Water vapor generation for chemical mechanical polishing

Abstract

To provide use of steam for cleaning or preheating in chemical mechanical polishing.SOLUTION: A steam generating apparatus 410 includes a barrier 426 provided in a canister 420 and dividing the canister 420 into a lower chamber 422 and an upper chamber 424. The lower chamber 422 is positioned to receive water 440 from a water inlet 432. A valve 482 of a steam outlet 436 receives steam 446 from the upper chamber 424. The barrier 426 has a plurality of apertures 428 for the steam 446 to pass from the lower chamber 422 to the upper chamber 424 and allows condensed water to pass from the upper chamber 424 to the lower chamber 422. The steam generating apparatus 410 includes a heating element 430 configured to apply heat to a portion of the lower chamber 422, and includes a controller 12 configured to modify a flow rate of water through the water inlet 432 to keep a water level 442 above the heating element 430 and below the steam outlet 436.SELECTED DRAWING: Figure 4A

Description

[Technical field]

[0001] This disclosure relates to chemical mechanical polishing (CMP), and in particular to the use of steam for cleaning or preheating during CMP. [Background technology]

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

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

[0004] In one aspect, a water vapor generating device includes a canister having a water inlet and a water vapor outlet. The water vapor generating device includes a barrier within the canister dividing the canister into a lower chamber and an upper chamber. The lower chamber is positioned to receive water from the water inlet. A valve at the water vapor outlet receives water vapor from the upper chamber. The barrier has a number of openings for water vapor to pass from the lower chamber to the upper chamber and allows condensed water to pass from the upper chamber to the lower chamber. The water vapor generating device includes a heating element configured to apply heat to a portion of the lower chamber. The water vapor generating device 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 water vapor outlet.

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

[0006] The canister may be quartz. The barrier may be quartz. The canister and 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 positioned to monitor the water level in the bypass pipe. The controller may be configured to receive a signal from the water level sensor. The controller may be configured to vary the flow rate of water through the water inlet based on the signal from the water level sensor to keep the water level in the canister above the heating element and below the water vapor outlet.

[0008] The openings may be located near an edge of the barrier. The openings may be located proximate to an inner diameter surface of the canister. The openings may be located only proximate to an inner diameter surface of the canister.

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

[0010] In one aspect, a water vapor generating device includes a canister having a lower chamber and an upper chamber. The canister has a water inlet and a water vapor outlet. The lower chamber is positioned to receive water from the water inlet. A valve on the water vapor outlet receives water vapor from the upper chamber. The water vapor generating device includes a heating element configured to apply heat to a portion of the lower chamber. The water vapor generating device includes 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 vapor outlet.

[0011] Implementations 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 water vapor outlet in parallel with the canister. A water level sensor may monitor the water level in the bypass tube.

[0013] Potential advantages may 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. In addition, steam generators can produce substantially pure gas, e.g., steam with little or no liquid suspended in the steam. 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 quickly and efficiently cleaned. Water vapor can be more effective than liquid water at dissolving or otherwise removing polishing by-products, dried slurry, debris, etc. from surfaces in the polishing system, thereby reducing defects on the substrate.

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

[0017] The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other aspects, features, and advantages will become apparent from the description and drawings, and from the claims. [Brief description of the drawings]

[0018] [Figure 1] 1 is a schematic plan view of an embodiment of a polishing apparatus; [Figure 2A] 1 is a schematic cross-sectional view of an exemplary carrier head water vapor processing assembly. [Figure 2B] 1 is a schematic cross-sectional view of an exemplary conditioning head water vapor processing assembly. [Figure 3A] 1 is a schematic cross-sectional view of one embodiment of a polishing station of a polishing apparatus. [Figure 3B] 1 is a schematic top view of an exemplary polishing station of a chemical mechanical polishing apparatus. [Figure 4A] 1 is a schematic cross-sectional view of an exemplary water vapor generator. [Figure 4B] 1 is a schematic cross-sectional top view of an exemplary water vapor generator. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Chemical mechanical polishing works by a combination of mechanical wear and chemical etching at the interface between the substrate, the polishing fluid, and the polishing pad. During the polishing process, friction between the surface of the substrate and the polishing pad generates a significant amount of heat. In addition, some processes also include an in-situ pad conditioning step, in which a conditioning disk, for example a disk coated with abrasive diamond particles, is pressed against the rotating polishing pad to condition and texture the surface of the polishing pad. Heat can also be generated by wear during the conditioning 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 increase by about 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 will be at a lower temperature and therefore may act as a heat sink. Similarly, the slurry dispensed onto the polishing pad may act as a heat sink. Overall, these effects result in spatial and temporal variations in the temperature of the polishing pad.

[0021] Both chemically related variables (e.g., the onset and rate of the reactions involved) and mechanically related variables (e.g., the surface friction coefficient and viscoelasticity of the polishing pad) in the CMP process are strongly temperature dependent. As a result, variations in the surface temperature of the polishing pad can lead to changes in removal rate, polishing uniformity, erosion, dishing, and residue. By controlling the surface temperature of the polishing pad more closely during polishing, the temperature variations can be reduced, and the polishing performance, as measured, for example, as intra-wafer or inter-wafer non-uniformity, can be improved.

[0022] Additionally, debris and slurry can accumulate on various components of the CMP apparatus during CMP. If these polishing by-products later break off from the components, they can scratch or otherwise damage the substrate, increasing polishing defects. Water jets have been used to clean various components of the CMP apparatus system. However, large amounts of water are required to perform this task.

[0023] A technique that can address one or more of these problems is to use water vapor, i.e., gaseous H2O produced by boiling, to clean and / or preheat various components of a 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 hot water. In addition, water vapor can be sprayed at high velocities to clean and / or preheat components. Furthermore, water vapor can be more effective than liquid water in dissolving or otherwise removing polishing by-products.

[0024] 1 is a top 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.

[0025] The polishing apparatus 2 also includes a number of carrier heads 70, each 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 may include multiple load cups 8, e.g., two load cups 8a, 8b, adapted to facilitate transfer of substrates between the carrier heads 70 and a factory interface (not shown) or other device (not shown) by a transfer robot 9. The load cups 8 generally facilitate transfer 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, may be disposed at substantially equal angular intervals about the center of the platform 4. This is not necessary, but may provide a good footprint for the polishing apparatus.

[0027] In a polishing operation, one carrier head 70 is positioned at each polishing station. Two additional carrier heads can be positioned in the load and unload station 6 to exchange polished substrates for unpolished substrates while other substrates are being polished at the polishing stations 20.

[0028] Carrier heads 70 are carried by a support structure that allows each carrier head to be moved along a path that passes through first polishing station 20a, second polishing station 20b, third polishing station 20c, and fourth polishing station 20d in that order, such that each carrier head can be selectively positioned over polishing stations 20 and load cup 8.

[0029] In some embodiments, each carrier head 70 is coupled to a carriage 78 that is mounted on the support structure 72. The carriage 78 can be moved along the support structure 72, e.g., a track, to position the carrier head 70 over a selected polishing station 20 or load cup 8. Alternatively, the carrier heads 70 can be suspended from a carousel, the rotation of which moves all of the carrier heads simultaneously along a circular path.

[0030] Each polishing station 20 of the polishing apparatus 2 may include a port, for example, at the end of a slurry delivery arm 39, for dispensing a polishing fluid 38 (see FIG. 3A), such as 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 abrading the polishing pad 30 to maintain the polishing pad 30 in a consistent polishing condition.

[0031] 3A and 3B show an embodiment of a polishing station 20 of a chemical mechanical polishing system. The polishing station 20 includes a rotatable, disk-shaped platen 24 on which a polishing pad 30 rests. The platen 24 is operable to rotate about an axis 25 (see arrow A in FIG. 3B). For example, a motor 22 can turn a drive shaft 28 to rotate the platen 24. The polishing pad 30 can be a two-layer polishing pad having an outer polishing layer 34 and a softer backing layer 32.

[0032] 1, 3A, and 3B, polishing station 20 may include a supply port, for example, at the end of a slurry supply arm 39, for dispensing polishing fluid 38, for example, a polishing slurry, onto 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 in a conditioner head 93 at the end of an arm 94. The arm 94 and conditioner head 93 are supported by a base 96. The arm 94 may swing to sweep the conditioner head 93 and conditioner disk 92 across the polishing pad 30. A wash cup 250 may be positioned adjacent to the platen 24 in a position that allows the arm 94 to move the conditioner head 93.

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

[0035] Carrier head 70 may include a flexible membrane 80 having a substrate mounting surface that contacts the backside of substrate 10 and a number of pressurizable chambers 82 for applying different pressures to different zones (e.g., different radial zones) on substrate 10. Carrier head 70 may include a retaining ring 84 for holding the substrate. In some embodiments, 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 a metal.

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

[0037] 3A and 3B, as the carrier head 70 sweeps across the polishing pad 30, any exposed surfaces of the carrier head 70 tend to become covered with slurry. For example, the slurry may adhere to the outer or inner diameter surfaces of the retaining ring 84. Generally, for surfaces that are not kept wet, the slurry tends to solidify and / or dry. As a result, particles may form on the carrier head 70. When these particles become dislodged, they can scratch the substrate, causing polishing defects.

[0038] Additionally, the slurry may solidify on the carrier head 70 or the sodium hydroxide in the slurry may crystallize on the surface of the carrier head 70 and / or one of the substrates 10 and corrode the surface of the carrier head 70. The solidified slurry is difficult to remove and the crystallized sodium hydroxide is difficult to put back into solution.

[0039] Similar problems may occur with the regulator head 93, for example particles may form on the regulator head 93, the slurry may cake 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 clean the components, such as the carrier head 70 and the conditioner head 93, with a liquid water jet. However, the components can be difficult to clean with a water jet alone and may require significant amounts of water. Additionally, the components in contact with the polishing pad 30, such as the carrier head 70, the substrate 10, and the conditioner disk 92, may act as a heat sink that impedes polishing pad temperature uniformity.

[0041] 2A, the polishing apparatus 2 includes one or more carrier head water vapor processing assemblies 200. Each water vapor processing assembly 200 can be used to clean and / or preheat the carrier head 70 and the substrate 10.

[0042] The water vapor treatment assembly 200 may be part of the load cup 8, such as part of load cup 8a or 8b. Alternatively or additionally, the water vapor treatment assembly 200 may be provided in one or more inter-platen 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 for supplying water vapor 245 to the carrier head and / or substrate disposed within a cavity 208 defined by the housing 206. For example, the nozzles 225 may be disposed on one or more interior surfaces of the housing 206, such as the floor 206a and / or the sidewalls 206b and / or the ceiling of the cavity. The nozzles 225 may be oriented to direct water vapor inwardly into the cavity 206. The water vapor 245 may be generated using a water vapor generator 410, such as the water vapor generators described below. A drain 235 may allow excess water, cleaning solution, and cleaning by-products to pass and prevent buildup within the load cup 8.

[0044] The actuator provides relative vertical motion between the housing 206 and the carrier head 70. For example, the shaft 210 may support the housing 206 and be vertically actuable to raise and lower the housing 206. Alternatively, the carrier head 70 may be movable vertically. The pedestal 204 may be coaxial with the shaft 210. The pedestal 204 may be vertically movable relative to the housing 206.

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

[0046] The water vapor is directed through the nozzles 225 to clean and / or preheat one or more surfaces of the substrate 10 and / or carrier head 70. For example, one or more of the nozzles can be positioned to direct water vapor to the exterior surface of the carrier head 70, the exterior surface 84a of the retaining ring 84, and / or the underside 84b of the retaining ring 84. One or more of the nozzles can be positioned to direct water vapor to a front surface of the substrate 10 held by the carrier head 70, i.e., the surface to be polished, or to a lower surface of the membrane 80 if the substrate 10 is not supported on the carrier head 70. One or more nozzles can be positioned below the pedestal 204 to direct water vapor upward to a front surface of the substrate 10 disposed on the pedestal 204. One or more nozzles can be positioned above the pedestal 204 to direct water vapor downward to a back surface of the substrate 10 disposed on the pedestal 204. Carrier head 70 may rotate within and / or move vertically relative to load cup 8 so that nozzles 225 can treat different areas of carrier head 70 and / or substrate 10. Substrate 10 may be placed on pedestal 204 so that an inner surface of carrier head 70, such as the underside of membrane 80 or the inner surface of retaining ring 84, can be steam treated.

[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 substrate 10 after each polishing operation. The nozzle 225 can spray water vapor 245 to heat the substrate 10 and / or carrier head 70.

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

[0049] The water vapor 245 delivered by the nozzles 225 can have an adjustable temperature, pressure, and flow rate to vary the cleaning and pre-heating of the carrier head 70 and the substrate 10. In some embodiments, the temperature, pressure, and / or flow rate can be independently adjustable 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., e.g., due to heat losses in transit. In some embodiments, the water vapor is delivered by the nozzle 225 at a temperature of 70-100° C., e.g., 80-90° C. In some embodiments, the water vapor delivered by the nozzle is superheated, i.e., at a temperature above the boiling point.

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

[0052] To avoid thermal degradation of the membrane, water can be mixed with the steam 245 to reduce the temperature, for example, to about 40-50° C. The temperature of the steam 245 can be reduced by mixing cooled water into the steam 245 or by mixing water of the same or substantially the same temperature into the steam 245 (because liquid water transfers less energy than gaseous water).

[0053] In some implementations, a temperature sensor 214 may be located in or adjacent to the water vapor processing assembly 200 to detect the temperature of the carrier head 70 and / or the substrate 10. A signal from the sensor 214 may be received by the controller 12 to monitor the temperature of the carrier head 70 and / or the substrate 10. The controller 12 may control the supply of water vapor by the assembly 100 based on the temperature measurements from the temperature sensor 214. For example, the controller may receive a target temperature value. If the controller 12 detects that the temperature measurements exceed the target temperature value, the controller 12 stops the flow of water vapor. As another example, the controller 12 may reduce the supply flow rate of the water vapor and / or reduce the temperature of the water vapor, 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 may initiate when to start the supply of water vapor and may stop the supply of water vapor when the timer expires. The timer may be set based on empirical testing to achieve a desired temperature of the carrier head 70 and the substrate 10 during cleaning and / or preheating.

[0055] FIG. 2B shows a conditioner water vapor treatment assembly 250, including a housing 255. The housing 255 may take the form of a "cup" for receiving the conditioner disk 92 and the conditioner head 93. Water vapor is circulated through a supply line 280 in the housing 255 to one or more nozzles 275. The nozzles 275 may spray water vapor 295 to remove polishing by-products, such as debris or slurry particles, left on the conditioner disk 92 and / or the conditioner head 93 after each conditioning operation. The nozzles 275 may be positioned within the housing 255, for example, on the floor, sidewalls, or ceiling of the interior of the housing 255. One or more nozzles may be positioned to clean the underside of the pad conditioner disk and / or the underside, sidewalls, and / or top surface of the conditioner head 93. A water vapor generator 410 may be used to generate the water vapor 295. The drain 285 may allow excess water, cleaning solution, and cleaning by-products to pass through and prevent buildup within the housing 255.

[0056] The conditioner head 93 and conditioner disk 92 can be lowered at least partially into the housing 255 where they are steamed. When the conditioner disk 92 is returned to operation, the conditioner head 93 and conditioner disk 92 are lifted out of the housing 255 and placed on the polishing pad 30 to condition the polishing pad 30. When the conditioning operation is completed, the conditioner head 93 and conditioner disk 92 are lifted off the polishing pad and swung back into the housing cup 255 for removing polishing by-products on the conditioner head 93 and conditioner disk 92. In some embodiments, the housing 255 is vertically operable, for example, attached to a vertical drive shaft 260.

[0057] The housing 255 is positioned to receive the pad conditioner disk 92 and the conditioner head 93. The conditioner disk 92 and the conditioner head 93 are rotatable within the housing 255 and / or vertically movable within the housing 255 to allow the nozzles 275 to steam various surfaces of the conditioner disk 92 and the conditioner head 93.

[0058] The water vapor 295 delivered by the nozzles 275 may have an adjustable temperature, pressure, and / or flow rate. In some embodiments, the temperature, pressure, and / or flow rate may be independently adjustable for each nozzle or between groups of nozzles. This allows for variation in cleaning of the regulator disk 92 or regulator head 93, thus making the cleaning more effective.

[0059] For example, the temperature of the water vapor 295 can be between 90 and 200° C. when the water vapor 295 is generated (e.g., in the water vapor generator 410 of FIG. 4A). When the water vapor 295 is dispensed by the nozzle 275, the temperature of the water vapor 295 can be between 90 and 150° C., e.g., due to heat losses in transit. In some embodiments, the water vapor can be delivered by the nozzle 275 at a temperature between 70 and 100° C., e.g., between 80 and 90° C. In some embodiments, the water vapor delivered by the nozzle is superheated, i.e., at a temperature above the boiling point.

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

[0061] In some implementations, a temperature sensor 264 may be located in or adjacent to the housing 255 to detect the temperature of the regulator head 93 and / or the regulator disk 92. A signal from the temperature sensor 264 may be received by the controller 12 to monitor the temperature of the regulator head 93 or the regulator disk 92 to detect the temperature of the pad regulator disk 92. The controller 12 may control the supply of water vapor by the assembly 250 based on the temperature measurements from the temperature sensor 264. For example, the controller may receive a target temperature value. If the controller 12 detects that the temperature measurements exceed the target temperature value, the controller 12 stops the flow of water vapor. As another example, the controller 12 may reduce the supply flow rate of the water vapor and / or reduce the temperature of the water vapor, for example, to prevent overheating of components during cleaning and / or pre-heating.

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

[0063] 3A, in some embodiments, the polishing station 20 includes a temperature sensor 64 for monitoring the temperature within the polishing station or within components of 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 (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 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.

[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. Additionally, the temperature sensor 64 may be in direct contact with the polishing pad.

[0065] In some embodiments, multiple temperature sensors can 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 alternatively or in addition to an IR camera.

[0066] 3A as being positioned to monitor the temperature of the polishing pad 30 and / or the slurry 38 on the pad 30, the temperature sensor 64 may also be positioned inside the carrier head 70 to measure the temperature of the substrate 10. The temperature sensor 64 may be in direct contact (i.e., a contacting sensor) with the semiconductor wafer of the substrate 10. In some implementations, multiple temperature sensors are included within the polishing station 22, for example, to measure the temperature of various components of / 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 fluid 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 may be chilled below room temperature (e.g., 5-15 degrees Celsius). In some implementations, the cooling system 102 uses an air-liquid mist (e.g., an aerosolized mist of a liquid such as water). In particular, the cooling system may have a nozzle that creates an aerosolized mist of water that is chilled below room temperature. In some implementations, a solid material may be mixed with the gas and / or liquid. The solid material may be a chilled material (e.g., ice) or a material that absorbs heat when dissolved in water (e.g., by a chemical reaction).

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

[0070] 3A and 3B, an exemplary cooling system 102 includes an arm 110 that extends over the platen 24 and polishing pad 30 from the edge of the polishing pad to or near the center of the polishing pad 30 (e.g., within 5% of the total 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 that raises or lowers the arm 110 and / or a rotary actuator that swings the arm 110 laterally over the platen 24. The arm 110 is positioned to avoid collisions with other hardware components, such as the polishing head 70, the pad conditioning disk 92, and the slurry dispensing arm 39.

[0071] The exemplary cooling system 102 includes a plurality of nozzles 120 suspended from an 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 a 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 in a mist 122 toward the polishing pad 30. The cooling system 102 may include a source 130 of liquid cooling medium and a gas source 132 (see FIG. 3B). The liquid from source 130 and the gas from source 132 may be mixed, for example, in a mixing chamber 134 (see FIG. 3A) in or on the arm 110 before being directed through the nozzles 120 to generate the mist 122.

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

[0074] The various nozzles can spray onto different radial zones 124 on the polishing pad 30. Adjacent radial zones 124 may overlap. In some embodiments, the nozzles 120 generate a mist that impinges on the polishing pad 30 along an elongated region 128. For example, the nozzles 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, may have a longitudinal axis parallel to a radius extending through the region 128 (see region 128a). Alternatively, the nozzle 120 produces a cone-shaped mist.

[0076] 1 shows the mist overlapping, the nozzles 120 may be oriented such that the elongated regions do not overlap. For example, at least some of the nozzles 120, such as all of the nozzles 120, may be oriented such that the elongated region 128 is at an oblique angle to a 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 from that nozzle (see arrow A) is at an oblique angle to the polishing surface 36. In particular, the mist 122 may be directed from the nozzles 120 such that it has a horizontal component (see arrow A) in a direction opposite to the direction of movement of the polishing pad 30 within the region of impingement caused by the rotation of the platen 24.

[0078] 3A and 3B show the nozzles 120 as being uniformly spaced, this is not necessary. The nozzles 120 may be non-uniformly distributed either radially or angularly, or both. For example, the nozzles 120 may be clustered more tightly along the radial direction toward the edge of the polishing pad 30. In addition, while FIGS. 3A and 3B show nine nozzles, there may be a greater or lesser number of nozzles, e.g., between three and twenty nozzles.

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

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

[0081] The exemplary heating system 104 includes an arm 140 that extends over the platen 24 and polishing pad 30 from the edge of the polishing pad to or near the center of the polishing pad 30 (e.g., within 5% of the total radius of the polishing pad). The arm 140 may be supported by a base 142, which 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 positioned to avoid collisions with other hardware components, such as the polishing head 70, pad conditioning disk 92, and slurry dispensing arm 39.

[0082] Along the rotation direction of the platen 24, the arm 140 of the heating system 104 may be disposed between the arm 110 of the cooling system 102 and the carrier head 70. Along the rotation direction of the platen 24, the arm 140 of the heating system 104 may be disposed 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 may be disposed in order along the rotation direction of the platen 24.

[0083] A plurality of openings 144 are formed in the underside of the arm 140. Each opening 144 is configured to direct a gas or vapor, e.g., water vapor, onto the polishing pad 30. The arm 140 may be supported by a base 142 such that the openings 144 are separated from the polishing pad 30 by a gap. The gap may be 0.5-5 mm. In particular, the gap may be selected such that heat of the heating fluid is not significantly dissipated before the fluid reaches the polishing pad. For example, the gap may be selected such that water vapor emitted 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 can be configured to direct water vapor to the polishing pad 30.

[0085] In some implementations, process parameters such as flow rate, pressure, temperature, and / or liquid to gas mixture ratio can be independently controlled 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 heating fluid, e.g., the temperature of the water vapor.

[0086] The various openings 144 can direct the water vapor onto different radial zones on the polishing pad 30. Adjacent radial zones can overlap. Optionally, some of the openings 144 can be oriented such that the central axis of the spray from that 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 impingement caused by the rotation of the platen 24.

[0087] 3B shows the openings 144 as being uniformly spaced, but this is not necessary. The nozzles 120 may be non-uniformly distributed either radially or angularly, or both. For example, the openings 144 may be more tightly clustered toward the center of the polishing pad 30. As another example, the openings 144 may be more tightly clustered at a radius corresponding to the radius at which polishing fluid 38 is delivered to the polishing pad 30 by the slurry delivery arm 39. Additionally, while FIG. 3B shows nine openings, there may be more or fewer openings.

[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., 3 to 20 nozzles) that direct a cleaning fluid, such as water, at high intensity onto the polishing pad 30 to clean the pad 30 and remove used slurry, polishing debris, and the like.

[0089] 3B, the exemplary rinsing system 106 includes an arm 150 that extends over the platen 24 and polishing pad 30 from the edge of the polishing pad to or near the center of the polishing pad 30 (e.g., within 5% of the total radius of the polishing pad). The arm 150 may be supported by a base 152, which 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 positioned to avoid collisions with other hardware components, such as the polishing head 70, the pad conditioning disk 92, and the slurry dispensing arm 39.

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

[0091] Figure 3B shows the openings 154 as being evenly spaced, although this is not necessary. Additionally, although Figures 3A and 3B show nine nozzles, there may be a greater or lesser number of nozzles, for example, from three to twenty nozzles.

[0092] The polishing system 2 may also include a controller 12 for controlling the operation of various components, such as 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 to a desired temperature profile and generate a feedback signal to a control mechanism (e.g., actuator, power supply, pump, valve, etc.) for each nozzle or opening. The feedback signal is calculated by the controller 12, for example, based on an internal feedback algorithm, to cause the control mechanism to adjust the amount of cooling or heating 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 to evenly distribute 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 delivery arm 39 and the carrier head 70.

[0094] FIG. 3B shows separate arms for each subsystem, e.g., heating system 104, cooling system 102, and rinsing system 106, and the various subsystems can be included in a single assembly supported by a common arm. For example, the assembly can include a cooling module, a rinsing module, a heating module, a slurry supply module, and an optional wiper module. Each module can include a body, e.g., an arcuate body, that can be secured to a common mounting plate, which can be secured to the end of the arm such that the assembly is positioned above the polishing pad 30. Various fluid supply components, e.g., tubing, passages, etc., can extend inside each body. In some embodiments, the modules are individually removable from the mounting plate. Each module can have similar components to perform the functions of the arms of the associated system described above.

[0095] 4A, water vapor for processes described herein or other applications in a chemical mechanical polishing system can be generated using a water vapor generator 410. An exemplary water vapor generator 410 can include a canister 420 that encloses an interior space 425. The walls of the canister 420 can be made of an insulating material, such as quartz, that has very low levels of mineral contaminants. Alternatively, the walls of the canister can be formed of another material, for example, the inner surface of the canister can be coated with polytetrafluoroethylene (PTFE) or another plastic. In some implementations, the canister 420 can be 10-20 inches long and 1-5 inches wide.

[0096] 4A and 4B, in some embodiments, the interior space 425 of the canister 420 is divided into a lower chamber 422 and an upper chamber 424 by a barrier 426. The barrier 426 may be made of the same material as the walls of the canister, for example, quartz, stainless steel, aluminum, or a ceramic such as alumina. Quartz may be superior in that it has a lower risk of contamination. The barrier 426 may substantially prevent liquid water 440 from entering the upper chamber 424 by blocking water droplets splashed by boiling water. This causes dry water vapor to accumulate in the upper chamber 424.

[0097] The barrier 426 includes one or more openings 428. The openings 428 allow water vapor to pass from the lower chamber 422 into the upper chamber 424. The openings 428, particularly the openings 428 near the edges of the barrier 426, allow condensed water on the walls 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 along with the water 440.

[0098] The opening 428 may be located at an edge, e.g., only at the edge, of the barrier 426 where the barrier 426 meets the inner wall of the canister 420. The opening 428 may be located near the edge of the barrier 426, e.g., between the edge of the barrier 426 and the center of the barrier 426. This configuration may be advantageous in that the barrier 426 does not have an opening in the center, thus reducing the risk of liquid water droplets entering the upper chamber while still allowing condensed water on the sidewalls of the upper chamber 424 to flow out of the upper chamber.

[0099] However, in some embodiments, the openings are also spaced away from the edges, eg, across the width of the barrier 426, eg, evenly across the area of ​​the barrier 426.

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

[0101] One or more heating elements 430 may surround a portion of the lower chamber 422 of the canister 420. The heating element 430 may be, for example, a heating coil, e.g., a resistive heater, wrapped around the periphery of the canister 420. The heating element may also be provided by a thin film coating on the material of the sidewall of the canister, which may act as a heating element when an electric current is applied.

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

[0103] The heating element 430 can apply heat to a lower portion of the canister 420 up to the minimum water level 443a, i.e., 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] A water vapor outlet 436 can connect the upper chamber 424 to a water vapor supply passage 438. The water vapor supply passage 438 can be located at or near the top of the canister 420, for example, in the ceiling of the canister 420, thereby allowing water vapor to pass from the canister 420 into the water vapor supply passage 438 and to various components of the CMP apparatus. The water vapor supply passage 438 can be used to direct water vapor to various areas of the chemical mechanical polishing apparatus, for example, for water vapor cleaning and pre-heating of the carrier head 70, the substrate 10, and the pad conditioner disk 92.

[0105] 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 a water reservoir 434 through a water inlet 432 and into the lower chamber 422. The water 440 can fill the canister 420 at least to a water level 442 above the heating element 430 and below the barrier 426. As the water 440 is heated, a gaseous medium 446 is generated and rises through an opening 428 in the barrier 426. The opening 428 allows water vapor to rise and at the same time allows condensed water to fall, resulting in a gaseous medium 446 that is water vapor that is substantially liquid-free (e.g., has 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 a 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 in the bypass tube 444, and therefore in the canister 420. For example, the water level sensor 444 and the canister 420 are equally pressurized (e.g., both receive water from the same water reservoir 434, both have the same pressure at the top, e.g., both connect 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 be indicative of 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 a minimum water level 443a and below a maximum water level 443b, the minimum water level 443a being at least above the heating element 430, and the maximum water level 443b being well below the water vapor outlet 436 and the barrier 426, thereby providing enough space for the gas medium 446, e.g., water vapor, to accumulate near the top of the canister 420 and still be substantially free of 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 water vapor 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 into the canister 420 and adjust the flow rate of gas 446 out of 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 present). The controller 12 may also be coupled to a power source 484 for the heating element 430 to control the amount of heat provided to the water 440 in the canister 420.

[0110] 1, 2A, 2B, 3A, 3B, and 4A, the controller 12 can monitor the temperature measurements received by the 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 can continuously monitor the temperature measurements and control the temperature in a feedback loop to regulate the temperature 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 conditioning head 93 to increase the temperature of the carrier head 70 and / or the conditioning head 93 to match the temperature of the polishing pad 30. Reducing the temperature difference helps to prevent the carrier head 70 and / or the conditioning head 93 from acting as a heat sink on the relatively hot polishing pad 30, which can improve within-wafer uniformity.

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

[0112] Alternatively, the controller 12 can make the temperature 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 as they move from their respective cleaning and preheating stations to the polishing pad 30.

[0113] Although a number of embodiments of the invention have been described, it should be understood that various modifications can be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.

Claims

1. A water vapor generating device, comprising: a canister having a water inlet and a water vapor outlet; a barrier within the canister secured to an inner wall of the canister to divide the canister into a lower chamber and an upper chamber, the lower chamber being positioned to receive water from the water inlet at a floor of the canister, 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 including a plurality of resistive heating coils wrapped around a lower portion of the canister to apply heat to a portion of the lower chamber; Water level sensor, and a controller configured to vary a flow rate of water through the water inlet in response to a signal from the water level sensor to maintain a water level above the heating element and below the water steam outlet. An apparatus comprising:

2. The apparatus of claim 1 , wherein the canister is quartz.

3. The apparatus of claim 1, wherein the barrier is quartz.

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

5. 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.

6. The apparatus described in claim 5, wherein the water level sensor is disposed within the bypass pipe.

7. A chemical mechanical polishing system comprising: 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; 1. A water vapor generator comprising: a canister having a water inlet and a water vapor outlet; a barrier within the canister secured to an inner wall of the canister to divide the canister into a lower chamber and an upper chamber, the lower chamber being positioned to receive water from the water inlet at a floor of the canister, 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 including a plurality of resistive heating coils wrapped around a lower portion of the canister to apply heat to a portion of the lower chamber; Water level sensor, and a controller configured to vary a flow rate of water through the water inlet in response to a signal from the water level sensor to maintain a water level above the heating element and below the water steam outlet. A steam generator comprising: an arm extending above 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; A chemical mechanical polishing system comprising:

8. The chemical mechanical polishing system of claim 7, wherein the canister is quartz.

9. The chemical mechanical polishing system of claim 7, wherein the barrier is quartz.

10. The chemical mechanical polishing system of claim 7, wherein the canister and the barrier are coated with PTFE.

11. The chemical mechanical polishing system of claim 7, further comprising a bypass pipe connecting the water inlet and the water vapor outlet in parallel with the canister.

12. The chemical mechanical polishing system of claim 11, wherein the water level sensor is disposed within the bypass pipe.

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