip ring, on drive shaft 26 to controller 90. Alternatively, circuitry 76 may communicate with controller 90 by wireless signals. Controller 90 may be a computing device, e.g., a programmable computer, including a microprocessor, memory, and input / output circuitry. Although shown as a single block, controller 90 may be a networked system with functions distributed across multiple computers.

[0025] The polishing system 20 includes a temperature sensor 80 for monitoring the temperature of the polishing process, e.g., the temperature of the polishing pad 30 and / or the polishing liquid 42 on the polishing pad, or of the substrate. For example, the temperature sensor 80 may be an infrared (IR) sensor, e.g., an IR camera, positioned above the polishing pad 30 and configured to measure the temperature of the polishing pad 30 and / or the polishing liquid 42 on the polishing pad. In particular, the temperature sensor 64 may 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 may have a field of view that spans the radius of the polishing pad 30.

[0026] 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.

[0027] In some implementations, multiple temperature sensors may be spaced at different radial locations across the polishing pad 30 to provide the temperature at multiple points along the radius of the polishing pad 30. This technique can be used in place of or in addition to an IR camera.

[0028] 1 as being positioned to monitor the temperature of the polishing pad 30 and / or the polishing liquid 42 on the pad 30, it may be positioned within the carrier head 50 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 system 20, for example, to measure the temperatures of different components.

[0029] The polishing system 20 also includes a temperature control system 100 for controlling the temperature of the polishing pad 30 and / or the polishing liquid 42 on the polishing pad. The temperature control system 100 includes a cooling system and / or a heating system. In some implementations, both the cooling system and / or the heating system operate by supplying 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 liquid already present on the polishing pad).

[0030] 1 , an exemplary temperature control system 100 includes an arm 110 that spans the platen 22 and the polishing pad 30. A plurality of nozzles 120 are suspended from the arm 110, with each nozzle 120 configured to spray a temperature control fluid onto the polishing pad 30. The arm 110 may be supported by a base 112 such that the nozzles 120 are separated from the polishing pad 30 by a gap 126. Each nozzle 120 may be configured to start and stop the flow of fluid at each nozzle 120, for example, using the controller 12. Each nozzle 120 may be configured to direct aerosolized water in a spray 122 toward the polishing pad 30.

[0031] To operate as a cooling system, the temperature control fluid is a cooling liquid. The cooling liquid can be a gas, such as air, or a liquid, such as water. The cooling liquid can be at room temperature or chilled below room temperature, for example, between 5 and 15 degrees Celsius. In some implementations, the cooling system uses a spray of air and liquid, such as an aerosolized spray of liquid, such as water. In particular, the cooling system can have a nozzle that generates an aerosolized spray of water that is chilled below room temperature. In some implementations, a solid material can be mixed with the gas and / or liquid. The solid material can be a chilled material, such as ice, or a material that absorbs heat when dissolved in water, for example, by a chemical reaction. The cooling liquid can be below room temperature, for example, between -100 and 20 degrees Celsius, for example, below 0 degrees Celsius, when dispensed.

[0032] To operate as a heating system, the temperature control fluid is a heating fluid. The heating fluid can be a gas, such as steam or hot air, or a liquid, such as hot water, or a combination of gas and liquid. The heating fluid is above room temperature, for example, 40-120 degrees Celsius, for example, 90-110 degrees Celsius. The fluid can be water, such as substantially pure deionized water, or water containing additives or chemicals. In some implementations, the heating system uses a spray of steam. The steam can contain additives or chemicals.

[0033] Temperature control system 100 can include a single arm for dispensing either cooling or heating fluid, or two dedicated arms for dispensing cooling and heating fluid, respectively.

[0034] Other techniques can alternatively or additionally be used by the temperature control system 100 to control the temperature of the polishing process. For example, a heating or cooling fluid, such as steam or cold water, can be injected into the polishing liquid 42 (e.g., slurry) to raise or lower the temperature of the polishing liquid 42 before it is dispensed. As another example, resistive heaters can be supported in the platen 22 for heating the polishing pad 30 and / or in the carrier head 50 for heating the substrate 10.

[0035] Moderating the temperature of the slurry and polishing pad during polishing of the layer allows for enhanced interaction between charged abrasives such as cerium oxide. By using temperature control, the material removal rate can be advantageously increased by both adjusting the physical parameters of the polishing pad and altering the characteristics of the chemical interaction between the charged ceria and the fill layer.

[0036] In some implementations, a temperature sensor measures the temperature of the polishing process, e.g., the polishing pad or the polishing liquid or substrate on the polishing pad, and the controller 90 executes a closed-loop control algorithm to control the temperature control system, e.g., the flow rate or temperature of the cooling liquid or heating fluid, respectively, to maintain the polishing process at a desired temperature.

[0037] In some implementations, the in-situ monitor system measures the polishing rate for the substrate, and the controller 90 executes a closed-loop control algorithm to control the temperature control system, e.g., the flow rate or temperature of the cooling or heating fluid, respectively, to maintain the polishing rate at a desired rate.

[0038] FIG. 2 illustrates a method for implementing this technique, applicable to charged ceria slurries. Optionally, the controller 90 stores an indication of whether the slurry being used contains negatively or positively charged abrasive ceria particles (202). Polishing occurs as the slurry with abrasive ceria particles is dispensed onto the polishing pad (204). The controller 90 can store a desired temperature or temperature range, for example, as part of a polishing recipe. During polishing, the controller 90 can then operate to maintain the temperature of the polishing process at the desired temperature or temperature range (206), for example, using an open-loop or closed-loop algorithm. During polishing, the polishing process is monitored by an in-situ monitoring system, and the removal rate is calculated from the acquired data (208). Due to various causes, the removal rate may deviate from the desired polishing rate (210). For example, the controller 90 can detect whether the removal rate varies from the target polishing rate by more than a threshold amount. If this occurs, the controller 90 can cause the temperature control system to modify the process temperature to compensate for the removal rate and return to the desired polishing rate. However, what action to take may depend on the charge of the abrasive ceria particles.

[0039] In particular, with reference to Table 1, for a slurry of negatively charged abrasive ceria particles, if the removal rate is lower than the desired polishing rate, the temperature can be decreased to increase the polishing rate, whereas if the removal rate is higher than the desired polishing rate, the temperature can be increased to decrease the polishing rate, as follows: In contrast, for a slurry of positively charged abrasive ceria particles, if the removal rate is lower than the desired polishing rate, the temperature can be increased to increase the polishing rate, whereas if the removal rate is higher than the desired polishing rate, the temperature can be decreased to decrease the polishing rate, as follows: TIFF0007778806000001.tif35170

[0040] This data can be stored and accessed by the controller 90, for example as control logic or a look-up table, to determine how to adjust the temperature if the removal rate deviates from the desired polishing rate (212). Alternatively, the decision process for whether to increase or decrease the temperature can be embedded in the process recipe associated with the particular slurry provided by the controller.

[0041] The controller 90 then causes the temperature control system to adjust the temperature (214), for example, by increasing or decreasing the temperature and / or flow rate of the temperature control fluid to modify the process temperature, eg, the pad temperature.

[0042] Regarding increasing the processing temperature, the maximum desirable temperature depends on the glass transition temperature for the polishing pad. If the pad becomes too hot, it may become too viscoelastic, and the polishing process may not proceed as expected, for example, the polishing rate may decrease or defects may increase. Generally, the controller can be configured to maintain a temperature (relative to 0 degrees Celsius) below 2 / 3 of the melting point of the polishing layer.

[0043] Apart from the issue of the effect of electrostatic charge on the temperature dependence of the polishing rate, in many polishing applications, it is useful to reduce the polishing rate as the polishing process approaches the polishing end point to avoid overpolishing and reduce non-uniformity. On the other hand, it is beneficial to maintain a high polishing rate during bulk polishing of thick layers. One proposed approach to reducing the polishing rate is to reduce the pressure on the substrate. However, this may not be practical in some applications, such as polishing of embrittlement layers, when the carrier head is already operating at a low applied pressure.

[0044] An alternative or additional approach to reducing the applied pressure near the polishing endpoint is to modify the process temperature to reduce the polishing rate. For example, for a conventional silica slurry or a positively charged ceria slurry, the temperature can be reduced before the polishing endpoint to reduce the polishing rate.

[0045] 3 illustrates a method for carrying out this technique. For the first polished portion of the layer, the temperature of the polishing process is controlled to be within a first temperature range (302). This first portion can be performed from the beginning of the polishing process.

[0046] Control may be achieved by the controller 90 using a feedback loop that receives temperature measurements from the sensor 60 and adjusts the operation of the temperature control system 100. It will be appreciated that the temperature of the polishing pad at a particular location on the slurry or substrate may be a surrogate for the temperature of the polishing process.

[0047] Whether before or after polishing begins, a temperature transition time is determined to be before the expected endpoint time (304). The temperature transition time can be a recipe-based default value, in which case the temperature transition time can be determined by a user before polishing begins. Alternatively, the polishing process can be monitored by an in-situ monitoring system. The in-situ monitoring system can predict an estimated endpoint time based on the measured polishing rate of the substrate, and the transition time can be calculated based on the estimated endpoint time, for example, a default time, e.g., 10 seconds, or a percentage of the total polishing time before the estimated endpoint time, e.g., 5-10%.

[0048] Once the temperature transition time is reached, the controller 90 causes the temperature control system to reduce the polishing temperature to within a second, lower temperature range that is lower than the first temperature range (306). The second, lower temperature range may not overlap with the first temperature range, or may overlap with the first temperature range by only 25%. The midpoint of the second temperature range may be 20-40 degrees Celsius lower than the midpoint of the first temperature range. In some embodiments, the temperature of the polishing surface 36 may be reduced to 30 degrees Celsius or less, for example, 20 degrees Celsius or less.

[0049] Once the temperature of the polishing process reaches the second temperature range, for a subsequent portion of the polishing process for the same layer, the controller 90 causes the temperature control system 100 to maintain the temperature of the polishing process within the second temperature range (308). The subsequent portion of the polishing process may continue until the estimated endpoint time for the layer.

[0050] Another approach that can be used instead of reducing the applied pressure near the polishing endpoint is to increase the pressure on the substrate to reduce non-uniformity while also increasing the temperature control flow so that the temperature control system maintains the desired temperature. For example, for conventional silica slurries or positively charged ceria slurries, the pressure on the substrate and / or the platen rotation speed can be increased, and the coolant flow rate can be increased before the polishing endpoint to achieve higher non-uniformity without sacrificing the polishing rate.

[0051] 4 illustrates a method for carrying out this technique. For the first polished portion of the layer, the temperature of the polishing process is controlled to be within a first temperature range (402). Whether before or after polishing begins, it is determined whether the temperature transition time is before the expected endpoint time (404). These two steps can be performed as discussed above for steps 302 and 304.

[0052] When the temperature transition time is reached, the controller 90 adjusts the pressure in one or more chambers in the carrier head 50 to increase the pressure on the substrate (406). In conjunction with this, the controller 90 causes the temperature control system to increase the flow rate of a temperature control fluid, e.g., a coolant for a silica slurry or a positively charged ceria slurry, so that the temperature is maintained within the first temperature range (408). The subsequent portion of the polishing process may continue until the estimated endpoint time for the layer.

[0053] Regarding increasing the processing temperature, the maximum desirable temperature depends on the glass transition temperature for the polishing pad. If the pad becomes too hot, it may become too viscoelastic, and the polishing process may not proceed as expected, for example, the polishing rate may decrease or defects may increase. Generally, the controller can be configured to maintain a temperature (relative to 0 degrees Celsius) below 2 / 3 of the melting point of the polishing layer.

[0054] More generally, for conventional silica slurries or positively charged ceria slurries, to maximize the polishing rate, it may be desirable to perform the polishing process at the highest possible temperature before the viscoelastic properties of the polishing pad impair polishing performance. Thus, rather than increasing the temperature through friction between the substrate and the polishing pad, a temperature control system may be used to raise the temperature to the desired temperature at the beginning of the polishing process. Furthermore, the temperature can be maintained within a desired temperature range, for example, at about 50-66% of the melting point of the polishing layer (relative to 0 degrees Celsius).

[0055] While the specification contains many specific implementation details, these should not be construed as limiting the scope of any invention or the scope of what may be claimed, but rather as a description of features that may be specific to particular embodiments of a particular invention. Certain features described herein in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, while features may be described above as working in a particular combination and may even initially be claimed as such, one or more features from a claimed combination can, in some cases, be deleted from that combination, and the claimed combination may be directed to a subcombination or a variation of the subcombination.

[0056] Similarly, while operations may be illustrated in the figures and listed in the claims in a particular order, this should be understood as not requiring that such operations be performed in the particular order shown, or sequentially, or that all of the operations shown be performed, to achieve desirable results.

[0057] Although specific embodiments of the inventive subject matter have been described above, other embodiments are within the scope of the following claims. For example, the actions recited in the claims can be performed in a different order and still achieve desirable results. As one example, the processes depicted in the accompanying figures do not necessarily require the particular order or sequential order shown to achieve desirable results.

Claims

1. A polishing system comprising: dispensing a polishing slurry containing negatively charged ceria particles as abrasive particles onto a polishing pad; contacting a surface of a substrate with the polishing pad having the slurry present therein; causing the polishing system to generate relative motion between the substrate and the polishing pad to polish the surface of the substrate; calculating a removal rate for the substrate based on signals received from an in-situ monitor system; determining whether the calculated removal rate is less than a desired removal rate; In response to determining that the calculated removal rate is less than the desired removal rate, causing a temperature control system to reduce a temperature of an interface between the polishing pad and the substrate; A polishing method comprising:

2. The method of claim 1 , wherein the reducing the temperature comprises dispensing a cooling fluid onto the polishing pad.

3. The method of claim 2 , wherein the cooling fluid is DI water chilled to 20 degrees Celsius or less.

4. A polishing system comprising: dispensing a polishing slurry containing negatively charged ceria particles as abrasive particles onto a polishing pad; contacting a surface of a substrate with the polishing pad having the slurry present therein; causing the polishing system to generate relative motion between the substrate and the polishing pad to polish the surface of the substrate; calculating a removal rate for the substrate based on signals received from an in-situ monitor system; determining whether the calculated removal rate exceeds a desired removal rate; In response to determining that the calculated removal rate exceeds the desired removal rate, causing a temperature control system to increase a temperature of an interface between the polishing pad and the substrate; A polishing method comprising:

5. The method of claim 4 , wherein increasing the temperature comprises dispensing a heated fluid onto the polishing pad.

6. The method of claim 5 , wherein dispensing the heated fluid comprises spraying steam.

7. 1. A method for removing material from a substrate, comprising: dispensing a slurry onto a surface of a polishing pad, the slurry including a carrier liquid and an abrasive; storing whether the abrasive is positively or negatively charged; contacting a surface of a substrate with the polishing pad having the slurry present therein; causing the polishing system to generate relative motion between the substrate and the polishing pad to polish the surface of the substrate; calculating a removal rate for the substrate based on signals received from an in-situ monitor system; comparing the calculated removal rate to a desired removal rate and determining to increase the removal rate when the calculated removal rate is lower than the desired removal rate and determining to decrease the removal rate when the calculated removal rate is higher than the desired removal rate; determining whether to increase or decrease the temperature of the interface between the polishing pad and the substrate based on whether the abrasive is positively or negatively charged and whether to increase or decrease the removal rate; causing a temperature control system to increase or decrease the temperature of the interface as determined to modify the removal rate; A method comprising:

8. On one or more computers, causing a polishing system to polish a substrate on a polishing pad using a slurry having an abrasive; storing whether the abrasive is positively or negatively charged; calculating a removal rate for the substrate based on signals received from an in-situ monitor system; comparing the calculated removal rate to a desired removal rate; determining to increase the removal rate when the calculated removal rate is lower than the desired removal rate, and determining to decrease the removal rate when the calculated removal rate is higher than the desired removal rate; determining whether to increase or decrease the temperature of the interface between the polishing pad and the substrate based on whether the abrasive is positively or negatively charged and whether to increase or decrease the removal rate; causing a temperature control system to increase or decrease the temperature of the interface as determined to modify the removal rate; 1. A computer program product comprising instructions on a non-transitory computer-readable medium for causing a

9. 9. The computer program product of claim 8, wherein the instructions for increasing or decreasing the temperature of the interface include instructions for increasing the removal rate by increasing the temperature if the abrasive is positively charged, and instructions for increasing the removal rate by decreasing the temperature if the abrasive is negatively charged.

10. 9. The computer program product of claim 8, wherein the instructions for increasing or decreasing the temperature of the interface include instructions for decreasing the removal rate by decreasing the temperature if the abrasive is positively charged, and instructions for decreasing the removal rate by increasing the temperature if the abrasive is negatively charged.

11. A polishing system comprising: dispensing a polishing slurry onto a polishing pad; contacting a surface of a layer on a substrate with the polishing pad containing the slurry; and generating relative motion between the substrate and the polishing pad, thereby polishing the layer on the substrate; causing a temperature control system to control the polishing temperature within a first temperature range for a first polished portion of the layer; obtaining a temperature transition time that is before the endpoint time; Upon determining that the temperature transition time has been reached, increasing the pressure on the substrate while increasing the coolant flow rate with the temperature control system to continue to maintain the temperature of the polishing within the first temperature range; For subsequent polishing portions of the same layer, causing the polishing system to maintain the increased pressure and causing the temperature control system to control the temperature of the polishing to be within the first temperature range until the estimated endpoint time; A polishing method comprising:

12. The method of claim 11 , wherein the polishing slurry comprises silica abrasive particles or positively charged ceria particles.

13. The method of claim 11 , wherein the temperature transition time is set as a default value before polishing begins.

14. 12. The method of claim 11, comprising monitoring the substrate being polished with an in-situ monitoring system and determining an expected endpoint time based on a signal from the in-situ monitoring system, and obtaining the temperature transition time comprises calculating the temperature transition time based on the expected endpoint time.

15. 15. The method of claim 14, wherein calculating the temperature transition time comprises subtracting a predetermined period of time from the expected endpoint time or subtracting a percentage of the total polishing time from the expected endpoint time.

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