JP2013111679A - Elastic membrane and substrate holding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively inhibit excessive polishing of a substrate end and accurately control a polishing rate at the substrate end.SOLUTION: An elastic membrane 4 used for a substrate holding device has an abutting part 400 to be abutted against the substrate to press the substrate toward a polishing pad. A lower surface of the abutting part 400 has a flat region A and a rise region B located on an outer peripheral part of the flat region and rising upward.

Description

  The present invention is used for a substrate holding device that holds a substrate that is an object to be polished and presses the substrate against a polishing surface, particularly a substrate holding device that holds a substrate in a polishing device that polishes and flattens a substrate such as a semiconductor wafer. The present invention relates to an elastic film and a substrate holding device having the elastic film.

  In recent years, with higher integration and higher density of semiconductor devices, circuit wiring has become increasingly finer and the number of layers of multilayer wiring has increased. When trying to realize multilayer wiring while miniaturizing the circuit, the step becomes larger while following the surface unevenness of the lower layer, so as the number of wiring layers increases, the film coverage to the step shape in thin film formation (Step coverage) deteriorates. Therefore, in order to carry out multilayer wiring, it is necessary to improve the step coverage and perform a flattening process in an appropriate process. Further, since the depth of focus becomes shallower as the optical lithography becomes finer, it is necessary to planarize the surface of the semiconductor device so that the uneven steps on the surface of the semiconductor device are kept below the depth of focus.

Accordingly, 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 composed of a polishing pad, and a substrate holding apparatus for holding a semiconductor wafer. When polishing a semiconductor wafer using such a polishing apparatus, the semiconductor wafer is pressed against the polishing surface 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, when the relative pressing force between the semiconductor wafer being polished and the polishing surface of the polishing pad is not uniform over the entire surface of the semiconductor wafer, the pressing force applied to each part of the semiconductor wafer. Depending on the pressure, insufficient polishing or overpolishing occurs. In order to equalize the pressing force on the semiconductor wafer, a pressure chamber formed of an elastic film is provided in the lower part of the substrate holding device, and a fluid such as compressed air is supplied to the pressure chamber to supply fluid through the elastic film. The semiconductor wafer is pressed by pressure.

  The elastic film used in the substrate holding device efficiently transmits the fluid pressure in the pressure chamber formed on the upper surface of the elastic film to the substrate due to its flexible nature, and presses the substrate with uniform pressure to the edge of the substrate. Therefore, a flexible material such as rubber is generally used (see Patent Documents 1 and 2).

  Here, the edge (edge cut part) is provided at the outer peripheral edge of the film to be polished laminated on the substrate by applying a process called edge rinse or edge cut to the edge of the surface to be polished (front surface). Further, it has been proposed to change the width of the edge cut portion provided at the outer peripheral end of the film to be polished laminated on the substrate as it goes to the upper layer (see Patent Document 4). . When a substrate having such an edge cut portion is pressed against a polishing pad for polishing, pressure concentrates on the edge cut portion, resulting in overpolishing of the edge cut portion, and a good semiconductor element can be manufactured from the edge of the substrate. Therefore, there is a problem that the product yield deteriorates.

  As a method of reducing the polishing rate of the substrate edge, it has been proposed to individually control the contact area of the elastic film with the substrate and the pressure outside the contact area by a set pressure (Patent Document). 5). However, in the invention described in Patent Document 5, the contact area of the elastic film with the substrate changes due to a delicate balance of the set pressure, and the airbag pressure is controlled, for example, in order to control the polishing rate of the substrate edge. When adjusted, it is considered difficult to control the polishing rate of the desired region.

  Further, in the invention described in Patent Document 5, the outer peripheral part of the contact part of the elastic film is configured flexibly so as to control the contact region with the elastic film at the end of the substrate. However, depending on the applied pressure, not only may the desired effect be lost such as the outer peripheral portion of the contact portion of the elastic film being crushed, but the pressure of the elastic film having a small contact area with the substrate may not be obtained. Amplified on the outer periphery of the abutting part, and the polishing rate at the edge of the substrate changes very sensitively due to a slight change in pressure, resulting in the problem that stable control is hindered. Conceivable. On the contrary, even when trying to finely control the contact area of the outer peripheral part of the elastic film contact part to the substrate by adjusting the pressure, the outer peripheral part of the elastic film contact part of the elastic film is the polishing pad and the substrate. It is easy to deform due to the load caused by frictional force with the air bag, or to inflate outward due to the pressure of the air bag, etc., so it is considered that various problems may occur that the desired pressure cannot be applied to the substrate due to contact with the retainer ring. It is done. Furthermore, in order to control the polishing rate of the substrate edge, it is necessary to set conditions in consideration of the differential pressure between the two pressure chambers, and it is considered that there is a problem that the setting of the polishing conditions is very complicated.

  It has also been proposed to adjust the pressure applied to the edge of the substrate by adjusting the upward lifting force acting on the outer peripheral part of the elastic film by preliminarily determining the surface area of the upper and lower surfaces of the spacer ring. (See Patent Document 6). However, in the invention described in Patent Document 6, the non-contact width of the elastic film is changed in accordance with the pressure in the pressure chamber to control the polishing rate at the edge of the substrate. Independent control is considered difficult.

  Suggested to use edge load ring to reduce over-polishing of flat part (orientation flat part) at substrate edge and adjust polishing rate of flat part by adjusting width of outer periphery non-contact part of edge load ring (See Patent Document 7). However, in the invention described in Patent Document 7, the pressing force applied to the substrate by the edge load ring depends on the airbag pressure that presses the central portion of the substrate. For this reason, the polishing rate distribution at the edge of the substrate is accurately and independently determined. It is thought that it cannot be controlled.

  Further, as the elastic film, an elastic film having a thick outer peripheral part (see Patent Document 8) or an elastic film formed so as to increase in thickness toward the outer peripheral part is used. It has been proposed that the pressure applied to the part gradually decreases as it goes to the outer peripheral part of the substrate (see Patent Document 9). However, even with the inventions described in Patent Documents 8 and 9, it is considered that the polishing rate distribution at the edge of the substrate cannot be precisely controlled independently.

  In addition, in order to control the polishing rate distribution up to the edge of the semiconductor wafer with respect to various polishing target films, pressurization located above the edge of the semiconductor wafer, such as the elastic film shown in Patent Documents 1 and 2, etc. Attempts have been made to improve the controllability of the semiconductor wafer edge in a narrower range by reducing the radial width of the chamber. However, since the elastic films disclosed in Patent Documents 1 and 2 have a folded portion in the partition wall, a force that causes the folded portion to be crushed works depending on the pressure difference between the pressure chambers on the inside and outside of the partition wall. The shape of the elastic membrane partition changes depending on the difference condition, and discontinuous changes occur in the pressure distribution to the semiconductor wafer. For this reason, it is considered that it is not suitable when various pressure conditions are changed in order to finely control the polishing rate at the edge of the semiconductor wafer for various films to be polished.

JP 2007-268654 A JP 2009-131920 A JP 2003-197621 A JP 2008-193117 A JP-T-2004-516644 JP-T-2002-527893 Japanese translation of PCT publication No. 2002-530876 US Patent Application Publication No. 2009/0023368 JP 2002-75936 A

  The present invention has been made in view of the above circumstances, and an elastic film and a substrate holding apparatus that can effectively control overpolishing of the substrate end and precisely control the polishing rate of the substrate end. The purpose is to provide.

  The invention according to claim 1 is an elastic film used in a substrate holding device, wherein the elastic film has a contact portion that contacts the substrate and presses the substrate toward the polishing pad. The lower surface of the contact portion is an elastic film characterized by having a flat flat region and a rising region that is located on the outer periphery of the flat region and rises upward.

  Thus, by providing the rising region on the lower surface of the contact portion, it is possible to locally reduce the pressing force to the substrate facing the rising region. Sometimes, by setting the range of the rising region to a range where it is desired to reduce the polishing rate, it becomes possible to control the polishing rate with a desired width, and it is possible to easily cope with the width of various edge cut portions. In addition, by changing the pressure of the edge pressure chamber that presses the edge of the substrate, it becomes possible to precisely control the polishing rate of the edge of the substrate. For example, even when the airbag pressure is changed, the rise of the contact portion It is possible to locally reduce the polishing rate of the substrate edge corresponding to the region.

  The invention according to claim 2 is the elastic film according to claim 1, wherein a step is provided between the flat region and the rising region of the contact portion.

  According to a third aspect of the present invention, there is provided an elastic film used in a substrate holding device, the elastic film having an abutting portion that abuts against the substrate and presses the substrate toward the polishing pad. The lower surface of the contact portion is an elastic film characterized by having a flat region having an outer diameter smaller than the outer diameter of the pressure chamber forming region of the corresponding contact portion.

  The invention according to claim 4 is the elastic film according to claim 3, wherein the flat region of the contact portion is partitioned by a step provided on an outer peripheral portion of the flat region.

  According to a fifth aspect of the present invention, there is provided an elastic film used in the substrate holding device, the elastic film having an abutting portion that abuts against the substrate and presses the substrate toward the polishing pad. The contact portion includes a flat plate-like portion having a flat flat area on the lower surface, and a rising portion having a rising area located on the outer periphery of the flat plate-like portion and rising upward from the flat area. The first edge peripheral wall portion extending upward from the rising portion is connected to the second edge peripheral wall portion positioned radially inward of the first edge peripheral wall portion and extending upward from the rising portion. It is an elastic membrane.

  As described above, by providing the rising portion on the outer peripheral portion of the contact portion, the deformation of the rising portion can be adjusted by the elastic force of the rising portion. Further, the first and second edge peripheral wall portions are connected to the rising portion, an edge pressure chamber is formed between the first and second edge peripheral wall portions, and the pressing force to the substrate pressed by the edge pressure chamber is lowered. By doing so, it is possible to independently and precisely control the polishing rate of the substrate edge.

  The invention according to claim 6 is the elastic film according to claim 5, wherein a step is provided between the flat region and the rising region of the contact portion.

  The invention according to claim 7 is an elastic film used in a substrate holding device, the elastic film having a contact portion that contacts the substrate and presses the substrate toward the polishing pad, and The contact portion includes a flat plate-like portion having a substantially constant thickness and a thick-walled end portion that is located on the outer peripheral portion of the flat plate-like portion and gradually increases in thickness radially outward. The end portion includes a first edge peripheral wall portion extending upward from the thick end portion and a second edge peripheral wall portion extending radially inward of the first edge peripheral wall portion and extending upward from the thick end portion. It is an elastic film characterized by being connected.

  Thus, by providing the thick end portion on the outer peripheral portion of the contact portion, the pressing force to the substrate end portion can be relaxed and lowered by the elastic force of the thick end portion. Also, the first and second edge peripheral wall portions are connected to the thick end portion, an edge pressure chamber is formed between the first and second edge peripheral wall portions, and the pressing force to the substrate pressed by the edge pressure chamber By lowering, it is possible to independently and precisely control the polishing rate of the substrate edge.

  The invention according to claim 8 is an elastic film used in a substrate holding device, wherein the elastic film has a contact portion that contacts the substrate and presses the substrate toward the polishing pad. The contact portion includes a first edge peripheral wall portion that extends upward from the corresponding contact portion and is disposed on an outer periphery of the corresponding contact portion, and is positioned on the radially inner side of the first edge peripheral wall portion and upward from the contact portion. An extended second edge peripheral wall portion is connected, and the second edge peripheral wall portion extends from the connecting portion with the abutting portion to the radially inner side in an approximately obliquely upward direction, and the radial direction from the upper inclined portion. An elastic membrane having a horizontal portion extending in a substantially horizontal direction toward the inside and a vertical portion extending upward from the horizontal portion in a substantially vertical direction.

  Thus, the edge pressure chamber formed between the first edge peripheral wall portion and the second edge peripheral wall portion by providing the second edge peripheral wall portion with the upward inclined portion extending substantially obliquely upward toward the radially inner side. As a result, it is possible to narrow a region for pressing the substrate, or to arrange a plurality of pressure chambers concentrated on the outer periphery of the substrate. This enables precise control of the polishing rate distribution at the substrate edge.

  The invention described in claim 9 is characterized in that the lower surface of the abutting portion has a flat flat region and a rising region that is located on the outer periphery of the flat region and rises upward. It is an elastic membrane.

The invention according to claim 10 is the elastic film according to claim 9, wherein a step is provided between the flat region and the rising region of the contact portion.
According to an eleventh aspect of the present invention, there is provided a substrate holding apparatus including the elastic film according to any one of the first to tenth aspects.

  According to the present invention, it is possible to effectively suppress over-polishing of the substrate end and to finely control the polishing rate of the substrate end.

It is a mimetic diagram showing the whole polisher composition provided with the substrate holding device concerning the present invention. It is sectional drawing which shows the structural example of the substrate holding apparatus with which the grinding | polishing apparatus shown in FIG. 1 is equipped. It is a principal part expanded sectional view which shows the principal part of the elastic film of embodiment of this invention with which the board | substrate holding apparatus shown in FIG. 2 is equipped. A polishing rate distribution (Example 1) when a semiconductor wafer is actually polished by using the substrate holding device shown in FIG. 2 using the elastic film shown in FIG. 3 is used. It is a graph shown with the grinding | polishing rate distribution (Comparative Example 1) when grind | polished similarly to the above. It is a principal part expanded sectional view which shows the principal part of the elastic film used for a comparative example. Using the substrate holding apparatus shown in FIG. 2 using the elastic film shown in FIG. 3, the polishing rate distribution (Examples 2 to 4) when the semiconductor wafer is actually polished by changing the pressure in the edge pressure chamber is shown. 4 is a graph showing a polishing rate distribution (Comparative Examples 2 to 4) when a semiconductor wafer is actually polished under the same conditions as described above using an elastic film 500 having no rising region B. It is a principal part expanded sectional view which shows the principal part of the elastic film of other embodiment of this invention. It is a principal part expanded sectional view which shows the principal part of the elastic film of other embodiment of this invention. It is a principal part expanded sectional view which shows the principal part of the elastic film of other embodiment of this invention. It is a principal part expanded sectional view which shows the principal part of the elastic film of other embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each of the following embodiments, the same or corresponding components are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a schematic diagram showing the overall configuration of a polishing apparatus provided with a substrate holding apparatus according to the present invention. As shown in FIG. 1, the polishing apparatus includes a polishing table 100 and a substrate holding device 1 that holds a substrate W such as a semiconductor wafer that is an object to be polished and presses it against a polishing surface on the polishing table 100. . The polishing table 100 is connected to a motor (not shown) disposed below the table via a table shaft 100a, and is rotatable around the table shaft 100a. A polishing pad 101 is affixed to the upper surface of the polishing table 100, and the surface of the polishing pad 101 constitutes a polishing surface 101a for polishing the substrate W. A polishing liquid supply nozzle 102 is installed above the polishing table 100, and the polishing liquid Q is supplied to the polishing surface 101 a of the polishing pad 101 on the polishing table 100 by the polishing liquid supply nozzle 102.

  The substrate holding apparatus 1 is connected to a main shaft 111, and the main shaft 111 moves up and down with respect to the polishing head 110 by a vertical movement mechanism 124. By moving the main shaft 111 up and down, the entire substrate holding apparatus 1 is moved up and down with respect to the polishing head 110 for positioning. A rotary joint 125 is attached to the upper end of the main shaft 111.

  A vertical movement mechanism 124 that moves the main shaft 111 and the substrate holding apparatus 1 up and down is supported by a bridge 128 that rotatably supports the main shaft 111 via a bearing 126, a ball screw 132 attached to the bridge 128, and a support 130. The support base 129 and an AC servo motor 138 provided on the support base 129 are provided. A support base 129 that supports the servo motor 138 is fixed to the polishing head 110 via a column 130.

  The ball screw 132 includes a screw shaft 132a connected to the servo motor 138 and a nut 132b into which the screw shaft 132a is screwed. The main shaft 111 moves up and down integrally with the bridge 128. Therefore, when the servo motor 138 is driven, the bridge 128 moves up and down via the ball screw 132, and thereby the main shaft 111 and the substrate holding device 1 move up and down.

  The main shaft 111 is coupled to the rotary cylinder 112 via a key (not shown). The rotating cylinder 112 includes a timing pulley 113 on the outer periphery thereof. A motor 114 is fixed to the polishing head 110, and the timing pulley 113 is connected to a timing pulley 116 provided on the motor 114 via a timing belt 115. Accordingly, when the motor 114 is driven to rotate, the rotary cylinder 112 and the main shaft 111 rotate together via the timing pulley 116, the timing belt 115, and the timing pulley 113, and the substrate holding device 1 rotates. The polishing head 110 is supported by a head shaft 117 that is rotatably supported by a frame (not shown).

  In the polishing apparatus configured as shown in FIG. 1, the substrate holding apparatus 1 can hold a substrate W such as a semiconductor wafer on its lower surface. The polishing head 110 is configured to be pivotable about the head shaft 117, and the substrate holding device 1 holding the substrate W on the lower surface is moved above the polishing table 100 from the receiving position of the substrate W by the rotation of the polishing head 110. Moved. Then, the substrate holding device 1 is lowered to press the substrate W against the polishing surface 101 a of the polishing pad 101. At this time, the substrate holding device 1 and the polishing table 100 are rotated, and the polishing liquid Q is supplied from the polishing liquid supply nozzle 102 provided above the polishing table 100 to the polishing surface 101 a of the polishing pad 101. In this manner, in the presence of the polishing liquid Q, the surface of the substrate W is polished by bringing the substrate W into sliding contact with the polishing surface 101a of the polishing pad 101.

  Next, the substrate holding apparatus 1 of the embodiment of the present invention provided in the polishing apparatus shown in FIG. 1 will be described in detail with reference to FIG.

  As shown in FIG. 2, the substrate holding device 1 basically includes a device main body 2 that presses the substrate against the polishing surface 101a and a retainer ring 3 that directly presses the polishing surface 101a. The apparatus main body 2 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 3 is attached to the outer peripheral portion of the upper member 300 of the apparatus main body 2. The upper member 300 is connected to the main shaft 111 by a bolt (not shown). 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 apparatus main body 2 including the upper member 300, the intermediate member 304, and the lower member 306 is formed of a resin such as engineering plastic (for example, PEEK).

  On the lower surface of the lower member 306, the elastic film 4 that contacts the back surface of the substrate is attached. The elastic film 4 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 4 is formed of a rubber material having excellent strength and durability, such as ethylene propylene rubber (EPDM), polyurethane rubber, silicon rubber and the like.

  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 (not shown), and these stoppers are equally provided in the circumferential direction of the substrate holding device 1.

  A center pressure chamber 5 is formed at the center of the elastic membrane 4. The ripple holder 319 is formed with a flow path 324 communicating with the center pressure chamber 5, 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 pressure chamber 5 through the flow path 325 and the flow path 324. The

  The ripple holder 318 is configured to press the intermediate peripheral wall portion 314b and the second edge peripheral wall portion 314c of the elastic film 4 against the lower surface of the lower member 306 by the claw portions 318b and 318c, respectively. The ripple holder 319 is the center peripheral wall of the elastic film 4 The portion 314a is pressed against the lower surface of the lower member 306 by the claw portion 319a.

  An annular ripple pressure chamber 6 is formed between the center peripheral wall portion 314 a and the intermediate peripheral wall portion 314 b of the elastic film 4. A gap (not shown) is formed between the ripple holder 318 and the ripple holder 319 of the elastic film 4, and a flow path 342 communicating with the gap 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 is rippled through these flow paths. It is supplied to the pressure chamber 6. This flow path 342 is also connected to a vacuum pump (not shown) so that it can be switched, and the substrate can be adsorbed to the lower surface of the elastic film 4 by the operation of the vacuum pump.

  The ripple holder 318 is formed with a flow path communicating with the annular outer pressure chamber 7 formed by the intermediate peripheral wall portion 314 b and the second edge peripheral wall portion 314 c of the elastic film 4. The lower member 306 is formed with a flow channel communicating with the flow channel of the ripple holder 318 via a connector, and the intermediate member 304 is formed with a flow channel communicating with the flow channel of the lower member. The flow path of the ripple holder 318 is connected to a fluid supply source (not shown) via the flow path of the lower member 306 and the flow path of the intermediate member 304, and the pressurized fluid passes through these flow paths to the outer pressure. Supplyed to the chamber 7.

  The edge holder 316 is configured to hold the first peripheral wall portion 314 d of the elastic film 4 on the lower surface of the lower member 306. The edge holder 316 is formed with a flow path communicating with the annular edge pressure chamber 8 formed by the first edge peripheral wall portion 314 d and the second edge peripheral wall portion 314 c of the elastic film 4. The lower member 306 is formed with a flow channel communicating with the flow channel of the edge holder 316, and the intermediate member 304 is formed with a flow channel communicating with the flow channel of the lower member 306. The flow path of the edge holder 316 is connected to a fluid supply source (not shown) via the flow path of the lower member 306 and the flow path of the intermediate member 304, and the pressurized fluid passes through these flow paths to the edge. It is supplied to the pressure chamber 8. The center pressure chamber 5, the ripple pressure chamber 6, the outer pressure chamber 7, and the edge pressure chamber 8 are connected to a fluid supply source via regulators R1 to R5 and open / close valves V1 to V5 (not shown).

  As described above, in the substrate holding device 1, the pressure chamber formed between the elastic film 4 and the lower member 306, that is, the center pressure chamber 5, the ripple pressure chamber 6, the outer pressure chamber 7, and the edge pressure chamber 8. By adjusting the pressure of the fluid to be supplied, the pressing force for pressing the substrate W against the polishing pad 101 can be adjusted for each portion of the substrate W.

  Next, details of the elastic film 4 of the embodiment of the present invention provided in the substrate holding device 1 are shown in FIG. As shown in FIG. 3, the elastic film 4 has a contact portion 400 that covers the lower surface of the lower member 306 shown in FIG. 2 and contacts the back surface of the substrate W shown in FIG. The center peripheral wall 314a, the intermediate peripheral wall 314b, the second edge peripheral wall 314c, and the first peripheral wall 314d are connected to the upper surface of 400.

  The lower surface of the contact portion 400 of the elastic film 4 is chamfered and sandwiches a step 402 that rises at an angle nearly perpendicular to the flat surface region A located at the center and the flat region A located at the outer periphery. The flat region A is integrated with the lower surface of the flat plate portion 400a having a substantially constant thickness at the center, and the rising region B is integrated with the outer peripheral portion of the flat plate portion 400a. It is formed on the lower surface of the connected rising portion 400b. The width of the rising region B is usually 5 mm or less, but is arbitrarily set according to individual process requirements.

  As described above, the edge pressure chamber 8 (see FIG. 2) is formed between the first edge peripheral wall portion 314d and the second edge peripheral wall portion 314c, and the inside of the inner peripheral surface of the first edge peripheral wall portion 314d is pressurized. A chamber forming region C is formed. In this example, the step 402 is located inward of the inner peripheral surface of the first edge peripheral wall portion 314d, and the rising region B has an inner diameter smaller than the outer diameter of the pressure chamber forming region C, whereby the edge The rising end portion 400b is configured to be deformed downward by pressurization in the pressure chamber 8.

  In this example, the flat region A and the rising region B are partitioned by a step 402, but instead of the step 402, a tapered shape or a round shape may be used. However, in the case of a round shape, for example, the bulge of the outer peripheral portion of the elastic film 4 changes due to the pressure pressing the inside of the edge pressure chamber 8 (see FIG. 2), and the contact surface outer diameter of the contact portion 400 with the substrate is changed. May change. By dividing the flat portion A and the rising region B by the step 402, such an adverse effect can be prevented.

  As described above, by providing the rising region B on the lower surface of the contact portion 400, the pressing force to the substrate facing the rising region B can be locally reduced. Sometimes, by setting the range of the rising region B to a range where the polishing rate is desired to be lowered, it becomes possible to control the polishing rate with a desired width, and it is possible to easily cope with the widths of various edge cut portions. Further, by changing the pressure of the edge pressure chamber 8 (see FIG. 2) formed between the first edge peripheral wall portion 314d and the second edge peripheral wall portion 314c that presses the substrate end portion, The polishing rate can be precisely controlled. For example, even when the airbag pressure is changed, the polishing rate at the edge of the substrate corresponding to the rising region B of the contact portion 400 can be locally reduced.

  4 shows, as Example 1, a polishing rate distribution when a semiconductor wafer is actually polished using the substrate holding apparatus 1 shown in FIG. 2 using the elastic film 4 shown in FIG. FIG. 4 shows a comparative example of the polishing rate distribution when the semiconductor film is actually polished using the substrate holding apparatus 1 shown in FIG. 2 using the elastic film 500 having no rising region B shown in FIG. It is shown as 1. The polishing conditions of Example 1 and Comparative Example 1 are the same.

  In FIG. 4, a region A and a region B correspond to the flat region A and the rising region B shown in FIG. The same applies to FIG.

  As a semiconductor wafer to be polished, a semiconductor wafer in which a pattern, an edge cut portion, or the like was not formed on the surface to be polished and an oxide film was formed on the entire surface of the silicon substrate was used. The same applies to the polishing with the results shown in FIG. 6 below.

  From FIG. 4, it can be seen that the polishing rate in the rising region B is reduced by using the elastic film 4 of this example. In the polishing using the elastic film 500 of the comparative example, the polishing rate distribution is almost uniform over the entire area of the semiconductor wafer, and in the polishing using the elastic film 4 of this example, the polishing is performed at the end of the semiconductor wafer. Although the polishing rate is decreasing, this is because the semiconductor wafer having no edge cut portion is polished as described above. That is, since an edge cut portion exists in a wafer on which a semiconductor element is actually formed, when polishing using the elastic film 500 of the comparative example is performed, pressure is concentrated on the edge cut portion and overpolishing occurs. However, by performing polishing using the elastic film 4 of this example, over-polishing of the edge cut portion can be effectively suppressed.

  FIG. 6 shows an edge pressure chamber formed between the first edge peripheral wall portion 314d and the second edge peripheral wall portion 314c using the substrate holding device 1 shown in FIG. 2 using the elastic film 4 shown in FIG. Examples 2 to 4 show polishing rate distributions when the semiconductor wafer is actually polished by changing the pressure of 8 (see FIG. 2). FIG. 6 shows polishing rate distributions as comparative examples 2 to 4 when the elastic film 500 having no rising region B shown in FIG. 5 is used and a semiconductor wafer is actually polished under the same conditions as described above. . The polishing conditions of Example 2 and Comparative Example 2, Example 3 and Comparative Example 3, and Example 4 and Comparative Example 4 are the same, and the pressure in the edge pressure chamber 8 is set to Example 2, Example 3, It becomes small in order of Example 4.

  From FIG. 6, in the polishing using the elastic film 4 of this example, even when the pressure in the edge pressure chamber 8 is variously changed in order to precisely control the polishing rate of the edge of the semiconductor wafer, It can be seen that the polishing rate of the rising region B can be locally reduced as compared with the polishing using the elastic film 500.

From the above, it can be seen that the following effects can be obtained by using the elastic film 4 of this example.
(1) The polishing rate at the edge of the substrate corresponding to the rising region B can be locally reduced. This is particularly effective in preventing over-polishing at the edge cut portion of the pattern wafer.
(2) Since the flat region A is not different from a conventional general elastic film, it can be easily applied when the polishing rate is to be reduced only by the outermost periphery of the elastic film that has been conditioned until now.
(3) Since the polishing rate of the portion corresponding to the rising region B is lowered, the region (width) for decreasing the polishing rate at the edge of the substrate can be changed by changing the width of the rising region B.

  (4) Since the polishing rate at the edge of the substrate corresponding to the rising region B can be locally reduced, by setting the outer diameter of the elastic film to be substantially equal to the inner diameter of the retainer ring, Concentricity can be maintained. This is an effect that cannot be obtained when the outer diameter of the entire elastic membrane is simply reduced.

(5) By providing a step 402 between the flat region A and the rising region B, unlike the case where the flat region A and the rising region B are partitioned by a taper shape or a round shape, the flat region is changed when the pressing force is changed. It is possible to prevent the outer diameter of A from changing.
(6) When the elastic membrane swells in the outer diameter direction due to pressurization in the pressure chamber, the contact range where the elastic membrane and the retainer ring come into contact is narrow. For this reason, the friction loss with respect to the pressing force of the substrate is small, and variations in the pressing force in the circumferential direction can be suppressed.

  FIG. 7 shows an elastic membrane 4a according to another embodiment of the present invention. The elastic film 4a of this example is different from the elastic film 4 shown in FIG. 3 in that a flat plate portion 400d having a thin portion 400c between a center peripheral wall portion 314a and an intermediate peripheral wall portion 314b is used instead of the flat plate portion 400a. Instead of the rising portion 400b, a thick rising portion 400e that is thicker than the plate portion 400d and thicker than the rising portion 400b is used. The thin portion 400c has a circular shape in which a plurality of the thin portions 400c are arranged uniformly in the circumferential direction, and a hole 400g that penetrates the contact portion 400 is formed at the center thereof.

  As described above, by providing the thick rising portion 400e on the outer peripheral portion of the contact portion 400, the deformation of the thick rising portion 400e can be adjusted by the elastic force of the thick rising portion 400e.

  FIG. 8 shows an elastic membrane 4b according to still another embodiment of the present invention. 3 differs from the elastic membrane shown in FIG. 3 in this example in that the flat plate portion 400a and the thick end portion 400f that is integrally connected to the outer peripheral portion of the flat plate portion 400a are gradually increased in thickness in the radial direction. It is in the point which comprises the contact part 400 which touches.

  Then, a thick end 400f is provided in a range to be controlled, and the first edge peripheral wall 314d and the second edge peripheral wall 314c are connected to the thick end 400f, and the first edge peripheral wall 314d and the second edge peripheral wall are connected. An edge pressure chamber 8 (see FIG. 2) is formed between the portion 314c and the polishing speed of the portion corresponding to the thick end portion 400f is controlled by this edge pressure chamber.

  As described above, by providing the thick end 400f on the outer peripheral portion of the contact portion 400, the pressing force to the substrate end can be relaxed and lowered by the elastic force of the thick end 400f. The width D of the thick end portion 400f is generally 15 mm or less or 10% or less of the substrate radius in the case of a substrate having a radius of 300 mm. By providing the thick end portion 400f on the outer peripheral portion of the contact portion 400, it is possible to prevent the outer peripheral portion of the elastic film from being deformed as in the invention described in Patent Document 5, and to the end portion of the substrate. It becomes possible to apply a desired pressure.

  Further, the load on the elastic film due to the frictional force acting between the polishing pad 101 and the substrate W shown in FIG. For this reason, in this example, the shape which becomes thick gradually as the thickness of the thick end part 400f goes to an outer periphery is employ | adopted. The thick-walled end portion 400f can suppress the expansion of the elastic film in the outer diameter direction even when, for example, an airbag pressure is applied, and thus, for example, an unintended pressure loss due to contact with the retainer ring can be prevented. It becomes possible to prevent. Further, by providing the thick end portion 400f, it is possible to control a relatively wide range of polishing rates. Further, in this example, the polishing rate of the substrate end portion is adjusted by adjusting the pressure of the edge pressure chamber 8 (see FIG. 2) formed between the first edge peripheral wall portion 314d and the second edge peripheral wall portion 314c. It can be controlled independently, and there is no need to consider the differential pressure as in the invention described in Patent Document 5, and the setting of polishing conditions becomes very easy.

  FIG. 9 shows an elastic membrane 4c according to still another embodiment of the present invention. The elastic film 4c of this example is different from the elastic film 4 shown in FIG. 3 as follows. That is, instead of the flat plate portion 400a, a flat plate portion 400d having a thin portion 400c between the center peripheral wall portion 314a and the intermediate peripheral wall portion 314b is used. The thin portion 400c has a circular shape in which a plurality of the thin portions 400c are arranged uniformly in the circumferential direction, and a hole 400g that penetrates the contact portion 400 is formed at the center thereof. Further, instead of the second edge peripheral wall portion 314c, an upper inclined portion 404a extending substantially obliquely upward from the connection portion with the contact portion 400 toward the radially inner side, and from the upper inclined portion 404a toward the radially inner side. A second edge peripheral wall portion 404 having a horizontal portion 404b extending in a substantially horizontal direction and a vertical portion 404c extending upward from the horizontal portion 404b in a substantially vertical direction is used. Further, the third edge peripheral wall portion 406 is connected to the upper surface of the flat portion 400d at a position radially inward of the second edge peripheral wall portion 404, and the second edge peripheral wall portion 404 and the third edge peripheral wall portion 406 are connected to each other. A second edge pressure chamber is formed between them.

  In this manner, the second edge peripheral wall portion 404 is formed between the first edge peripheral wall portion 404d and the second edge peripheral wall portion 404 by providing the upper inclined portion 404a extending substantially obliquely upward toward the radially inner side. The region where the substrate is pressed by the edge pressure chamber 8 (see FIG. 2) is narrowed, and further, a third edge peripheral wall portion 406 is provided, and the second edge peripheral wall portion 404 and the third edge peripheral wall portion 406 are arranged between the second edge peripheral wall portion 406 and the third edge peripheral wall portion 406. By providing the two-edge pressure chamber, a plurality of pressure chambers can be concentrated on the outer periphery of the substrate. This enables precise control of the polishing rate distribution at the substrate edge.

  The first edge peripheral wall portion 314d, the second edge peripheral wall portion 404, and the third edge peripheral wall portion 406 are formed in the vicinity of the outer periphery of the substrate, usually within a range of about 30 mm from the substrate edge, for example. Each interval between the edge peripheral wall portion 404 and the third edge peripheral wall portion 406 is desirably 20 mm or less. In this example, the stretchability in the longitudinal direction of the elastic membrane is ensured by the portion extending in the substantially horizontal direction.

  FIG. 10 shows an elastic membrane 4d according to still another embodiment of the present invention. The elastic film 4d of this example is different from the elastic film 4c shown in FIG. 9 in that a contact portion 400 that does not have the rising region B on the lower surface, that is, does not have the rising end portion 400b, is used. The first edge peripheral wall portion 314d, the second edge peripheral wall portion 404, and the third edge peripheral wall portion 406 are connected to the outer peripheral portion of 400.

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

DESCRIPTION OF SYMBOLS 1 Substrate holding device 3 Retainer ring 4, 4a, 4b, 4c, 4d Elastic film 5 Center pressure chamber 6 Ripple pressure chamber 7 Outer pressure chamber 8 Edge pressure chamber 100 Polishing table 101 Polishing pad 101a Polishing surface 102 Polishing liquid supply nozzle 110 Polishing Head 124 Vertical movement mechanism 314a Center peripheral wall portion 314b Intermediate peripheral wall portion 314c Second edge peripheral wall portions 314d and 404 First peripheral wall portion 400 Abutting portions 400a and 400d Flat plate portion 400b Rising portion 400e Thick rising portion 400f Thick portion 402 Step 406 Third edge peripheral wall portion A flat region B rising region C pressure chamber forming region

Claims (11)

An elastic film used in a substrate holding device,
The elastic film has a contact portion that contacts the substrate and presses the substrate toward the polishing pad,
The elastic film according to claim 1, wherein the lower surface of the contact portion includes a flat flat region and a rising region that is located on an outer peripheral portion of the flat region and rises upward.   The elastic film according to claim 1, wherein a step is provided between the flat region and the rising region of the contact portion. An elastic film used in a substrate holding device,
The elastic film has a contact portion that contacts the substrate and presses the substrate toward the polishing pad,
The elastic membrane according to claim 1, wherein the lower surface of the contact portion has a flat region having an outer diameter smaller than the outer diameter of the pressure chamber forming region of the corresponding contact portion.   The elastic film according to claim 3, wherein the flat area of the contact portion is partitioned by a step provided on an outer peripheral portion of the flat area. An elastic film used in a substrate holding device,
The elastic film has a contact portion that contacts the substrate and presses the substrate toward the polishing pad,
The abutting portion has a flat plate-like portion having a flat flat region on the lower surface, and a rising portion having a rising region located on the outer peripheral portion of the flat plate-like portion and rising upward from the flat region,
Connected to the rising portion are a first edge peripheral wall portion extending upward from the rising portion and a second edge peripheral wall portion positioned radially inward of the first edge peripheral wall portion and extending upward from the rising portion. An elastic membrane characterized in that   The elastic film according to claim 5, wherein a step is provided between the flat region and the rising region of the contact portion. An elastic film used in a substrate holding device,
The elastic film has a contact portion that contacts the substrate and presses the substrate toward the polishing pad,
The contact portion has a flat plate-like portion having a substantially constant thickness, and a thick-walled end portion that is positioned on the outer peripheral portion of the flat plate-like portion and gradually increases in thickness radially outward.
The thick end portion includes a first edge peripheral wall portion extending upward from the thick end portion, and a second edge positioned radially inward of the first edge peripheral wall portion and extending upward from the thick end portion. An elastic membrane having a peripheral wall connected thereto. An elastic film used in a substrate holding device,
The elastic film has a contact portion that contacts the substrate and presses the substrate toward the polishing pad,
The contact portion includes a first edge peripheral wall portion that extends upward from the corresponding contact portion and is disposed on an outer periphery of the corresponding contact portion, and is disposed radially inward of the first edge peripheral wall portion and extends from the contact portion. A second edge peripheral wall portion extending upward is connected;
The second edge peripheral wall portion includes an upper inclined portion extending substantially obliquely upward from the connecting portion with the contact portion toward the radially inner side, and a horizontal extending substantially horizontally from the upper inclined portion toward the radially inner side. And a vertical portion extending upward from the horizontal portion in a substantially vertical direction.   The elastic film according to claim 8, wherein the lower surface of the contact portion includes a flat flat region and a rising region that is located on an outer peripheral portion of the flat region and rises upward.   The elastic film according to claim 9, wherein a step is provided between the flat region and the rising region of the contact portion.   A substrate holding apparatus comprising the elastic film according to claim 1.

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