Cleaning a polishing head with a flexure

Abstract

Methods and systems for cleaning for a chemical mechanical polishing system, including moving a carrier head of the chemical mechanical polishing system over a treatment station of the chemical mechanical polishing system; pressurizing a first pressurizable chamber of the carrier head, the first pressurizable chamber arranged between a membrane assembly and a lower carrier body of the carrier head, such that a membrane assembly arranged beneath the lower carrier body is displaced from a home position; and directing a gas from an orifice of the treatment station onto a component of the carrier head to clean polishing by-product off the component.

Description

Attorney Docket No.44023978WO01;05542-1634WO1 CLEANING A POLISHING HEAD WITH A FLEXURE TECHNICAL FIELD

[0001] This disclosure relates to a carrier head for use in chemical mechanical polishing (CMP). BACKGROUND

[0002] An integrated circuit is typically formed on a substrate by the sequential deposition of conductive, semiconductive, or insulative layers on a semiconductor wafer. A variety of fabrication processes require planarization of a layer on the substrate. For example, one fabrication step involves depositing a filler layer over a non-planar surface and planarizing the filler layer. For certain applications, the filler layer is planarized until the top surface of a patterned layer is exposed. For example, a metal layer can be deposited on a patterned insulative layer to fill the trenches and holes in the insulative layer. After planarization, the remaining portions of the metal in the trenches and holes of the patterned layer form vias, plugs, and lines to provide conductive paths between thin film circuits on the substrate. As another example, a dielectric layer can be deposited over a patterned conductive layer, and then planarized to enable subsequent photolithographic 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 placed against a rotating polishing pad. The carrier head provides a controllable load on the substrate to push it against the polishing pad. A polishing slurry with abrasive particles is typically supplied to the surface of the polishing pad. SUMMARY

[0001] In general, an aspect disclosed herein is a method of cleaning for a chemical mechanical polishing system, including moving a carrier head of the chemical mechanical polishing system over a treatment station of the chemical mechanical polishing system; pressurizing a first pressurizable chamber of the carrier head, the first pressurizable chamber arranged between a membrane assembly and a lower carrier body of the carrier head, such that a membrane assembly arranged beneath the lower carrier body is displaced from a home position; and directing a gas from an orifice of the treatmentAttorney Docket No.44023978WO01;05542-1634WO1 station onto a component of the carrier head to clean polishing by-product off the component.

[0002] Examples may include one or more of the following features. Pressurizing the first pressurizable chamber may displace the membrane assembly toward or away from the lower carrier body along a central axis of the carrier head. Pressurizing the first pressurizable chamber may displace the membrane assembly toward the lower carrier body, and then away from the lower carrier body. The method may include repeatedly displacing the membrane assembly toward and away from the lower carrier body. The component may include one or more of a retaining ring of the carrier head, or a flexible membrane secured to a membrane support supported by the membrane assembly. The flexible membrane may have a lower surface that provides a substrate mounting surface and a side surface, and the component may include the lower surface and the side surface. The gas may include of a steam. The steam may be a dry steam. The gas may include a mixture of steam and atmosphere. The method may include rotating the component in the treatment station as steam is directed onto the component. The method may include causing the component to move vertically in the treatment station as steam is directed onto the component by adjusting a pressure in the first pressurizable chamber. Cleaning the component may include removing coagulated slurry. Cleaning the component may include removing coagulated polishing debris. The method may include moving the carrier head over a polishing pad of the chemical mechanical polishing system. The method may include contacting a brush of the treatment station to the component of the carrier head; and causing relative motion between the brush the component to clean polishing by-product off the component.

[0003] In general, an aspect disclosed herein is a chemical mechanical polishing system, including a carrier head including a housing for attachment to a drive shaft, where the housing may include an upper carrier body and a lower carrier body; a retaining ring suspended from the lower carrier body; a membrane assembly arranged beneath the lower carrier body, the membrane assembly supporting a membrane support beneath the membrane assembly; and a first flexible seal forming a first pressurizable chamber between the lower carrier body and the membrane support; a flexure connecting the membrane support to the lower carrier body, the flexure extending through the first pressurizable chamber; a treatment station spaced apart from the polishing pad, the treatment station having a plurality of nozzles to direct a fluid into a cavity of the treatment station and onto the carrier head positioned above the cavity in the treatmentAttorney Docket No.44023978WO01;05542-1634WO1 station; and an actuator to move the carrier head between the treatment station and the platen.

[0004] Examples may include one or more of the following features. A first portion of the plurality of nozzles may be arranged to direct the fluid onto an inner surface of a retaining ring of the carrier head, and a second portion of the plurality of nozzles may be arranged to direct the fluid onto a side surface, a bottom surface, or both, of a flexible membrane supported by the membrane support. The system may include a boiler in fluid connection with the plurality of nozzles. The membrane assembly may include a membrane support, a flexible membrane secured to the membrane support, and the flexible membrane may have a lower surface that provides a substrate mounting surface. The system may include a controller configured to: move the carrier head over the treatment station; pressurize the first pressurizable chamber such that the membrane assembly may be displaced from a home position; and direct a gas from an orifice of the nozzles onto a component of the carrier head to clean polishing by-product off the component. The system may include a brush, an actuator configured to cause motion of the brush, and the controller configured to cause the actuator to move the brush into contact with the component of the carrier head; and cause relative motion between the brush and the component to clean polishing by-product off the component.

[0004] Advantages may include, but are not limited to, the following.

[0005] Cleaning polishing by-product from interior surfaces through steam treating of the carrier head reduces wear on the interior components, such as the flexible membrane and the inner surfaces of the retaining ring. Reducing wear can extend the lifespan of such components and reduce downstream maintenance. Reducing downstream maintenance can increase polishing throughput of systems using such a carrier head and steam treating assembly. Cleaning polishing by-product from interior surfaces reduces defects on the substrate associated with congealed polishing liquid becoming trapped beneath the substrate during a polishing operating. Reducing defects related to the polishing by- product increases within wafer uniformity (WWU) and wafer-to-wafer uniformity (WTWU).

[0006] The details of one or more examples are set forth in the accompanying drawings and the description below. Other aspects, features, and advantages will be apparent from the description and drawings, and from the claims.Attorney Docket No.44023978WO01;05542-1634WO1 BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG.1 is a schematic cross-sectional view of an example of a polishing apparatus.

[0008] FIG.2A is a schematic cross-sectional view of an example carrier head.

[0009] FIG.2B is a schematic cross-sectional view of the example carrier head in which a membrane assembly is extended.

[0010] FIG.2C is a schematic cross-sectional view of the example carrier head in which a membrane assembly is retracted.

[0011] FIG.2D is a is a schematic cross-sectional view of the example carrier head and steam treating assembly having a brush.

[0012] FIG.3 is a flow chart diagram depicting an example method of cleaning for a chemical mechanical polishing system.

[0013] Like reference symbols in the various drawings indicate like elements. DETAILED DESCRIPTION

[0014] Chemical mechanical polishing operates by a combination of mechanical abrasion and chemical etching at the interface between the substrate, polishing liquid, and polishing pad. The abrasion and chemical etching of the substrate creates debris which can coat various components of the CMP apparatus during CMP. The debris and the slurry constitute polishing by-products and can accumulate on the components during one or more CMP processes. The polishing by-products can scratch or otherwise damage the substrate if they come loose from the components. This can result in an increase in polishing defects. Water jets have been used to clean various components of the CMP apparatus system. However, a large quantity of water is needed to perform this task. In some examples, the carrier head includes vents connecting the top surface of the carrier head and the space between the retaining ring and flexible membrane. Water flows through the carrier head from the top surface to perform cleaning of carrier head surfaces.

[0015] A technique that could address one or more of these issues is to clean various components of the CMP apparatus using steam at a cleaning station, i.e., gaseous H2O generated by boiling. Less steam may be required to impart an equivalent amount of energy as hot water, e.g., due to the latent heat of the steam. Additionally, steam can be sprayed at high velocities to clean and / or preheat the components. In addition, steam can be more effective than liquid water in dissolving or otherwise removing polishing by- products. Further, directing the steam at the space between the retaining ring and flexibleAttorney Docket No.44023978WO01;05542-1634WO1 membrane increases cleaning efficiency by allowing the steam to contact only the surfaces to be cleaned without unnecessary travel through the carrier head.

[0016] Further, in some polishing systems, a membrane supported by a membrane assembly of a carrier head is used to apply pressure on a substrate during polishing. A carrier head having a diaphragm separating the membrane assembly from a lower carrier body provides a chamber which can be pressurized. Pressurizing the chamber urges the membrane against, or away from, the substrate. This allows independent movement of the membrane assembly from vertical motion of a lower carrier body.

[0017] A system including such a carrier head can alter the vertical position of the membrane assembly during steam cleaning at the cleaning station. This facilitates cleaning difficult to reach surfaces of the flexible membrane and retaining ring by adjusting the vertical position during steam cleaning.

[0018] FIG.1 illustrates an example of a chemical mechanical polishing apparatus 100. The polishing apparatus 100 includes a rotatable disk-shaped platen 120 on which a polishing pad 110 is situated. The platen is operable to rotate about an axis 125. For example, a motor 121, e.g., a DC induction motor, can turn a drive shaft 124 to rotate the platen 120.

[0019] The polishing pad 110 can be a two-layer polishing pad with an outer polishing layer 112 and a softer backing layer 114. In some examples, a plurality of slurry-transport grooves 116 are formed in the top surface of the polishing layer 112 of the polishing pad 110.

[0020] The polishing apparatus 100 can include a port 130 to dispense polishing liquid 132, such as abrasive slurry, onto the polishing pad 110. The polishing apparatus can also include a polishing pad conditioner to abrade the polishing pad 110 to maintain the polishing pad 110 in a consistent abrasive state.

[0021] The polishing apparatus 100 includes at least one carrier head 140. The carrier head 140 is operable to hold a substrate 10 against the polishing pad 110 such as during a polishing process. The carrier head 140 can control at least the pressure applied to the substrate 10, e.g., the downward pressure on the backside of the substrate which results in an upward pressure of the pad on the front side of the substrate 10.

[0022] The carrier head 140 can include a retaining ring 84 to retain the substrate 10 below a flexible membrane 144. The carrier head 140 also includes one or more independently controllable pressurizable lower chambers 146 defined by the membrane 144, e.g., three chambers 146a-146c, which can apply independently controllableAttorney Docket No.44023978WO01;05542-1634WO1 pressurizes to associated zones on the flexible membrane 144 and thus on the substrate 10. Although only three chambers 146a-146c are illustrated in FIG.1 for ease of illustration, there could be one or two chambers, or four or more chambers, e.g., five chambers.

[0023] The carrier head 140 is suspended from a support structure 150, e.g., a carousel or track, and is connected by a drive shaft 152 to a carrier head rotation motor 154, e.g., a DC induction motor, so that the carrier head can rotate about an axis 155. Optionally each carrier head 140 can oscillate laterally, e.g., on sliders on the support structure 150, or by rotational oscillation of the carousel itself, or by sliding along the track. In typical operation, the platen is rotated about its central axis 125, and each carrier head is rotated about its central axis 155 and translated laterally across the top surface of the polishing pad.

[0024] The polishing apparatus 100 includes a steam treating assembly 200. The steam treating assembly 200 can be used for cleaning of the carrier head 140 and / or substrate 10. The steam treating assembly 200 can be part of a load cup 8.

[0025] The load cup 8 includes a housing 206. Multiple nozzles 225 are supported by the housing 206 or a separate support to deliver steam 245 to the carrier head 140 positioned in a cavity 208 defined by the housing 206. For example, nozzles 225 can be positioned on one or more interior surfaces of the housing 206, e.g., a floor 206a and / or a side wall 206b. The nozzles 225 can be oriented to direct steam inwardly into the cavity 208. A steam generator 410 in fluid connection with the nozzles 225 generates the steam 245. Examples of the steam generator 410 include a boiler such as a flash boiler or a regular boiler. A drain 235 can permit excess water, cleaning solution, and cleaning by- product to pass through to prevent accumulation in the load cup 8.

[0026] A controller 190, such as a programmable computer, is connected to the motors 121, 154 to control the rotation rate of the platen 120 and carrier head 140. Carrier Head

[0027] FIG.2A is a schematic cross-sectional view of the carrier head 140 above the steam treating assembly 200. The carrier head 140 includes a housing 102 with an upper carrier body 104 and lower carrier body 106, a gimbal mechanism 108 (which may be considered part of the lower carrier body 106), the retaining ring 84 connected to theAttorney Docket No.44023978WO01;05542-1634WO1 housing 102 (e.g., connected the upper carrier body 104 or the lower carrier body 106), and a membrane assembly 400. The upper carrier body 104 is secured to the drive shaft 152 to rotate the entire carrier head 140. The upper carrier body 104 can generally be circular in shape, e.g., rotationally symmetric. The lower carrier body 106 is located beneath the upper carrier body 104.

[0028] The lower carrier body 106 is vertically movable relative to the upper carrier body 104. An upper flexible seal 164 seals a pressurizable loading chamber 111 between the lower carrier body 106 and the upper carrier body 104. The upper flexible seal 164 flexes to accommodate a change in vertical position between the upper carrier body 104 and the lower carrier body 106.

[0029] The vertical position of the lower carrier body 106 relative to the upper carrier body 104 is controlled by a pressure in the loading chamber 111. Pressurizing the loading chamber 111 with a positive pressure moves the lower carrier body 106 downward. Pressurizing the loading chamber with a negative pressure moves the lower carrier body 106 upward. As used herein, references to positive pressure includes pressures which are greater than atmospheric pressure. References to negative pressure includes pressures which are less than atmospheric pressure. In some embodiments, the vertical position of the lower carrier body 106 relative to the upper carrier body 104 is controlled by an actuator.

[0030] The gimbal mechanism 108 permits the lower carrier body 106 to gimbal and vertically move relative to the upper carrier body 104 while preventing lateral motion of the lower carrier body 106 relative to the upper carrier body 104. In some examples, there is no gimbal.

[0031] A volume between the lower carrier body 106 and the membrane assembly 400 can be sealed by a lower flexible seal 162 to form a pressurizable upper chamber 134. This lower flexible seal 162 can flex to accommodate the change in vertical position between the lower carrier body 106 and the membrane assembly 400. Pressure in the pressurizable upper chamber 134 can control the downward load on the membrane assembly 400 and / or the vertical position of the membrane assembly 400 relative to the housing 102, e.g., relative to the lower carrier body 106.

[0032] Each chamber in the carrier head 140 can be fluidly coupled by passages through the upper carrier body 104 and the lower carrier body 106 to an associated pressure source (e.g., a pressure sources 922, 924, or 926), such as a pump or pressure or vacuum line. There can be one or more passages for the loading chamber 111, for theAttorney Docket No.44023978WO01;05542-1634WO1 pressurizable upper chamber 134, and for each of the individually pressurizable lower chambers 146. One or more passages from the lower carrier body 106 can be linked to passages in the upper carrier body 104 by flexible tubing that extends inside the loading chamber 111 or outside the carrier head 140. Pressurization of each chamber can be independently controlled with respect to another chamber, e.g., pressurization of the chambers can be individually controlled. In particular, pressurization of each lower chamber 146 can be independently controlled. This permits different pressures to be applied to different radial regions of the substrate 10 during polishing, thereby compensating for non-uniform polishing rates.

[0033] The membrane assembly 400 can include a membrane support 138 and the flexible membrane 144. The flexible membrane 144 has a circular lower portion 170 having a lower outer surface 174 that provides a mounting surface for a substrate, e.g., the substrate 10 shown in FIG.1. The flexible membrane 144 also has a plurality of flaps 172, e.g., annular flaps, which extend from the inner surface 176 of the lower portion 170 to define the individually controllable pressurizable lower chambers 146. For example, the ends of the flaps 172, e.g., the ends adjacent the lower portion 138a, can be clamped to the membrane support 138.

[0034] The flexible membrane 144 includes a side surface 178 extending upward from an edge of the circular lower portion 170. Polishing by-products may accumulate on the outer surface 174 and the side surface 178 during polishing operations.

[0035] The membrane support 138 can include a disk-shaped lower portion 138a and an annular upper portion 138b that extends upwardly from the disk-shaped lower portion 138a at an outer edge thereof. The flaps 172 of the flexible membrane 144 can be clamped to the disk-shaped lower portion 138a. The membrane support 138 can be formed of a material that is more rigid than the membrane 144, e.g., a metal, ceramic, or hard plastic. The membrane support 138 can be considered inflexible under the pressure regimes typically occurring the polishing process.

[0036] The pressurizable upper chamber 134 is configured to extend across the top of the membrane support 138 and be contained by the lower flexible seal 162. In particular, the pressurizable upper chamber 134 can be bounded on the bottom by the top surface 139 of the disk-shaped lower-portion 138a, on the sides by the inner surface 141 of the annular upper portion 138b, and on the top by the bottom surface 161 of the lower flexible seal 162, and the bottom surface 107 of the lower carrier body 106.Attorney Docket No.44023978WO01;05542-1634WO1

[0037] The lower carrier body 106 can be connected to the membrane assembly 400 by an annular flexure 160. The flexure 160 is more rigid than the lower flexible seal 162, but less rigid than the membrane support 138. The membrane assembly 400 is suspended from the lower carrier body 106 by the flexure 160. In addition, the flexure 160 acts as a spring, urging the membrane assembly 400 toward a “neutral” position while still permitting the membrane assembly 400 to move vertically relative to the housing 102 based on the pressure in the pressurizable upper chamber 134. The flexure 160 can be connected to the lower carrier body 106 and the membrane assembly 400 using fasteners, e.g., adhesive, screw, bolt, clamp, or by interlocking, to name a few examples.

[0038] The flexure 160 extends through the pressurizable upper chamber 134 between the inner surface 141 of the upper portion 138b of the membrane assembly 400 and a sidewall 163 of a downward projection 189 of the lower carrier body 106. The projection 189 extends downward toward the upper surface 139 of the lower portion 138a of the membrane support 138.

[0039] Thus, the pressurizable upper chamber 134 can include a lower portion 134a below the flexure 160, and an upper portion 134b above the flexure 160. The lower portion 134a and upper portion 134b are fluidically coupled to stay at the same pressure. In some examples, the flexure 160 has gaps or apertures to permit the flow of gas. The flexure 160 can be an annular body that includes multiple apertures therethrough. As another example, the flexure 160 can be provide by multiple arcuate pieces that are separated by gaps. In some examples, the lower portion 134a and the upper portion 134b are connected by a passage 186 through the housing 102, e.g., through the lower carrier body 106. In this case, the flexure 160 can be an annular body that is fluid impermeable, e.g., a solid unitary body without apertures or gaps.

[0040] The upper flexible seal 164 and the lower flexible seal 162 can be composed of a flexible material such as a rubber, e.g., silicone rubber, ethylene propylene diene terpolymer (EPDM), or a fluoroelestomer, or a plastic film, e.g., polyethylene terephthalate (PET) or polyoxymethylene.

[0041] The flexure 160 is sufficiently stiff to resist lateral motion so as to keep the membrane assembly 400 centered below the lower carrier body 106. However, the flexure 160 can be sufficiently flexible to permit vertical motion of the membrane assembly 400 relative to the housing 102. The flexure 160 permits the assembly 400 to vertically move relative to the lower carrier body 106 by flexing, e.g., bendably deflecting.Attorney Docket No.44023978WO01;05542-1634WO1

[0042] The flexure 160 causes the lower carrier body 106 to be in a home position when the upper chamber 134 is at a neutral pressure, e.g., atmospheric pressure. The home position is a vertical position to which the lower carrier body 106 returns when the upper chamber 134 is at a neutral pressure.

[0043] The controller 190 regulates the pressure of the various chambers of the carrier head 140. The controller 190 is coupled to a plurality of pressure sources, e.g., pressure source 922, pressure source 924, and pressure source 926. The pressure sources 922, 924, 926 can be, for example, a pump, a facilities gas line and controllable valve, etc. Each of the pressure sources 922, 924, 926 can be individually connected to a pressurizable chamber. In the example of FIG.2A, pressure source 922 connects to loading chamber 111, pressure source 924 is connected to the pressurizable lower chambers 146, and pressure source 926 is connected to the pressurizable upper chamber 134. Although only one pressure source 924 is shown for ease of illustration, there can be one per lower chamber 146 so that each lower chamber 146a-146c can be individually controlled.

[0044] One or more sensors 930 measure the pressure(s) applied by the pressure sources 922, 924, 926, e.g., the pressures in the individually pressurizable lower chambers 146, the pressurizable upper chamber 134, and the loading chamber 111. The sensor 930 communicates the measured pressure(s) to the controller 190. The controller 190 causes the pressure sources 922, 924, 926 to increase and / or decrease the pressure in the pressurizable lower chambers 146, the pressurizable upper chamber 134, and / or the loading chamber 111. Steam Treating Assembly

[0045] An actuator 240 actuates to provide vertical motion to the housing 206. Thus, the actuator 240 moves the housing 206 relative to the carrier head 140 when the carrier head 140 is above the housing 206, e.g., within the cavity 208. For example, a shaft 210 supports the housing 206. The actuator 240 moves the shaft 210 to raise and lower the housing 206. Alternatively, the carrier head 140 can move vertically.

[0046] In operation, the carrier head 140 can be positioned over the load cup 8, and the housing 206 can be raised (or the carrier head 140 lowered) so that the carrier head 140 is partially within the cavity 208. The steam generator 410 provides steam to the supply line 230. The supply line 230 directs the steam to the nozzles 225. The nozzlesAttorney Docket No.44023978WO01;05542-1634WO1 225 direct the steam to one or more surface of the carrier head 140. The steam cleans the polishing by-products from the surfaces of the carrier head 140.

[0047] The nozzles 225 are positioned to direct steam onto at least one surface of the carrier head 140. The nozzles 225 in FIG.2A are positioned to direct steam onto at least the outer surface 106a of the lower carrier body 106, the outer surface 84a of the retaining ring 84, the inner surface 84c of the retaining ring 84, or the bottom surface 84b of the retaining ring 84. One or more of the nozzles 225 directs steam onto the outer surface 174 of the membrane 144.

[0048] The carrier head 140 can rotate within the load cup 8 and / or move vertically relative to the load cup 8 to allow the nozzles 225 to treat different areas of the carrier head 140. Examples of areas which the nozzles 225 can be positioned to treat include interior surfaces of the carrier head 140, the lower surface 174 of the membrane 144, the side surface 178 of the membrane 144, or the inner surfaces 84c of the retaining ring 84.

[0049] The steam generator 410 circulates steam through a supply line 230. The supply line 230 extends through the housing 206 to the nozzles 225. The nozzles 225 spray the steam 245 onto surface of the carrier head 140 to remove organic residues, polishing by-product (e.g., coagulated slurry, or slurry particles), or debris left on the carrier head 140 after each polishing operation.

[0050] The steam 245 delivered by the nozzles 225 can have an adjustable temperature, pressure, and flow rate to vary the cleaning and preheating of the carrier head 140 and the substrate 10. In some examples, the temperature, pressure and / or flow rate can be independently adjustable for each nozzle or between groups of the nozzles 225.

[0051] For example, the temperature of the steam 245 can be in a range from 90 °C to 200 ºC when the steam 245 is generated (e.g., in the steam generator 410). The temperature of the steam 245 can be between 90 ºC to 150 ºC when the steam 245 is dispensed by the nozzles 225, e.g., due to heat loss in transit. In some examples, steam is delivered by the nozzles 225 at a temperature of 70-100 ºC, e.g., 80-90 ºC. In some examples, the steam delivered by the nozzles is superheated, i.e., is at a temperature above the boiling point.

[0052] The flow rate of the steam 245 can be in a range from 1 to 1000 cc / minute when the steam 245 is delivered by the nozzles 225, depending on heater power and pressure. In some examples, the steam is mixed with other gases, e.g., is mixed withAttorney Docket No.44023978WO01;05542-1634WO1 normal atmosphere or with N2. Alternatively, the fluid delivered by the nozzles 225 is substantially purely water. In some examples, the steam 245 delivered by the nozzles 225 is mixed with liquid water, e.g., aerosolized water. For example, liquid water and steam can be combined at a relative flow ratio (e.g., with flow rates in sccm) 1:1 to 1:10. However, if the amount of liquid water is low, e.g., less than 5 wt%, e.g., less than 3 wt%, e.g., less than 1 wt%, then the steam will have superior heat transfer qualities. Thus, in some examples the steam is dry steam, i.e., is substantially free of water droplets.

[0053] To avoid degrading the flexible membrane 144 with heat, water can be mixed with the steam 245 to reduce the temperature as liquid water transfers less energy than gaseous water. In some examples, the temperature of the steam 245 is reduced to around 40-50 ºC. The temperature of the steam 245 can be reduced by mixing cooled water into the steam 245, or mixing water at the same or substantially the same temperature into the steam 245.

[0054] In some examples, a temperature sensor 214 can be installed in or adjacent the steam treating assembly 200 to detect the temperature of the carrier head 140 and / or the substrate 10. A signal from the sensor 214 can be received by a controller 190 to monitor the temperature of the carrier head 140 and / or the substrate 10. The controller 190 controls delivery of the steam by the steam treating assembly 200 based on the temperature measurement from the temperature sensor 214. For example, the controller 190 can receive a target temperature value. If the controller 190 detects that the temperature measurement exceeds a target value, the controller 190 halts the flow of steam. As another example, the controller 190 reduces the steam delivery flow rate and / or reduce the steam temperature, e.g., to prevent overheating of the components during cleaning and / or preheating.

[0055] In some examples, the controller 190 includes a timer. In this case, the controller 190 can start when delivery of the steam begins, and can halt delivery of steam upon expiration of the timer. The timer can be set based on empirical testing to attain a desired temperature of the carrier head 140 and substrate 10 during cleaning and / or preheating. Steam Treating of The Carrier HeadAttorney Docket No.44023978WO01;05542-1634WO1

[0056] The carrier head 140 having a lower carrier body 106 moveable with respect to the upper carrier body 104 advantageously allows increased cleaning efficiency of the components of the carrier head 140. Extending or retracting the lower carrier body 106 allows the steam 245 to more directly contact the inner surface 84c of the retaining ring 84, the outer surface 174 of the flexible membrane 144, the side surface 178 of the flexible membrane 144, or a combination of these surfaces.

[0057] As used in this specification, the terms ‘extending’ or ‘retracting’ are used to describe relative motion and position between the lower carrier body 106 and the upper carrier body 104. Extending refers to pressurizing the upper chamber 134 to a positive pressure and causing the lower carrier body 106 to ‘extend’ downward with respect to the upper carrier body 104, e.g., away from the upper carrier body 104. Retracting refers to pressurizing the upper chamber 134 to a negative pressure and causing the lower carrier body 106 to ‘retract’ upward with respect to the upper carrier body 104, e.g., toward the upper carrier body 104.

[0058] FIG.2B is a schematic illustration depicting the carrier head 140 in an extended position. The controller 190 causes the pressure source 926 to increase a pressure in the upper chamber 134 until a positive pressure is achieved. The positive pressure in the upper chamber 134 causes the membrane support 138 to move downward with respect to the lower carrier body 106. The flexure 160 flexes to facilitate the membrane support 138 moving downward.

[0059] The controller 190 causes the pressure source 926 to pressurize the upper chamber 134 until the membrane support 138 is in the extended position. The position of the membrane support 138 is determined by

[0060] The membrane support 138 being in the extended position facilitates increased access for the steam 245 to contact previously hard to reach surfaces on the carrier head 140. The membrane support 138 being in the extended position allows the steam 245 increased access to contact the circular lower portion 170, the side surface 178 of the flexible membrane 144, and side surfaces of the membrane support 138. The membrane support 138 being in the extended position can displace the lower portion 170 by mm below the bottom surface 174 of the flexible membrane 144.

[0061] FIG.2C is a schematic illustration depicting the carrier head 140 in a retracted position. The controller 190 causes the pressure source 926 to decrease a pressure in the upper chamber 134. The pressure source 926 decreases a pressure in the upper chamber 134 until a negative pressure is achieved in the upper chamber 134. The negative pressureAttorney Docket No.44023978WO01;05542-1634WO1 in the upper chamber 134 causes the membrane support 138 to move upward with respect to the lower carrier body 106. The flexure 160 flexes to facilitate the membrane support 138 moving upward. The membrane support 138 being in the retracted position facilitates increased access for the steam 245 to contact the circular lower portion 170, and the inner surface 84c of the retaining ring 84.

[0062] In some examples, the steam treating assembly 200 includes a brush for cleaning the carrier head 140, the membrane assembly 138, or the membrane 144. FIG. 2D is a schematic illustration depicting the carrier head 140 arranged above an example steam treating assembly 200 having a brush 298. The brush 298 is connected to an actuator 299 which controls the motion of the brush 298. The actuator 299 is connected to the controller 190 and receives instructions to operate the brush 298. Although illustrated as a cylindrical brush in FIG.2D, the brush should also be a disc-shaped brush that contacts a generally flat rotating circular surface to the carrier head 140, the membrane assembly 138, or the membrane 144.

[0063] The brush 298 cleans polishing by-product from the carrier head 140 when the membrane assembly 138 is in the retracted, or extended, position. The brush 298 advantageously increases polishing by-product cleaning by performing mechanical removal of the polishing by-product. The brush 298 cleans before, during, or after steam is applied to the carrier head 140 by the nozzles 225.

[0064] Some examples of the brush 298 include a rotary brush, an oscillating brush. The actuator 299 operates the brush 298 according to the brushing modality of the brush 298. The actuator 299 functions to adjust a position of the brush 298 such that the brush 298 contacts the surfaces of the retaining ring 84, the membrane 144, or the membrane assembly 138.

[0065] The actuator 299 operates to adjust a motional speed, e.g., a rotational or oscillatory speed, of the brush 298. In some examples, the actuator 299 adjust the motional speed of the brush 298 according to the material of the surface to be contacted. For example, the actuator 299 operates the brush 298 at lower motional speeds when the brush is in contact with low durometer materials, e.g., the membrane 144, and operates the brush 298 at higher motional speeds when the brush is in contact with high durometer materials, e.g., the retaining ring 84, or membrane assembly 138.

[0066] In some examples, the controller 190 causes the lower carrier body 106 to move between the extended and retracted positions. Moving the lower carrier body 106 between the extended and retracted positions generates relative motion between the steamAttorney Docket No.44023978WO01;05542-1634WO1 245 and the lower carrier body 106 which can increase the steam cleaning efficiency. The membrane support 138 being in the retracted position can displace the lower portion 170 by mm above the bottom surface 84b of the retaining ring 84.

[0067] In some examples, the controller 190 causes rotational relative motion between the carrier head 140 and the nozzles 225 while the steam 245 is flowing from the nozzles 225. The controller 190 causes the rotational relative motion by commanding the actuator 240 to rotate the housing 206, the motor 121 to rotate the drive shaft 124 and carrier head 140, or both. The rotational relative motion causes the steam cleaning process to be more efficient and reduces the total steam cleaning time before the carrier head 140 components are clean.Attorney Docket No.44023978WO01;05542-1634WO1 Method of Cleaning

[0068] FIG.3 is a flow chart diagram depicting a method 300 of controlling pressure in one or more pressurizable chambers. The method 300 can be used to control any of the apparatuses and systems disclosed herein, such as polishing apparatus 100.

[0069] A carrier head moves over a treatment station of a chemical mechanical polishing system (step 302). The carrier head can have a housing having an upper carrier body and a lower carrier body, and a membrane assembly beneath the lower carrier body. The lower carrier body and the membrane assembly can be connected by a flexure, and a space between the lower carrier body and the membrane assembly defines a pressurizable chamber. The pressurizable chamber is connected to a pressure source and one or more pressure sensors, the pressure sensor can measure the pressure within the chamber and a controller can regulate the pressure source to increase, decrease, or maintain the pressure within the chamber based on the readings from the sensor.

[0070] A pressure source pressurizes a first pressurizable chamber of the carrier head such that a membrane assembly is displaced from a home position (step 304). Pressurizing the pressure in the first pressurizable chamber includes displacing the membrane assembly upward or downward from the home position. Displacing the membrane assembly moves the membrane assembly into an extended or a retracted position with respect to the lower carrier head. In some examples, the membrane is displaced from the home position multiple times, e.g., upward from the home position, downward from the home position, or both, multiple times, e.g., at least twice.

[0071] A steam generator directs a gas from an orifice of the treatment station onto a component of the carrier head to clean polishing by-product off the component (step 306). One or more nozzles of a steam treating assembly are positioned to direct the gas onto at least one surface of the carrier head. The nozzles are positioned to direct steam onto at least the outer surface of the lower carrier body, the outer surface of a retaining ring, the bottom surface of the retaining ring, the lower surface of the membrane, the side surface of the membrane, the inner surfaces of the retaining ring, or outer surface of the membrane. The gas removes polishing by-products from the carrier head, the membrane assembly, or a flexible membrane on the membrane assembly.

[0072] Optionally, steps of the method can be performed in an order different than described. The steps of the method can be performed concurrently, or sequentially. InAttorney Docket No.44023978WO01;05542-1634WO1 some examples, the steps of displacing the membrane from the home position (304) occur concurrently with directing the gas from the orifice onto the component of the carrier head (306). In some examples, displacing the membrane (304) occurs multiple times during directing the gas from the orifice onto the component of the carrier head (306).

[0073] Optionally, a controller of the polishing apparatus causes the carrier head to rotate, a membrane assembly of the carrier head to move between the extended and the retracted position, or both. The gas can be a steam, e.g., a wet steam, or a dry steam.

[0074] The controller and other computing devices part of systems described in this specification can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware. For example, the controller can include a processor to execute a computer program as stored in a computer program product, e.g., in a non-transitory machine-readable storage medium. Such a computer program (also known as a program, software, software application, or code) can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a standalone program or as a module, component, subroutine, or other unit suitable for use in a computing environment.

[0075] In context of the controller, “configured” indicates that the controller has the necessary hardware, firmware or software or combination to perform the desired function when in operation (as opposed to simply being programmable to perform the desire function).

[0076] While this document contains many specific example details, these should not be construed as limitations on the scope of any inventions or of what may be claimed, but rather as descriptions of features specific to particular embodiments of particular inventions. Certain features that are described in this document in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

[0077] A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made withoutAttorney Docket No.44023978WO01;05542-1634WO1 departing from the spirit and scope of the invention. Accordingly, other examples are within the scope of the following claims.

Claims

Attorney Docket No.44023978WO01;05542-1634WO1 What is claimed is:

1. A method of cleaning for a chemical mechanical polishing system, comprising: moving a carrier head of the chemical mechanical polishing system over a treatment station of the chemical mechanical polishing system; pressurizing a first pressurizable chamber of the carrier head, the first pressurizable chamber arranged between a membrane assembly and a lower carrier body of the carrier head, such that a membrane assembly arranged beneath the lower carrier body is displaced from a home position; and directing a gas from an orifice of the treatment station onto a component of the carrier head to clean polishing by-product off the component.

2. The method of claim 1, wherein pressurizing the first pressurizable chamber displaces the membrane assembly toward or away from the lower carrier body along a central axis of the carrier head.

3. The method of claim 2, wherein pressurizing the first pressurizable chamber displaces the membrane assembly toward the lower carrier body, and then away from the lower carrier body.

4. The method of claim 3, comprising repeatedly displacing the membrane assembly toward and away from the lower carrier body.

5. The method of claim 1, wherein the component comprises one or more of a retaining ring of the carrier head, or a flexible membrane secured to a membrane support supported by the membrane assembly.

6. The method of claim 5, wherein the flexible membrane has a lower surface that provides a substrate mounting surface and a side surface, and the component comprises the lower surface and the side surface.

7. The method of claim 1, wherein the gas consists of a steam.

8. The method of claim 7, wherein the steam is a dry steam.Attorney Docket No.44023978WO01;05542-1634WO1 9. The method of claim 8, wherein the gas comprises a mixture of steam and atmosphere.

10. The method of claim 7, comprising rotating the component in the treatment station as steam is directed onto the component.

11. The method of claim 7, comprising causing the component to move vertically in the treatment station as steam is directed onto the component by adjusting a pressure in the first pressurizable chamber.

12. The method of claim 1, wherein cleaning the component comprises removing coagulated slurry.

13. The method of claim 1, wherein cleaning the component comprises removing coagulated polishing debris.

14. The method of claim 1, comprising moving the carrier head over a polishing pad of the chemical mechanical polishing system.

15. The method of claim 1, comprising contacting a brush of the treatment station to the component of the carrier head, and causing relative motion between the brush the component to clean polishing by-product off the component.

16. A chemical mechanical polishing system, comprising: a platen to support a polishing pad; a carrier head, comprising: a housing for attachment to a drive shaft, wherein the housing comprises an upper carrier body and a lower carrier body; a retaining ring suspended from the lower carrier body; a membrane assembly arranged beneath the lower carrier body, the membrane assembly supporting a membrane support beneath the membrane assembly; andAttorney Docket No.44023978WO01;05542-1634WO1 a first flexible seal forming a first pressurizable chamber between the lower carrier body and the membrane support; a flexure connecting the membrane support to the lower carrier body, the flexure extending through the first pressurizable chamber; a treatment station spaced apart from the polishing pad, the treatment station having a plurality of nozzles to direct a fluid into a cavity of the treatment station and onto the carrier head positioned above the cavity in the treatment station; and an actuator to move the carrier head between the treatment station and the platen.

17. The system of claim 16, wherein a first portion of the plurality of nozzles are arranged to direct the fluid onto an inner surface of a retaining ring of the carrier head, and a second portion of the plurality of nozzles are arranged to direct the fluid onto a side surface, a bottom surface, or both, of a flexible membrane supported by the membrane support.

18. The system of claim 16, comprising a boiler in fluid connection with the plurality of nozzles.

19. The system of claim 16, wherein the membrane assembly includes a membrane support, a flexible membrane secured to the membrane support, and the flexible membrane has a lower surface that provides a substrate mounting surface.

20. The system of claim 16, comprising a controller configured to: move the carrier head over the treatment station; pressurize the first pressurizable chamber such that the membrane assembly is displaced from a home position; and direct a gas from an orifice of the nozzles onto a component of the carrier head to clean polishing by-product off the component.

21. The system of claim 20, comprising a brush, an actuator configured to cause motion of the brush, and the controller configured to: cause the actuator to move the brush into contact with the component of the carrier head; andAttorney Docket No.44023978WO01;05542-1634WO1 cause relative motion between the brush and the component to clean polishing by-product off the component.

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