US20100056028A1 - Substrate holding apparatus and polishing apparatus - Google Patents
Substrate holding apparatus and polishing apparatus Download PDFInfo
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- US20100056028A1 US20100056028A1 US12/613,016 US61301609A US2010056028A1 US 20100056028 A1 US20100056028 A1 US 20100056028A1 US 61301609 A US61301609 A US 61301609A US 2010056028 A1 US2010056028 A1 US 2010056028A1
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- elastic membrane
- semiconductor wafer
- polishing
- substrate
- abutment portion
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Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
- H01L21/304—Mechanical treatment, e.g. grinding, polishing, cutting
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B37/00—Lapping machines or devices; Accessories
- B24B37/27—Work carriers
- B24B37/30—Work carriers for single side lapping of plane surfaces
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B41/00—Component parts such as frames, beds, carriages, headstocks
- B24B41/06—Work supports, e.g. adjustable steadies
- B24B41/061—Work supports, e.g. adjustable steadies axially supporting turning workpieces, e.g. magnetically, pneumatically
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B49/00—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation
- B24B49/10—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation involving electrical means
- B24B49/105—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation involving electrical means using eddy currents
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Manufacturing & Machinery (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
- Mechanical Treatment Of Semiconductor (AREA)
Abstract
The present invention relates to a substrate holding apparatus for holding a substrate such as a semiconductor wafer in a polishing apparatus for polishing the substrate to a flat finish. The substrate holding apparatus according to the present invention comprises a top ring body having a receiving space therein, and a vertically movable member which is vertically movable within the receiving space in the top ring body. An abutment member having an elastic membrane is attached to a lower surface of the vertically movable member. The elastic membrane of the abutment member comprises an abutment portion, having a flange projecting outwardly, brought into direct or indirect contact with the substrate, and a connecting portion extending upwardly from a base portion of the flange of the abutment portion and being connected to the vertically movable member. The connecting portion is made of a material having a flexibility higher than that of material of the abutment portion.
Description
- This application is a National Stage application of PCT/JP02/12816, filed Dec. 6, 2002.
- The present invention relates to a substrate holding apparatus for holding a substrate to be polished and pressing the substrate against a polishing surface, and more particularly to a substrate holding apparatus for holding a substrate such as a semiconductor wafer in a polishing apparatus for polishing the substrate to a flat finish. The present invention also relates to a polishing apparatus having such a substrate holding apparatus.
- In recent years, semiconductor devices have become more integrated, and structures of semiconductor elements have become more complicated. Further, a number of layers in multilayer interconnections used for a logical system has been increased. Accordingly, irregularities on a surface of a semiconductor device become increased, so that step heights on the surface of the semiconductor device tend to be larger. This is because, in a manufacturing process of a semiconductor device, a thin film is formed on a semiconductor device, then micromachining processes, such as patterning or forming holes, are performed on the semiconductor device, and these processes are repeated many times to form subsequent thin films on the semiconductor device.
- When a number of irregularities is increased on a surface of a semiconductor device, the following problems arise. A thickness of a film formed in a portion having a step is relatively small when a thin film is formed on a semiconductor device. An open circuit is caused by disconnection of interconnections, or a short circuit is caused by insufficient insulation between interconnection layers. As a result, good products cannot be obtained, and yield tends to be reduced. Further, even if a semiconductor device initially works normally, reliability of the semiconductor device is lowered after long-term use. At a time of exposure during a lithography process, if an irradiation surface has irregularities, then a lens unit in an exposure system is locally unfocused. Therefore, if the irregularities of the surface of the semiconductor device are increased, then this becomes problematic in that it is difficult to form a fine pattern itself on the semiconductor device.
- Accordingly, in a manufacturing process of a semiconductor device, it increasingly becomes important to planarize a surface of the semiconductor device. The most important one of planarizing technologies is CMP (Chemical Mechanical Polishing). In such chemical mechanical polishing, with use of a polishing apparatus, while a polishing liquid containing abrasive particles such as silica (SiO2) therein is supplied onto a polishing surface such as a polishing pad, a substrate such as a semiconductor wafer is brought into sliding contact with the polishing surface, so that the substrate is polished.
- This type of polishing apparatus comprises a polishing table having a polishing surface constituted by a polishing pad, and a substrate holding apparatus, which is called as a top ring or a carrier head, for holding a semiconductor wafer. When a semiconductor wafer is polished with such a polishing apparatus, the semiconductor wafer is held and pressed against the polishing table under a predetermined pressure by the substrate holding apparatus. At this time, the polishing table and the substrate holding apparatus are moved relatively to each other to bring the semiconductor wafer into sliding contact with the polishing surface, so that a surface of the semiconductor wafer is polished to a flat mirror finish.
- In such a polishing apparatus, if a relative pressing force between the semiconductor wafer being polished and the polishing surface of the polishing pad is not uniform over an entire surface of the semiconductor wafer, then the semiconductor wafer may insufficiently be polished or may excessively be polished at some portions depending on a pressing force applied to those portions of the semiconductor wafer. Therefore, it has been attempted to form a surface, for holding a semiconductor wafer, of a substrate holding apparatus by an elastic membrane made of an elastic material such as rubber and to supply fluid pressure such as air pressure to a backside surface of the elastic membrane to uniformize pressing forces applied to the semiconductor wafer over an entire surface of the semiconductor wafer.
- Further, the polishing pad is so elastic that pressing forces applied to a peripheral portion of the semiconductor wafer being polished become non-uniform, and hence only the peripheral portion of the semiconductor wafer may excessively be polished, which is referred to as “edge rounding”. In order to prevent such edge rounding, there has been used a substrate holding apparatus in which a semiconductor wafer is held at its peripheral portion by a guide ring or a retainer ring, and an annular portion of the polishing surface that corresponds to the peripheral portion of the semiconductor wafer is pressed by the guide ring or retainer ring.
- A thickness of a thin film formed on a surface of a semiconductor wafer varies from position to position in a radial direction of the semiconductor wafer depending on a film deposition method or characteristics of a film deposition apparatus. Specifically, the thin film has a film thickness distribution in the radial direction of the semiconductor wafer. Since a conventional substrate holding apparatus, as described above, for uniformly pressing an entire surface of a semiconductor wafer polishes the semiconductor wafer uniformly over the entire surface thereof, it cannot realize a polishing amount distribution that is equal to the aforementioned film thickness distribution on the surface of the semiconductor wafer. Therefore, the conventional polishing apparatus cannot sufficiently cope with the film thickness distribution in the radial direction, and insufficient or excessive polishing is caused.
- Further, the aforementioned film thickness distribution on the surface of the semiconductor wafer varies depending on a type of a film deposition method or a film deposition apparatus. Specifically, positions and a number of portions having a large film thickness in a radial direction and differences in thickness between thin film portions and thick film portions vary depending on the type of a film deposition method or the film deposition apparatus. Therefore, a substrate holding apparatus capable of easily coping with various film thickness distributions at low cost has been required rather than a substrate holding apparatus capable of coping with only a specific film thickness distribution.
- In a substrate holding apparatus having a structure for pressing a portion of a polishing surface that corresponds to a peripheral portion of a semiconductor wafer by a guide ring or retainer ring in order to prevent edge rounding, non-uniform polishing such as edge rounding cannot sufficiently be suppressed in some cases by merely controlling pressing forces of the aforementioned guide ring or retainer ring. Generally, no devices are formed on a peripheral portion of a semiconductor wafer. Nevertheless, for a purpose of preventing elution of metal or other defects, it is required that a polishing rate is intentionally reduced at a peripheral portion of a semiconductor wafer so that an underlayer film is not exposed, or, on the contrary, a polishing rate is intentionally increased at a peripheral portion of a semiconductor wafer so as to remove a film on the peripheral portion of the semiconductor wafer. A conventional polishing apparatus cannot sufficiently control a polishing rate at a peripheral portion of a semiconductor wafer to a desired level.
- The present invention has been made in view of the above prior art. It is, therefore, a first object of the present invention to provide a substrate holding apparatus and a polishing apparatus which can polish a thin film, formed on a surface of a workpiece such as a semiconductor wafer, having a film thickness distribution, and can obtain a uniform film thickness after polishing.
- Further, the present invention has been made in view of the above prior art in which a polishing rate at a peripheral portion of a workpiece cannot sufficiently be controlled to a desired level. It is, therefore, a second object of the present invention to provide a substrate holding apparatus and a polishing apparatus which can uniformly polish a workpiece such as a semiconductor wafer while controlling a polishing rate at a peripheral portion of the workpiece to a desired level.
- In order to attain the first object, according to a first aspect of the present invention, there is provided a substrate holding apparatus for holding and pressing a substrate to be polished against a polishing surface, characterized in that: the substrate holding apparatus comprises a top ring body having a receiving space therein, and a vertically movable member which is vertically movable within the receiving space in the top ring body; an abutment member having an elastic membrane is attached to a lower surface of the vertically movable member; the elastic membrane of the abutment member comprises an abutment portion, having flanges projecting outwardly and inwardly, brought into direct or indirect contact with the substrate, and connecting portion extending upwardly from base portions of the flanges of the abutment portion and being connected to the vertically movable member; and the connecting portions are made of a material having a flexibility higher than that of material of the abutment portion.
- With this arrangement, pressures to be applied to the substrate can independently be controlled, and hence a pressing force applied to a thicker area of a thin film can be made higher than a pressing force applied to a thinner area of the thin film, thereby selectively increasing a polishing rate of the thicker area of the thin film. Thus, an entire surface of a substrate can be polished exactly to a desired level irrespective of a film thickness distribution obtained at a time the thin film is formed. Further, even if the vertically movable member is pressed downwardly for polishing, excessive downward forces are not applied to the substrate which is brought into close contact with the abutment portion because the connecting portion is elastically deformed, so that a uniform polishing rate can be achieved in an area between the base portions of the flanges. Further, even if the vertically movable member is lifted for polishing, excessive upward forces are not applied to the abutment portion because the connecting portion is likely to extend, so that a vacuum is not formed near the base portions of the flanges to achieve a uniform polishing rate in an area between the base portions.
- According to a second aspect of the present invention, there is provided a substrate holding apparatus for holding and pressing a substrate to be polished against a polishing surface, characterized in that: the substrate holding apparatus comprises a top ring body having a receiving space therein, and a vertically movable member which is vertically movable within the receiving space in the top ring body; an abutment member having an elastic membrane is attached to a lower surface of the vertically movable member; the elastic membrane of the abutment member comprises an abutment portion, having flanges projecting outwardly and inwardly, brought into direct or indirect contact with the substrate, and connecting portions extending upwardly from base portions of the flanges of the abutment portion and being connected to the vertically movable member; and the connecting portions comprise a thin portion having a thickness smaller than that of the abutment portion.
- With this arrangement, an entire surface of a substrate can be polished exactly to a desired level irrespective of a film thickness distribution obtained at a time the thin film is formed. Simultaneously, even if the vertically movable member is pressed downwardly for polishing, excessive downward forces are not applied to the substrate which is brought into close contact with the abutment portion because the connecting portion is likely to be deformed at the thin portion, so that a uniform polishing rate can be achieved in an area between the base portions of the flanges. Further, even if the vertically movable member is lifted for polishing, excessive upward forces are not applied to the abutment portion because the thin portions are likely to extend, so that a vacuum is not formed near the base portions of the flanges to achieve a uniform polishing rate in an area between the base portions. Particularly, when the thin portions are formed so as to be constricted inwardly in cross-section, these effects can effectively be achieved.
- According to a third aspect of the present invention, there is provided a substrate holding apparatus for holding and pressing a substrate to be polished against a polishing surface, characterized in that: the substrate holding apparatus comprises a top ring body having a receiving space therein, and a vertically movable member which is vertically movable within the receiving space in the top ring body; an abutment member having an elastic membrane is attached to a lower surface of the vertically movable member; the elastic membrane of the abutment member comprises an abutment portion, having flanges projecting outwardly and inwardly, brought into direct or indirect contact with the substrate, and connecting portions extending upwardly from base portions of the flanges of the abutment portion and being connected to the vertically movable member; and adhesiveness of a lower surface of the base portions of the flanges of the abutment portion is weakened.
- With this arrangement, an entire surface of a substrate can be polished exactly to a desired level irrespective of a film thickness distribution obtained at a time a thin film is formed. Simultaneously, even if the vertically movable member is lifted for polishing, a vacuum is unlikely to be formed near the base portions of the flanges because the base portions of the flanges is unlikely to be brought into close contact with the substrate. Therefore, a uniform polishing rate can be achieved in an area between base portions.
- In this case, an intermediate member having a low adhesiveness to the substrate may be disposed on a lower surface of the base portions of the flanges of the abutment portion to weaken adhesiveness of the lower surface of the base portions of the flanges. Alternatively, adhesiveness between the base portions of the flanges and the substrate may be weakened by, for example, forming a groove in the lower surface of the base portions of the flanges, or by forming the lower surface of the base portions as a rough surface.
- According to a fourth aspect of the present invention, there is provided a substrate holding apparatus for holding and pressing a substrate to be polished against a polishing surface, characterized in that: the substrate holding apparatus comprises a top ring body having a receiving space therein, and a vertically movable member which is vertically movable within the receiving space in the top ring body; an abutment member having an elastic membrane is attached to a lower surface of the vertically movable member; the elastic membrane of the abutment member comprises an abutment portion, having flanges projecting outwardly and inwardly, brought into direct or indirect contact with the substrate, and connecting portions extending upwardly from base portions of the flanges of the abutment portion and being connected to the vertically movable member; and a hard member made of a material harder than that of the elastic membrane is embedded in the base portions of the flanges of the abutment portion. In this case, the hard member should preferably have an annular shape.
- With this arrangement, an entire surface of a substrate can be polished exactly to a desired level irrespective of a film thickness distribution obtained at a time the thin film is formed. Simultaneously, even if the vertically movable member is downwardly pressed for polishing, excessive downward forces are not applied to the substrate which is brought into close contact with the abutment portion because downward forces by the connecting portions are dispersed by the hard members, so that a uniform polishing rate can be achieved in an area between base portions of the flanges. Further, even if the vertically movable member is lifted for polishing, a vacuum is not formed near the base portions of the flanges because the hard member prevents deformation of the vicinity of the base portions of the flanges. Therefore, a uniform polishing rate can be achieved in an area between the base portions of the flanges.
- According to a fifth aspect of the present invention, there is provided a substrate holding apparatus for holding and pressing a substrate to be polished against a polishing surface, characterized in that: the substrate holding apparatus comprises a top ring body having a receiving space therein, and a vertically movable member which is vertically movable within the receiving space in the top ring body; an abutment member having an elastic membrane is attached to a lower surface of the vertically movable member; and the elastic membrane of the abutment member comprises an abutment portion, having flanges projecting outwardly and inwardly, brought into direct or indirect contact with the substrate, an extending portion extending outwardly from a base portion of each flange to a position inward of a tip of this flange to form a groove between the extending portion and the flange of the abutment portion, and a connecting portion extending upwardly from an outward end of the extending portion and being connected to the vertically movable member.
- With this arrangement, an entire surface of a substrate can be polished exactly to a desired level irrespective of a film thickness distribution obtained at a time a thin film is formed. Further, in a case where the vertically movable member is lifted for polishing after the substrate is brought into close contact with the abutment portion, upward forces by the connecting portion are converted into forces in horizontal or oblique directions by the extending portion, and these converted forces are applied to the base portions of the flanges. Therefore, upward forces applied to the base portions of the flanges can be made extremely small, so that excessive upward forces are not applied to the abutment portion. Accordingly, a vacuum is not formed near the base portions, so that a uniform polishing rate can be achieved in an area between the base portions.
- According to a preferred aspect of the present invention, the connecting portion positioned radially inwardly and the connecting portion positioned radially outwardly have different thicknesses. In this case, it is desirable that the connecting portion positioned radially inwardly has a thickness smaller than a thickness of the connecting portion positioned radially outwardly.
- According to a preferred aspect of the present invention, the flange projecting radially outwardly and the flange projecting radially inwardly have different lengths. In this case, it is desirable that the flange projecting radially outwardly has a length larger than that of the flange projecting radially inwardly.
- Because a cylinder having a smaller curvature generally has a stiffness larger than a cylinder having a larger curvature, a vertical force applied to the base portion of the flange by the connecting portion positioned radially inwardly becomes larger than a force applied to the base portion of the flange by the connecting portion positioned radially outwardly. Therefore, with the above arrangement, forces applied to the base portions of the flange positioned radially inwardly and the flange positioned radially outwardly can be adjusted to the same level, or a sealing capability can be enhanced at the flange projecting radially outwardly, so that a uniform polishing rate can be achieved in an area between the base portions.
- According to a sixth aspect of the present invention, there is provided a substrate holding apparatus for holding and pressing a substrate to be polished against a polishing surface, characterized in that: the substrate holding apparatus comprises a top ring body having a receiving space therein, and a vertically movable member which is vertically movable within the receiving space in the top ring body; an abutment member having an elastic membrane which is brought into direct or indirect contact with the substrate is attached to a lower surface of the vertically movable member; and the vertically movable member is made of a material having a large stiffness.
- With this arrangement, when the vertically movable member is made of a material having a large stiffness and a light weight, e.g., epoxy resin, the vertically movable member becomes unlikely to be bent, so that polishing rates are prevented from being locally increased. Further, when a material having no magnetism is selected as a material of the vertically movable member, a film thickness of a thin film formed on a surface of a semiconductor wafer to be polished can be measured with a film thickness method using eddy current in such a state that the semiconductor wafer is held.
- According to a seventh aspect of the present invention, there is provided a substrate holding apparatus for holding and pressing a substrate to be polished against a polishing surface, characterized in that: an abutment member having an elastic membrane is attached to a lower surface of a top ring; the elastic membrane of the abutment member comprises an abutment portion, having a flange projecting outwardly, brought into direct or indirect contact with the substrate, and a connecting portion extending upwardly from a base portion of the flange of the abutment portion and being connected to the top ring; and the top ring has a support portion for supporting the flange of the abutment member.
- With this arrangement, an entire surface of a substrate can be polished exactly to a desired level irrespective of a film thickness distribution obtained at a time a thin film is formed. Simultaneously, when a pressurized fluid is supplied into a space around the abutment member, the flange is prevented from being deformed and attached to a lower surface of the top ring, thereby achieving stable polishing.
- In this case, it is desirable that the support portion has a radial length larger than a radial length of the flange of the abutment member. With such a support portion, the flange of the abutment member can be supported more reliably, so that more stable polishing can be achieved.
- According to a preferred aspect of the present invention, a fluid introduction groove for introducing a fluid into an upper surface of the flange of the abutment member is formed in the support portion. With this arrangement, since a pressurized fluid can be introduced into the upper surface of the flange, adhesiveness of the flange to the substrate can be enhanced to achieve stable polishing.
- According to an eighth aspect of the present invention, there is provided a substrate holding apparatus for holding and pressing a substrate to be polished against a polishing surface, characterized in that: the substrate holding apparatus comprises a top ring body having a receiving space therein, a vertically movable member which is vertically movable within the receiving space in the top ring body, and a seal ring being brought into contact with an upper surface of a peripheral portion of the substrate; and the vertically movable member has a support portion for supporting the seal ring, with the support portion having a radial length in a range of from 1 mm to 7 mm.
- With this arrangement, an entire surface of a substrate can be polished exactly to a desired level irrespective of a film thickness distribution obtained at a time a thin film is formed. Simultaneously, when a pressurized fluid is supplied into a space around the seal ring, the seal ring is prevented from being deformed and attached to a lower surface of the vertically movable member. Further, a peripheral portion of the substrate is likely to be excessively polished. However, when the support portion has a radial length in a range of from 1 mm to 7 mm, it is possible to prevent excessive polishing.
- According to a preferred aspect of the present invention, a fluid introduction groove for introducing a fluid into an upper surface of the seal ring is formed in the support portion of the vertically movable member. With this arrangement, since a pressurized fluid can be introduced into the upper surface of the seal ring, adhesiveness of the seal ring to the substrate can be enhanced to achieve stable polishing.
- In order to attain the second object, according to a ninth aspect of the present invention, there is provided a substrate holding apparatus for holding and pressing a substrate to be polished against a polishing surface, characterized in that: the substrate holding apparatus comprises a top ring body for holding the substrate, with an edge bag being brought into contact with a peripheral portion of the substrate, and a torque transmitting member being brought into contact with the substrate radially inwardly of the edge bag; and a pressure of a first pressure chamber defined in the edge bag and a pressure of a second pressure chamber defined radially inwardly of the edge bag are independently controlled.
- With this arrangement, sufficient torque can be transmitted to the substrate by the torque transmitting member. Further, an entire surface of the substrate except the peripheral portion thereof can be pressed against the polishing surface at a uniform force by pressure of the second pressure chamber, and pressure of the first pressure chamber can be controlled independently of the pressure of the second pressure chamber. Therefore, it is possible to control a polishing rate at the peripheral portion of the substrate, i.e., a polishing profile of the peripheral portion of the substrate.
- According to a preferred aspect of the present invention, the torque transmitting member has a communication hole communicating a space inside of the torque transmitting member and a space outside of the torque transmitting member with each other.
- Further, in view of controlling a polishing rate of a peripheral portion of the semiconductor wafer, it is desirable that the edge bag defining the first pressure chamber comprises a member having a radial width in a range of from 1 mm to 10 mm.
- According to a preferred aspect of the present invention, the substrate holding apparatus comprises a retainer ring secured to or formed integrally with the top ring body for holding a side edge portion of the substrate; and a pressing force to press the retainer ring against the polishing surface is controlled independently of a pressure of the pressure chamber. In this manner, when the pressing force of the retainer ring is also controlled, more detailed control can be achieved.
- A polishing apparatus according to the present invention comprises the aforementioned substrate holding apparatus and a polishing table having a polishing surface.
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FIG. 1 is a cross-sectional view showing an entire arrangement of a polishing apparatus having a substrate holding apparatus according to the present invention; -
FIG. 2 is a vertical cross-sectional view showing a substrate holding apparatus according to a first embodiment of the present invention; -
FIG. 3 is a bottom view of the substrate holding apparatus shown inFIG. 2 ; -
FIG. 4 is a vertical cross-sectional view showing a first example of a ring tube in the substrate holding apparatus according to the first embodiment of the present invention; -
FIG. 5 is a vertical cross-sectional view showing an elastic membrane of the ring tube shown inFIG. 4 ; -
FIGS. 6A through 6C are vertical cross-sectional views showing deformation of the elastic membrane of the ring tube; -
FIG. 7 is a vertical cross-sectional view showing a second example of an elastic membrane of a ring tube in a substrate holding apparatus according to the present invention; -
FIG. 8 is a vertical cross-sectional view showing a third example of an elastic membrane of a ring tube in a substrate holding apparatus according to the present invention; -
FIG. 9 is a vertical cross-sectional view showing a fourth example of an elastic membrane of a ring tube in a substrate holding apparatus according to the present invention; -
FIG. 10 is a vertical cross-sectional view showing a fifth example of an elastic membrane of a ring tube in a substrate holding apparatus according to the present invention; -
FIG. 11 is a vertical cross-sectional view showing a sixth example of an elastic membrane of a ring tube in a substrate holding apparatus according to the present invention; -
FIGS. 12A through 12C are vertical cross-sectional views showing a seventh example of an elastic membrane of a ring tube in a substrate holding apparatus according to the present invention; -
FIG. 13 is a vertical cross-sectional view showing a substrate holding apparatus according to a second embodiment of the present invention; -
FIG. 14 is a bottom view of the substrate holding apparatus shown inFIG. 13 ; -
FIG. 15 is a vertical cross-sectional view showing a ring tube in the substrate holding apparatus according to the second embodiment of the present invention; -
FIG. 16 is a vertical cross-sectional view showing a ring tube without any support portions in a chucking plate; -
FIG. 17 is a partial perspective view showing a support portion of a chucking plate ofFIG. 15 ; -
FIG. 18 is a vertical cross-sectional view showing a seal ring without any support portions in a chucking plate; -
FIG. 19 is a vertical cross-sectional view showing a seal ring in the substrate holding apparatus ofFIG. 15 ; -
FIG. 20 is a vertical cross-sectional view showing a substrate holding apparatus according to a third embodiment of the present invention; -
FIG. 21 is a partial cross-sectional view showing an edge bag ofFIG. 20 ; and -
FIG. 22 is a partial cross-sectional view showing a torque transmitting member ofFIG. 20 . - A substrate holding apparatus and a polishing apparatus according to embodiments of the present invention will be described in detail below with reference to the drawings.
-
FIG. 1 is a cross-sectional view showing an entire arrangement of a polishing apparatus having a substrate holding apparatus according to the present invention. The substrate holding apparatus serves to hold a substrate such as a semiconductor wafer to be polished and to press the substrate against a polishing surface on a polishing table. As shown inFIG. 1 , a polishing table 100 having apolishing pad 101 attached on an upper surface thereof is provided underneath atop ring 1 constituting a substrate holding apparatus according to the present invention. A polishingliquid supply nozzle 102 is provided above the polishing table 100, and a polishing liquid Q is supplied onto thepolishing pad 101 on the polishing table 100 from the polishingliquid supply nozzle 102. - Various kinds of polishing pads are available on the market. For example, some of these are SUBA800, IC-1000, and IC-1000/SUBA400 (two-layer cloth) manufactured by Rodel Inc., and Surfin xxx-5 and Surfin 000 manufactured by Fujimi Inc. SUBA800, Surfin xxx-5, and Surfin 000 are non-woven fabrics bonded by urethane resin, and IC-1000 is made of rigid foam polyurethane (single-layer). Foam polyurethane is porous and has a large number of fine recesses or holes formed in its surface.
- The
top ring 1 is connected to a topring drive shaft 11 by auniversal joint 10, and the topring drive shaft 11 is coupled to a topring air cylinder 111 fixed to atop ring head 110. The topring air cylinder 111 operates to move the topring drive shaft 11 vertically to thereby lift and lower thetop ring 1 as a whole and to press aretainer ring 3 fixed to a lower end of atop ring body 2 against thepolishing pad 101. The topring air cylinder 111 is connected to acompressed air source 120 via a regulator R1, which can regulate pressure of compressed air or the like which is supplied to the topring air cylinder 111. Thus, it is possible to adjust a pressing force to press thepolishing pad 101 with theretainer ring 3. - The top
ring drive shaft 11 is connected to arotary sleeve 112 by a key (not shown). Therotary sleeve 112 has a timingpulley 113 fixedly disposed at a peripheral portion thereof. Atop ring motor 114 is fixed to thetop ring head 110, and the timingpulley 113 is coupled to a timingpulley 116 mounted on thetop ring motor 114 via atiming belt 115. Therefore, when thetop ring motor 114 is energized for rotation, therotary sleeve 112 and the topring drive shaft 11 are rotated in unison with each other via the timingpulley 116, thetiming belt 115, and the timingpulley 113 to thereby rotate thetop ring 1. Thetop ring head 110 is supported on a topring head shaft 117 fixedly supported on a frame (not shown). - Next, a substrate holding apparatus according to a first embodiment of the present invention will be described below.
FIG. 2 is a vertical cross-sectional view showingtop ring 1 of the substrate holding apparatus according to the first embodiment, andFIG. 3 is a bottom view of thetop ring 1 shown inFIG. 2 . As shown inFIG. 2 , thetop ring 1 constituting a substrate holding apparatus comprises atop ring body 2 in the form of a cylindrical housing with a receiving space defined therein, and aretainer ring 3 fixed to a lower end of thetop ring body 2. Thetop ring body 2 is made of a material having high strength and rigidity, such as metal or ceramic. Theretainer ring 3 is made of highly rigid synthetic resin, ceramic, or the like. - The
top ring body 2 comprises acylindrical housing 2 a, an annularpressurizing sheet support 2 b fitted into a cylindrical portion of thehousing 2 a, and anannular seal 2 c fitted over an outer circumferential edge of an upper surface of thehousing 2 a. Theretainer ring 3 is fixed to the lower end of thehousing 2 a of thetop ring body 2. Theretainer ring 3 has a lower portion projecting radially inwardly. Theretainer ring 3 may be formed integrally with thetop ring body 2. - Top
ring drive shaft 11 is disposed above a central portion of thehousing 2 a of thetop ring body 2, and thetop ring body 2 is coupled to the topring drive shaft 11 byuniversal joint 10. Theuniversal joint 10 has a spherical bearing mechanism by which thetop ring body 2 and the topring drive shaft 11 are tillable with respect to each other, and a rotation transmitting mechanism for transmitting rotation of the topring drive shaft 11 to thetop ring body 2. The spherical bearing mechanism and the rotation transmitting mechanism transmit a pressing force and a rotating force from the topring drive shaft 11 to thetop ring body 2 while allowing thetop ring body 2 and the topring drive shaft 11 to be tilted with respect to each other. - The spherical bearing mechanism comprises a hemispherical
concave recess 11 a defined centrally in a lower surface of the topring drive shaft 11, a hemisphericalconcave recess 2 d defined centrally in an upper surface of thehousing 2 a, and aball bearing 212 made of a highly hard material such as ceramic and interposed between theconcave recesses ring drive shaft 11, and driven pins (not shown) fixed to thehousing 2 a. Even if thetop ring body 2 is tilted with respect to the topring drive shaft 11, the drive pins and the driven pins remain in engagement with each other while contact points are displaced because the drive pins and the driven pins are vertically movable relatively to each other. Thus, the rotation transmitting mechanism reliably transmits rotational torque of the topring drive shaft 11 to thetop ring body 2. - The
top ring body 2 and theretainer ring 3 secured to thetop ring body 2 have a space defined therein, which accommodates therein aseal ring 204 having a lower surface brought into contact with a peripheral portion of a semiconductor wafer W held by thetop ring 1, anannular holder ring 205, and a disk-shaped chucking plate 206 (vertically movable member) which is vertically movable within the receiving space in thetop ring body 2. Theseal ring 204 has a radially outer edge clamped between theholder ring 205 and thechucking plate 206 secured to a lower end of theholder ring 205 and extends radially inwardly so as to cover a lower surface of thechucking plate 206 near its outer circumferential edge. A lower end surface of theseal ring 204 is brought into contact with an upper surface of the semiconductor wafer W to be polished. The semiconductor wafer W has a recess defined in an outer edge thereof, which is referred to as a notch or orientation flat, for recognizing (identifying) an orientation of the semiconductor wafer. Theseal ring 204 should preferably extend radially inwardly of thechucking plate 206 from an innermost position of such notch or orientation flat. - The chucking
plate 206 may be made of metal. However, when a thickness of a thin film formed on a surface of a semiconductor wafer is measured by a method using eddy current in a state such that this semiconductor wafer to be polished is held by the top ring, the chuckingplate 206 should preferably be made of a non-magnetic material, e.g., an insulating material such as fluororesin, epoxy resin, or ceramic. - A pressurizing
sheet 207 comprising an elastic membrane extends between theholder ring 205 and thetop ring body 2. The pressurizingsheet 207 has a radially outer edge clamped between thehousing 2 a and the pressurizingsheet support 2 b of thetop ring body 2, and a radially inner edge clamped between anupper end portion 205 a and astopper 205 b of theholder ring 205. Thetop ring body 2, the chuckingplate 206, theholder ring 205, and the pressurizingsheet 207 jointly define apressure chamber 221 in thetop ring body 2. As shown inFIG. 2 , afluid passage 31 comprising tubes and connectors communicates with thepressure chamber 221, which is connected tocompressed air source 120 via a regulator R2 provided in thefluid passage 31. The pressurizingsheet 207 is made of a highly strong and durable rubber material such as ethylene propylene rubber (EPDM), polyurethane rubber, or silicone rubber. - In a case where the pressurizing
sheet 207 is made of an elastic material such as rubber, if the pressurizingsheet 207 is fixedly clamped between theretainer ring 3 and thetop ring body 2, then a desired horizontal surface cannot be maintained on a lower surface of theretainer ring 3 because of elastic deformation of the pressurizingsheet 207 as an elastic material. In order to prevent such a drawback, the pressurizingsheet 207 is clamped between thehousing 2 a of thetop ring body 2 and the pressurizingsheet support 2 b provided as a separate member in the present embodiment. Theretainer ring 3 may vertically be movable with respect to thetop ring body 2, or theretainer ring 3 may have a structure capable of pressing the polishing surface independently of thetop ring body 2. In such cases, the pressurizingsheet 207 is not necessarily fixed in the aforementioned manner. - A cleaning
liquid passage 251 in the form of an annular groove is defined in an upper surface of thehousing 2 a near its outer circumferential edge over which theseal 2 c of thetop ring body 2 is fitted. The cleaningliquid passage 251 communicates with afluid passage 32 via a through-hole 252 formed in theseal 2 c, and is supplied with a cleaning liquid (pure water) via thefluid passage 32. A plurality ofcommunication holes 253 are defined in thehousing 2 a and the pressurizingsheet support 2 b in communication with the cleaningliquid passage 251. The communication holes 253 communicate with a small gap G defined between an outer circumferential surface of theseal ring 204 and an inner circumferential surface of theretainer ring 3. - A
central bag 208 and aring tube 209 which serve as abutment members brought into contact with the semiconductor wafer W are mounted in a space defined between the chuckingplate 206 and the semiconductor wafer W. In the present embodiment, as shown inFIGS. 2 and 3 , thecentral bag 208 is disposed centrally on a lower surface of thechucking plate 206, and thering tube 209 is disposed radially outwardly of thecentral bag 208 in a surrounding relationship relative thereto. Each of theseal ring 204, thecentral bag 208, and thering tube 209 is made of a highly strong and durable rubber material such as ethylene propylene rubber (EPDM), polyurethane rubber, or silicone rubber. - A space defined between the chucking
plate 206 and the semiconductor wafer W is divided into a plurality of spaces by thecentral bag 208 and thering tube 209. Accordingly, apressure chamber 222 is defined between thecentral bag 208 and thering tube 209, and apressure chamber 223 is defined radially outwardly of thering tube 209. - The
central bag 208 comprises anelastic membrane 281 brought into contact with the upper surface of the semiconductor wafer W, and acentral bag holder 282 for detachably holding theelastic membrane 281 in position. Thecentral bag holder 282 has threadedholes 282 a defined therein, and thecentral bag 208 is detachably fastened to a center of the lower surface of thechucking plate 206 byscrews 255 threaded into the threadedholes 282 a. Thecentral bag 208 has acentral pressure chamber 224 defined therein by theelastic membrane 281 and thecentral bag holder 282. - Similarly, the
ring tube 209 comprises anelastic membrane 291 brought into contact with the upper surface of the semiconductor wafer W, and aring tube holder 292 for detachably holding theelastic membrane 291 in position. Thering tube holder 292 has threadedholes 292 a defined therein, and thering tube 209 is detachably fastened to the lower surface of thechucking plate 206 byscrews 256 threaded into the threadedholes 292 a. Thering tube 209 has anintermediate pressure chamber 225 defined therein by theelastic membrane 291 and thering tube holder 292. - In the present embodiment, the
pressure chamber 224 is formed by theelastic membrane 281 of thecentral bag 208 and thecentral bag holder 282, and thepressure chamber 225 is formed by theelastic membrane 291 of thering tube 209 and thering tube holder 292. Thepressure chambers -
Fluid passages pressure chambers central pressure chamber 224, and theintermediate pressure chamber 225, respectively. Thepressure chambers 222 to 225 are connected to thecompressed air source 120 as a supply source via respective regulators R3, R4, R5 and R6 connected respectively to thefluid passages 33 to 36. Thefluid passages 31 to 36 are connected to the respective regulators R1 to R6 through a rotary joint (not shown) mounted on an upper end of thetop ring shaft 110. - The
pressure chamber 221 above the chuckingplate 206 and thepressure chambers 222 to 225 are supplied with pressurized fluids such as pressurized air or atmospheric air or evacuated, via thefluid passages FIG. 1 , the regulators R2 to R6 connected to thefluid passages pressure chambers 221 to 225 can respectively regulate pressures of the pressurized fluids supplied to the respective pressure chambers. Thus, it is possible to independently control the pressures in thepressure chambers 221 to 225 or independently introduce atmospheric air or vacuum into thepressure chambers 221 to 225. In this manner, the pressures in thepressure chambers 221 to 225 are independently varied with the regulators R2 to R6, so that pressing forces to press the semiconductor wafer W against thepolishing pad 101 can be adjusted in local areas of the semiconductor wafer W. In some applications, thepressure chambers 221 to 225 may be connected to avacuum source 121. - In this case, the pressurized fluid or the atmospheric air supplied to the
pressure chambers 222 to 225 may independently be controlled in terms of temperature. With this configuration, it is possible to directly control a temperature of a workpiece such as a semiconductor wafer from a backside of a surface to be polished. Particularly, when each of the pressure chambers is independently controlled in terms of temperature, a rate of chemical reaction can be controlled during a chemical polishing process of CMP. - The chucking
plate 206 has radiallyinner suction portions 261 extended downwardly therefrom between thecentral bag 208 and thering tube 209. The chuckingplate 206 has radiallyouter suction portions 262 extended downwardly therefrom outside of thering tube 209. In the present embodiment, eightsuction portions - The
inner suction portions 261 and theouter suction portions 262 havecommunication holes fluid passages inner suction portions 261 and theouter suction portions 262 are connected to thevacuum source 121 such as a vacuum pump via thefluid passages suction portions vacuum source 121, a negative pressure is developed at lower opening ends of the communication holes 261 a, 262 a thereof to attract a semiconductor wafer W to lower ends of theinner suction portions 261 and theouter suction portions 262. Theinner suction portions 261 and theouter suction portions 262 haveelastic sheets - Since there is a small gap G between the outer circumferential surface of the
seal ring 204 and the inner circumferential surface of theretainer ring 3, theholder ring 205, the chuckingplate 206, and theseal ring 204 attached to thechucking plate 206 can vertically be moved with respect to thetop ring body 2 and theretainer ring 3, and hence are of a floating structure with respect to thetop ring body 2 and theretainer ring 3. Thestopper 205 b of theholder ring 205 has a plurality ofteeth 205 c projecting radially outwardly from an outer circumferential edge thereof. Downward movement of members including theholder ring 205 is limited to a predetermined range by engaging theteeth 205 c with an upper surface of the radially inwardly projecting portion of theretainer ring 3. - Next, operation of the
top ring 1 thus constructed will be described in detail below. - In the polishing apparatus constructed above, when a semiconductor wafer W is to be delivered to the polishing apparatus, the
top ring 1 as a whole is moved to a position to which the semiconductor wafer W is transferred, and the communication holes 261 a, 262 a of theinner suction portions 261 and theouter suction portions 262 are connected via thefluid passages vacuum source 121. The semiconductor wafer W is attracted under vacuum to the lower ends of theinner suction portions 261 and theouter suction portions 262 by suction effect of the communication holes 261 a, 262 a. With the semiconductor wafer W attracted to thetop ring 1, thetop ring 1 as a whole is moved to a position above the polishing table 100 having a polishing surface (polishing pad 101) thereon. An outer circumferential edge of the semiconductor wafer W is held by theretainer ring 3 so that the semiconductor wafer W is not removed from thetop ring 1. - For polishing the semiconductor wafer W, attraction of semiconductor wafer W by the
suction portions top ring 1. Simultaneously, the topring air cylinder 111 connected to the topring drive shaft 11 is actuated to press theretainer ring 3 fixed to a lower end of thetop ring 1 against the polishing surface on the polishing table 100 under a predetermined pressure. In such a state, pressurized fluids are respectively supplied to thepressure chambers central pressure chamber 224, and theintermediate pressure chamber 225 under respective pressures, thereby pressing the semiconductor wafer W against the polishing surface on the polishing table 100. The polishingliquid supply nozzle 102 supplies a polishing liquid Q onto thepolishing pad 101 in advance, so that the polishing liquid Q is held on thepolishing pad 101. Thus, the semiconductor wafer W is polished by thepolishing pad 101 with the polishing liquid Q being present between a (lower) surface, to be polished, of the semiconductor wafer W and thepolishing pad 101. - Local areas of the semiconductor wafer W that are positioned beneath the
pressure chambers pressure chambers central pressure chamber 224 is pressed via theelastic membrane 281 of thecentral bag 208 against the polishing surface under pressure of the pressurized fluid supplied to thecentral pressure chamber 224. A local area of the semiconductor wafer W that is positioned beneath theintermediate pressure chamber 225 is pressed via theelastic membrane 291 of thering tube 209 against the polishing surface under pressure of the pressurized fluid supplied to theintermediate pressure chamber 225. - Therefore, polishing pressures acting on respective local areas of the semiconductor wafer W can be adjusted independently by controlling pressures of the pressurized fluids supplied to the
respective pressure chambers 222 to 225. Specifically, the respective regulators R3 to R6 independently regulate the pressures of the pressurized fluids supplied to thepressure chambers 222 to 225 for thereby adjusting pressing forces applied to press the local areas of the semiconductor wafer W against thepolishing pad 101 on the polishing table 100. With the polishing pressures on the respective local areas of the semiconductor wafer W being adjusted independently to desired values, the semiconductor wafer W is pressed against thepolishing pad 101 on the polishing table 100 that is being rotated. Similarly, pressure of the pressurized fluid supplied to the topring air cylinder 111 can be regulated by the regulator R1 to adjust a force with which theretainer ring 3 presses thepolishing pad 101. While the semiconductor wafer W is being polished, the force with which theretainer ring 3 presses thepolishing pad 101 and the pressing force with which the semiconductor wafer W is pressed against thepolishing pad 101 can appropriately be adjusted for thereby applying polishing pressures in a desired pressure distribution to a central area (C1 inFIG. 3 ), an inner area (C2) between the central area and an intermediate area, the intermediate area (C3), a peripheral area (C4) of the semiconductor wafer W, and a peripheral portion of theretainer ring 3 which is positioned outside of the semiconductor wafer W. - In this manner, the semiconductor wafer W is divided into four concentric circular and annular areas (C1 to C4), which can respectively be pressed under independent pressing forces. A polishing rate depends on a pressing force applied to a semiconductor wafer W against a polishing surface. As described above, since the pressing forces applied to those areas can independently be controlled, polishing rates of the four circular and annular areas (C1 to C4) of the semiconductor wafer W can independently be controlled. Consequently, even if a thickness of a thin film to be polished on the surface of the semiconductor wafer W suffers radial variations, the thin film on the surface of the semiconductor wafer W can be polished uniformly without being insufficiently or excessively polished over an entire surface of the semiconductor wafer. More specifically, even if the thickness of the thin film to be polished on the surface of the semiconductor wafer W differs depending on a radial position of the semiconductor wafer W, pressure in a pressure chamber positioned over a thicker area of the thin film is made higher than pressure in other pressure chambers, or pressure in a pressure chamber positioned over a thinner area of the thin film is made lower than pressure in other pressure chambers. In this manner, a pressing force applied to the thicker area of the thin film against the polishing surface is made higher than a pressing force applied to the thinner area of the thin film against the polishing surface, thereby selectively increasing a polishing rate of the thicker area of the thin film. Consequently, the entire surface of the semiconductor wafer W can be polished exactly to a desired level over the entire surface of the semiconductor wafer W irrespective of a film thickness distribution produced at a time the thin film is formed.
- Any unwanted edge rounding on a circumferential edge of the semiconductor wafer W can be prevented by controlling a pressing force applied to the
retainer ring 3. If the thin film to be polished on the circumferential edge of the semiconductor wafer W has large thickness variations, then the pressing force applied to theretainer ring 3 is intentionally increased or reduced to thus control a polishing rate of the circumferential edge of the semiconductor wafer W. When the pressurized fluids are supplied to thepressure chambers 222 to 225, the chuckingplate 206 is subjected to upward forces. In the present embodiment, pressurized fluid is supplied to thepressure chamber 221 via thefluid passage 31 to prevent thechucking plate 206 from being lifted under these forces due to thepressure chambers 222 to 225. - As described above, the pressing force applied by the top
ring air cylinder 111 to press theretainer ring 3 against thepolishing pad 101, and the pressing forces applied by the pressurized air supplied to thepressure chambers 222 to 225 to press the local areas of the semiconductor wafer W against thepolishing pad 101, are appropriately adjusted to polish the semiconductor wafer W. When polishing of the semiconductor wafer W is finished, the semiconductor wafer W is attracted to the lower ends of theinner suction portions 261 and theouter suction portions 262 under vacuum in the same manner as described above. At this time, supply of the pressurized fluids into thepressure chambers 222 to 225 to press the semiconductor wafer W against the polishing surface is stopped, and thepressure chambers 222 to 225 are vented to an atmosphere. Accordingly, the lower ends of theinner suction portions 261 and theouter suction portions 262 are brought into contact with the semiconductor wafer W. Thepressure chamber 221 is vented to the atmosphere or evacuated to develop a negative pressure therein. If thepressure chamber 221 is maintained at a high pressure, then the semiconductor wafer W is strongly pressed against the polishing surface only in areas brought into contact with theinner suction portions 261 and theouter suction portions 262. Therefore, it is necessary to decrease pressure in thepressure chamber 221 immediately. Accordingly, arelief port 239 penetrating from thepressure chamber 221 through thetop ring body 2 may be provided for decreasing the pressure in thepressure chamber 221 immediately, as shown inFIG. 2 . In this case, when thepressure chamber 221 is pressurized, it is necessary to continuously supply pressurized fluid into thepressure chamber 221 via thefluid passage 31. Therelief port 239 comprises a check valve for preventing an outside air from flowing into thepressure chamber 221 at a time when a negative pressure is developed in thepressure chamber 221. - After attraction of the semiconductor wafer W, the
top ring 1 as a whole is moved to a position to which the semiconductor wafer W is to be transferred, and then a fluid (e.g., compressed air or a mixture of nitrogen and pure water) is ejected to the semiconductor wafer W via the communication holes 261 a, 262 a of theinner suction portions 261 and theouter suction portions 262 to release the semiconductor wafer W from thetop ring 1. - The polishing liquid Q used to polish the semiconductor wafer W tends to flow through the small gap G between the outer circumferential surface of the
seal ring 204 and theretainer ring 3. If the polishing liquid Q is firmly deposited in the gap G, then theholder ring 205, the chuckingplate 206, and theseal ring 204 are prevented from smoothly moving vertically with respect to thetop ring body 2 and theretainer ring 3. To avoid such a drawback, a cleaning liquid (pure water) is supplied through thefluid passage 32 to the cleaningliquid passage 251. Accordingly, the pure water is supplied via a plurality ofcommunication holes 253 to a region above the gap G, thus cleaning the gap G to prevent the polishing liquid Q from being firmly deposited in the gap G. The pure water should preferably be supplied after a polished semiconductor wafer W is released and until a next semiconductor wafer to be polished is attracted to thetop ring 1. It is also preferable to discharge all supplied pure water out of thetop ring 1 before the next semiconductor wafer is polished, and hence to provide theretainer ring 3 with a plurality of through-holes 3 a shown inFIG. 2 . Furthermore, if a pressure buildup is developed in aspace 226 defined between theretainer ring 3, theholder ring 205, and the pressurizingsheet 207, then it acts to prevent thechucking plate 206 from being elevated in thetop ring body 2. Therefore, in order to allow thechucking plate 206 to be elevated smoothly in thetop ring body 2, the through-holes 3 a should preferably be provided for equalizing pressure in thespace 226 with atmospheric pressure. - As described above, according to a substrate holding apparatus of the first embodiment, the pressures in the
pressure chambers pressure chamber 224 in thecentral bag 208, and thepressure chamber 225 in thering tube 209 are independently controlled to control pressing forces acting on the semiconductor wafer W. - A first example of the
ring tube 209 in the substrate holding apparatus according to the first embodiment of the present invention will be described in detail below. Although only thering tube 209 will be described below, the following description can be applied to thecentral bag 208. -
FIG. 4 is a vertical cross-sectional view showing thering tube 209 shown inFIG. 2 , andFIG. 5 is a vertical cross-sectional view showing theelastic membrane 291 of thering tube 209 shown inFIG. 4 . As shown inFIGS. 4 and 5 , theelastic membrane 291 of thering tube 209 in a first example has anabutment portion 291b having flanges 291 a projecting outwardly and inwardly, and connectingportions 291 c connected via thering tube holder 292 to thechucking plate 206. The connectingportions 291 c extend upwardly frombase portions 291 d of theflanges 291 a. A lower surface of theabutment portion 291 b is brought into contact with the upper surface of the semiconductor wafer W. Theflanges 291 a, theabutment portion 291 b, and the connectingportions 291 c are integrally made of the same material. - As described above, when a semiconductor wafer is polished, pressurized fluids are supplied to the
pressure chamber 222, and thepressure chamber 223 surrounding thering tube 209. Thus, theflanges 291 a are brought into close contact with the semiconductor wafer W by pressurized fluids supplied to thepressure chambers pressure chamber pressure chamber 225 is considerably higher than pressure of the pressurized fluid supplied to thepressure chamber 225 defined in thering tube 209, high-pressure fluid surrounding thepressure chamber 225 is prevented from flowing into a lower portion of thering tube 209. Therefore, theflanges 291 a can widen a range of pressure control in each of the pressure chambers, for thereby pressing the semiconductor wafer more stably. -
Openings 291 e are formed in central portions of theabutment portion 291 b of thering tube 209, and thus a pressurized fluid supplied to theintermediate pressure chamber 225 directly contacts with the upper surface of the semiconductor wafer W through theopenings 291 e of theabutment portion 291 b. Since a pressurized fluid is supplied to theintermediate pressure chamber 225 during polishing, the pressurized fluid presses theabutment portion 291 b of thering tube 209 against the upper surface of the semiconductor wafer W. Therefore, even if theopenings 291 e are formed in theabutment portion 291 b, a pressurized fluid in theintermediate pressure chamber 225 hardly flows out to an exterior of theintermediate pressure chamber 225. Further, when the semiconductor wafer W is released, a downward pressure can be applied through theopenings 291 e to the semiconductor wafer W by a pressurized fluid, so that the semiconductor wafer W can more smoothly be released. - When the pressurized fluid supplied to the
intermediate pressure chamber 225 is controlled in terms of temperature and a temperature of the semiconductor wafer W is controlled from a backside of the wafer to be polished, as described above, theopenings 291 e formed in theabutment portion 291 b of thering tube 209 can increase an area in which the pressurized fluid controlled in terms of temperature is brought into contact with the semiconductor wafer W. Therefore, controllability in terms of temperature of the semiconductor wafer W can be improved. Further, when polishing of the semiconductor wafer W is finished and the semiconductor wafer W is released, theintermediate pressure chamber 225 is opened to outside air via theopenings 291 e. Thus, the fluid supplied into theintermediate pressure chamber 225 is prevented from remaining in theintermediate pressure chamber 225. Therefore, even if semiconductor wafers W are continuously polished, controllability in terms of temperature of the semiconductor wafer W can be maintained. - In a case where the
aforementioned flanges 291 a are provided at theabutment portion 291 b of thering tube 209, when a pressurized fluid is supplied to thepressure chamber 221 to press the chuckingplate 206 downwardly for polishing, downward forces may excessively be applied to portions of the semiconductor wafer W near thebase portions 291 d of theflanges 291 a of thering tube 209 by the connectingportions 291 c, so that a polishing rate may be locally increased at these portions. - On the other hand, as shown in
FIGS. 6A through 6C , in a case where, after the semiconductor wafer W is brought into close contact with theabutment portion 291 b of thering tube 209, thepressure chamber 221 is supplied with a pressure smaller than a sum of pressing forces applied to thepressure chambers 222 to 225 to polish the semiconductor wafer in such a state that the chuckingplate 206 is lifted, upward forces may be applied to portions near thebase portions 291 d of theflanges 291 a which are brought into close contact with the semiconductor wafer W by the connectingportions 291 c. Thus, avacuum 293 may be formed near thebase portions 291 d (seeFIG. 6C ), so that a polishing rate may be locally lowered at these portions. - In view of the above, in the present embodiment, the connecting
portions 291 c of thering tube 209 are made of a soft material having a higher flexibility than theabutment portion 291 b. With this configuration, even if thechucking plate 206 is downwardly pressed for polishing, excessive downward forces are not applied to the semiconductor wafer W which is brought into close contact with theabutment portion 291 b because the connectingportions 291 c are likely to be elastically deformed, so that a uniform polishing rate can be achieved over an entire surface of theabutment portion 291 b except theflanges 291 a. Further, even if thechucking plate 206 is lifted for polishing, excessive upward forces are not applied to theabutment portion 291 b because the connectingportions 291 c are likely to extend. Thus, a vacuum is not formed near thebase portions 291 d of theflanges 291 a, so that a uniform polishing rate can be achieved over the entire surface of theabutment portion 291 b except theflanges 291 a. Only vertically extendingportions 291 f (seeFIG. 5 ) of the connectingportions 291 c may be made of a soft material having a high flexibility, or, in addition thereto,portions 291 g held by thering tube holder 292 may also be made of a soft material having a high flexibility. -
FIG. 7 is a vertical cross-sectional view showing a second example of an elastic membrane of a ring tube in a substrate holding apparatus according to the present invention. In the ring tube of the second example, connectingportions 291 c have thin portions 294 having a thickness smaller than a thickness ofabutment portion 291 b. The thin portions 294 are constricted inwardly as shown inFIG. 7 . With such thin portions 294, even if chuckingplate 206 is pressed downwardly for polishing, excessive downward forces are not applied to semiconductor wafer W which is brought into close contact with theabutment portion 291 b because the connectingportions 291 c are likely to be deformed at the thin portions 294, so that a uniform polishing rate can be achieved over an entire surface of theabutment portion 291 b exceptflanges 291 a. Further, even if thechucking plate 206 is lifted for polishing, excessive upward forces are not applied to theabutment portion 291 b because the thin portions 294 are likely to extend. Thus, a vacuum is not formed nearbase portions 291 d of theflanges 291 a, so that a uniform polishing rate can be achieved over the entire surface of theabutment portion 291 b except theflanges 291 a. Particularly, when the thin portions 294 are formed so as to be constricted inwardly in cross-section, the above effects can effectively be achieved. -
FIG. 8 is a vertical cross-sectional view showing a third example of an elastic membrane of a ring tube in a substrate holding apparatus according to the present invention. In the ring tube of the third example, intermediate members 295 having a low adhesiveness to semiconductor wafer W are attached to lower surfaces ofbase portions 291 d offlanges 291 a. Any member can be used as intermediate member 295 as long as it has a low adhesiveness to the wafer W. For example, a cellophane tape may be used as the intermediate member 295. The intermediate member 295 should preferably be as thin as possible, and preferably have a thickness of at most 0.2 mm. With this arrangement, even if thechucking plate 206 is lifted for polishing, a vacuum is unlikely to be formed near thebase portions 291 d of theflanges 291 a because thebase portions 291 d of theflanges 291 a are unlikely to be brought into close contact with the semiconductor wafer W. Therefore, a uniform polishing rate can be achieved over an entire surface ofabutment portion 291 b except theflanges 291 a. Instead of mounting such intermediate members 295, adhesiveness between thebase portions 291 d of theflanges 291 a and the semiconductor wafer W may be weakened, for example, by forming a groove in lower surfaces of thebase portions 291 d of theflanges 291 a, or by forming the lower surfaces of thebase portions 291 d as rough surfaces. -
FIG. 9 is a vertical cross-sectional view showing a fourth example of an elastic membrane of a ring tube in a substrate holding apparatus according to the present invention. In the ring tube of the fourth example, ring-like hard members 296 made of a material harder than elastic membrane 291 (e.g., stainless steel) are embedded inbase portions 291 d offlanges 291 a. With this arrangement, even if chuckingplate 206 is downwardly pressed for polishing, excessive downward forces are not applied to semiconductor wafer W which is brought into close contact withabutment portion 291 b because downward forces by connectingportions 291 c are dispersed by the hard members 296, so that a uniform polishing rate can be achieved over an entire surface of theabutment portion 291 b except theflanges 291 a. Further, even if chuckingplate 206 is lifted for polishing, a vacuum is not formed near thebase portions 291 d of theflanges 291 a because the hard members 296 prevent deformation of the vicinity of thebase portions 291 d of theflanges 291 a. Therefore, a uniform polishing rate can be achieved over the entire surface of theabutment portion 291 b except theflanges 291 a. -
FIG. 10 is a vertical cross-sectional view showing a fifth example of an elastic membrane of a ring tube in a substrate holding apparatus according to the present invention. The fifth example corresponds to an example of a ring tube in which a connectingportion 291 h positioned radially inwardly, i.e., near a center of semiconductor wafer W, has a thickness smaller than that of a connecting portion 291 i positioned radially outwardly, in theelastic membrane 291 of the ring tube of the first example. Because a cylinder having a smaller curvature generally has a stiffness larger than a cylinder having a larger curvature, a vertical force applied to the base portion of the flange by the connecting portion positioned radially inwardly becomes larger than a force applied to the base portion of the flange by the connecting portion positioned radially outwardly. Therefore, as shown in the fifth example, when the connectingportion 291 h positioned radially inwardly is thinner than the connecting portion 291 i positioned radially outwardly, vertical forces applied to the base portions of the flanges by these connectingportions 291 h, 291 i can be adjusted to the same level, and a uniform polishing rate can be achieved over an entire surface ofabutment portion 291 b exceptflanges 291 a. When the connecting portion positioned radially inwardly is made of a material having a flexibility higher than that of material of the connecting portion positioned radially outwardly in the ring tube of the first example, similar effects are expected. -
FIG. 11 is a vertical cross-sectional view showing a sixth example of an elastic membrane of a ring tube in a substrate holding apparatus according to the present invention. The sixth example corresponds to an example of a ring tube in which aflange 291 j projecting radially outwardly has a length larger than aflange 291 k projecting radially inwardly, in theelastic membrane 291 of the ring tube of the first example. With this arrangement, a sealing capability can be enhanced at theflange 291 j projecting radially outwardly, so that a uniform polishing rate can be achieved over an entire surface ofabutment portion 291 b. -
FIGS. 12A through 12C are vertical cross-sectional views showing a seventh example of a ring tube in a substrate holding apparatus according to the present invention. As shown inFIG. 12A ,elastic membrane 391 of the ring tube of the seventh example has anabutment portion 391b having flanges 391 a projecting outwardly, extendingportions 391 d extending outwardly frombase portions 391 c of theflanges 391 a to formgrooves 392 between the extendingportions 391 d and theflanges 391 a, and connectingportions 391 e connected viaring tube holder 292 to chuckingplate 206. The extendingportions 391 d extend outwardly from thebase portions 391 c of theflanges 391 a to positions inward of tips of theflanges 391 a, and the connectingportions 391 e extend upwardly from outward ends of the extendingportions 391 d. Theflanges 391 a, theabutment portion 391 b, the connectingportions 391 e, and the extendingportions 391 d are integrally made of the same material. Anopening 391 f is formed in a central portion of theabutment portion 391 b. - With this arrangement, in a case where the
chucking plate 206 is lifted for polishing after semiconductor wafer W is brought into close contact with theabutment portion 391 b (seeFIG. 12B ), upward forces by the connectingportions 391 e are converted into forces in horizontal or oblique directions by the extendingportions 391 d, and these converted forces are applied to thebase portions 391 c of theflanges 391 a (seeFIG. 12C ). Therefore, upward forces applied to thebase portions 391 c of theflanges 391 a can be made extremely small, so that excessive upward forces are not applied to theabutment portion 391 b. Accordingly, a vacuum is not formed near thebase portions 391 d, so that a uniform polishing rate can be achieved over an entire surface of theabutment portion 391 b except theflanges 391 a. In this case, a thickness of the connectingportions 391 e or a length of theflanges 391 a may be varied between the connecting portion disposed radially inwardly and the connecting portion disposed radially outwardly, as with the ring tube in the fifth or sixth example. Further, the length of the extendingportions 391 d may be varied between the extending portion disposed radially inwardly and the extending portion disposed radially outwardly. Furthermore, a thickness of theflanges 391 a may be varied according to a type of a film formed on a semiconductor wafer to be polished or the polishing pad. When resistance or polishing torque transmitted to the semiconductor wafer is large, the thickness of theflanges 391 a should preferably be made larger in order to prevent torsion of theflanges 391 a. - In the substrate holding apparatus according to the first embodiment described above, the
fluid passages central bag 208 and thering tube 209 are brought into direct contact with the semiconductor wafer W. However, the present invention is not limited to such a configuration. For example, an elastic pad may be interposed between thecentral bag 208 andring tube 209 and the semiconductor wafer W so that thecentral bag 208 and thering tube 209 are brought into indirect contact with the semiconductor wafer W. Further, the above examples may appropriately be combined with each other. - In the substrate holding apparatus according to the first embodiment described above, the polishing surface is constituted by the polishing pad. However, the polishing surface is not limited to this. For example, the polishing surface may be constituted by a fixed abrasive. The fixed abrasive is formed into a flat plate comprising abrasive particles fixed by a binder. With the fixed abrasive used for polishing, a polishing process is performed by abrasive particles self-generated from the fixed abrasive. The fixed abrasive comprises abrasive particles, a binder, and pores. For example, cerium dioxide (CeO2) having an average particle diameter of 0.5 μm is used as an abrasive particle, and epoxy resin is used as a binder. Such a fixed abrasive forms a harder polishing surface. The fixed abrasive includes a fixed abrasive pad having a two-layer structure formed by a thin layer of a fixed abrasive and an elastic polishing pad attached to a lower surface of the layer of the fixed abrasive. IC-1000 described above may be used for another hard polishing surface.
- As described above, according to the substrate holding apparatus of the first embodiment of the present invention, pressures to be applied to the substrate can independently be controlled, and hence a pressing force applied to a thicker area of a thin film can be made higher than a pressing force applied to a thinner area of the thin film, thereby selectively increasing a polishing rate of the thicker area of the thin film. Thus, an entire surface of a substrate can be polished exactly to a desired level irrespective of a film thickness distribution obtained at a time the thin film is formed. Further, even if a vertically movable member is pressed downwardly for polishing, excessive downward forces are not applied to a substrate which is brought into close contact with the abutment portion, so that a uniform polishing rate can be achieved in an area between the base portions of the flanges. Further, even if a vertically movable member is lifted for polishing, excessive upward forces are not applied to the abutment portion, so that a vacuum is not formed near the base portions of the flanges to achieve a uniform polishing rate in an area between the base portions.
- Next, a substrate holding apparatus according to a second embodiment of the present invention will be described below.
FIG. 13 is a vertical cross-sectional view showing atop ring 1 as a substrate holding apparatus according to the second embodiment of the present invention, andFIG. 14 is a bottom view showing thetop ring 1 shown inFIG. 13 . As shown inFIG. 13 , thetop ring 1 constituting a substrate holding apparatus comprises atop ring body 2 in the form of a cylindrical housing with a receiving space defined therein, and aretainer ring 3 fixed to a lower end of thetop ring body 2. Thetop ring body 2 is made of a material having high strength and rigidity, such as metal or ceramic. Theretainer ring 3 is made of highly rigid synthetic resin, ceramic, or the like. - The
top ring body 2 comprises acylindrical housing 2 a, an annularpressurizing sheet support 2 b fitted into a cylindrical portion of thehousing 2 a, and anannular seal 2 c fitted over an outer circumferential edge of an upper surface of thehousing 2 a. Theretainer ring 3 is fixed to a lower end of thehousing 2 a of thetop ring body 2. Theretainer ring 3 has a lower portion projecting radially inwardly. Theretainer ring 3 may be formed integrally with thetop ring body 2. - A top
ring drive shaft 11 is disposed above a central portion of thehousing 2 a of thetop ring body 2, and thetop ring body 2 is coupled to the topring drive shaft 11 by auniversal joint 10. Theuniversal joint 10 has a spherical bearing mechanism by which thetop ring body 2 and the topring drive shaft 11 are liftable with respect to each other, and a rotation transmitting mechanism for transmitting rotation of the topring drive shaft 11 to thetop ring body 2. The spherical bearing mechanism and the rotation transmitting mechanism transmit a pressing force and a rotating force from the topring drive shaft 11 to thetop ring body 2 while allowing thetop ring body 2 and the topring drive shaft 11 to be tilted with respect to each other. - The spherical bearing mechanism comprises a hemispherical
concave recess 11 a defined centrally in a lower surface of the topring drive shaft 11, a hemisphericalconcave recess 2 d defined centrally in an upper surface of thehousing 2 a, and aball bearing 12 made of a highly hard material such as ceramic and interposed between theconcave recesses ring drive shaft 11, and driven pins (not shown) fixed to thehousing 2 a. Even if thetop ring body 2 is tilted with respect to the topring drive shaft 11, the drive pins and the driven pins remain in engagement with each other while contact points are displaced because the drive pins and the driven pins are vertically movable relatively to each other. Thus, the rotation transmitting mechanism reliably transmits rotational torque of the topring drive shaft 11 to thetop ring body 2. - The
top ring body 2 and theretainer ring 3 secured to thetop ring body 2 have a space defined therein, which accommodates therein aseal ring 404 having a lower surface brought into contact with a peripheral portion of a semiconductor wafer W held by thetop ring 1, anannular holder ring 405, and a disk-shaped chucking plate 406 (vertically movable member) which is vertically movable within the receiving space in thetop ring body 2. - The
seal ring 404 has a radially outer edge clamped between theholder ring 405 and thechucking plate 406 secured to a lower end of theholder ring 405 and extends radially inwardly so as to cover a lower surface of thechucking plate 406 near its outer circumferential edge. A lower end surface of theseal ring 404 is brought into contact with an upper surface of semiconductor wafer W to be polished. Theseal ring 404 is made of a highly strong and durable rubber material such as ethylene propylene rubber (EPDM), polyurethane rubber, or silicone rubber. The semiconductor wafer W has a recess defined in an outer edge thereof, which is referred to as a notch or orientation flat, for recognizing (identifying) an orientation of the semiconductor wafer. Theseal ring 404 should preferably extend radially inwardly of thechucking plate 406 from an innermost position of such a notch or orientation flat. - A pressurizing
sheet 407 comprising an elastic membrane extends between theholder ring 405 and thetop ring body 2. The pressurizingsheet 407 has a radially outer edge clamped between thehousing 2 a and the pressurizingsheet support 2 b of thetop ring body 2, and a radially inner edge clamped between anupper end portion 405 a and astopper 405 b of theholder ring 405. Thetop ring body 2, the chuckingplate 406, theholder ring 405, and the pressurizingsheet 407 jointly define apressure chamber 421 in thetop ring body 2. As shown inFIG. 13 , afluid passage 31 comprising tubes and connectors communicates with thepressure chamber 421, which is connected to acompressed air source 120 via a regulator R2 provided on the fluid passage 31 (seeFIG. 1 ). The pressurizingsheet 407 is made of a highly strong and durable rubber material such as ethylene propylene rubber (EPDM), polyurethane rubber, or silicone rubber. - In a case where the pressurizing
sheet 407 is made of an elastic material such as rubber, if the pressurizingsheet 407 is fixedly clamped between theretainer ring 3 and thetop ring body 2, then a desired horizontal surface cannot be maintained on a lower surface of theretainer ring 3 because of elastic deformation of the pressurizingsheet 407 as an elastic material. In order to prevent such a drawback, the pressurizingsheet 407 is clamped between thehousing 2 a of thetop ring body 2 and the pressurizingsheet support 2 b provided as a separate member in the present embodiment. Theretainer ring 3 may vertically be movable with respect to thetop ring body 2, or theretainer ring 3 may have a structure capable of pressing the polishing surface independently of thetop ring body 2. In such cases, the pressurizingsheet 407 is not necessarily fixed in the aforementioned manner. - A cleaning
liquid passage 451 in the form of an annular groove is defined in an upper surface of thehousing 2 a near its outer circumferential edge over which theseal 2 c of thetop ring body 2 is fitted. The cleaningliquid passage 451 communicates with afluid passage 32 via a through-hole 452, and is supplied with a cleaning liquid (pure water) via thefluid passage 32. A plurality of communication holes 453 is defined in thehousing 2 a and the pressurizingsheet support 2 b in communication with the cleaningliquid passage 451. The communication holes 453 communicate with a small gap G defined between an outer circumferential surface of theseal ring 404 and an inner circumferential surface of theretainer ring 3. - The chucking
plate 406 has acentral port 408 provided on a lower surface of a central portion of thechucking plate 406, with anopening 408 a defined at a central portion of thecentral port 408. Aring tube 409 which serves as an abutment member brought into contact with the semiconductor wafer W is mounted in a space defined between the chuckingplate 406 and the semiconductor wafer W. In the present embodiment, as shown in FIGS. 13 and 14, thering tube 409 is disposed radially outwardly of thecentral port 408 in a surrounding relation relative thereto. The chuckingplate 406 hassuction portions 440 extended downwardly therefrom outside of thering tube 409. In the present embodiment, sixsuction portions 440 are provided. - The
ring tube 409 comprises anelastic membrane 491 brought into contact with an upper surface of the semiconductor wafer W, and aring tube holder 492 for detachably holding theelastic membrane 491 in position. Thering tube 409 has apressure chamber 422 defined therein by theelastic membrane 491 and thering tube holder 492. A space defined between the chuckingplate 406 and the semiconductor wafer W is divided into a plurality of spaces by thering tube 409. Accordingly, apressure chamber 423 is defined radially inwardly of thering tube 409, i.e., around thecentral port 408, and apressure chamber 424 is defined radially outwardly of thering tube 409, i.e., around thesuction portions 440. Theelastic membrane 491 of thering tube 409 is made of a highly strong and durable rubber material such as ethylene propylene rubber (EPDM), polyurethane rubber, or silicone rubber, as with the pressurizingsheet 407. - A
fluid passage 33 comprising tubes and connectors communicates with thepressure chamber 422 in thering tube 409. Thepressure chamber 422 is connected to thecompressed air source 120 via a regulator R3 connected to thefluid passage 33. Afluid passage 34 comprising tubes and connectors communicates with the opening 408 a of thecentral port 408. Thecentral port 408 is connected to thecompressed air source 120 via a regulator R4 connected to thefluid passage 34. Eachsuction portion 440 has a communication hole 440 a communicating with afluid passage 35 comprising tubes and connectors. Thesuction portions 440 are connected to thecompressed air source 120 via a regulator R5 connected to thefluid passages 35. Thecompressed air source 120 develops a negative pressure at opening ends of communication holes 440 a of thesuction portions 440 to attract a semiconductor wafer W to thesuction portions 440. Thesuction portions 440 have elastic sheets 440 b, such as thin rubber sheets, attached to their lower ends, for thereby elastically contacting and holding the semiconductor wafer W on lower surfaces thereof. Thepressure chambers 421 to 424 are connected to respective regulators R2 to R5 through a rotary joint (not shown) mounted on an upper end of thetop ring shaft 110. - The
pressure chamber 421 above the chuckingplate 406 and thepressure chambers fluid passages FIG. 1 , the regulators R2 to R5 connected to thefluid passages pressure chambers 421 to 424 can respectively regulate pressures of the pressurized fluids supplied to the respective pressure chambers. Thus, it is possible to independently control pressures in thepressure chambers 421 to 424 or independently introduce atmospheric air or vacuum into thepressure chambers 421 to 424. In this manner, the pressures in thepressure chambers 421 to 424 are independently varied with the regulators R2 to R5, so that pressing forces to press the semiconductor wafer W against polishingpad 101 can be adjusted in local areas of the semiconductor wafer W. - In this case, pressurized fluid or atmospheric air supplied to the
pressure chambers 422 to 424 may independently be controlled in terms of temperature. With this configuration, it is possible to directly control temperature of a workpiece such as a semiconductor wafer from a backside of the surface to be polished. Particularly, when each of the pressure chambers is independently controlled in terms of temperature, a rate of chemical reaction can be controlled during chemical polishing process of CMP. - Since there is a small gap G between the outer circumferential surface of the
seal ring 404 and the inner circumferential surface of theretainer ring 3, theholder ring 405, the chuckingplate 406, and theseal ring 404 attached to thechucking plate 406 can vertically be moved with respect to thetop ring body 2 and theretainer ring 3, and hence are of a floating structure with respect to thetop ring body 2 and theretainer ring 3. Thestopper 405 b of theholder ring 405 has a plurality ofteeth 405 c projecting radially outwardly from an outer circumferential edge thereof. Downward movement of members including theholder ring 405 is limited to a predetermined range by engaging theteeth 405 c with an upper surface of a radially inwardly projecting portion of theretainer ring 3. - For example, in a case where the chucking plate is made of PPS (polyphenylene sulfide), if pressure in the
pressure chamber 421 is higher than pressures in thepressure chambers 422 to 424 below the chuckingplate 406, the chucking plate is bent so that thesuction portions 440 press the semiconductor wafer W to increase polishing rates at those local areas. Accordingly, the chuckingplate 406 in the present embodiment is made of a material having a larger stiffness and a lighter weight than that of PPS, e.g., epoxy resin, preferably a fiber reinforced material such as a glass fiber reinforced material. Thus, with the chuckingplate 406 made of a material having a large stiffness, even if the pressure in thepressure chamber 421 is higher than the pressures in thepressure chambers 422 to 424 below the chuckingplate 406, the chuckingplate 406 becomes unlikely to be bent, so that polishing rates are prevented from being locally increased. Particularly, since epoxy resin has no magnetism, it is suitable for cases where a film thickness of a thin film formed on a surface of a semiconductor wafer to be polished is measured with a film thickness method using eddy current in such a state that the semiconductor wafer is held by a top ring. The material is not limited to epoxy resin, and it is also effective to use other resin having a large stiffness, fiber reinforced materials thereof, or ceramics. - Next, operation of the
top ring 1 thus constructed will be described in detail below. - In the polishing apparatus constructed above, when a semiconductor wafer W is to be delivered to the polishing apparatus, the
top ring 1 as a whole is moved to a position to which the semiconductor wafer W is transferred, and the communication holes 440 a of thesuction portions 440 are connected via thefluid passage 35 to thevacuum source 121. The semiconductor wafer W is attracted under vacuum to lower ends of thesuction portions 440 by suction effect of the communication holes 440 a. With the semiconductor wafer W attracted to thetop ring 1, thetop ring 1 as a whole is moved to a position above the polishing table 100 having a polishing surface (polishing pad 101) thereon. An outer circumferential edge of the semiconductor wafer W is held by theretainer ring 3 so that the semiconductor wafer W is not removed from thetop ring 1. - For polishing the semiconductor wafer W, attraction of semiconductor wafer W by the
suction portions 440 is released, and the semiconductor wafer W is held on a lower surface of thetop ring 1. Simultaneously, topring air cylinder 111 connected to the topring drive shaft 11 is actuated to press theretainer ring 3 fixed to the lower end of thetop ring 1 against the polishing surface on the polishing table 100 under a predetermined pressure (seeFIG. 1 ). In such a state, pressurized fluids are respectively supplied to thepressure chambers liquid supply nozzle 102 supplies a polishing liquid Q onto thepolishing pad 101 in advance, so that the polishing liquid Q is held on thepolishing pad 101. Thus, the semiconductor wafer W is polished by thepolishing pad 101 with the polishing liquid Q being present between a (lower) surface, to be polished, of the semiconductor wafer W and thepolishing pad 101. - Local areas of the semiconductor wafer W that are positioned beneath the
pressure chambers pressure chambers central pressure chamber 422 is pressed via theelastic membrane 491 of thering tube 409 against the polishing surface under pressure of the pressurized fluid supplied to thepressure chamber 422. Therefore, polishing pressures acting on respective local areas of the semiconductor wafer W can be adjusted independently by controlling pressures of the pressurized fluids supplied to therespective pressure chambers 422 to 424. Specifically, the respective regulators R3 to R5 independently regulate the pressures of the pressurized fluids supplied to thepressure chambers 422 to 424 for thereby adjusting the pressing forces applied to press the local areas of the semiconductor wafer W against thepolishing pad 101 on the polishing table 100. With the polishing pressures on the respective local areas of the semiconductor wafer W being adjusted independently to desired values, the semiconductor wafer W is pressed against thepolishing pad 101 on the polishing table 100 that is being rotated. Similarly, pressure of the pressurized fluid supplied to the topring air cylinder 111 can be regulated by the regulator R1 to adjust a force with which theretainer ring 3 presses thepolishing pad 101. While the semiconductor wafer W is being polished, the force with which theretainer ring 3 presses thepolishing pad 101 and the pressing force with which the semiconductor wafer W is pressed against thepolishing pad 101 can appropriately be adjusted for thereby applying polishing pressures in a desired pressure distribution to a central area (C1 inFIG. 14 ), an intermediate area (C2), a peripheral area (C3), and a peripheral portion of theretainer ring 3 which is positioned outside of the semiconductor wafer W. - In this manner, the semiconductor wafer W is divided into three concentric circular and annular areas (C1 to C3), which can respectively be pressed under independent pressing forces. A polishing rate depends on a pressing force applied to a semiconductor wafer W against a polishing surface. As described above, since the pressing forces applied to those areas can independently be controlled, polishing rates of the three circular and annular areas (C1 to C3) of the semiconductor wafer W can independently be controlled. Consequently, even if a thickness of a thin film to be polished on a surface of the semiconductor wafer W suffers radial variations, the thin film on the surface of the semiconductor wafer W can be polished uniformly without being insufficiently or excessively polished over an entire surface of the semiconductor wafer. More specifically, even if the thickness of the thin film to be polished on the surface of the semiconductor wafer W differs depending on a radial position on the semiconductor wafer W, pressure in a pressure chamber positioned over a thicker area of the thin film is made higher than pressure in other pressure chambers, or pressure in a pressure chamber positioned over a thinner area of the thin film is made lower than pressure in other pressure chambers. In this manner, a pressing force applied to the thicker area of the thin film against the polishing surface is made higher than a pressing force applied to the thinner area of the thin film against the polishing surface, thereby selectively increasing a polishing rate of the thicker area of the thin film. Consequently, an entire surface of the semiconductor wafer W can be polished exactly to a desired level over the entire surface of the semiconductor wafer W irrespective of a film thickness distribution produced at a time the thin film is formed.
- Any unwanted edge rounding on a circumferential edge of the semiconductor wafer W can be prevented by controlling the pressing force applied to the
retainer ring 3. If the thin film to be polished on the circumferential edge of the semiconductor wafer W has large thickness variations, then the pressing force applied to theretainer ring 3 is intentionally increased or reduced to thus control a polishing rate of the circumferential edge of the semiconductor wafer W. When pressurized fluids are supplied to thepressure chambers 422 to 424, the chuckingplate 406 is subjected to upward forces. In the present embodiment, the pressurized fluid is supplied to thepressure chamber 421 via thefluid passage 31 to prevent thechucking plate 406 from being lifted under forces due to thepressure chambers 422 to 424. - As described above, the pressing force applied by the top
ring air cylinder 111 to press theretainer ring 3 against thepolishing pad 101 and the pressing forces applied by the pressurized air supplied to thepressure chambers 422 to 424 to press the local areas of the semiconductor wafer W against thepolishing pad 101 are appropriately adjusted to polish the semiconductor wafer W. When polishing of the semiconductor wafer W is finished, the semiconductor wafer W is attracted again to the lower ends of thesuction portions 440 under vacuum. At this time, supply of the pressurized fluids into thepressure chambers 422 to 424 to press the semiconductor wafer W against the polishing surface is stopped, and thepressure chambers 422 to 424 are vented to an atmosphere. Accordingly, the lower ends of thesuction portions 440 are brought into contact with the semiconductor wafer W. Thepressure chamber 421 is vented to the atmosphere or evacuated to develop a negative pressure therein. If thepressure chamber 421 is maintained at a high pressure, then the semiconductor wafer W is strongly pressed against the polishing surface only in areas brought into contact with thesuction portions 440. - After attraction of the semiconductor wafer W, the
top ring 1 as a whole is moved to a position to which the semiconductor wafer W is to be transferred, and then a fluid (e.g., compressed air or a mixture of nitrogen and pure water) is ejected to the semiconductor wafer W via the communication holes 440 a of thesuction portions 440 to release the semiconductor wafer W from thetop ring 1. - The polishing liquid Q used to polish the semiconductor wafer W tends to flow through the small gap G between the outer circumferential surface of the
seal ring 404 and theretainer ring 3. If the polishing liquid Q is firmly deposited in the gap G, then theholder ring 405, the chuckingplate 406, and theseal ring 404 are prevented from smoothly moving vertically with respect to thetop ring body 2 and theretainer ring 3. To avoid such a drawback, a cleaning liquid (pure water) is supplied through thefluid passage 32 to the cleaningliquid passage 451. Accordingly, the pure water is supplied via a plurality ofcommunication holes 453 to a region above the gap G, thus cleaning the gap G to prevent the polishing liquid Q from being firmly deposited in the gap G. The pure water should preferably be supplied after a polished semiconductor wafer W is released and not until a next semiconductor wafer to be polished is attracted to thetop ring 1. It is also preferable to discharge all supplied pure water out of thetop ring 1 before the next semiconductor wafer is polished, and hence to provide theretainer ring 3 with a plurality of through-holes 3 a shown inFIG. 13 . Furthermore, if a pressure buildup is developed in a space 425 defined between theretainer ring 3, theholder ring 405, and the pressurizingsheet 407, then it acts to prevent thechucking plate 406 from being elevated in thetop ring body 2. Therefore, in order to allow thechucking plate 406 to be elevated smoothly in thetop ring body 2, the through-holes 3 a should preferably be provided for equalizing pressure in the space 425 with atmospheric pressure. - As described above, according to a substrate holding apparatus of the second embodiment, pressures in the
pressure chambers - The
ring tube 409 of the substrate holding apparatus according to the second embodiment of the present invention will be described in detail below. -
FIG. 15 is a vertical cross-sectional view showing thering tube 409 shown inFIG. 13 . As shown inFIG. 15 , theelastic membrane 491 of thering tube 409 in the present embodiment has anabutment portion 491b having flanges 491 a projecting outwardly and inwardly, and connectingportions 491 c connected via thering tube holder 492 to thechucking plate 406. The connectingportions 491 c extend upwardly frombase portions 491 d of theflanges 491 a. A lower surface of theabutment portion 491 b is brought into contact with the upper surface of the semiconductor wafer W. Theflanges 491 a, theabutment portion 491 b, and the connectingportions 491 c are integrally made of the same material. - As described above, when a semiconductor wafer is polished, pressurized fluids are supplied to the
pressure chamber 422, and thepressure chambers ring tube 409. Thus, theflanges 491 a are brought into close contact with the semiconductor wafer W by the pressurized fluids supplied to thepressure chambers pressure chamber pressure chamber 422 is considerably higher than pressure of the pressurized fluid supplied to thepressure chamber 422 defined in thering tube 409, high-pressure fluid surrounding thepressure chamber 422 is prevented from flowing into a lower portion of thering tube 409. Therefore, theflanges 491 a can widen a range of pressure control in each of the pressure chambers, for thereby pressing the semiconductor wafer more stably. -
Openings 491 e are formed at a plurality of central portions of theabutment portion 491 b of thering tube 409, and thus a pressurized fluid supplied to thepressure chamber 422 directly contacts with the upper surface of the semiconductor wafer W through theopenings 491 e of theabutment portion 491 b. Since a pressurized fluid is supplied to thepressure chamber 422 during polishing, the pressurized fluid presses theabutment portion 491 b of thering tube 409 against the upper surface of the semiconductor wafer W. Therefore, even if theopenings 491 e are formed in theabutment portion 491 b, a pressurized fluid in thepressure chamber 422 hardly flows out to an exterior of thepressure chamber 422. Further, when the semiconductor wafer W is released, a downward pressure can be applied through theopenings 491 e to the semiconductor wafer W by a pressurized fluid, so that the semiconductor wafer W can more smoothly be released. - When the pressurized fluid supplied to the
intermediate pressure chamber 422 is controlled in terms of temperature and a temperature of the semiconductor wafer W is controlled from the backside of the surface to be polished, as described above, theopenings 491 e formed in theabutment portion 491 b of thering tube 409 can increase an area in which the pressurized fluid controlled in terms of temperature is brought into contact with the semiconductor wafer W. Therefore, controllability in terms of temperature of the semiconductor wafer W can be improved. Further, when polishing of the semiconductor wafer W is finished and the semiconductor wafer W is released, thepressure chamber 422 is opened to outside air via theopenings 491 e. Thus, fluid supplied into thepressure chamber 422 is prevented from remaining in thepressure chamber 422. Therefore, even if semiconductor wafers W are continuously polished, controllability in terms of temperature of the semiconductor wafer W can be maintained. - As shown in
FIG. 15 , the chuckingplate 406 hassupport portions 406 a for supporting theflanges 491 a of thering tube 409. If thechucking plate 406 has nosupport portions 406 a, then theflanges 491 a may be deformed and attached to a lower surface of thechucking plate 406 as shown inFIG. 16 when pressurized fluids are supplied to thepressure chambers ring tube 409. In such a state, it is impossible to properly control pressures of thepressure chambers 422 to 424. Accordingly, in the present embodiment, thesupport portions 406 a are provided on thechucking plate 406 for supporting theflanges 491 a of thering tube 409, as described above, to prevent theflanges 491 a from being attached to the lower surface of thechucking plate 406 and to stabilize pressures of thepressure chambers 422 to 424. In this case, when the support portions have radial lengths larger than radial lengths of theflanges 491 a, it is possible to support theflanges 491 a more reliably. - In this case, the
flanges 491 a of thering tube 409 are brought into contact with thesupport portions 406 a of thechucking plate 406. In order to enhance adhesiveness of theflanges 491 a to the semiconductor wafer W, it is necessary to press theflanges 491 a by pressurized fluids supplied to thepressure chambers FIG. 17 ,fluid introduction grooves 406 b are formed in thesupport portions 406 a of thechucking plate 406 for stably pressing theflanges 491 a by pressurized fluids supplied to thepressure chambers flanges 491 a and the semiconductor wafer W. - Similarly, with respect to the
seal ring 404, theseal ring 404 may be attached to a peripheral portion of thechucking plate 406 by a pressurized fluid supplied to thepressure chamber 424, as shown inFIG. 18 . Accordingly, in the present embodiment, asupport portion 406 c is provided at a peripheral portion of thechucking plate 406 for supporting theseal ring 404, as shown inFIG. 19 . In this case, as with thesupport portions 406 a, fluid introduction grooves may be formed in thesupport portion 406 c for stably pressing theseal ring 404 by a pressurized fluid supplied to thepressure chamber 424 to enhance adhesiveness between theseal ring 404 and the semiconductor wafer W. Further, since such grooves can introduce pressurized fluid to an outermost portion of a semiconductor wafer, a uniform pressing force can be achieved at a peripheral portion of the wafer. - When the
retainer ring 3 is pressed against thepolishing pad 101, thepolishing pad 101 may be raised (rebounded) near theretainer ring 3 so that a polishing rate is locally increased at the peripheral portion of semiconductor wafer W. In the present embodiment, a radial length d of thesupport portion 406 c of thechucking plate 406 is shortened to prevent the semiconductor wafer W from being excessively polished at the peripheral portion thereof. When effects of rebound are small, the length d is shortened to concentrate pressing forces, or the length d is lengthened to disperse the pressing forces, for varying polishing rates. Specifically, the length d is varied in a range of 1 mm to 7 mm to achieve desired polishing rates. - In the substrate holding apparatus according to the second embodiment described above, the
fluid passages ring tube 409 is brought into direct contact with the semiconductor wafer W. However, the present invention is not limited to such a configuration. For example, an elastic pad may be interposed between thering tube 409 and the semiconductor wafer W so that thering tube 409 is brought into indirect contact with the semiconductor wafer W. - In the second embodiment shown in
FIGS. 13 through 19 , the polishing surface is constituted by the polishing pad. However, the polishing surface is not limited to this. The polishing surface may be constituted by a fixed abrasive as described in the first embodiment shown inFIGS. 2 through 12 . - As described above, according to the substrate holding apparatus of the second embodiment of the present invention, pressures to be applied to a substrate can independently be controlled, and hence a pressing force applied to a thicker area of a thin film can be made higher than a pressing force applied to a thinner area of the thin film, thereby selectively increasing a polishing rate of the thicker area of the thin film. Thus, an entire surface of a substrate can be polished exactly to a desired level irrespective of a film thickness distribution obtained at a time the thin film is formed. Further, with a vertically movable member made of a material having a large stiffness and a light weight, e.g., epoxy resin, the vertically movable member becomes unlikely to be bent, so that polishing rates are prevented from being locally increased. Further, when a material having no magnetism is selected as a material of the vertically movable member, it is suitable for cases where a film thickness of a thin film formed on a surface of a semiconductor wafer to be polished is measured with a film thickness method using eddy current in such a state that the semiconductor wafer is held by a top ring.
- Next, a substrate holding apparatus according to a third embodiment of the present invention will be described below.
FIG. 20 is a vertical cross-sectional view showing atop ring 1 according to the third embodiment of the present invention. As shown inFIG. 20 , thetop ring 1 constituting a substrate holding apparatus comprises atop ring body 2 in the form of a cylindrical housing with a receiving space defined therein, and aretainer ring 3 fixed to a lower end of thetop ring body 2. Thetop ring body 2 is made of a material having high strength and rigidity, such as metal or ceramic. Theretainer ring 3 is made of highly rigid synthetic resin, ceramic, or the like. - The
top ring body 2 comprises acylindrical housing 2 a, an annularpressurizing sheet support 2 b fitted into a cylindrical portion of thehousing 2 a, and anannular seal 2 c fitted over an outer circumferential edge of an upper surface of thehousing 2 a. Theretainer ring 3 is fixed to a lower end of thehousing 2 a of thetop ring body 2. Theretainer ring 3 has a lower portion projecting radially inwardly. Theretainer ring 3 may be formed integrally with thetop ring body 2. - A top
ring drive shaft 11 is disposed above a central portion of thehousing 2 a of thetop ring body 2, and thetop ring body 2 is coupled to the topring drive shaft 11 by auniversal joint 10. Theuniversal joint 10 has a spherical bearing mechanism by which thetop ring body 2 and the topring drive shaft 11 are tiltable with respect to each other, and a rotation transmitting mechanism for transmitting rotation of the topring drive shaft 11 to thetop ring body 2. The spherical bearing mechanism and the rotation transmitting mechanism transmit a pressing force and a rotating force from the topring drive shaft 11 to thetop ring body 2 while allowing thetop ring body 2 and the topring drive shaft 11 to be tilted with respect to each other. - The
top ring body 2 and theretainer ring 3 secured to thetop ring body 2 have a space defined therein, which accommodates therein anedge bag 504 having a lower surface brought into contact with a peripheral portion of a semiconductor wafer W held by thetop ring 1, aholder ring 505, a disk-shapedchucking plate 506 which is vertically movable within the receiving space in thetop ring body 2, and atorque transmitting member 507 having a lower surface brought into contact with the semiconductor wafer W at a radially inward position of theedge bag 504. - The chucking
plate 506 may be made of metal. However, when a thickness of a thin film formed on a surface of a semiconductor wafer to be polished is measured by a method using eddy current in such a state that the semiconductor wafer is held by the top ring, the chuckingplate 506 should preferably be made of a non-magnetic material, e.g., an insulating material such as fluororesin or ceramic. - A pressurizing
sheet 508 comprising an elastic membrane extends between theholder ring 505 and thetop ring body 2. The pressurizingsheet 508 has a radially outer edge clamped between thehousing 2 a and the pressurizingsheet support 2 b of thetop ring body 2, and a radially inner edge clamped between anupper end portion 505 a and astopper 505 b of theholder ring 505. Thetop ring body 2, the chuckingplate 506, theholder ring 505, and the pressurizingsheet 508 jointly define apressure chamber 521 in thetop ring body 2. As shown inFIG. 20 , afluid passage 31 comprising tubes and connectors communicates with thepressure chamber 521, which is connected to acompressed air source 120 via a regulator R2 provided on the fluid passage 31 (seeFIG. 1 ). The pressurizingsheet 508 is made of a highly strong and durable rubber material such as ethylene propylene rubber (EPDM), polyurethane rubber, or silicone rubber. - A cleaning
liquid passage 551 in the form of an annular groove is defined in an upper surface of thehousing 2 a near its outer circumferential edge over which theseal 2 c of thetop ring body 2 is fitted. The cleaningliquid passage 551 communicates with afluid passage 32 via a through-hole formed in theseal 2 c, and is supplied with a cleaning liquid (pure water) via thefluid passage 32. A plurality ofcommunication holes 553 are defined in thehousing 2 a and the pressurizingsheet support 2 b in communication with the cleaningliquid passage 551. The communication holes 553 communicate with a small gap G defined between an outer circumferential surface of theedge bag 504 and an inner circumferential surface of theretainer ring 3. -
FIG. 21 is a partial cross-sectional view showing theedge bag 504 ofFIG. 20 . As shown inFIG. 21 , theedge bag 504 has a radially outer edge clamped between thestopper 505 b of theholder ring 505 and anedge bag holder 506 a disposed below theholder ring 505, and a radially inner edge clamped between theedge bag holder 506 a and achucking plate body 506 b. A lower end surface of theedge bag 504 is brought into contact with a peripheral portion of the semiconductor wafer W to be polished. Theedge bag 504 comprises an elastic membrane made of a highly strong and durable rubber material such as ethylene propylene rubber (EPDM), polyurethane rubber, or silicone rubber. - A lower surface of the
edge bag 504 is brought into contact with the peripheral portion of the semiconductor wafer W and provided with aflange 541 projecting radially inwardly. Theedge bag 504 has a (first)pressure chamber 522 defined therein by the elastic membrane. Afluid passage 33 comprising tubes and connectors communicates with thepressure chamber 522. Thepressure chamber 522 is connected to thecompressed air source 120 via a regulator R3 connected to thefluid passages 33. - Upon polishing, semiconductor wafer W is rotated in accordance with rotation of the
top ring 1. Since theaforementioned edge bag 504 has a small contact area with the semiconductor wafer W, rotational torque may fail to completely be transmitted to the semiconductor wafer W. Accordingly, thetorque transmitting member 507 is secured to thechucking plate 506 for transmitting sufficient torque to the semiconductor wafer W by abutment with the semiconductor wafer W. Thetorque transmitting member 507 is in the form of an annular bag and is brought into contact with the semiconductor wafer W with a contact area large enough to transmit sufficient torque to the semiconductor wafer W. -
FIG. 22 is a partial cross-sectional view showing thetorque transmitting member 507 ofFIG. 20 . As shown inFIG. 22 , thetorque transmitting member 507 comprises anelastic membrane 571 brought into contact with the upper surface of the semiconductor wafer W, and a torque transmittingmember holder 572 for detachably holding theelastic membrane 571 in position. Thetorque transmitting member 507 has aspace 560 defined therein by theelastic membrane 571 and the torque transmittingmember holder 572. Theelastic membrane 571 of thetorque transmitting member 507 is made of a highly strong and durable rubber material such as ethylene propylene rubber (EPDM), polyurethane rubber, or silicone rubber, as with theedge bag 504. - As shown in
FIG. 22 , theelastic membrane 571 of thetorque transmitting member 507 has anabutment portion 571b having flanges 571 a projecting outwardly and inwardly, and connectingportions 571 c connected via the torque transmittingmember holder 572 to thechucking plate 506. Two connectingportions 571 c extend upwardly frombase portions 571 d of theflanges 571 a. A lower surface of theabutment portion 571 b is brought into contact with an upper surface of the semiconductor wafer W. The connectingportions 571 c have a plurality of communication holes 573 provided at radially inward and outward positions, and an interior ofinternal space 560 of thetorque transmitting member 507 is communicated withexternal spaces 561, 562. - When the two connecting
portions 571 c extending vertically are arranged at relatively near positions, the connectingportions 571 c have sufficient strength to transmit torque. With theflanges 571 a, it is possible to maintain a contact area with the semiconductor wafer W. - The space defined between the chucking
plate 506 and the semiconductor wafer W is divided into a plurality of spaces, i.e., apressure chamber 522 disposed radially inwardly of theedge bag 504, thespace 560 in thetorque transmitting member 507, a space 561 between theedge bag 504 and thetorque transmitting member 507, and aspace 562 disposed radially inwardly of thetorque transmitting member 507. As described above, the communication holes 573 are provided in the connectingportions 571 c of thetorque transmitting member 507. Accordingly, the space 561, thespace 560, and thespace 562 are communicated with each other through the communication holes 573, so that a (second)pressure chamber 523 is formed radially inwardly of theedge bag 504. - A
fluid passage 34 comprising tubes and connectors communicates with thespace 560 in thetorque transmitting member 507. Thespace 560 is connected to thecompressed air source 120 via a regulator R4 connected to thefluid passage 34. Afluid passage 35 comprising tubes and connectors communicates with the space 561 between theedge bag 504 and thetorque transmitting member 507. The space 561 is connected to thecompressed air source 120 via a regulator R5 connected to thefluid passage 35. Afluid passage 36 comprising tubes and connectors communicates with thespace 562 disposed radially inwardly of thetorque transmitting member 507. Thespace 562 is connected to thecompressed air source 120 via a regulator (not shown) connected to thefluid passage 36. Thepressure chambers 521 to 523 are connected to respective regulators through a rotary joint (not shown) mounted on an upper end oftop ring shaft 110. - Since the space 561, the
space 560, and thespace 562 are communicated with each other, as described above, one fluid passage can supply a pressurized fluid so as to uniformly control pressure of thepressure chamber 523 without a plurality of fluid passages. However, in order to obtain good responsiveness when pressure of thepressure chamber 523 is varied, it is desirable to provide a plurality offluid passages fluid passages fluid passages - When the semiconductor wafer is polished, pressurized fluids are supplied to the
pressure chamber 522 and thepressure chamber 523, respectively. Theflange 541 is provided at a lower end surface of theedge bag 504. Theflange 541 is brought into close contact with the semiconductor wafer W by the pressurized fluid supplied to thepressure chamber 523. Accordingly, the pressurized fluid in thepressure chamber 523 is prevented from flowing into a lower portion of theedge bag 504. Therefore, theflange 541 can realize a stable control when pressures of thepressure chamber 522 and thepressure chamber 523 are varied. Here, a radial width d of the elastic membrane defining thepressure chamber 522 in theedge bag 504 should preferably be in a range of from about 1 mm to about 10 mm in view of controlling a polishing rate at a peripheral portion of the semiconductor wafer W, and is set to be 5 mm in the present embodiment. - The
pressure chamber 521 above the chuckingplate 506 and thepressure chambers fluid passages fluid passages pressure chambers 521 to 523 can respectively regulate pressures of the pressurized fluids supplied to respective pressure chambers. Thus, it is possible to independently control the pressures in thepressure chambers 521 to 523 or independently introduce atmospheric air or vacuum into thepressure chambers 521 to 523. With this arrangement, the pressures of thepressure chambers 521 to 523 can press an entire surface of the semiconductor wafer W except a peripheral portion thereof at a uniform force, and pressure of thepressure chamber 522 can be controlled independently of pressure of thepressure chamber 523. Therefore, it is possible to control a polishing rate at the peripheral portion of the semiconductor wafer W, i.e., a polishing profile of the peripheral portion of the semiconductor wafer W. Additionally, when a pressing force of theretainer ring 3 is controlled, more detailed control can be achieved. - In this case, the pressurized fluid or the atmospheric air supplied to the
pressure chambers - The chucking
plate 506 has suction portions 540 extended downwardly therefrom between theedge bag 504 and thetorque transmitting member 507. In the present embodiment, four suction portions 540 are provided. The suction portions 540 havecommunication holes 540 a communicating with afluid passage 37 comprising tubes and connectors. The suction portions 540 are connected to thecompressed air source 120 via a regulator (not shown) connected tofluid passage 37. Thecompressed air source 120 can develop a negative pressure at lower opening ends of the communication holes 540 a of the suction portion 540 to attract a semiconductor wafer W to lower ends of the suction portions 540. The suction portions 540 haveelastic sheets 540 b, such as thin rubber sheets, attached to their lower ends, for thereby elastically contacting and holding the semiconductor wafer W on lower surfaces thereof. - Next, operation of the
top ring 1 thus constructed will be described in detail below. - In the polishing apparatus constructed above, when a semiconductor wafer W is to be delivered to the polishing apparatus, the
top ring 1 as a whole is moved to a position to which the semiconductor wafer W is transferred, and the communication holes 540 a of the suction portions 540 are connected via thefluid passage 37 to thecompressed air source 120. The semiconductor wafer W is attracted under vacuum to lower ends of the suction portions 540 by suction effect of the communication holes 540 a. With the semiconductor wafer W attracted to thetop ring 1, thetop ring 1 as a whole is moved to a position above the polishing table 100 having a polishing surface (polishing pad 101) thereon. An outer circumferential edge of the semiconductor wafer W is held by theretainer ring 3 so that the semiconductor wafer W is not removed from thetop ring 1. - For polishing the semiconductor wafer W, attraction of semiconductor wafer W by the suction portions 540 is released, and the semiconductor wafer W is held on a lower surface of the
top ring 1. Simultaneously, the topring air cylinder 111 connected to the topring drive shaft 11 is actuated to press theretainer ring 3 fixed to the lower end of thetop ring 1 against the polishing surface on the polishing table 100 under a predetermined pressure. In such a state, pressurized fluids are respectively supplied to thepressure chamber 522 and thepressure chamber 523 under respective pressures, thereby pressing the semiconductor wafer W against the polishing surface on the polishing table 100. The polishingliquid supply nozzle 102 supplies a polishing liquid Q onto thepolishing pad 101 in advance, so that the polishing liquid Q is held on thepolishing pad 101. Thus, the semiconductor wafer W is polished by thepolishing pad 101 with the polishing liquid Q being present between the (lower) surface, to be polished, of the semiconductor wafer W and thepolishing pad 101. - Local areas of the semiconductor wafer W that are positioned beneath the
pressure chamber 522 and thepressure chamber 523 are pressed against the polishing surface under the pressures of pressurized fluids supplied to thepressure chamber 522 and thepressure chamber 523. Therefore, by controlling the pressurized fluids supplied to thepressure chamber 522 and thepressure chamber 523, polishing pressure applied to the semiconductor wafer W is adjusted so as to press an entire surface of the semiconductor wafer W, except a peripheral portion thereof, against the polishing surface at a uniform force. Simultaneously, a polishing rate at the peripheral portion of the semiconductor wafer W can be controlled to control a polishing profile of the peripheral portion of the semiconductor wafer W. Similarly, the regulator R2 regulates pressure of pressurized fluid supplied topressure chamber 521 to change a pressing force to press theretainer ring 3 against thepolishing pad 101. In this manner, during polishing, the pressing force to press theretainer ring 3 against thepolishing pad 101 and the pressing force to press the semiconductor wafer W against thepolishing pad 101 are properly adjusted to control a polishing profile of the peripheral portion of the semiconductor wafer W in great detail. The semiconductor wafer W located below thepressure chamber 523 has an area to which a pressing force is applied via theabutment portion 571 b of thetorque transmitting member 507 by a fluid, and an area to which a pressure of the pressurized fluid is directly applied. Pressing forces applied to these areas have the same pressure. - As described above, the pressing force applied by the top
ring air cylinder 111 to press theretainer ring 3 against thepolishing pad 101 and the pressing forces applied by the pressurized fluids supplied to thepressure chamber 522 and thepressure chamber 523 to press the semiconductor wafer W against thepolishing pad 101 are appropriately adjusted to polish the semiconductor wafer W. When polishing of the semiconductor wafer W is finished, the semiconductor wafer W is attracted to the lower ends of the suction portions 540 under vacuum. At this time, supply of the pressurized fluids into thepressure chamber 522 and thepressure chamber 523 is stopped, and thepressure chamber 522 and thepressure chamber 523 are vented to the atmosphere. Accordingly, the lower ends of the suction portions 540 are brought into contact with the semiconductor wafer W. Thepressure chamber 521 is vented to an atmosphere or evacuated to develop a negative pressure therein. This is because if thepressure chamber 521 is maintained at a high pressure, then the semiconductor wafer W is strongly pressed against the polishing surface only in areas brought into contact with the suction portions 540. - After attraction of the semiconductor wafer W, the
top ring 1 as a whole is moved to a position to which the semiconductor wafer W is to be transferred, and then a fluid (e.g., compressed air or a mixture of nitrogen and pure water) is ejected to the semiconductor wafer W via the communication holes 540 a of the suction portions 540 to release the semiconductor wafer W from thetop ring 1. - The polishing liquid Q used to polish the semiconductor wafer W tends to flow through the small gap G between the outer circumferential surface of the
edge bag 504 and theretainer ring 3. If the polishing liquid Q is firmly deposited in the gap G, then theholder ring 505, the chuckingplate 506, and theedge bag 504 are prevented from smoothly moving vertically with respect to thetop ring body 2 and theretainer ring 3. To avoid such a drawback, a cleaning liquid (pure water) is supplied through thefluid passage 32 to the cleaningliquid passage 551. Accordingly, the pure water is supplied via a plurality ofcommunication holes 553 to a region above the gap G, thus cleaning the gap G to prevent the polishing liquid Q from being firmly deposited in the gap G. The pure water should preferably be supplied after a polished semiconductor wafer W is released and until a next semiconductor wafer to be polished is attracted to thetop ring 1. - In the third embodiment described above, the
fluid passages - In the third embodiment shown in
FIGS. 20 through 22 , the polishing surface is constituted by the polishing pad. However, the polishing surface is not limited to this. The polishing surface may be constituted by a fixed abrasive, as described in the first embodiment. - As described above, according to the third embodiment of the present invention, sufficient torque can be transmitted to the substrate by the torque transmitting member. Further, an entire surface of a substrate except a peripheral portion thereof can be pressed against a polishing surface at a uniform force by pressure of a second pressure chamber, and pressure of a first pressure chamber can be controlled independently of the pressure of the second pressure chamber. Therefore, it is possible to control a polishing rate at a peripheral portion of semiconductor wafer W, i.e., a polishing profile of the peripheral portion of the semiconductor wafer W.
- The present invention is suitable for use in a substrate holding apparatus for holding a substrate such as a semiconductor wafer in a polishing apparatus for polishing the substrate to a flat finish, and a polishing apparatus having such a substrate holding apparatus.
Claims (28)
1-23. (canceled)
24. An elastic membrane to be brought into contact with a substrate, said elastic membrane comprising:
an abutment portion configured to be brought into direct contact with the substrate;
a first annular connecting portion extending upwardly from said abutment portion to form a first wall; and
a second annular connecting portion extending upwardly from said abutment portion to form a second wall,
wherein said first annular connecting portion and said second annular connecting portion are concentric with each other, and
wherein said second annular connecting portion is located radially outwardly of said first annular connecting portion.
25. The elastic membrane according to claim 24 , wherein said elastic membrane is made of an elastic material.
26. The elastic membrane according to claim 24 , wherein said first annular connecting portion is thinner than said second annular connecting portion.
27. The elastic membrane according to claim 24 , further comprising a portion to be held by an elastic membrane holder.
28. The elastic membrane according to claim 24 , wherein said abutment portion has an opening.
29. An elastic membrane for use in a substrate holding apparatus for holding a substrate and pressing the substrate against a polishing surface, said elastic membrane comprising:
an abutment portion configured to be brought into direct or indirect contact with the substrate; and
a connecting portion extending upwardly from said abutment portion, said connecting portion having a thin portion which is thinner than said abutment portion.
30. The elastic membrane according to claim 29 , wherein said thin portion is formed so as to be constricted inwardly in cross-section.
31. The elastic membrane according to claim 29 , further comprising a portion to be held by an elastic membrane holder.
32. The elastic membrane according to claim 29 , wherein said abutment portion has an opening.
33. An elastic membrane for use in a substrate holding apparatus for holding a substrate and pressing the substrate against a polishing surface, the substrate holding apparatus including a top ring body having a space formed therein and a vertically movable member capable of moving vertically in the space of the top ring body, said elastic membrane comprising:
an abutment portion configured to be brought into direct or indirect contact with the substrate, said abutment portion being located below the vertically movable member; and
a connecting portion extending upwardly from said abutment portion and to be connected to the vertically movable member, said connecting portion having a thin portion which is thinner than said abutment portion.
34. The elastic membrane according to claim 33 , wherein said thin portion is formed so as to be constricted inwardly in cross-section.
35. The elastic membrane according to claim 33 , further comprising a portion to be held by an elastic membrane holder.
36. The elastic membrane according to claim 33 , wherein said abutment portion has an opening.
37. An elastic membrane for use in a substrate holding apparatus, said elastic membrane comprising:
an abutment portion configured to be brought into direct or indirect contact with a substrate, said abutment portion having a flange projecting outwardly; and
a connecting portion extending upwardly from a base portion of said flange, wherein said abutment portion, said flange, and said connecting portion are formed integrally, and
wherein said connecting portion is made of a material that is different from a material of said abutment portion.
38. The elastic membrane according to claim 37 , wherein said abutment portion is made of a rubber material, and said connecting portion is made of a material harder than said rubber material.
39. The elastic membrane according to claim 37 , wherein said abutment portion is made of ethylene propylene rubber, polyurethane rubber, or silicone rubber.
40. The elastic membrane according to claim 37 , further comprising a portion to be held by an elastic membrane holder.
41. The elastic membrane according to claim 37 , wherein said abutment portion has an opening.
42. An elastic membrane for use in a substrate holding apparatus, said elastic membrane comprising:
an abutment portion configured to be brought into direct or indirect contact with a substrate, said abutment portion having a flange projecting outwardly;
a connecting portion extending upwardly from a base portion of said flange; and
a member detachably attached to a lower surface of said base portion of said flange,
wherein said abutment portion, said flange, and said connecting portion are formed integrally.
43. The elastic membrane according to claim 42 , wherein said member has a lower adhesiveness to the substrate than an adhesiveness of said abutment portion to the substrate.
44. The elastic membrane according to claim 42 , wherein said abutment portion is made of ethylene propylene rubber, polyurethane rubber, or silicone rubber.
45. The elastic membrane according to claim 42 , further comprising a portion to be held by an elastic membrane holder.
46. The elastic membrane according to claim 42 , wherein said abutment portion has an opening.
47. An elastic membrane for use in a substrate holding apparatus, said elastic membrane comprising:
an abutment portion configured to be brought into direct or indirect contact with a substrate, said abutment portion having a flange projecting outwardly;
a connecting portion extending upwardly from a base portion of said flange; and
a hard member embedded in said base portion of said flange, said hard member being made of a material harder than material of said abutment portion, said flange, and said connecting portion,
wherein said abutment portion, said flange, and said connecting portion are formed integrally.
48. The elastic membrane according to claim 47 , wherein said abutment portion is made of ethylene propylene rubber, polyurethane rubber, or silicone rubber.
49. The elastic membrane according to claim 47 , further comprising a portion to be held by an elastic membrane holder.
50. The elastic membrane according to claim 47 , wherein said abutment portion has an opening.
Priority Applications (1)
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US12/613,016 US20100056028A1 (en) | 2001-12-06 | 2009-11-05 | Substrate holding apparatus and polishing apparatus |
Applications Claiming Priority (9)
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JP2001372771A JP4107835B2 (en) | 2001-12-06 | 2001-12-06 | Substrate holding device and polishing device |
JP2001-372771 | 2001-12-06 | ||
JP2001-379337 | 2001-12-12 | ||
JP2001379337A JP4049579B2 (en) | 2001-12-12 | 2001-12-12 | Substrate holding device and polishing device |
PCT/JP2002/012816 WO2003049168A1 (en) | 2001-12-06 | 2002-12-06 | Substrate holding device and polishing device |
US10/497,151 US7033260B2 (en) | 2001-12-06 | 2002-12-06 | Substrate holding device and polishing device |
US11/312,571 US7311585B2 (en) | 2001-12-06 | 2005-12-21 | Substrate holding apparatus and polishing apparatus |
US11/987,978 US7632173B2 (en) | 2001-12-06 | 2007-12-06 | Substrate holding apparatus and polishing apparatus |
US12/613,016 US20100056028A1 (en) | 2001-12-06 | 2009-11-05 | Substrate holding apparatus and polishing apparatus |
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US11/987,978 Division US7632173B2 (en) | 2001-12-06 | 2007-12-06 | Substrate holding apparatus and polishing apparatus |
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US11/987,978 Expired - Lifetime US7632173B2 (en) | 2001-12-06 | 2007-12-06 | Substrate holding apparatus and polishing apparatus |
US12/613,016 Abandoned US20100056028A1 (en) | 2001-12-06 | 2009-11-05 | Substrate holding apparatus and polishing apparatus |
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US11/312,571 Expired - Lifetime US7311585B2 (en) | 2001-12-06 | 2005-12-21 | Substrate holding apparatus and polishing apparatus |
US11/987,978 Expired - Lifetime US7632173B2 (en) | 2001-12-06 | 2007-12-06 | Substrate holding apparatus and polishing apparatus |
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Also Published As
Publication number | Publication date |
---|---|
US20080119121A1 (en) | 2008-05-22 |
EP1453081A1 (en) | 2004-09-01 |
KR100914988B1 (en) | 2009-09-02 |
EP1453081A4 (en) | 2008-07-09 |
US7311585B2 (en) | 2007-12-25 |
US20050107015A1 (en) | 2005-05-19 |
KR100939556B1 (en) | 2010-01-29 |
AU2002354440A1 (en) | 2003-06-17 |
KR20090045425A (en) | 2009-05-07 |
US7632173B2 (en) | 2009-12-15 |
US7033260B2 (en) | 2006-04-25 |
KR20050044692A (en) | 2005-05-12 |
WO2003049168A1 (en) | 2003-06-12 |
US20060099892A1 (en) | 2006-05-11 |
TW200300721A (en) | 2003-06-16 |
TWI266674B (en) | 2006-11-21 |
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