Water vapor generation for chemical mechanical polishing

Abstract

To provide a method capable of quickly and efficiently cleaning various components of a CMP device.SOLUTION: A water vapor generator 410 includes a canister 420 having a water inlet 432 and a water vapor outlet 436. The water vapor generator includes a barrier 426 in the canister for dividing the canister into a lower chamber 422 and an upper chamber 424. The lower chamber is arranged to receive water from the water inlet. A valve 482 of the water vapor outlet receives water vapor from the upper chamber. The barrier has a plurality of openings allowing the water vapor to transfer from the lower chamber to the upper chamber, and allows condensed water to transfer from the upper chamber to the lower chamber. The water vapor generator includes a heating element configured to apply heat to a part of the lower chamber. The water vapor generator includes a controller which is configured to change the flow rate of the water passing through the water inlet, so as to maintain a water level to the upper side of the heating element and the lower side of the water vapor outlet.SELECTED DRAWING: Figure 4A

Description

Technical Field

[0001] The present disclosure relates to chemical mechanical polishing (CMP), and more particularly to the use of steam for cleaning or preheating during CMP.

Background Art

[0002] Integrated circuits are typically formed on a substrate by sequentially depositing conductive, semiconductive, or insulating layers on a semiconductor wafer. In various manufacturing processes, planarization of the layers on the substrate is required. 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 trenches and holes within the insulating layer. After planarization, vias, plugs, and lines that provide conductive paths between thin film circuits on the substrate are formed by the portions of metal remaining in the trenches and holes of the patterned layer. As another example, a dielectric layer can be deposited on a patterned conductive layer and then planarized to enable subsequent photolithography steps.

[0003] Chemical mechanical polishing (CMP) is an accepted method of planarization. This planarization method typically requires that the substrate be attached to a carrier head. The exposed surface of the substrate is typically positioned against a rotating polishing pad. The carrier head applies a controllable load to the substrate and presses it against the polishing pad. Typically, a polishing slurry containing abrasive particles is supplied to the surface of the polishing pad.

Summary of the Invention

[0004] In one aspect, the water vapor generation device includes a canister having a water inlet and a water vapor outlet. The water vapor generation device includes a barrier within the canister that divides the canister into a lower chamber and an upper chamber. The lower chamber is arranged to receive water from the water inlet. The valve at the water vapor outlet receives water vapor from the upper chamber. The barrier has a plurality of openings for water vapor to move from the lower chamber to the upper chamber and allows condensed water to move from the upper chamber to the lower chamber. The water vapor generation device includes a heating element configured to apply heat to a portion of the lower chamber. The water vapor generation device includes a controller configured to change the flow rate of water through the water inlet to maintain a water level above the heating element and below the water vapor outlet.

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

[0006] The canister may be made of quartz. The barrier may be made of quartz. The canister and the barrier may be coated with PTFE.

[0007] A bypass pipe may connect the water inlet and the water vapor outlet in parallel with the canister. A water level sensor may be arranged to monitor the water level within the bypass pipe. The controller may be configured to receive a signal from the water level sensor. The controller may be configured to change the flow rate of water through the water inlet based on the signal from the water level sensor to maintain the water level within the canister above the heating element and below the water vapor outlet.

[0008] The plurality of openings may be positioned near the edge of the barrier. The plurality of openings may be positioned immediately adjacent to the inner diameter surface of the canister. The plurality of openings may be positioned only immediately adjacent to the inner diameter surface of the canister.

[0009] The heating element may include a heating coil. The heating coil may be wound around the lower chamber of the canister.

[0010] In one aspect, a steam generator includes a canister having a lower chamber and an upper chamber. The canister has a water inlet and a steam outlet. The lower chamber is arranged to receive water from the water inlet. A valve at the steam outlet receives steam from the upper chamber. The steam generator includes a heating element configured to apply heat to a portion of the lower chamber. The steam generator includes a controller configured to vary the flow rate of water through the water inlet to maintain a water level above the heating element and below the steam outlet.

[0011] Embodiments may include one or more of the following features.

[0012] The canister may be quartz. A bypass tube may connect the water inlet and the steam outlet in parallel with the canister. A water level sensor may monitor the water level in the bypass tube.

[0013] Potential advantages include, but are not limited to, one or more of the following.

[0014] Steam, i.e., gaseous H2O produced by boiling, can be produced in sufficient quantities with low levels of contaminants. Additionally, the steam generator can produce a substantially pure gas, e.g., steam having little or no liquid suspended therein. Such steam, also known as dry steam, can provide a gaseous form of H2O with higher energy transfer and lower liquid content than other steam alternatives such as flash steam.

[0015] Various components of the CMP apparatus can be cleaned quickly and efficiently. Steam can be more effective than liquid water in dissolving or otherwise removing polishing by-products, dry slurry, debris, etc. from surfaces within the polishing system. Thereby, defects on the substrate can be reduced.

[0016] Various components of the CMP apparatus can be preheated. Temperature variations across the entire polishing pad and thus across the entire substrate can be reduced, thereby reducing within-wafer non-uniformity (WIWNU). Temperature variations across a polishing operation can be reduced. This can improve the predictability of polishing during the CMP process. Temperature variations from one polishing operation to another can be reduced. This can improve the uniformity between wafers.

[0017] Details of one or more embodiments are described in the accompanying drawings and the following description. Other aspects, features, and advantages will become apparent from these descriptions, the drawings, and the claims.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2A

Figure 2B

Figure 3A

Figure 3B

Figure 4A

Figure 4B

Modes for Carrying Out the Invention

[0019] 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 significant amount of heat is generated due to the friction between the surface of the substrate and the polishing pad. Additionally, some processes also include in-situ pad adjustment steps, where an adjustment disk, e.g., a disk coated with polishing diamond particles, is pressed against the rotating polishing pad to adjust the surface and texture of the polishing pad. Heat can also be generated by the wear of the adjustment process. For example, in a typical 1-minute copper CMP process with a nominal downforce pressure of 2 psi and a removal rate of 8000 Å / min, the surface temperature of a polyurethane polishing pad can rise by approximately 30 degrees Celsius.

[0020] On the other hand, if the polishing pad has been heated by a previous polishing operation, when a new substrate is first lowered into contact with the polishing pad, it is at a lower temperature and can thus act as a heat sink. Similarly, the slurry dispensed onto the polishing pad can act as a heat sink. Overall, these effects result in spatial and temporal variations in the temperature of the polishing pad.

[0021] Both the chemical-related variables (e.g., the initiation and rate of the reactions involved) and the mechanical-related variables (e.g., the surface friction coefficient and viscoelasticity of the polishing pad) in the CMP process are strongly temperature-dependent. As a result, fluctuations in the surface temperature of the polishing pad can lead to changes in the removal rate, polishing uniformity, erosion, dishing, and residues. By more precisely controlling the temperature of the surface of the polishing pad during polishing, the temperature fluctuations can be reduced, and for example, the polishing performance, as measured by non-uniformity within a wafer or non-uniformity between wafers, can be improved.

[0022] Furthermore, debris and slurry can accumulate on various components of the CMP apparatus during CMP. When these polishing by-products later dislodge from the components, they can scratch or otherwise damage the substrate, increasing the likelihood of polishing defects. Water jets have been used to clean various components of the CMP apparatus system. However, a large amount of water is required to perform this operation.

[0023] A technique that can address one or more of these problems is to use water vapor, i.e., gaseous H2O generated by boiling, to clean and / or preheat various components of the CMP apparatus. For example, due to the latent heat of water vapor, less water vapor may be required to impart the same amount of energy as warm water. In addition, the water vapor can be sprayed at high speed to clean and / or preheat the components. Furthermore, water vapor can be more effective than liquid water in dissolving or otherwise removing polishing by-products.

[0024] FIG. 1 is a plan view of a chemical mechanical polishing apparatus 2 for processing one or more substrates. The polishing apparatus 2 includes a polishing platform 4 that at least partially supports and houses a plurality of polishing stations 20. For example, the polishing apparatus may include four polishing stations 20a, 20b, 20c, and 20d. Each polishing station 20 is adapted to polish a substrate held within a carrier head 70. Not all components of each station are shown in FIG. 1.

[0025] The polishing apparatus 2 also includes a number of carrier heads 70, each carrier head being configured to transport a substrate. The polishing apparatus 2 also includes a transfer station 6 for loading and unloading substrates from the carrier heads. The transfer station 6 can include a plurality of load cups 8, for example two load cups 8a, 8b, adapted to facilitate the transfer of substrates between the robot 9 and each of the carrier heads 70 by loading and unloading the carrier heads 70.

[0026] The stations of the polishing apparatus 2, including the transfer station 6 and the polishing station 20, can be arranged at substantially equal angular intervals around the center of the platform 4. This is not necessarily required, but can provide a good installation area for the polishing apparatus.

[0027] During the polishing operation, one carrier head 70 is placed at each polishing station. Two additional carrier heads can be placed within the load and unload station 6 to exchange the unpolished substrate for the polished substrate while another substrate is being polished at the polishing station 20.

[0028] The carrier heads 70 are held by a support structure that can move each carrier head along a path that passes through the first polishing station 20a, the second polishing station 20b, the third polishing station 20c, and the fourth polishing station 20d in that order. This allows each carrier head to be selectively positioned over the polishing stations 20 and the load cups 8.

[0029] In some embodiments, each carrier head 70 is coupled to a carriage 78 attached to a support structure 72. By moving the carriage 78 along the support structure 72, e.g., a track, the carrier head 70 can be positioned over a selected polishing station 20 or load cup 8. Alternatively, the carrier head 70 may be suspended from a carousel, and rotation of the carousel moves all carrier heads simultaneously along a circular path.

[0030] Each polishing station 20 of the polishing apparatus 2 may include a port, e.g., at the end of a slurry supply arm 39, for dispensing a polishing fluid 38 (see FIG. 3A), e.g., a polishing slurry, onto the polishing pad 30. Each polishing station 20 of the polishing apparatus 2 may also include a pad conditioner 93 for wearing down the polishing pad 30 to maintain the polishing pad 30 in a consistent polishing state.

[0031] FIGS. 3A and 3B illustrate an example of a polishing station 20 of a chemical mechanical polishing system. The polishing station 20 includes a rotatable disk-shaped platen 24, and the polishing pad 30 is on the platen 24. The platen 24 is operable to rotate about an axis 25 (see arrow A in FIG. 3B). For example, a motor 22 can rotate 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.

[0032] Referring to FIGS. 1, 3A, and 3B, the polishing station 20 may include a supply port, e.g., at the end of a slurry supply arm 39, for dispensing a polishing fluid 38, e.g., a polishing slurry, onto the polishing pad 30.

[0033] The polishing station 20 may include a pad conditioner 90 having a conditioner disk 92 (see FIG. 2B) to maintain the surface roughness of the polishing pad 30. The conditioner disk 92 may be disposed within a conditioner head 93 at the end of an arm 94. The arm 94 and the conditioner head 93 are supported by a base 96. The arm 94 may swing to sweep the conditioner head 93 and the conditioner disk 92 across the polishing pad 30. The cleaning cup 250 may be positioned adjacent to the platen 24 at a position where the arm 94 can move the conditioner head 93.

[0034] The carrier head 70 is operable to hold the substrate 10 against the polishing pad 30. The carrier head is suspended from a support structure 72 (e.g., a carousel or a track) so that the carrier head can rotate about an axis 71 and is coupled to a carrier head rotation motor 76 by a drive shaft 74. Optionally, the carrier head 70 can vibrate laterally, for example, by movement along a track, such as on a slider on a carousel, or by rotational vibration of the carousel itself.

[0035] The carrier head 70 may include a flexible membrane 80 having a substrate mounting surface that contacts the back side of the substrate 10 and a plurality of pressurizable chambers 82 for applying different pressures to different zones (e.g., different radial zones) on the substrate 10. The carrier head 70 may include a retaining ring 84 for holding the substrate. In some embodiments, the retaining ring 84 may include a lower plastic portion 86 that contacts the polishing pad and an upper portion 88 of a harder material, such as metal.

[0036] In operation, the platen is rotated about its central axis 25, the carrier head is rotated about its central axis 71 (see arrow B in FIG. 3B), and is translated laterally (see arrow C in FIG. 3B) across the upper surface of the polishing pad 30.

[0037] Referring to FIGS. 3A and 3B, as the carrier head 70 sweeps across the polishing pad 30, any exposed surface of the carrier head 70 tends to be covered with slurry. For example, the slurry can adhere to the outer diameter or inner diameter surface of the retaining ring 84. Generally, in the case of a surface that is not maintained in a wet state, the slurry tends to solidify and / or dry. As a result, particles can be formed on the carrier head 70. When these particles come off, the particles may scratch the substrate, resulting in polishing defects.

[0038] Furthermore, the slurry may solidify on the carrier head 70, or sodium hydroxide in the slurry may crystallize on one of the surfaces of the carrier head 70 and / or the substrate 10, which may corrode the surface of the carrier head 70. The solidified slurry is difficult to remove, and the crystallized sodium hydroxide is difficult to return to solution.

[0039] Similar problems occur with the regulator head 93. For example, particles may be formed on the regulator head 93, the slurry may solidify on the regulator head 93, or sodium hydroxide in the slurry may crystallize on one of the surfaces of the regulator head 93.

[0040] One solution is to wash the components, such as the carrier head 70 and the regulator head 93, with a liquid water jet. However, the components may be difficult to wash with the water jet alone, and a significant amount of water may be required. Furthermore, components that contact the polishing pad 30, such as the carrier head 70, the substrate 10, and the regulator disk 92, may act as heat sinks that interfere with the uniformity of the polishing pad temperature.

[0041] To address these problems, as shown in FIG. 2A, the polishing apparatus 2 includes one or more carrier head steam treatment assemblies 200. Each steam treatment assembly 200 can be used for cleaning and / or preheating the carrier head 70 and the substrate 10.

[0042] The steam treatment assembly 200 may be part of the load cup 8, such as part of load cup 8a or 8b. Alternatively or additionally, the steam treatment assembly 200 may be provided at one or more platen - between stations 9 positioned between adjacent polishing stations 20.

[0043] The load cup 8 includes a pedestal 204 for holding the substrate 10 during the load / unload process. The load cup 8 also includes a housing 206 that surrounds or substantially surrounds the pedestal 204. A plurality of nozzles 225 are supported by the housing 206 or a separate support to supply steam 245 to the carrier head and / or the substrate disposed within the cavity 208 defined by the housing 206. For example, the nozzles 225 may be disposed on one or more inner surfaces of the housing 206, such as on the floor 206a and / or side walls 206b and / or the ceiling of the cavity. The nozzles 225 may be oriented to direct steam inwardly into the cavity 206. The steam 245 may be generated using a steam generator 410, such as the steam generator described hereinafter. The drain pipe 235 may allow excess water, cleaning solution, and cleaning by - products to pass through and can prevent accumulation within the load cup 8.

[0044] The actuator provides relative vertical movement between the housing 206 and the carrier head 70. For example, a shaft 210 may support the housing 206 and be operable in the vertical direction to raise and lower the housing 206. Alternatively, the carrier head 70 may be movable in the vertical direction. The pedestal 204 may be co - axial with the shaft 210. The pedestal 204 may be movable in the vertical direction relative to the housing 206.

[0045] In operation, the carrier head 70 may be disposed on the load cup 8, and the housing 206 may be raised (or the carrier head 70 may be lowered) such that the carrier head 70 is partially within the cavity 208. The substrate 10 may start on the pedestal 204 and be chucked on the carrier head 70, and / or may start on the carrier head 70 and be de-chucked on the pedestal 204.

[0046] Water vapor is guided through the nozzle 225 to clean and / or preheat one or more surfaces of the substrate 10 and / or the carrier head 70. For example, one or more of the nozzles can be arranged to direct water vapor to the outer surface of the carrier head 70, the outer surface 84a of the retaining ring 84, and / or the lower surface 84b of the retaining ring 84. One or more of the nozzles can be arranged to direct water vapor to the front surface of the substrate 10 held by the carrier head 70, i.e., the surface to be polished, or to the lower surface of the film 80 if the substrate 10 is not supported on the carrier head 70. One or more nozzles can be arranged below the pedestal 204 to direct water vapor upward to the front surface of the substrate 10 disposed on the pedestal 204. One or more nozzles can be arranged above the pedestal 204 to direct water vapor downward to the back surface of the substrate 10 disposed on the pedestal 204. The carrier head 70 can rotate within the load cup 8 and / or move in a direction perpendicular to the load cup 8 so that the nozzle 225 can process various areas of the carrier head 70 and / or the substrate 10. The substrate 10 can be placed on the pedestal 204 so that the inner surface of the carrier head 70, e.g., the lower surface of the film 80 or the inner surface of the retaining ring 84, can be treated with water vapor.

[0047] Water vapor is circulated from a water vapor source through a supply line 230 through the housing 206 to the nozzle 225. The nozzle 225 can spray water vapor 245 to remove organic residues, by-products, debris, and slurry particles remaining on the carrier head 70 and the substrate 10 after each polishing operation. The nozzle 225 can spray water vapor 245 to heat the substrate 10 and / or the carrier head 70.

[0048] The inter-platen station 9 can be similarly constructed and operated, but it does not necessarily have to have a substrate support pedestal.

[0049] The water vapor 245 supplied by the nozzle 225 can have adjustable temperature, pressure, and flow rate to vary the cleaning and preheating of the carrier head 70 and the substrate 10. In some embodiments, the temperature, pressure, and / or flow rate can be adjusted independently for each nozzle or among groups of nozzles.

[0050] For example, the temperature of the water vapor 245 can be 90 - 200 °C when the water vapor 245 is generated (e.g., in the water vapor generator 410 of FIG. 4A). When the water vapor 245 is dispensed by the nozzle 225, the temperature of the water vapor 245 can be between 90 and 150 °C, for example, due to heat loss during movement. In some embodiments, the water vapor is supplied by the nozzle 225 at a temperature of 70 - 100 °C, for example 80 - 90 °C. In some embodiments, the water vapor supplied by the nozzle is superheated, i.e., at a temperature above the boiling point.

[0051] The flow rate of the water vapor 245 can be 1 - 1000 cc / min when the water vapor 245 is supplied by the nozzle 225, depending on the output and pressure of the heater. In some embodiments, the water vapor is mixed with other gases, for example, mixed with normal atmosphere or N2. Alternatively, the fluid supplied by the nozzle 225 is substantially pure water. In some embodiments, the water vapor 245 supplied by the nozzle 225 is mixed with liquid water, for example, aerosolized water. For example, the liquid water and the water vapor can be combined at a relative flow rate ratio of 1:1 to 1:10 (e.g., at a flow rate in sccm). However, when the amount of liquid water is small, for example, less than 5 wt%, for example, less than 3 wt%, for example, less than 1 wt%, the water vapor will have excellent heat transfer characteristics. Therefore, in some embodiments, the water vapor is dry water vapor, i.e., substantially free of water droplets.

[0052] To avoid film degradation due to heat, water can be mixed with the water vapor 245 to lower the temperature, for example, to about 40 - 50 °C. The temperature of the water vapor 245 can be reduced by mixing the cooled water into the water vapor 245, or by mixing water at the same or substantially the same temperature into the water vapor 245 (since liquid water transfers less energy than gaseous water).

[0053] In some embodiments, a temperature sensor 214 can be installed within or adjacent to the steam treatment assembly 200 to detect the temperature of the carrier head 70 and / or the substrate 10. The signal from the sensor 214 can be received by the controller 12 to monitor the temperature of the carrier head 70 and / or the substrate 10. The controller 12 can control the supply of steam by the assembly 100 based on the temperature measurements from the temperature sensor 214. For example, the controller can receive a target temperature value. If the controller 12 detects that the measured temperature value exceeds the target temperature value, the controller 12 stops the flow of steam. As another example, the controller 12 can reduce the supply flow rate of the steam and / or reduce the temperature of the steam, for example, to prevent overheating of components during cleaning and / or preheating.

[0054] In some embodiments, the controller 12 includes a timer. In this case, the controller 12 can start when starting the supply of steam and can stop the supply of steam when the timer expires. The timer can be set based on empirical tests to achieve the desired temperature of the carrier head 70 and the substrate 10 during cleaning and / or preheating.

[0055] Figure 2B shows a regulator steam treatment assembly 250 that includes a housing 255. The housing 255 can take the form of a "cup" for receiving a regulator disk 92 and a regulator head 93. Steam is circulated through a supply line 280 in the housing 255 to one or more nozzles 275. The nozzles 275 can spray steam 295 to remove abrasive by-products, such as debris or slurry particles, left on the regulator disk 92 and / or the regulator head 93 after each adjustment operation. The nozzles 275 can be positioned within the housing 255, for example, on the floor, sidewall, or ceiling inside the housing 255. One or more nozzles can be arranged to clean the lower surface of the pad regulator disk and / or the lower surface, sidewall, and / or upper surface of the regulator head 93. A steam generator 410 can be used to generate the steam 295. A drain pipe 285 can allow excess water, cleaning solution, and cleaning by-products to pass through and prevent accumulation within the housing 255.

[0056] The regulator head 93 and the regulator disk 92 can be at least partially lowered into the housing 255 that is steam-treated. When the regulator disk 92 is returned to operation, the regulator head 93 and the adjustment disk 92 are lifted from the housing 255 and placed on the polishing pad 30 to adjust the polishing pad 30. When the adjustment operation is completed, the regulator head 93 and the adjustment disk 92 are lifted from the polishing pad and swung back into the housing cup 255 for removing abrasive by-products on the regulator head 93 and the regulator disk 92. In some embodiments, the housing 255 is vertically operable and is, for example, attached to a vertical drive shaft 260.

[0057] The housing 255 is arranged to receive the pad regulator disk 92 and the regulator head 93. The regulator disk 92 and the regulator head 93 are rotatable within the housing 255 and / or movable vertically within the housing 255 to enable the nozzles 275 to steam-treat various surfaces of the regulator disk 92 and the regulator head 93.

[0058] The steam 295 supplied by the nozzle 275 may have an adjustable temperature, pressure, and / or flow rate. In some embodiments, the temperature, pressure, and / or flow rate may be adjustable independently for each nozzle or among groups of nozzles. This enables variations in the cleaning of the regulator disk 92 or the regulator head 93, and thus the cleaning becomes more effective.

[0059] For example, the temperature of the steam 295 can be between 90 and 200 °C when the steam 295 is generated (e.g., within the steam generator 410 of FIG. 4A). When the steam 295 is dispensed by the nozzle 275, the temperature of the steam 295 can be between 90 and 150 °C, for example due to heat loss during movement. In some embodiments, the steam can be supplied by the nozzle 275 at a temperature between 70 and 100 °C, such as between 80 and 90 °C. In some embodiments, the steam supplied by the nozzle is superheated, i.e., at a temperature above the boiling point.

[0060] The flow rate of the steam 295 can be between 1 and 1000 cc / min when the steam 295 is supplied by the nozzle 275. In some embodiments, the steam is mixed with other gases, for example, with normal atmosphere or N2. Alternatively, the fluid supplied by the nozzle 275 is substantially pure water. In some embodiments, the steam 295 supplied by the nozzle 275 is mixed with liquid water, such as aerosolized water. For example, the liquid water and the steam may be combined at a relative flow rate ratio of 1:1 to 1:10 (e.g., at a flow rate in sccm). However, when the amount of liquid water is small, for example, less than 5 wt%, for example, less than 3 wt%, for example, less than 1 wt%, the steam will have excellent heat transfer characteristics. Thus, in some embodiments, the steam is dry steam, i.e., substantially free of water droplets.

[0061] In some embodiments, the temperature sensor 264 may be disposed within or adjacent to the housing 255 to detect the temperature of the regulator head 93 and / or the regulator disk 92. The signal from the temperature sensor 264 is received by the controller 12 to monitor the temperature of the regulator head 93 or the regulator disk 92 and detect the temperature of the pad regulator disk 92. The controller 12 can control the supply of water vapor by the assembly 250 based on the temperature measurement from the temperature sensor 264. For example, the controller can receive a target temperature value. When the controller 12 detects that the temperature measurement exceeds the target temperature value, the controller 12 stops the flow of water vapor. As another example, the controller 12 can reduce the supply flow rate of water vapor and / or reduce the temperature of the water vapor, for example, to prevent overheating of components during cleaning and / or preheating.

[0062] In some embodiments, the controller 12 includes a timer. In this case, the controller 12 may start when starting the supply of water vapor and can stop the supply of water vapor when the timer expires. The timer may be set based on empirical tests to achieve the desired temperature of the regulator disk 92 during cleaning and / or preheating, for example, to prevent overheating.

[0063] Referring to FIG. 3A, in some embodiments, the polishing station 20 includes a temperature sensor 64 for monitoring the temperature within the polishing station or within a component of the polishing station / within the polishing station, such as the temperature of the polishing pad 30 and / or the slurry 38 on the polishing pad. For example, the temperature sensor 64 may be an infrared (IR) sensor, an infrared (IR) sensor (e.g., an IR camera) disposed above the polishing pad 30 and configured to measure the temperature of the polishing pad 30 and / or the slurry 38 on the polishing pad. In particular, the temperature sensor 64 may be configured to measure the temperature at a plurality of points along the radius of the polishing pad 30 in order to generate a radial temperature profile. For example, the IR camera may have a field of view that extends across the radius of the polishing pad 30.

[0064] In some embodiments, the temperature sensor is a contact sensor rather than a non-contact sensor. For example, the temperature sensor 64 may be a thermocouple or an IR thermometer disposed on or within the platen 24. Further, the temperature sensor 64 may be in direct contact with the polishing pad.

[0065] In some embodiments, a plurality of temperature sensors can be spaced apart at various radial positions across the polishing pad 30 in order to provide temperature at a plurality of points along the radius of the polishing pad 30. This technique can be used alternatively or additionally to an IR camera.

[0066] Although shown in FIG. 3A as being disposed to monitor the temperature of the polishing pad 30 and / or the slurry 38 on the pad 30, the temperature sensor 64 may be disposed inside the carrier head 70 to measure the temperature of the substrate 10. The temperature sensor 64 can be in direct contact (i.e., a contacting sensor) with the semiconductor wafer of the substrate 10. In some embodiments, for example, a plurality of temperature sensors are included within the polishing station 22 to measure the temperature of various components within the polishing station / within the polishing station.

[0067] 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 may include a cooling system 102 and / or a heating system 104. At least one of the cooling system 102 and the heating system 104, and in some embodiments both, operate by supplying a temperature control medium (e.g., a liquid, vapor, or mist) onto the polishing surface 36 of the polishing pad 30 (or onto the polishing liquid already present on the polishing pad).

[0068] In the cooling system 102, the cooling medium may be a gas (e.g., air) or a liquid (e.g., water). The medium may be at room temperature or cooled to below room temperature (e.g., 5 to 15 degrees Celsius). In some embodiments, the cooling system 102 uses a mist of air and liquid (e.g., an aerosolized mist of a liquid such as water). In particular, the cooling system can have nozzles that generate an aerosolized mist of water cooled to below room temperature. In some embodiments, a solid material can be mixed with the gas and / or liquid. The solid material may be a cooled material (e.g., ice) or a material that absorbs heat when dissolved in water (e.g., by a chemical reaction).

[0069] The cooling medium can be supplied by flowing through one or more apertures (e.g., holes or slots optionally formed within the nozzles) within a coolant supply arm. The apertures can be provided by a manifold connected to a source of coolant.

[0070] As shown in FIGS. 3A and 3B, an exemplary cooling system 102 includes an arm 110 that extends over the platen 24 and the polishing pad 30 from the edge of the polishing pad towards or near the center of the polishing pad 30 (e.g., within 5% of the overall radius of the polishing pad). The arm 110 may be supported by a base 112, which may be supported on the same frame 40 as the platen 24. The base 112 may include one or more actuators, such as a linear actuator to raise or lower the arm 110 and / or a rotational actuator to swing the arm 110 laterally over the platen 24. The arm 110 is arranged to avoid collisions with other hardware components such as the polishing head 70, the pad adjustment disk 92, and the slurry dispensing arm 39.

[0071] The exemplary cooling system 102 includes a plurality of nozzles 120 suspended from the arm 110. Each nozzle 120 is configured to spray a liquid cooling medium (e.g., water) onto the polishing pad 30. The arm 110 may be supported by the base 112 such that the nozzles 120 are separated from the polishing pad 30 by a gap 126.

[0072] Each nozzle 120 may be configured to direct aerosolized water within the mist 122 onto the polishing pad 30. The cooling system 102 may include a source 130 of the liquid cooling medium and a gas source 132 (see FIG. 3B). The liquid from the source 130 and the gas from the source 132 may be mixed, for example, within a mixing chamber 134 (see FIG. 3A) within or on the arm 110 before being directed through the nozzles 120 to generate the mist 122.

[0073] In some embodiments, process parameters, such as flow rate, pressure, temperature, and / or the mixing ratio of liquid and gas, can be controlled independently for each nozzle. For example, the coolant for each nozzle 120 can flow through an independently controllable cooler to independently control the temperature of the mist. As another example, a set of separate pumps for gas and liquid can be connected to each nozzle to independently control the flow rate, pressure, and the mixing ratio of gas and liquid for each nozzle.

[0074] The various nozzles can spray onto various radial zones 124 on the polishing pad 30. Adjacent radial zones 124 may overlap. In some embodiments, the nozzle 120 generates a mist that impinges on the polishing pad 30 along an elongated region 128. For example, the nozzle can be configured to generate a mist within a generally planar triangular space.

[0075] One or more of the elongated regions 128, for example all of the elongated regions 128, can have a longitudinal axis parallel to the radius extending through the region 128 (see region 128a). Alternatively, the nozzle 120 generates a conical mist.

[0076] Although FIG. 1 shows a state where the mist itself overlaps, the nozzles 120 may be oriented such that the elongated regions do not overlap. For example, at least some of the nozzles 120, for example all of the nozzles 120, may be oriented such that the elongated region 128 is at an oblique angle to the radius passing through the elongated region (see 128b).

[0077] At least some of the nozzles 120 may be oriented such that the central axis of the spray (see arrow A) from the nozzle is at an oblique angle to the polishing surface 36. In particular, the mist 122 can be directed from the nozzle 120 such that it has a horizontal component in a direction opposite to the direction of movement of the polishing pad 30 within the region of impact caused by the rotation of the platen 24 (see arrow A).

[0078] Figures 3A and 3B show the nozzles 120 as being arranged at uniform intervals, but this is not necessarily required. The nozzles 120 may be non-uniformly distributed either radially or angularly or both. For example, the nozzles 120 can be clustered more densely along the radial direction towards the edge of the polishing pad 30. Additionally, although Figures 3A and 3B show nine nozzles, a greater or fewer number of nozzles, for example, from three to twenty nozzles, may be present.

[0079] In the heating system 104, the heating medium may be a gas, such as steam (e.g., from a steam generator 410, see Figure 4A), or heated air, or a liquid, such as heated water, or a combination of a gas and a liquid. The medium is above room temperature (e.g., 40 to 120 degrees Celsius, e.g., 90 to 110 degrees Celsius). The medium may be water (substantially pure deionized water or water containing additives or chemicals). In some embodiments, the heating system 104 uses a spray of steam. The steam may contain additives or chemicals.

[0080] The heating medium can be supplied by flowing through apertures (e.g., holes or slots provided by one or more nozzles) on the heating supply arm. The apertures can be provided by a manifold connected to the source of the heating medium.

[0081] The exemplary heating system 104 includes an arm 140 that extends over the platen 24 and the polishing pad 30 from the edge of the polishing pad towards or near the center of the polishing pad 30 (e.g., within 5% of the entire radius of the polishing pad). The arm 140 may be supported by a base 142, and the base 142 may be supported on the same frame 40 as the platen 24. The base 142 may include one or more actuators, such as a linear actuator that raises or lowers the arm 140 and / or a rotary actuator that swings the arm 140 laterally over the platen 24. The arm 140 is arranged to avoid collisions with other hardware components such as the polishing head 70, the pad adjustment disk 92, and the slurry dispensing arm 39.

[0082] Along the direction of rotation of the platen 24, the arm 140 of the heating system 104 can be arranged between the arm 110 of the cooling system 102 and the carrier head 70. Along the direction of rotation of the platen 24, the arm 140 of the heating system 104 can be arranged between the arm 110 of the cooling system 102 and the slurry supply arm 39. For example, the arm 110 of the cooling system 102, the arm 140 of the heating system 104, the slurry supply arm 39, and the carrier head 70 can be arranged in order along the direction of rotation of the platen 24.

[0083] A plurality of openings 144 are formed in the lower surface of the arm 140. Each opening 144 is configured to direct a gas or vapor, such as steam, onto the polishing pad 30. The arm 140 may be supported by the base 142 such that the openings 144 are separated from the polishing pad 30 by a gap. The gap may be between 0.5 and 5 mm. In particular, the gap may be selected such that the heat of the heated fluid does not dissipate significantly before the fluid reaches the polishing pad. For example, the gap can be selected such that the steam released from the openings does not condense before reaching the polishing pad.

[0084] The heating system 104 can include a source 148 of water vapor, such as a water vapor generator 410 (see FIG. 4A), which can be connected to the arm 140 by piping. Each opening 144 may be configured to direct water vapor to the polishing pad 30.

[0085] In some embodiments, process parameters, such as flow rate, pressure, temperature, and / or the mixing ratio of liquid and gas, can be controlled independently for each nozzle. For example, the fluid for each opening 144 can flow through an independently controllable heater to independently control the temperature of the heated fluid, such as the temperature of the water vapor.

[0086] The various openings 144 can direct water vapor onto different radial zones on the polishing pad 30. Adjacent radial zones can overlap. Optionally, a portion of the openings 144 may be oriented such that the central axis of the spray from the opening is at an oblique angle to the polishing surface 36. The water vapor can be directed from one or more of the openings 144 to have a horizontal component in a direction opposite to the direction of movement of the polishing pad 30 within the region of impact caused by the rotation of the platen 24.

[0087] FIG. 3B shows the openings 144 arranged at uniform intervals, but this is not necessarily required. The nozzles 120 may be non-uniformly distributed either radially or angularly or both. For example, the openings 144 can cluster more densely towards the center of the polishing pad 30. As another example, the openings 144 can cluster more densely at a radius corresponding to the radius at which the polishing liquid 38 is supplied to the polishing pad 30 by the slurry supply arm 39. Further, FIG. 3B shows nine openings, but more or fewer openings may be present.

[0088] The polishing system 20 may also include a high-pressure rinse system 106. The high-pressure rinse system 106 includes a plurality of nozzles 154 (e.g., from 3 to 20 nozzles) that direct a cleaning fluid, such as water, onto the polishing pad 30 with high intensity to clean the pad 30 and remove used slurry, polishing debris, and the like.

[0089] As shown in FIG. 3B, an exemplary rinse system 106 includes an arm 150 that extends over the platen 24 and the polishing pad 30 from the edge of the polishing pad towards or near the center of the polishing pad 30 (e.g., within 5% of the total radius of the polishing pad). The arm 150 may be supported by a base 152, and the base 152 may be supported on the same frame 40 as the platen 24. The base 152 may include one or more actuators, such as a linear actuator that raises or lowers the arm 150 and / or a rotary actuator that swings the arm 150 laterally over the platen 24. The arm 150 is arranged to avoid collisions with other hardware components such as the polishing head 70, the pad adjustment disk 92, and the slurry dispensing arm 39.

[0090] Along the direction of rotation of the platen 24, the arm 150 of the rinse system 106 may be between the arm 110 of the cooling system 102 and the arm 140 of the heating system 104. For example, the arm 110 of the cooling system 102, the arm 150 of the rinse system 106, the arm 140 of the heating system 104, the slurry supply arm 39, and the carrier head 70 can be arranged in order along the direction of rotation of the platen 24. Alternatively, along the direction of rotation of the platen 24, the arm 110 of the cooling system 102 may be between the arm 150 of the rinse system 106 and the arm 140 of the heating system 104. For example, the arm 150 of the rinse system 106, the arm 110 of the cooling system 102, the arm 140 of the heating system 104, the slurry supply arm 39, and the carrier head 70 can be arranged in order along the direction of rotation of the platen 24.

[0091] FIG. 3B shows the apertures 154 being arranged at uniform intervals, but this is not necessarily required. Additionally, FIGS. 3A and 3B show nine nozzles, but a greater or lesser number of nozzles, for example, from three to twenty nozzles, may be present.

[0092] The polishing system 2 may also include various components, such as a controller 12 for controlling the operation of the temperature control system 100. The controller 12 is configured to receive temperature measurements from the temperature sensors 64 for each radial zone of the polishing pad. The controller 12 can compare the measured temperature profile with a desired temperature profile and generate a feedback signal to the control mechanism (e.g., actuator, power supply, pump, valve, etc.) for each nozzle or aperture. The feedback signal can be calculated by the controller 12 based on, for example, an internal feedback algorithm to adjust the amount of cooling or heating of the control mechanism so that the polishing pad and / or slurry reaches (or at least approaches) the desired temperature profile.

[0093] In some embodiments, the polishing system 20 includes a wiper blade or body 170 for uniformly dispersing the polishing fluid 38 across the polishing pad 30. Along the direction of rotation of the platen 24, the wiper blade 170 may be between the slurry supply arm 39 and the carrier head 70.

[0094] FIG. 3B shows separate arms for each subsystem, such as heating system 104, cooling system 102, and rinse system 106, and various subsystems can be included within a single assembly supported by a common arm. For example, the assembly may include a cooling module, a rinse module, a heating module, a slurry supply module, and an optional wiper module. Each module can include a body, such as an arcuate body, that can be fixed to a common mounting plate, and the common mounting plate can be fixed to the end of the arm so that the assembly can be positioned over the polishing pad 30. Various fluid supply components, such as tubes and passages, can extend inside each body. In some embodiments, the modules are individually removable from the mounting plate. Each module can have similar components for performing the functions of the arms of the associated systems described above.

[0095] Referring to FIG. 4A, steam for the processes described herein, or other applications in a chemical mechanical polishing system, can be generated using a steam generator 410. An exemplary steam generator 410 can include a canister 420 that encloses an internal space 425. The walls of the canister 420 can be made of a heat insulating material having a very low level of mineral contaminants, such as quartz. Alternatively, the walls of the canister may be formed of another material, for example, the inner surface of the canister may be coated with polytetrafluoroethylene (PTFE) or another plastic. In some embodiments, the canister 420 can be 10 to 20 inches in length and 1 to 5 inches in width.

[0096] Referring to FIGS. 4A and 4B, in some embodiments, the internal space 425 of the canister 420 is divided by a barrier 426 into a lower chamber 422 and an upper chamber 424. The barrier 426 can be made of the same material as the wall of the canister, such as a ceramic like quartz, stainless steel, aluminum, or alumina. Quartz may be excellent in that the risk of contamination is lower. The barrier 426 can substantially prevent liquid water 440 from entering the upper chamber 424 by blocking water droplets scattered by boiling water. Thereby, dry steam accumulates in the upper chamber 424.

[0097] The barrier 426 includes one or more openings 428. The openings 428 allow water vapor to move from the lower chamber 422 into the upper chamber 424. The openings 428, particularly those near the edge of the barrier 426, allow condensed water on the wall of the upper chamber 424 to drip into the lower chamber 422, reducing the liquid content in the upper chamber 424 and allowing that liquid to be reheated together with the water 440.

[0098] The openings 428 can be positioned at the edge of the barrier 426 where the barrier 426 meets the inner wall of the canister 420, for example, only at the edge. The openings 428 can be positioned near the edge of the barrier 426, for example, between the edge of the barrier 426 and the center of the barrier 426. This configuration can be advantageous in that it still allows condensed water on the side wall of the upper chamber 424 to flow out of the upper chamber while reducing the risk of liquid water droplets entering the upper chamber.

[0099] However, in some embodiments, the openings are also spaced apart and arranged uniformly away from the edge, for example, across the width of the barrier 426, for example, across the entire area of the barrier 426.

[0100] Referring to FIG. 4A, the water inlet 432 can connect the water reservoir 434 to the lower chamber 422 of the canister 420. The water inlet 432 can be disposed at or near the lower end of the canister 420 to provide water 440 to the lower chamber 422.

[0101] One or more heating elements 430 can surround a portion of the lower chamber 422 of the canister 420. The heating element 430 can be, for example, a heating coil wound around the outer periphery of the canister 420, such as a resistive heater. The heating element can also be provided by a thin film coating on the material of the side wall of the canister, and when an electric current is applied, this thin film coating can act as a heating element.

[0102] The heating element 430 can also be positioned within the lower chamber 422 of the canister 420. For example, the heating element can be coated with a material that can prevent contaminants, such as metal contaminants, from the heating element from moving into the water vapor.

[0103] The heating element 430 can apply heat to the lower portion of the canister 420 up to the minimum water level 443a. That is, the heating element 430 can cover the portion of the canister 420 below the minimum water level 443a to prevent overheating and reduce unnecessary energy consumption.

[0104] The water vapor outlet 436 can connect the upper chamber 424 to the water vapor supply passage 438. The water vapor supply passage 438 can be positioned at or near the upper end of the canister 420, such as at the ceiling of the canister 420. Thereby, water vapor can move from the canister 420 into the water vapor supply passage 438 and to various components of the CMP apparatus. Using the water vapor supply passage 438, water vapor can be directed to various areas of the chemical mechanical polishing apparatus, for example, for water vapor cleaning and preheating of the carrier head 70, the substrate 10, and the pad conditioner disk 92.

[0105] Referring to FIG. 4A, in some embodiments, a filter 470 configured to reduce contaminants in the water vapor 446 is coupled to the water vapor outlet 438. The filter 470 may be an ion exchange filter.

[0106] Water 440 can flow from the water reservoir 434 through the water inlet 432 into the lower chamber 422. The water 440 can fill the canister 420 up to a water level 442 that is at least above the heating element 430 and below the barrier 426. When the water 440 is heated, a gas medium 446 is generated and rises through the opening 428 of the barrier 426. The opening 428 allows the water vapor to rise and at the same time allows the condensed water to fall, resulting in a gas medium 446 that is substantially liquid-free water vapor (e.g., having no liquid water droplets suspended in the water vapor).

[0107] In some embodiments, the water level is determined using a water level sensor 460 that measures the water level 442 in the bypass tube 444. The bypass tube connects the water reservoir 434 to the water vapor supply passage 438 in parallel with the canister 420. The water level sensor 460 can indicate where the water level 442 is within the bypass tube 444 and thus within the canister 420. For example, the water level sensor 444 and the canister 420 are subject to equal pressure (e.g., both receive water from the same water reservoir 434 and both have the same pressure at the top, e.g., both are connected to the water vapor supply passage 438). Thus, the water level 442 is the same between the water level sensor and the canister 420. In some embodiments, the water level 442 in the water level sensor 444 can indicate the water level 442 in the canister 420 in other ways. For example, the water level 442 in the water level sensor 444 is scaled to indicate the water level 442 in the canister 420.

[0108] In operation, the water level 442 in the canister is above the minimum water level 443a and below the maximum water level 443b. The minimum water level 443a is at least above the heating element 430, and the maximum water level 443b is well below the steam outlet 436 and the barrier 426. Thereby, a gas medium 446, such as steam, accumulates near the upper end of the canister 420, and sufficient space is provided to substantially exclude liquid water.

[0109] In some embodiments, the controller 12 is coupled to a valve 480 that controls the flow rate of fluid through the water inlet 432, a valve 482 that controls the flow rate of fluid through the steam outlet 436, and / or a water level sensor 460. Using the water level sensor 460, the controller 12 is configured to adjust the flow rate of water 440 entering the canister 420 and the flow rate of gas 446 exiting the canister 420 to maintain the water level 442 above the minimum water level 443a (and above the heating element 430) and below the maximum water level 443b (and below the barrier 426, if the barrier 426 is present). The controller 12 may also be coupled to a power source 484 for the heating element 430 to control the amount of heat supplied to the water 440 in the canister 420.

[0110] Referring to FIGS. 1, 2A, 2B, 3A, 3B, and 4A, the controller 12 can monitor the temperature measurements received by sensors 64, 214, and 264 and control the temperature control system 100, the water inlet 432, and the water vapor outlet 436. The controller 12 may continuously monitor the temperature measurements and control the temperature within a feedback loop to adjust the temperatures of the polishing pad 30, the carrier head 70, and the conditioning disk 92. For example, the controller 12 can receive the temperature of the polishing pad 30 from the sensor 64 and control the water inlet 432 and the water vapor outlet 436 to control the supply of water vapor to the carrier head 70 and / or the conditioner head 93 and increase the temperature of the carrier head 70 and / or the conditioner head 93 to match the temperature of the polishing pad 30. Reducing the temperature difference helps prevent the carrier head 70 and / or the conditioner head 93 from acting as a heat sink on the relatively hot polishing pad 30 and can improve the uniformity within the wafer.

[0111] In some embodiments, the controller 12 stores the desired temperatures for the polishing pad 30, the carrier head 70, and the conditioning disk 92. The controller 12 can monitor the temperature measurements from sensors 64, 214, and 264 and control the temperature control system 100, the water inlet 432, and the water vapor outlet 436 to set the temperatures of the polishing pad 30, the carrier head 70, and / or the conditioning disk 92 to the desired temperatures. By achieving the desired temperatures, the controller 12 can improve the uniformity within the wafer and the uniformity between wafers.

[0112] Alternatively, the controller 12 can set the temperatures of the carrier head 70 and / or the conditioner head 93 slightly higher than the temperature of the polishing pad 30, allowing the carrier head 70 and / or the conditioner head 93 to be cooled to the same or substantially the same temperature as the polishing pad 30 when moving from their respective cleaning and preheating stations to the polishing pad 30.

[0113] Numerous embodiments of the present invention have been described. However, it should be understood that various modifications can be made without departing from the essence and scope of the present invention. Accordingly, other embodiments are also included within the scope of the following claims.

Claims

1. A water vapor generating device, comprising: a canister having a water inlet and a water vapor outlet; a barrier within the canister dividing the canister into a lower chamber and an upper chamber, the lower chamber being positioned to receive water from the water inlet, the water vapor outlet valve receiving water vapor from the upper chamber, the barrier having a plurality of openings through which water vapor can pass from the lower chamber to the upper chamber and allowing condensed water to pass from the upper chamber to the lower chamber, at least some of the openings being positioned proximate an inner diameter surface of the canister; a heating element configured to apply heat to a portion of the lower chamber; and An apparatus comprising: a controller configured to vary a flow rate of water through the water inlet to maintain a water level above the heating element and below the water steam outlet.

2. The apparatus of claim 1 , wherein the canister and / or the barrier is quartz.

3. The apparatus of claim 1 , wherein the canister and the barrier are coated with PTFE.

4. 2. The apparatus of claim 1, further comprising a bypass line connecting said water inlet and said water vapor outlet in parallel with said canister.

5. 5. The apparatus of claim 4, further comprising a water level sensor disposed to monitor a water level in the bypass pipe, and a controller configured to receive a signal from the water level sensor, the controller configured to vary the flow rate of water through the water inlet based on the signal from the water level sensor to maintain a water level in the canister above the heating element and below the water vapor outlet.

6. The apparatus of claim 1 , wherein the plurality of openings are located only proximate the inner diameter surface of the canister.

7. The apparatus of claim 1 , wherein the heating element comprises a heating coil.

8. The apparatus of claim 7 , wherein the heating coil is wrapped around the lower chamber of the canister.

9. The apparatus of claim 1 , wherein the water inlet is below a top end of the heating element.

10. 10. The apparatus of claim 9, wherein the water inlet is at a lower end of the lower chamber of the canister.

11. A water vapor generating device, comprising: a canister having a lower chamber and an upper chamber, the canister having a water inlet and a water vapor outlet, the lower chamber being arranged to receive water from the water inlet and a water vapor outlet valve to receive water vapor from the upper chamber; a heating element configured to apply heat to a portion of the lower chamber; and An apparatus comprising: a controller configured to vary a flow rate of water through the water inlet to maintain a water level above the heating element and below the water steam outlet.

12. 12. The apparatus of claim 11, further comprising a bypass line connecting the water inlet and the water vapor outlet in parallel with the canister.

13. 13. The apparatus of claim 12, further comprising a water level sensor for monitoring a water level in the bypass pipe, the controller being configured to vary the flow rate of water through the water inlet based on a signal from the water level sensor.

14. a platen for supporting the polishing pad; a carrier head for holding a substrate in contact with the polishing pad; a motor for generating relative motion between the platen and the carrier head; a water vapor generator, the water vapor generator comprising: a canister having a water inlet and a water vapor outlet; a barrier within the canister dividing the canister into a lower chamber and an upper chamber, the lower chamber being arranged to receive water from the water inlet, the water vapor outlet valve receiving water vapor from the upper chamber, the barrier having a plurality of openings through which water vapor can pass from the lower chamber to the upper chamber, and allowing condensed water to pass from the upper chamber to the lower chamber; a heating element configured to apply heat to a portion of the lower chamber; and a controller configured to vary a flow rate of water through the water inlet to maintain a water level above the heating element and below the water steam outlet; The chemical mechanical polishing system further comprises:

1. A chemical mechanical polishing system comprising: an arm extending over the platen; and at least one nozzle connected to the water vapor outlet of the water vapor generator and oriented to deliver water vapor from the water vapor generator onto the polishing pad.

Images