JP7641916B2 - Use of water vapor for preheating or cleaning CMP components - Patents.com - Google Patents

Description

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

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 may be deposited over 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 may be deposited over a patterned conductive layer and then planarized to allow for subsequent photolithography steps.

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.

In one aspect, a method of temperature control for a chemical mechanical polishing system includes directing a gas containing water vapor through an orifice to a component in the polishing system to raise the temperature of the component to an elevated temperature while the component is spaced from a polishing pad of the polishing system, and moving the component into contact with the polishing pad before the component returns to ambient temperature.

Implementations may include one or more of the following features:

The temperature of the component may be measured while the water vapor is directed to the component, and the water vapor is stopped when the component reaches a target temperature. The temperature of the polishing pad may be measured, and the target temperature may be based on the measured temperature.

A timer may be set and the steam may be stopped when the timer expires.

The temperature of the component can be approximately equal to the temperature of the polishing pad when the component contacts the polishing pad. The elevated temperature can be higher than the temperature of the polishing pad.

The gas may have a temperature of 70-100°C. The water vapor may be dry steam. The gas may consist of water vapor.

To direct water vapor to the component at the processing station, the component may be spaced apart from the polishing pad. The component may be rotated within the processing station as water vapor is directed to the component. The component may be moved vertically within the processing station as water vapor is directed to the component.

The components may include a carrier head or a substrate to be polished. The water vapor may be directed to the components at a substrate transfer station. The water vapor may be directed to the components at an inter-platen station.

The component may include a regulator disk or a regulator head. The water vapor may be directed to the component at a wash cup of the regulator disk.

In another aspect, a chemical mechanical polishing system includes a platen for supporting a polishing pad, a boiler, a processing station spaced from the polishing pad and having a plurality of nozzles for directing steam from the boiler to a body disposed within the processing station, an actuator for moving a component from the processing station into contact with the polishing pad, and a controller for causing the processing station to direct the steam to the component to increase the temperature of the component to an elevated temperature and causing the actuator to move the component from the processing station into contact with the polishing pad before the component returns to an ambient temperature.

Implementations may include one or more of the following features:

The components may include a carrier head or a substrate. The components may include a conditioner head or a conditioner disk.

In another aspect, a method of cleaning for a chemical mechanical polishing system includes directing a gas containing water vapor through an orifice to a component in the polishing system while the component is spaced from a polishing pad of the polishing system, and moving the component into contact with the polishing pad to clean the component.

Implementations may include one or more of the following features:

A timer may be set and the steam may be stopped when the timer expires.

The gas may have a temperature of 70-100°C. The gas may have a temperature of 80-100°C. The water vapor may include dry water vapor. The gas may consist of water vapor. The gas may include a mixture of water vapor and atmosphere.

The component may be disposed within a processing station and may be spaced apart from the polishing pad for directing water vapor to the component at the processing station. The component may be rotated within the processing station as water vapor is directed to the component. The component may be moved vertically within the processing station as water vapor is directed to the component.

The components may include a carrier head or a substrate to be polished. The water vapor may be directed to the components at a substrate transfer station. The water vapor may be directed to the components at an inter-platen station.

The component may include a regulator disk or a regulator head. The water vapor may be directed to the component at a wash cup of the regulator disk.

Cleaning the component may include removing solidified slurry. Cleaning the component may include removing solidified abrasive debris.

In one aspect, a chemical mechanical polishing system includes a platen for supporting a polishing pad, a boiler, a processing station spaced from the polishing pad, the processing station having a plurality of nozzles for directing steam from the boiler to a body disposed within the processing station, an actuator for moving a component from the processing station into contact with the polishing pad, and a controller for causing the processing station to direct the steam to the component to fully raise the temperature of the component to the elevated temperature and causing the actuator to move the component from the processing station into contact with the polishing pad.

Implementations may include one or more of the following features:

The components may include a carrier head or a substrate to be polished.

The components may include a regulator disk or a regulator head.

Potential advantages may include, but are not limited to, one or more of the following:

Water vapor, i.e., gaseous _H2O produced by boiling, can be produced in sufficient quantities with low levels of contaminants. In addition, water vapor generators can produce substantially pure gas, e.g., water vapor with little or no liquid suspended in the water vapor. Such water vapor, also known as dry water vapor, can provide a gaseous form of _H2O with higher energy transfer and lower liquid content than other water vapor alternatives such as flash steam.

Various components of the CMP apparatus can be cleaned quickly and efficiently. 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, which can reduce defects on the substrate.

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.

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.

1 is a schematic plan view of an embodiment of a polishing apparatus; 1 is a schematic cross-sectional view of an exemplary carrier head water vapor processing assembly. 1 is a schematic cross-sectional view of an exemplary conditioning head water vapor processing assembly. 1 is a schematic cross-sectional view of one embodiment of a polishing station of a polishing apparatus. 1 is a schematic top view of a polishing station of one embodiment of a chemical mechanical polishing apparatus.

Chemical mechanical polishing works by a combination of mechanical wear and chemical etching at the interface between the substrate, polishing fluid, and 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, where a conditioning disk, e.g., a disk coated with abrasive diamond particles, is pressed against the rotating polishing pad to condition and texture the surface of the polishing pad. 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.

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.

Both chemically-related variables (e.g., the initiation and rate of 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 residues. By more closely controlling the temperature of the surface of the polishing pad during polishing, temperature variations can be reduced, improving polishing performance, as measured, for example, as within-wafer or between-wafer non-uniformity.

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, resulting in increased 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.

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.

Figure 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 Figure 1.

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.

The stations of the polishing apparatus 2, including the transfer station 6 and the polishing station 20, may be positioned 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.

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 unpolished substrates for polished substrates while other substrates are being polished at the polishing station 20.

The carrier heads 70 are held by a support structure that allows each carrier head to move 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 cup 8.

In some embodiments, each carrier head 70 is coupled to a carriage 78 that is mounted to a 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, with rotation of the carousel moving all of the carrier heads simultaneously along a circular path.

Each polishing station 20 of the polishing apparatus 2 may include a port, for example at the end of a slurry supply arm 39, for dispensing a polishing fluid 38 (see FIG. 3A), for example 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.

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.

With reference to Figures 1, 3A, and 3B, the polishing station 20 may include a supply port, for example at the end of a slurry supply arm 39, for dispensing a polishing fluid 38, for example a polishing slurry, onto the polishing pad 30.

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 255 may be positioned adjacent to the platen 24 in a position that allows the arm 94 to move the conditioner head 93.

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

The carrier head 70 may include a flexible membrane 80 having a substrate mounting surface that contacts the backside of the substrate 10 and a number 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 retaining the substrate. In some implementations, 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.

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 translated laterally (see arrow C in FIG. 3B) across the upper surface of the polishing pad 30.

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.

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, corroding 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.

Similar problems can occur with the regulator head 92, for example particles can form on the regulator head 92, the slurry can cake on the regulator head 92, or sodium hydroxide in the slurry can crystallize on one of the surfaces of the regulator head 92.

One solution is to clean the components, such as the carrier head 70 and the conditioner head 92, 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, can act as a heat sink that impedes polishing pad temperature uniformity.

To address these issues, as shown in FIG. 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 substrate 10.

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 interplaten stations 9 positioned between adjacent polishing stations 20.

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 the 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 by using a water vapor generator 410, such as a boiler, such as a flash boiler or a conventional boiler. A drain 235 may allow excess water, cleaning solution, and cleaning by-products to pass through and prevent accumulation within the load cup 8.

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 vertically movable. The pedestal 204 may be coaxial with the shaft 210. The pedestal 204 may be vertically movable relative to the housing 206.

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.

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 outer surface of the carrier head 70, the outer 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 the front surface of the substrate 10 held by the carrier head 70, i.e., the surface to be polished, or to the underside 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 the 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 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 vertically relative to the load cup 8 so that the nozzles 225 can treat different areas of the carrier head 70 and/or the substrate 10. The substrate 10 can be placed on the pedestal 204 so that an inner surface of the carrier head 70, such as the underside of the membrane 80 or the inner surface of the retaining ring 84, can be steam treated.

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.

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

The water vapor 245 delivered by the nozzles 225 can have adjustable temperature, pressure, and flow rate to vary the cleaning and pre-heating of the carrier head 70 and the substrate 10. In some implementations, the temperature, pressure, and/or flow rate can be independently adjustable for each nozzle or between groups of nozzles.

For example, when the water vapor 245 is generated (e.g., in the water vapor generator 410), the temperature of the water vapor 245 may be between 90 and 200° C. When the water vapor 245 is dispensed by the nozzle 225, e.g., due to heat losses in the transfer, the temperature of the water vapor 245 may be between 90 and 150° C. In some implementations, the water vapor is delivered by the nozzle 225 at a temperature of 70-100° C., e.g., 80-90° C. In some implementations, the water vapor delivered by the nozzle is superheated, i.e., at a temperature above the boiling point.

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 (e.g., 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.

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

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.

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.

FIG. 2B shows a conditioner water vapor processing 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.

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 from 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 from the polishing pad and swung back into the housing cup 255 to remove polishing by-products on the conditioner head 93 and conditioner disk 92. In some embodiments, the housing 255 is vertically operable, e.g., attached to a vertical drive shaft 260.

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 nozzle 275 to steam various surfaces of the conditioner disk 92 and the conditioner head 93.

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.

For example, when the water vapor 295 is generated (e.g., in the water vapor generator 410), the temperature of the water vapor 295 may be between 90 and 200° C. When the water vapor 295 is dispensed by the nozzle 275, the temperature of the water vapor 295 may be between 90 and 150° C., e.g., due to heat losses in the transfer. In some implementations, the water vapor may be delivered by the nozzle 275 at a temperature of 70-100° C., e.g., 80-90° C. In some implementations, the water vapor delivered by the nozzle is superheated, i.e., at a temperature above the boiling point.

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 (e.g., 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.

In some implementations, a temperature sensor 264 may be located in or adjacent to the housing 255 and may 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 may stop 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.

In some embodiments, the controller 12 includes a timer. In this case, the controller 12 may initiate when to begin supplying steam and may stop supplying 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, e.g., to prevent overheating.

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/within the polishing station, such as the temperature of the polishing pad 30 and/or the slurry 38 thereon. 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 thereon. 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.

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.

In some embodiments, multiple temperature sensors can be spaced at various radial locations across the polishing pad 30 to provide 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.

Although shown in FIG. 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 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 in the polishing station 22, for example, to measure the temperature of various components of/within the polishing station.

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., 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).

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 a mist of air and liquid (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).

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). The apertures may be provided by a manifold connected to a source of coolant.

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.

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.

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 the source 130 and the gas from the 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.

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.

The various nozzles can spray onto various radial zones 124 on the polishing pad 30. Adjacent radial zones 124 may overlap. In some implementations, 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.

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.

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, e.g., 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).

At least some of the nozzles 120 may be oriented such that the central axis of the spray (see arrow A) from that nozzle 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.

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 more tightly clustered 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.

In the heating system 104, the heating medium may be a gas, such as water vapor (e.g., from the water vapor generator 410) or heated air, or a liquid, such as 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 implementations, the heating system 104 uses a spray of water vapor. The water vapor may include additives or chemicals.

The heating medium may be delivered by flowing through apertures (e.g., holes or slots provided by one or more nozzles) on the heating delivery arm. The apertures may be provided by a manifold connected to a source of heating medium.

An 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, the pad conditioning disk 92, and the slurry dispensing arm 39.

Along the rotation direction of the platen 24, the arm 140 of the heating system 104 can 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 can 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 can be disposed in a sequence along the rotation direction of the platen 24.

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 from 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.

The heating system 104 may include a source 148 of water vapor, such as a steam generator 410, which may be coupled to the arm 140 by a tube. Each opening 144 may be configured to direct water vapor to the polishing pad 30.

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.

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.

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 the polishing liquid 38 is delivered to the polishing pad 30 by the slurry delivery arm 39. Additionally, while FIG. 3B shows nine openings, there may be a greater or lesser number of openings.

The polishing system 20 may also include a high-pressure rinse system 106. The high-pressure rinse system 106 includes multiple nozzles 154 (e.g., 3 to 20 nozzles) that direct a cleaning fluid, e.g., water, at high intensity onto the polishing pad 30 to clean the pad 30 and remove used slurry, polishing debris, and the like.

3B, the exemplary rinse 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.

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.

While FIG. 3B shows the openings 154 as being evenly spaced, this is not necessary. Additionally, 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.

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 may 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.

In some embodiments, the polishing system 20 includes a wiper blade or body 170 to uniformly 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.

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.

1, 2A, 2B, 3A, and 3B, the controller 12 may monitor the temperature measurements received by the sensors 64, 214, and 264 and may control the amount of water vapor supplied to the temperature control system 100 and the water vapor processing assemblies 200 and 250. The controller 12 may continuously monitor the temperature measurements and may 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 may receive the temperature of the polishing pad 30 from the sensor 64 and control the supply of water vapor to the carrier head 70 and/or the conditioning disk 92 to increase the temperature of the carrier head 70 and/or the conditioning disk 92 to match the temperature of the polishing pad 30. Reducing the temperature difference helps to prevent the carrier head 70 and/or the conditioning disk 92 from acting as a heat sink on the relatively hot polishing pad 30, which may improve within-wafer uniformity.

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, 264 and control the temperature control system 100 and the water vapor treatment assemblies 200 and/or 250 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.

Alternatively, the controller 12 can cause the temperature of the carrier head 70 and/or the conditioner head 92 to be slightly higher than the temperature of the polishing pad 30 and to be reduced to the same or substantially the same temperature as the polishing pad 30 as the carrier head 70 and/or the conditioner head 92 move from their respective cleaning and preheating stations to the polishing pad 30.

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

Claims (15)

1. A method of temperature control for a chemical mechanical polishing system, comprising:
1. The method of claim 1, further comprising: directing a gas containing water vapor through an orifice to a component within the polishing system to raise a temperature of the component to an elevated temperature while the component is spaced from a polishing pad of the polishing system; and moving the heated component into contact with the polishing pad before the heated component returns to an ambient temperature. The method of claim 1, comprising: measuring a temperature of the component while the water vapor is being directed to the component; measuring a temperature of the polishing pad; calculating a target temperature based on the measured temperature; and stopping the water vapor when the component reaches the target temperature. The method of claim 1, wherein the temperature of the component is approximately equal to the temperature of the polishing pad when the component contacts the polishing pad. 1. A method of cleaning for a chemical mechanical polishing system, comprising:
The method includes: directing a gas containing water vapor through an orifice to a component in the polishing system while the component is spaced from a polishing pad of the polishing system to wash polishing by-products from the component; and moving the cleaned component into contact with the polishing pad.
The method , wherein the component comprises a regulator disk or a regulator head. The method of claim 1 or 4, wherein the gas has a temperature of 70 to 100°C. The method of claim 1 or 4, wherein the water vapor comprises dry water vapor. The method of claim 1 or 4, comprising placing the component in a treatment station spaced from the polishing pad, and directing water vapor to the component at the treatment station. The method of claim 1 or 4, wherein the component includes a carrier head or a substrate to be polished. The method of claim 8, wherein the water vapor is directed to the component at a substrate transfer station or an inter-platen station. The method of claim 1 , wherein the component comprises a regulator disk or a regulator head. The method of claim 4 or 10, wherein water vapor is directed to the component at a regulator disk wash cup. 1. A chemical mechanical polishing system comprising:
a platen for supporting the polishing pad;
Boiler and
a treatment station spaced from the polishing pad, the treatment station having a plurality of nozzles for directing steam from the boiler to a body disposed within the treatment station;
an actuator for moving a component from the processing station into contact with the polishing pad;
and a controller, the controller comprising:
causing the processing station to direct the water vapor to the component to increase a temperature of the component to an elevated temperature;
The system is configured to cause the actuator to move the component from the processing station into contact with the polishing pad before the component returns to ambient temperature. 1. A chemical mechanical polishing system comprising:
a platen for supporting the polishing pad;
Boiler and
a treatment station spaced from the polishing pad, the treatment station having a plurality of nozzles for directing steam from the boiler to a body disposed within the treatment station;
an actuator for moving a component from the processing station into contact with the polishing pad;
and a controller, the controller comprising:
causing the processing station to direct the water vapor to the component to clean the component;
configured to cause the actuator to move the cleaned component from the processing station into contact with the polishing pad ;
The system, wherein the component includes a conditioner head or a conditioner disk. The system of claim 12 or 13, wherein the component includes a carrier head or a substrate. The system of claim 12 , wherein the component comprises a conditioner head or a conditioner disk.

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