JP2006324413A - Substrate retaining device and polishing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate retaining device capable of controlling a pressure for pushing a polishing surface by a retainer ring along the circumferential direction. <P>SOLUTION: A top ring main body 20 as the substrate retaining device is provided with a top ring main body 200 for pushing a wafer W against the polishing surface 22a, and the retainer ring 302 provided on the circumferential part of the top ring main body 200 to push the polishing surface 22a. The retainer ring 302 is provided with a pressure control mechanism for controlling a pressure for pushing the polishing surface 22a by the retainer ring 302, so as to form a predetermined pressure distribution not uniform along the circumferential direction of the retainer ring 302. The pressure control mechanism is constituted of a ring member 408 contacted with the polishing surface 22a, and a plurality of pressure chambers 410 for pushing the ring member 408 against the polishing surface 22 by fluid whose pressures are controlled independently. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a substrate holding device that holds a substrate as an object to be polished and presses it against a polishing surface, and more particularly to a substrate holding device that holds the substrate in a polishing device that polishes and flattens a substrate such as a semiconductor wafer. is there. The present invention also relates to a polishing apparatus provided with such a substrate holding device.

  In recent years, semiconductor devices have become increasingly finer and the element structure has become more complex, and as the number of layers of logic-based multilayer wiring has increased, the unevenness of the surface of the semiconductor device has increased and the level difference has a tendency to increase. This is because, in the manufacture of semiconductor devices, the process of forming a thin film, micropatterning for patterning and opening and then forming the next thin film is repeated many times.

  If the irregularities on the surface of the semiconductor device increase, the film thickness at the stepped part will become thinner during thin film formation, open due to disconnection of the wiring, short circuit due to insulation failure between wiring layers, etc. There is a tendency to decrease. In addition, even if the device normally operates normally at the beginning, a problem of reliability occurs for a long time use. Further, when the irradiation surface is uneven during exposure in the lithography process, the lens focus of the exposure system becomes partially unfocused. Therefore, when the unevenness of the surface of the semiconductor device increases, it becomes difficult to form a fine pattern itself.

Therefore, in the semiconductor device manufacturing process, a planarization technique for the surface of the semiconductor device is becoming increasingly important. Among the planarization techniques, the most important technique is chemical mechanical polishing (CMP). This chemical mechanical polishing uses a polishing apparatus to slide a substrate such as a semiconductor wafer onto the polishing surface while supplying a polishing liquid containing abrasive grains such as silica (SiO ₂ ) onto the polishing surface such as a polishing pad. Polishing in contact.

  This type of polishing apparatus includes a polishing table having a polishing surface made of a polishing pad, and a substrate holding device for holding a semiconductor wafer. When polishing a semiconductor wafer using such a polishing apparatus, the semiconductor wafer is pressed against the polishing table with a predetermined pressure while the semiconductor wafer is held by the substrate holding apparatus. At this time, by moving the polishing table and the substrate holding device relative to each other, the semiconductor wafer comes into sliding contact with the polishing surface, and the surface of the semiconductor wafer is polished to a flat and mirror surface.

  In such a polishing apparatus, since the polishing pad used as the polishing surface has elasticity, the pressing force applied to the outer peripheral edge of the semiconductor wafer being polished becomes uneven, and only the outer peripheral edge of the semiconductor wafer is polished much. May cause non-uniform polishing such as so-called “edge fringing”. In order to prevent such edge fringing, a substrate holding device having a structure in which the side edge portion of the semiconductor wafer is held by the retainer ring and the polishing surface located on the outer peripheral side of the semiconductor wafer is pressed by the retainer ring is also used. ing.

  Here, the conventional retainer ring is configured to press the polishing surface evenly over the entire length in the circumferential direction. However, as described above, since the polishing pad used as the polishing surface has elasticity, the resistance due to elastic deformation of the polishing pad is extremely large at the outermost periphery of the retainer ring located upstream in the rotation direction of the polishing table. Become. For this reason, the retainer ring is pushed downstream in the rotation direction of the polishing table, and the retainer ring is inclined. The conventional substrate holding device prevents the semiconductor wafer from jumping out of the substrate holding device by increasing the pressure with which the retainer ring presses the polishing surface even if such inclination of the retainer ring occurs. The non-uniformity of the polishing profile due to the inclination of the retainer ring has been eliminated by averaging due to the rotation of the semiconductor wafer.

  However, in the conventional retainer ring described above, it is difficult to improve the controllability of the polishing pad temperature and the polishing profile. Therefore, in order to further improve the controllability of the polishing pad temperature and the polishing profile, it is necessary to control the pressure with which the retainer ring presses the polishing surface along the circumferential direction.

  The present invention has been made in view of such problems of the prior art, and includes a substrate holding device capable of controlling the pressure with which the retainer ring presses the polishing surface along the circumferential direction, and such a substrate holding device. An object of the present invention is to provide a polishing apparatus.

  According to the first aspect of the present invention, there is provided a substrate holding device capable of controlling the pressure with which the retainer ring presses the polishing surface along the circumferential direction. The substrate holding apparatus includes a top ring body that presses the substrate against the polishing surface, and a retainer ring that is provided on the outer periphery of the top ring body and presses the polishing surface. The retainer ring includes a pressure control mechanism that controls a pressure at which the retainer ring presses the polishing surface so as to form a predetermined pressure distribution that is not uniform along the circumferential direction of the retainer ring.

  Here, the pressure control mechanism can be constituted by a ring member that contacts the polishing surface and a plurality of pressure chambers that press the ring member against the polishing surface by a fluid whose pressure is controlled independently. Alternatively, the pressure control mechanism includes a lower ring member having a lower surface in contact with the polishing surface and an upper surface formed with a tapered surface, and a lower surface formed with a tapered surface capable of contacting the tapered surface of the lower ring member. And an upper ring member that changes a radial force acting on the lower ring member by abutting the tapered surface into a downward force. The pressure control mechanism includes a lower ring member having a lower surface in contact with the polishing surface and an upper surface formed with a tapered surface, and a lower surface formed with a tapered surface capable of contacting the tapered surface of the lower ring member. An upper ring member that changes a radial force acting on the lower ring member to a downward force by the contact of the tapered surface, and presses the upper ring member toward the polishing surface by a pressure-controlled fluid. And a regulating member that contacts the upper ring member and regulates the vertical movement of the upper ring member. The pressure control mechanism may control the pressure at which the retainer ring presses the polishing surface according to the rotation of the top ring main body so that the predetermined pressure distribution is constant when viewed from a stationary system. preferable.

  According to the second aspect of the present invention, there is provided a polishing apparatus including a substrate holding device capable of controlling the pressure with which the retainer ring presses the polishing surface along the circumferential direction. The polishing apparatus includes a rotatable polishing table having the polishing surface and the substrate holding device described above. In this case, the pressure control mechanism of the substrate holding device may be configured so that the retainer ring has the above-described pressure so that the pressure in the portion located downstream in the rotation direction of the polishing table is higher than the pressure in the portion located upstream. It is preferable to control the pressure for pressing the polishing surface.

  According to the present invention, a predetermined pressure distribution which is not uniform along the circumferential direction of the retainer ring can be formed by the pressure control mechanism described above. For example, the pressure at which the retainer ring presses the polishing pad can be controlled so that the pressure of the portion located on the downstream side in the rotation direction of the polishing table is higher than the portion located on the upstream side.

  Hereinafter, embodiments of a polishing apparatus according to the present invention will be described in detail with reference to FIGS. 1 to 9. In FIG. 1 to FIG. 9, the same or corresponding components are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a schematic view showing a polishing apparatus 10 according to the first embodiment of the present invention. As shown in FIG. 1, the polishing apparatus 10 includes a polishing table 12, a top ring head 16 connected to the upper end of a support shaft 14, a top ring shaft 18 attached to the free end of the top ring head 16, and a top. A substantially disc-shaped top ring 20 connected to the lower end of the ring shaft 18 is provided.

  The polishing table 12 is connected to a motor (not shown) disposed below the table 12a through a table shaft 12a, and is rotatable around the table shaft 12a. A polishing pad 22 is affixed to the upper surface of the polishing table 12, and the surface 22 a of the polishing pad 22 constitutes a polishing surface for polishing the semiconductor wafer W.

  There are various types of polishing pads available on the market, such as SUBA800, IC-1000, IC-1000 / SUBA400 (double-layer cloth) manufactured by Rodel, Surfin xxx-5 manufactured by Fujimi Incorporated, Surfin 000 etc. SUBA800, Surfin xxx-5, and Surfin 000 are non-woven fabrics in which fibers are hardened with urethane resin, and IC-1000 is a hard foamed polyurethane (single layer). The polyurethane foam is porous (porous) and has a large number of fine dents or pores on its surface.

  The top ring shaft 18 is rotated by driving a motor (not shown). The rotation of the top ring shaft 18 causes the top ring 20 to rotate around the top ring shaft 18. The top ring shaft 18 is moved up and down with respect to the top ring head 16 by a vertical movement mechanism 24, and the top ring 20 is moved up and down with respect to the top ring head 16 by the vertical movement of the top ring shaft 18. It comes to move. A rotary joint 25 is attached to the upper end of the top ring shaft 18.

  The top ring 20 can hold a substrate such as a semiconductor wafer W on the lower surface thereof. The top ring head 16 is configured to be rotatable about the support shaft 14, and the top ring 20 holding the semiconductor wafer W on the lower surface thereof is moved from the receiving position of the semiconductor wafer W by the rotation of the top ring head 16. Moved upward. Then, the top ring 20 is lowered to press the semiconductor wafer W against the surface (polishing surface) 22 a of the polishing pad 22. At this time, the top ring 20 and the polishing table 12 are rotated, and the polishing liquid is supplied onto the polishing pad 22 from a polishing liquid supply nozzle (not shown) provided above the polishing table 12. Thus, the surface of the semiconductor wafer W is polished by bringing the semiconductor wafer W into sliding contact with the polishing surface 22a of the polishing pad 22.

  A vertical movement mechanism 24 that moves the top ring shaft 18 and the top ring 20 up and down includes a bridge 28 that rotatably supports the top ring shaft 18 via a bearing 26, a ball screw 32 attached to the bridge 28, and a column 30. A support base 29 supported by the above-mentioned structure, and an AC servo motor 38 provided on the support base 29. A support base 29 that supports the servo motor 38 is fixed to the top ring head 16 via a support 30.

  The ball screw 32 includes a screw shaft 32a connected to the servo motor 38 and a nut 32b into which the screw shaft 32a is screwed. The top ring shaft 18 moves up and down integrally with the bridge 28. Therefore, when the servo motor 38 is driven, the bridge 28 moves up and down via the ball screw 32, and thereby the top ring shaft 18 and the top ring 20 move up and down.

  The polishing apparatus 10 includes a dressing unit 40 that dresses the polishing surface 22 a of the polishing table 12. The dressing unit 40 includes a dresser 50 that is slidably contacted with the polishing surface 22a, a dresser shaft 51 to which the dresser 50 is coupled, an air cylinder 53 provided at the upper end of the dresser shaft 51, and a dresser shaft 51 that is rotatable. And a swing arm 55 to be supported. The lower part of the dresser 50 is constituted by a dressing member 50a, and needle-like diamond particles adhere to the lower surface of the dressing member 50a. The air cylinder 53 is disposed on a support base 57 supported by support columns 56, and these support columns 56 are fixed to a swing arm 55.

  The swing arm 55 is driven by a motor (not shown) so as to turn around a support shaft 58. The dresser shaft 51 rotates by driving a motor (not shown), and the dresser 50 rotates around the dresser shaft 51 by the rotation of the dresser shaft 51. The air cylinder 53 moves the dresser 50 up and down via the dresser shaft 51 and presses the dresser 50 against the polishing surface 22a of the polishing pad 22 with a predetermined pressing force.

  Dressing of the polishing surface 22a of the polishing pad 22 is performed as follows. The dresser 50 is pressed against the polishing surface 22a by the air cylinder 53, and at the same time, pure water is supplied to the polishing surface 22a from a pure water supply nozzle (not shown). In this state, the dresser 50 rotates around the dresser shaft 51 to bring the lower surface (diamond particles) of the dressing member 50a into sliding contact with the polishing surface 22a. In this manner, the polishing pad 22 is scraped off by the dresser 50, and the polishing surface 22a is dressed.

  Next, the top ring 20 described above will be described in more detail. 2 to 5 are cross-sectional views of such a top ring 20, cut along a plurality of radial directions.

  As shown in FIGS. 2 to 5, the top ring 20 basically includes a top ring main body 200 that presses the semiconductor wafer W against the polishing surface 22a, and a retainer ring 302 that directly presses the polishing surface 22a. ing. The top ring body 200 includes a disk-shaped upper member 300, an intermediate member 304 attached to the lower surface of the upper member 300, and a lower member 306 attached to the lower surface of the intermediate member 304.

  The retainer ring 302 is attached to the outer peripheral portion of the upper member 300. The upper member 300 is connected to the top ring shaft 18 by a bolt 308. The intermediate member 304 is fixed to the upper member 300 via a bolt (not shown), and the lower member 306 is fixed to the upper member 300 via a bolt (not shown). The upper member 300, the intermediate member 304, and the lower member 306 are formed of a resin such as engineering plastic (for example, PEEK).

  An elastic film 314 that is in contact with the back surface of the semiconductor wafer is attached to the lower surface of the lower member 306. The elastic film 314 is attached to the lower surface of the lower member 306 by an annular edge holder 316 arranged on the outer peripheral side and annular ripple holders 318 and 319 arranged inside the edge holder 316. The elastic film 314 is formed of a rubber material having excellent strength and durability, such as ethylene propylene rubber (EPDM), polyurethane rubber, and silicon rubber. The edge holder 316 is held by a ripple holder 318, and the ripple holder 318 is attached to the lower surface of the lower member 306 by a plurality of stoppers 320. The ripple holder 319 is attached to the lower surface of the lower member 306 by a plurality of stoppers 322.

  As shown in FIG. 2, a center chamber 360 is formed at the center of the elastic film 314. The ripple holder 319 is formed with a flow path 324 communicating with the center chamber 360, and the lower member 306 is formed with a flow path 325 communicating with the flow path 324. The flow path 324 of the ripple holder 319 and the flow path 325 of the lower member 306 are connected to a fluid supply source (not shown), and pressurized fluid is supplied to the center chamber 360 through the flow path 325 and the flow path 324. It is like that.

  The ripple holder 318 is configured to press the ripple 314b and the edge 314c of the elastic film 314 against the lower surface of the lower member 306 by the claw portions 318b and 318c, respectively. It presses against the lower surface of the member 306.

  As shown in FIG. 3, an annular ripple chamber 361 is formed between the ripple 314 a and the ripple 314 b of the elastic film 314. A gap 314 f is formed between the ripple holder 318 and the ripple holder 319 of the elastic film 314, and a flow path 342 communicating with the gap 314 f is formed in the lower member 306. The intermediate member 304 is formed with a flow path 344 that communicates with the flow path 342 of the lower member 306. An annular groove 347 is formed at a connection portion between the flow path 342 of the lower member 306 and the flow path 344 of the intermediate member 304. The flow path 342 of the lower member 306 is connected to a fluid supply source (not shown) via the annular groove 347 and the flow path 344 of the intermediate member 304, and the pressurized fluid passes through these flow paths to the ripple chamber. 361 is supplied. The flow path 342 is also connected to a vacuum pump (not shown) so as to be switchable, so that the semiconductor wafer can be adsorbed to the lower surface of the elastic film 314 by the operation of the vacuum pump.

  As shown in FIG. 4, the ripple holder 318 is formed with a flow path 326 communicating with the annular outer chamber 362 formed by the ripple 314 b and the edge 314 c of the elastic film 314. The lower member 306 is formed with a flow path 328 that communicates with the flow path 326 of the ripple holder 318 via the connector 327, and the intermediate member 304 is formed with a flow path 329 that communicates with the flow path 328 of the lower member 306. ing. The flow path 326 of the ripple holder 318 is connected to a fluid supply source (not shown) via the flow path 328 of the lower member 306 and the flow path 329 of the intermediate member 304, and pressurized fluid passes through these flow paths. Are supplied to the outer chamber 362.

  As shown in FIG. 5, the edge holder 316 presses the edge 314 d of the elastic film 314 and holds it on the lower surface of the lower member 306. In the edge holder 316, a flow path 334 communicating with an annular edge chamber 363 formed by the edge 314c and the edge 314d of the elastic film 314 is formed. The lower member 306 is formed with a flow path 336 communicating with the flow path 334 of the edge holder 316, and the intermediate member 304 is formed with a flow path 338 communicating with the flow path 336 of the lower member 306. The flow path 334 of the edge holder 316 is connected to a fluid supply source (not shown) via the flow path 336 of the lower member 306 and the flow path 338 of the intermediate member 304, and pressurized fluid passes through these flow paths. It is supplied to the edge chamber 363 through.

  Thus, in the top ring 20 in the present embodiment, the pressure chambers formed between the elastic film 314 and the lower member 306, that is, the center chamber 360, the ripple chamber 361, the outer chamber 362, and the edge chamber 363 are formed. By adjusting the pressure of the fluid to be supplied, the pressing force for pressing the semiconductor wafer against the polishing pad 22 can be adjusted for each portion of the semiconductor wafer.

  FIG. 6 is an enlarged view of the retainer ring 302 shown in FIG. The retainer ring 302 holds the outer peripheral edge of the semiconductor wafer. As shown in FIG. 6, the retainer ring 302 has a cylindrical cylinder 400 whose upper portion is closed, a holding member 402 attached to the upper portion of the cylinder 400, and a holding member. An elastic film 404 held in the cylinder 400 by the member 402, a piston 406 connected to the lower end of the elastic film 404, and a ring member 408 pressed downward by the piston 406. Between the outer peripheral surface of the ring member 408 and the lower end of the cylinder 400, a connection sheet 420 that can be expanded and contracted in the vertical direction is provided. The connection sheet 420 has a role of preventing the polishing liquid (slurry) from entering by filling a gap between the ring member 408 and the cylinder 400.

  A seal member 422 that is bent upward and connects the elastic film 314 and the retainer ring 302 is formed on the edge (outer peripheral edge) 314 d of the elastic film 314. The seal member 422 is disposed so as to fill a gap between the elastic film 314 and the ring member 408, and is formed of a material that is easily deformed. The seal member 422 is provided to prevent the polishing liquid from entering the gap between the elastic film 314 and the retainer ring 302 while allowing relative movement between the top ring body 200 and the retainer ring 302. . In this embodiment, the seal member 422 is formed integrally with the edge 314d of the elastic film 314, and has a U-shaped cross section.

  Here, when the connection sheet 420 and the seal member 422 are not provided, the polishing liquid permeates into the top ring 20 and hinders normal operations of the top ring main body 200 and the retainer ring 302 constituting the top ring 20. End up. According to the present embodiment, the connection sheet 420 and the seal member 422 can prevent the polishing liquid from entering the top ring 20, and thus the top ring 20 can be operated normally. The elastic film 404, the connection sheet 420, and the seal member 422 are formed of a rubber material having excellent strength and durability, such as ethylene propylene rubber (EPDM), polyurethane rubber, and silicon rubber.

  The ring member 408 is divided into an upper ring member 408a that contacts the piston 406 and a lower ring member 408b that contacts the polishing surface 22a. Flange portions extending in the circumferential direction are formed on the outer peripheral surface of the upper ring member 408a and the outer peripheral surface of the lower ring member 408b, respectively. These flange portions are held by a clamp 430, whereby the upper ring member 408a and the lower ring member 408b are fastened.

  Here, the elastic membrane 404 has a plurality of diaphragms (not shown) in the circumferential direction, and a plurality of pressure chambers 410 divided in the circumferential direction are formed inside the elastic membrane 404. The number of pressure chambers 410 is preferably 3 or more. As shown in FIG. 6, the holding member 402 has flow paths 412 communicating with the respective pressure chambers 410, and a flow path 414 communicating with these flow paths 412 is formed in the upper part of the cylinder 400. Has been. Further, the upper member 300 is formed with a flow path 416 communicating with the flow path 414 of the cylinder 400. Each pressure chamber 410 is connected to a fluid supply source (not shown) via the flow path 412 of the holding member 402, the flow path 414 of the cylinder 400, and the flow path 416 of the upper member 300.

  The flow paths 412, 414, 416 communicating with each pressure chamber 410 are independent from each other, and a pressure controller (not shown) is provided for each pressure chamber 410. As described above, the fluid whose pressure is independently controlled by each pressure controller is supplied to each pressure chamber 410 through the flow paths 412, 414, and 416. Therefore, by adjusting the pressure of the fluid supplied to each pressure chamber 410 by each pressure controller, the elastic film 404 is expanded and contracted to move the piston 406 up and down, and the ring member 408 of the retainer ring 302 is polished at a desired pressure. 22 can be pressed.

  As described above, in the present embodiment, by independently controlling the pressure of the fluid supplied to the plurality of pressure chambers 410, a predetermined pressure distribution that is not uniform along the circumferential direction of the retainer ring 302 can be formed. . That is, in the present embodiment, the ring member 408 and the plurality of pressure chambers 410 that press the ring member form a pressure control mechanism that forms a predetermined pressure distribution that is not uniform along the circumferential direction of the retainer ring 302. It is functioning.

  By such a pressure control mechanism, for example, the pressure at which the retainer ring 302 presses the polishing pad 22 so that the pressure of the portion located on the downstream side in the rotation direction of the polishing table 12 is higher than the portion located on the upstream side. Can be controlled. In this case, it is necessary to dynamically change the pressure of the fluid supplied to each pressure chamber 410 as the top ring 20 rotates. However, when the rotation speed of the top ring 20 increases, the followability of pressure control increases. It will decline. In order to prevent such a decrease in follow-up performance of pressure control, for example, a pressure switching valve (not shown) is provided corresponding to each pressure chamber 410, and the pressure switching valve is switched as the top ring 20 rotates. Thus, a fluid having a pressure prepared in advance may be introduced into each pressure chamber 410.

  In the illustrated example, a rolling diaphragm is used as the elastic film 404. The rolling diaphragm is made of an elastic film having a bent portion, and the space of the chamber can be expanded by rolling the bent portion due to a change in the internal pressure of the chamber partitioned by the rolling diaphragm. When the chamber expands, the diaphragm does not slide with the outer member and hardly expands or contracts, so that the sliding friction is very small, the life of the diaphragm can be extended, and the retainer ring 302 is applied to the polishing pad 22. There is an advantage that the pressing force can be adjusted with high accuracy.

  With such a configuration, only the ring member 408 of the retainer ring 302 can be lowered. Therefore, even if the ring member 408 of the retainer ring 302 is worn, the distance between the lower member 306 and the polishing pad 22 can be maintained constant. Further, since the ring member 408 that contacts the polishing pad 22 and the cylinder 400 are connected by the elastic film 404 that can be deformed, a bending moment due to the offset of the load point does not occur.

  As shown in FIG. 6, a plurality of V-shaped grooves 418 extending in the vertical direction are formed uniformly on the inner surface of the upper ring member 408a. A plurality of pins 349 projecting outward are provided on the outer peripheral portion of the lower member 306, and the pins 349 engage with the V-shaped groove 418 of the ring member 408. The ring member 408 and the pin 349 are relatively slidable in the vertical direction within the V-shaped groove 418, and the rotation of the top ring main body 200 is retained by the pin 349 via the upper member 300 and the lower member 306. The top ring body 200 and the retainer ring 302 rotate together as a result of being transmitted to the ring 302. With such a configuration, the elastic membrane (rolling diaphragm) 404 can be prevented from being twisted and the life of the elastic membrane can be extended.

  FIG. 7 is a schematic diagram showing a top ring 1020 in the second embodiment of the present invention. As shown in FIG. 7, the retainer ring 1302 of the top ring 1020 includes an upper ring member 1408a and a lower ring member 1408b. FIG. 8 is an enlarged view of the upper ring member 1408a and the lower ring member 1408b. As shown in FIG. 8, the lower ring member 1408b has a lower surface 1400 that contacts the polishing surface 22a and an upper surface on which a tapered surface 1401 is formed. The upper ring member 1408a has a lower surface on which a tapered surface 1402 capable of contacting the tapered surface 1401 of the lower ring member 1408b is formed.

The retainer ring 1302 that can move up and down is configured to be slightly movable in the radial direction. During polishing, a frictional force generated between the retainer ring 1302 and the polishing surface 22 a and a radial force for holding the substrate W act on the retainer ring 1302. Therefore, the retainer ring 1302 being polished is always biased to the downstream side in the rotational direction of the polishing table 22. In the present embodiment, as shown in FIGS. 7 and 8, the radial force F _R acting on the retainer ring 1302 by bringing the upper ring member 1408a and the lower ring member 1408b into contact with each other at the tapered surfaces 1402, 1401. the is converted into a downward force F _D.

  Thus, in the present embodiment, the upper ring member 1408a having the tapered surface 1402 and the lower ring member 1408b having the tapered surface 1401 have a predetermined non-uniform pressure distribution along the circumferential direction of the retainer ring 1302. It functions as a pressure control mechanism to be formed, and in particular, the retainer ring 1302 makes the polishing pad 22 so that the pressure in the portion located on the downstream side in the rotation direction of the polishing table 12 is higher than the portion located on the upstream side. The pressing pressure is controlled. Note that a rolling element such as a roller may be disposed between the tapered surface 1401 and the tapered surface 1402. In this way, the downward force can be generated more smoothly.

  FIG. 9 is a partially enlarged view of the top ring in the third embodiment of the present invention. As shown in FIG. 9, the retainer ring 2302 of the top ring is a combination of the retainer ring 302 in the first embodiment and the retainer ring 1302 in the second embodiment. That is, the retainer ring 2302 includes a ring member 2408 divided into an upper ring member 2408a that contacts the piston 406 and a lower ring member 2408b that contacts the polishing surface 22a. The lower ring member 2408b includes the polishing surface 22a. And a lower surface 2400 that contacts the upper surface and an upper surface on which a tapered surface 1401 is formed. Further, the upper ring member 2408a has a lower surface on which a tapered surface 2402 capable of contacting the tapered surface 2401 of the lower ring member 2408b is formed.

  In the first embodiment, an example in which a plurality of pressure chambers 410 are formed has been described. However, in the retainer ring 1302 of this embodiment, the above-described upper ring member 2408a and lower ring member 2408b constitute a pressure control mechanism. Therefore, it is not always necessary to provide a plurality of pressure chambers 410.

  In this case, if the movement of the upper ring member 2408a in the vertical direction is not restricted, the pressure chamber 410 exists above the upper ring member 2408a, and therefore the tapered surfaces 2402 and 2401 of the upper ring member 2408a and the lower ring member 2408b The vertical force generated by the contact is absorbed by the pressure chamber 410, and no more force than that given by the pressure chamber 410 acts on the ring member 2408. Therefore, in the present embodiment, a regulating member 2500 that contacts the upper ring member 2408a and regulates the vertical movement of the upper ring member 2408a is provided on the inner peripheral surface of the cylinder 400. For example, rubber having a large friction coefficient can be used as the regulating member 2500.

  By providing such a regulating member 2500, it is possible to prevent the upper ring member 2408a on the downstream side in the rotational direction of the polishing table 22 from being lifted. Therefore, the force generated by the contact between the tapered surfaces 2402 and 2401 of the ring member 2408a and the lower ring member 2408b can be made larger than the force generated by the pressure chamber 410, and more actively in the rotational direction of the polishing table 22. The pressing force of the retainer ring 2302 on the downstream side can be increased. Note that a rolling element such as a roller may be disposed between the tapered surface 2401 and the tapered surface 2402 as in the second embodiment.

  Although one embodiment of the present invention has been described so far, it is needless to say that the present invention is not limited to the above-described embodiment, and may be implemented in various forms within the scope of the technical idea.

It is a figure which shows the grinding | polishing apparatus in the 1st Embodiment of this invention. It is sectional drawing of the top ring of the grinding | polishing apparatus shown in FIG. It is sectional drawing of the top ring of the grinding | polishing apparatus shown in FIG. It is sectional drawing of the top ring of the grinding | polishing apparatus shown in FIG. It is sectional drawing of the top ring of the grinding | polishing apparatus shown in FIG. FIG. 3 is an enlarged view of the vicinity of the retainer ring of the top ring shown in FIG. 2. It is a schematic diagram which shows the top ring in the 2nd Embodiment of this invention. It is an enlarged view of the retainer ring of the top ring shown in FIG. It is the elements on larger scale of the top ring in the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Polishing apparatus 20,1020 Top ring 22 Polishing pad 22a Polishing surface 40 Dressing unit 200 Top ring main body 300 Upper member 302, 1302, 2302 Retainer ring 304 Intermediate member 306 Lower member 314, 404 Elastic film 400 Cylinder 402 Holding member 406 Piston 408 , 2408 Ring member 408a, 1408a, 2408a Upper ring member 408b, 1408b, 2408b Lower ring member 1400, 2400 Lower surface 1401, 1402, 2401, 402 Taper surface 2500 Restriction member W Semiconductor wafer

Claims (7)

A substrate holding device comprising: a top ring body that presses a substrate against a polishing surface; and a retainer ring that is provided on an outer periphery of the top ring body and presses the polishing surface;
The retainer ring includes a pressure control mechanism that controls a pressure with which the retainer ring presses the polishing surface so as to form a predetermined pressure distribution that is not uniform along a circumferential direction of the retainer ring. A substrate holding device. The pressure control mechanism includes:
A ring member in contact with the polishing surface;
A plurality of pressure chambers that press the ring member against the polishing surface by independently pressure-controlled fluid;
The substrate holding apparatus according to claim 1, further comprising: The pressure control mechanism is
A lower ring member having a lower surface in contact with the polishing surface and an upper surface on which a tapered surface is formed;
An upper ring member having a lower surface formed with a tapered surface capable of coming into contact with the tapered surface of the lower ring member and changing a radial force acting on the lower ring member to a downward force by the contact of the tapered surface When,
The substrate holding apparatus according to claim 1, further comprising: The pressure control mechanism is
A lower ring member having a lower surface in contact with the polishing surface and an upper surface on which a tapered surface is formed;
An upper ring member having a lower surface formed with a tapered surface capable of coming into contact with the tapered surface of the lower ring member and changing a radial force acting on the lower ring member to a downward force by the contact of the tapered surface When,
A pressure chamber that presses the upper ring member toward the polishing surface with a pressure-controlled fluid;
A regulating member that contacts the upper ring member and regulates the movement of the upper ring member in the vertical direction;
The substrate holding apparatus according to claim 1, further comprising:   The pressure control mechanism controls the pressure by which the retainer ring presses the polishing surface according to the rotation of the top ring body so that the predetermined pressure distribution is constant when viewed from a stationary system. The substrate holding device according to any one of claims 1 to 4. A rotatable polishing table having the polishing surface;
A substrate holding device according to any one of claims 1 to 5,
A polishing apparatus comprising:   The pressure control mechanism of the substrate holding device is configured so that the retainer ring presses the polishing surface so that the pressure of the portion located downstream in the rotational direction of the polishing table is higher than the pressure of the portion located upstream. The polishing apparatus according to claim 6, wherein the pressure is controlled.

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