Polishing head, polishing apparatus, and method for manufacturing semiconductor wafers

Abstract

To provide a two-zone membrane head which can improve in-plane uniformity of a polished amount of a surface to be polished of a workpiece.SOLUTION: A polishing head includes a first annular member, a closing member which closes an upper surface side opening of an opening part of the first annular member, a membrane which closes a lower surface side opening of the opening part of the first annular member, and a second annular member which is positioned below the membrane and has an opening part for holding a workpiece to be polished. When a direction toward a center of the opening part of the first annular member is an inner side and the other direction is an outer side, a space formed by closing the opening part of the first annular member by the closing member and the membrane is partitioned into an inner side space and an outer side space by an annular partitioning wall of which an upper annular connection part is connected to the closing member and of which a lower annular connection part is connected to the membrane. An inner diameter of the lower annular connection part of the annular partitioning wall is larger than an inner diameter of the second annular member. A radius of the upper annular connection part of the annular partitioning wall is 33%-90% when a radius of the workpiece to be polished at an installation position is 100%.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a polishing head, a polishing apparatus, and a method for manufacturing semiconductor wafers. [Background technology]

[0002] There are two types of polishing equipment for workpieces such as semiconductor wafers: single-sided polishing equipment that polishes one side of the workpiece, and double-sided polishing equipment that polishes both sides of the workpiece. In single-sided polishing equipment, the surface of the workpiece to be polished, held in a polishing head, is usually pressed against a polishing pad attached to a platen, while the polishing head and platen are rotated, causing the surface of the workpiece to be polished and the polishing pad to slide against each other. By supplying polishing compound between the surface of the workpiece to be polished and the polishing pad in this sliding contact, the surface of the workpiece can be polished.

[0003] In the single-sided polishing apparatus described above, a rubber chuck system is known as a method for pressing the workpiece held in the polishing head against the polishing pad (see Patent Document 1). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 4833355 specification [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] In a rubber chuck type polishing head, the workpiece can be pressed by inflating the membrane (referred to as a rubber film in Patent Document 1) by introducing a gas such as air into the space behind the membrane.

[0006] Patent Document 1 discloses a polishing head in which the above space is partitioned into two spaces (see FIG. 1 of Patent Document 1, etc.). Hereinafter, a polishing head in which the space on the back surface of the membrane is partitioned into two spaces is referred to as a two-zone membrane head. When the present inventor examined the two-zone membrane head, it was found that the in-plane variation in the polishing amount easily occurs on the polishing target surface of the workpiece.

[0007] One aspect of the present invention aims to provide a two-zone membrane head capable of enhancing the in-plane uniformity of the polishing amount on the polishing target surface of a workpiece.

Means for Solving the Problems

[0008] One aspect of the present invention is as follows. [1] A first annular member, A closing member that closes the upper surface side opening of the opening of the first annular member, A membrane that closes the lower surface side opening of the opening of the first annular member, A second annular member that is located below the above membrane and has an opening for holding a workpiece to be polished, having, With the direction toward the center of the opening of the first annular member being the inner side and the other direction being the outer side, The space formed by closing the opening of the first annular member by the above closing member and the above membrane is partitioned into an inner space and an outer space by an annular partition wall in which an upper annular connection portion is connected to the above closing member and a lower annular connection portion is connected to the above membrane, The inner diameter of the lower annular connection portion of the above annular partition wall is larger than the inner diameter of the second annular member, and The radius of the upper annular connection portion of the above annular partition wall is 33% or more and 90% or less with respect to 100% of the radius of the installation position of the workpiece to be polished, a polishing head. [2] The shape of the polishing target surface of the above workpiece to be polished is concave, the polishing head according to [1]. [3] The above annular partition wall includes a side surface shape selected from the group consisting of an inclined shape and a horizontal shape in its cross-sectional shape, and The polishing head according to [1] or [2], wherein a region including the inner circumferential end of the second annular member and the outer circumferential end of the installation position of the workpiece to be polished is located vertically below at least a part of the side shape. [4] The closing member includes an upper disk-shaped member and a lower disk-shaped member having an outer diameter smaller than that of the upper disk-shaped member. The annular partition wall, wherein the upper annular connection portion is connected to the side surface of the lower disk-shaped member, of the polishing head according to any one of [1] to [3]. [5] The polishing head according to any one of [1] to [4], further having a back pad between the membrane and the second annular member. [6] An introduction path for introducing gas into the inner space, An introduction path for introducing gas into the outer space, The polishing head according to any one of [1] to [5], further having. [7] The shape of the polishing target surface of the workpiece to be polished is concave, The annular partition wall includes a side shape selected from the group consisting of an inclined shape and a horizontal shape as a cross-sectional shape, A region including the inner circumferential end of the second annular member and the outer circumferential end of the installation position of the workpiece to be polished is located vertically below at least a part of the side shape, [7] The closing member includes an upper disk-shaped member and a lower disk-shaped member having an outer diameter smaller than that of the upper disk-shaped member. The annular partition wall, wherein the upper annular connection portion is connected to the side surface of the lower disk-shaped member, The polishing head according to [1], further having a back pad between the membrane and the second annular member, An introduction path for introducing gas into the inner space, An introduction path for introducing gas into the outer space, The polishing head according to [1], further having. [8] The polishing head according to any one of [1] to [7], A polishing pad, A surface plate for supporting the polishing pad, A polishing apparatus having. A method for manufacturing a semiconductor wafer, comprising polishing the surface of a semiconductor wafer to be polished using the polishing apparatus described in [9][8] to form a polished surface. [Effects of the Invention]

[0009] According to one aspect of the present invention, a polishing head (2-zone membrane head) can improve the in-plane uniformity of the amount of polishing on the surface of the workpiece to be polished. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic cross-sectional view showing an example of a polishing head according to one aspect of the present invention. [Figure 2] Figure 1 is an explanatory diagram of the connection part of the annular partition wall 15A in the polishing head 1A shown. [Figure 3] Figure 1 is an explanatory diagram of the connection part of the annular partition wall 15A in the polishing head 1A shown. [Figure 4] This is an explanatory diagram of the inner wall surface of the annular partition wall and the upper surface of the membrane. [Figure 5] This is a schematic cross-sectional view showing an example of a polishing head according to one aspect of the present invention. [Figure 6] This is a schematic cross-sectional view showing an example of a polishing head according to one aspect of the present invention. [Figure 7] This is a schematic cross-sectional view showing an example of a polishing head according to one aspect of the present invention. [Figure 8] This is a schematic cross-sectional view showing an example of a polishing apparatus according to one aspect of the present invention. [Figure 9] This graph plots the GBIR values ​​before and after polishing for silicon wafers that underwent polishing treatment 1 using each of the polishing heads in the examples and comparative examples. [Figure 10] This graph plots the GBIR values ​​before and after polishing for silicon wafers that underwent polishing treatment 2 using the polishing heads of the examples and comparative examples. [Modes for carrying out the invention]

[0011] [Polishing head] A polishing head according to one aspect of the present invention comprises a first annular member, a closing member that closes the upper opening of the opening of the first annular member, a membrane that closes the lower opening of the opening of the first annular member, and a second annular member located below the membrane and having an opening for holding a workpiece to be polished. In the polishing head, with the direction toward the center of the opening of the first annular member being the inside and the other direction being the outside, the space formed by the closing of the opening of the first annular member by the closing member and the membrane is divided into an inner space and an outer space by an annular partition wall, the upper annular connecting portion of which is connected to the closing member and the lower annular connecting portion of which is connected to the membrane, the inner diameter of the lower annular connecting portion of the annular partition wall is larger than the inner diameter of the second annular member, and the radius of the upper annular connecting portion of the annular partition wall is 33% to 90%, with the radius of the installation position of the workpiece to be polished being 100%. The polishing head described above will be explained in more detail below. In this invention and specification, terms such as "bottom surface," "downward," "upper surface," "upper part," and "lower part" refer to the "bottom surface," "downward," "upper surface," "upper part," and "lower part" when the polishing head is in a state in which it is performing polishing. In this invention and specification, "inclined" and "horizontal" refer to the case where the polishing head is inclined with respect to the horizontal direction when it is in a state in which it is performing polishing, and the case where it is parallel to such a horizontal direction. In addition, the direction toward the center of the opening of the first annular member is called the inside, and the other direction is called the outside. "Annular" refers to a shape having an opening, and the plan view shape of the opening can be circular. The present invention will be described below based on the drawings, but the embodiments shown in the drawings are illustrative and the present invention is not limited to such embodiments. Also, the same parts are denoted by the same reference numerals in the drawings.

[0012] Figures 1 and 5 to 7 are schematic cross-sectional views showing an example of a polishing head according to one embodiment of the present invention. Polishing head 1A in Figure 1, polishing head 1B in Figure 5, polishing head 1C in Figure 6, and polishing head 1D in Figure 7 are sometimes collectively referred to as polishing head 1. Also, the annular partition wall 15A in Figure 1, annular partition wall 15B in Figure 5, annular partition wall 15C in Figure 6, and annular partition wall 15D in Figure 7 are sometimes collectively referred to as annular partition wall 15. The head body is not shown in Figures 1 and 5 to 7. The head body is located above the parts shown in Figures 1 and 5 to 7, and the parts shown in each figure are attached to the head body by known methods such as bolting.

[0013] In Figures 1 and 5 to 7, the polishing head 1 has a first annular member 11. The first annular member 11 has an annular upper surface and an annular lower surface, the inner diameter of the upper surface is the same as the inner diameter of the lower surface, and the outer diameter of the upper surface is the same as the outer diameter of the lower surface. That is, the first annular member 11 has a cylindrical outer shape, and the shape of its opening is also cylindrical. This also applies to the second annular member 12, which will be described later. In this invention and specification, "same value" is used to include both cases where they are perfectly identical and cases where errors that may inevitably occur during manufacturing are included. This also applies to terms related to the shape of cylinders, etc. As the first annular member 11, an annular ring made of a rigid material such as stainless steel (SUS), which is normally used for the polishing head of a single-sided polishing device, can be used.

[0014] The lower surface of the first annular member 11 is covered with a membrane 13. The membrane 13 only needs to close at least the opening on the lower side of the first annular member 11, but from the viewpoint of suppressing displacement when the membrane 13 expands and from suppressing the mixing of abrasive material into the opening of the first annular member 11, it is preferable to cover the entire annular lower surface of the first annular member 11 with the membrane 13 as well. The membrane 13 can be bonded to the annular lower surface of the first annular member 11 by known methods such as the use of an adhesive. It is also preferable to bond the membrane 13 so that it extends over part or all of the side surface of the first annular member 11, as shown in Figures 1 and 5 to 7. As the membrane 13, a film made of an elastic material such as rubber can be used. For example, fluororubber can be used as rubber. The thickness of the membrane 13 is not particularly limited and can be, for example, about 0.5 to 2 mm.

[0015] In Figures 1 and 5 to 7, a back pad 14 is attached to the lower surface of the membrane 13. The back pad 14 can be attached to the lower surface of the membrane 13 by known methods such as the use of adhesive. It is also possible for the outer peripheral region of the lower surface of the membrane 13 and the annular upper surface of the second annular member 12 to be in direct contact, but from the viewpoint of suppressing peeling and waviness of the membrane 13, it is preferable that the back pad 14 is interposed between the outer peripheral region of the lower surface of the membrane 13 and the annular upper surface of the second annular member 12. As the back pad 14, for example, a disc-shaped plate made of a material that exhibits adsorption due to the surface tension of water when it contains water (e.g., foamed polyurethane) can be used. This allows the workpiece to be held by the water-containing back pad 14 during polishing.

[0016] In Figures 1 and 5 to 7, the membrane 13 closes the lower opening of the first annular member 11. The upper opening of the first annular member 11 is closed by a closing member composed of an upper disc-shaped member 10a and a lower disc-shaped member 10b. The lower disc-shaped member 10b is a disc-shaped member with a smaller outer diameter than the upper disc-shaped member 10a. The upper disc-shaped member 10a and the lower disc-shaped member 10b can be disc-shaped flat plates with the same outer diameter at the top and bottom, and can be arranged concentrically, for example. In Figures 1 and 5 to 7, the upper disc-shaped member 10a and the lower disc-shaped member 10b are separate members and are fixed by any means (for example, by providing a recess on one and a protrusion on the other and fitting the protrusion into the recess, bolting, bonding with adhesive, etc.). However, the polishing head according to one aspect of the present invention is not limited to this configuration, and the occlusion member may be a member in which an upper disc-shaped portion and a lower disc-shaped portion having a smaller outer diameter than the upper disc-shaped portion are integrally molded. The material constituting the occlusion member is not particularly limited. In Figures 1 and 5 to 7, W indicates the workpiece placement position. When polishing a workpiece, when gas is introduced into the space surrounded by the first annular member 11, membrane 13 and occlusion member, the membrane 14 expands, and the workpiece placed at the workpiece placement position W is pressed via the back pad 14, thereby performing polishing.

[0017] In Figures 1 and 5 to 7, the space surrounded by the first annular member 11, the membrane 13, and the closure member is divided into an inner space 16a and an outer space 16b by an annular partition wall 15. The annular partition wall 15 can be made by molding an elastic material such as rubber into a desired shape. For example, fluororubber can be used as rubber. The thickness of the annular partition wall 15 can be, for example, about 0.5 to 1.5 mm. Gas can be introduced into the inner space 16a from a gas introduction passage 17a that penetrates the upper disc-shaped member 10a and the lower disc-shaped member 10b in the central part of the closure member, and into the outer space 16b from a gas introduction passage 17b that penetrates the upper disc-shaped member 10a in the outer peripheral region of the closure member, with the amount of gas introduced controlled independently. When polishing a workpiece, for example, by changing the amount of gas introduced from the gas introduction passage 17a into the inner space 16a and the amount of gas introduced from the gas introduction passage 17b into the outer space 16b, the polishing surface pressure applied to the outer peripheral region of the workpiece surface to be polished below the outer space 16b can be controlled independently of the polishing surface pressure applied to the central part of the workpiece surface to be polished below the inner space 16a. In Figures 1 and 5 to 7, there is one gas introduction passage 17a and one gas introduction passage 17b, but the embodiment is not limited to this, and two or more gas introduction passages 17a and two or more gas introduction passages 17b can be provided.

[0018] In Figures 1 and 5-7, a second annular member 12 is positioned below the membrane 13 via a back pad 14. The second annular member 12 is an annular member having an opening for holding the workpiece to be polished. Such annular members are generally also called retainers, retainer rings, templates, etc. The second annular member 12 can be an annular member made of a material commonly used for annular members called retainers of polishing heads (e.g., glass epoxy).

[0019] Figure 2 is an explanatory diagram of the connection portion (particularly the lower annular connection portion) of the annular partition wall 15A in the polishing head 1A shown in Figure 1. The annular partition wall 15A is connected to the upper annular connection portion C upperIt is connected to the closing member, and the lower annular connection part C lower This is connected to the membrane 13. For details, see the upper annular connection part C. upper It is connected to the side surface of the lower disc-shaped member 10b of the closing member, and the lower annular connection part C lower The second annular member is connected to the upper surface of the membrane 13. Known methods for connecting each connection include the use of adhesive, integral molding, and fitting of the protrusion into the recess. If we call the inner diameter of the lower annular connection portion of the annular partition wall d1 and the inner diameter of the second annular member d2, then in a polishing head according to one aspect of the present invention, the inner diameter d1 of the lower annular connection portion of the annular partition wall is larger than the inner diameter d2 of the second annular member. That is, the relationship "d1 > d2" is satisfied. Therefore, when polishing a workpiece, the second annular member is located vertically below the lower annular connection portion of the annular partition wall, and the outer peripheral region of the workpiece surface to be polished is not located there. This is considered to be the reason why localized variations in the amount of polishing (specifically, a localized decrease in the amount of polishing vertically below the connection portion) are likely to occur in workpieces polished using a polishing head in which the outer peripheral region of the workpiece surface to be polished is located vertically below the connection portion of the partition. In contrast, according to one aspect of the present invention, the inventors believe that by satisfying the relationship "d1 > d2", it is possible to suppress a local decrease in the amount of polishing vertically below the connection and polish the surface of the workpiece to be polished. If d2 is 100%, then d1 is greater than 100%, preferably greater than 102%, and more preferably 103% or more. With d2 as 100%, d1 can be, for example, 120% or less or 110% or less, or it can exceed the values ​​exemplified herein.

[0020] Figure 3 is an explanatory diagram of the connection portion (particularly the upper annular connection portion) of the annular partition wall 15A in the polishing head 1A shown in Figure 1. The annular partition wall 15A is connected to the upper annular connection portion C upper This is connected to the side surface of the lower disc-shaped member 10b of the closing member. In Figure 3, the two dotted lines represent the upper annular connection part C upper This is a straight line drawn vertically downwards. As shown by these two dotted lines, the upper annular connection part C upperBelow the vertical direction thereof, the outer peripheral region of the installation position W of the workpiece to be polished is located. Here, the "outer peripheral region" refers to a partial region extending from the outer peripheral edge inward in the radial direction. In FIGS. 1, 5 to 7, the upper annular connection portion C of the annular partition wall 15 upper is connected to the side surface of the lower disk-shaped member 10b of the closing member. Therefore, vertically below the upper annular connection portion C upper is also vertically below the side surface of the lower disk-shaped member 10b. In another embodiment, the upper annular connection portion C of the annular partition wall 15 upper can be connected to the lower surface of the lower disk-shaped member 10b or the lower surface of the upper disk-shaped member 10a. In this case, vertically below the upper annular connection portion C upper refers to vertically below the inner peripheral edge of the upper annular connection portion C upper . Let the opening inner diameter of the upper annular connection portion C upper be d3, and the outer diameter of the installation position W of the workpiece to be polished be d4. Then, the radius RC of the upper annular connection portion C upper is "RC upper = d3÷2", and the radius R of the installation position of the workpiece to be polished is "R = d4÷2". The outer diameter of the installation position (circular region) W of the workpiece to be polished is the same value as the diameter of the workpiece to be polished (the shape in plan view is circular). Therefore, the radius R of the installation position of the workpiece to be polished is the same value as the radius Rw of the workpiece to be polished. In the above polishing head, the radius RC upper of the upper annular connection portion C upper is 33% or more and 90% or less with respect to the radius R of the installation position of the workpiece to be polished taken as 100%. As a result of intensive studies by the inventor, it has been newly found that this contributes to suppressing the in-plane variation in the polishing amount and enhancing the in-plane uniformity of the polishing amount on the surface of the workpiece to be polished. The diameter of the workpiece to be polished can be, for example, 50 mm to 450 mm. For example, when the diameter of the workpiece to be polished is 300 mm, the radius RC upper of the upper annular connection portion C upper is preferably 50 mm or more and 135 mm or less. ​​If the shape of the surface to be polished of the workpiece is concave, and the inflection position obtained by taking the first derivative of the cross-sectional shape profile of the surface to be polished is at a distance X from the center of the surface to be polished outwards, then the upper annular connection part C upper Radius RC upper The following range is preferable with respect to the radius R of the installation position of the workpiece to be polished. The cross-sectional shape profile of the surface to be polished can be determined using a known cross-sectional shape measuring device. (1) When X is greater than 66% of the radius Rw of the workpiece to be polished, the upper annular connection part C upper Radius RC upper The radius R of the installation position of the workpiece to be polished is set to 100%, and is preferably 40% to 90%, more preferably 60% to 90%, even more preferably 70% to 90%, and even more preferably 80% to 90%. (2) When X is 66% or less of the radius Rw of the workpiece to be polished, the upper annular connection part C upper Radius RC upper The radius R of the installation position of the workpiece to be polished is preferably 33% to 80%, more preferably 33% to 70%, even more preferably 33% to 60%, even more preferably 33% to 50%, and even more preferably 33% to 40%.

[0021] Regarding the annular partition wall, it is preferable that the cross-sectional shape of the annular partition wall includes at least a portion of a side shape selected from the group consisting of inclined shapes and horizontal shapes, and it is more preferable that the region including the inner circumferential end of the second annular member and the outer circumferential end of the installation position of the workpiece to be polished is located vertically below at least a portion of such side shape. Having such a configuration means that when gas is introduced into the outer space during polishing, at least a portion of the inner wall surface of the annular partition wall may come into contact with the upper surface of the membrane. This can contribute to making it easier to control the amount of polishing in the plane of the workpiece to be polished (especially the outer peripheral region) by changing the amount of gas introduced into the outer space. During polishing, gas is usually introduced into both the outer and inner spaces. The fact that a polishing head has a configuration in which at least a portion of the inner wall surface of the annular partition wall comes into contact with the upper surface of the membrane when gas is introduced into the outer space during polishing can be confirmed, for example, by observing that when gas is introduced only into the outer space and not into the inner space, at least a portion of the inner wall surface of the partition wall comes into contact with the upper surface of the membrane. Figure 4 is an explanatory diagram of the inner wall surface of the annular partition wall and the upper surface of the membrane. In Figure 4, 15A inner indicates the inner wall surface of the annular partition wall 15A, and 13 upper This shows the top surface of membrane 13.

[0022] As specific examples of cross-sectional shapes, in the example shown in Figure 1, the cross-sectional shape of the annular partition wall 15A includes horizontal shapes at the top and bottom, with an inclined shape continuing from the lower horizontal shape. In the example shown in Figure 5, the cross-sectional shape of the annular partition wall 15B is an inclined shape. In the example shown in Figure 6, the cross-sectional shape of the annular partition wall 15C includes a horizontal shape. In the example shown in Figure 7, the cross-sectional shape of the annular partition wall 15D is a horizontal shape followed by an inclined shape. For example, in the example shown in Figure 1, by introducing gas into the outer space 16b during polishing, part or all of the inner wall surface of the lower horizontal cross-sectional shape can be brought into contact with the upper surface of the membrane 13. In the example shown in Figure 5, by introducing gas into the outer space 16b during polishing, part or all of the inner wall surface of the annular partition wall 15B, which has an inclined cross-sectional shape, can be brought into contact with the upper surface of the membrane 13. In the example shown in Figure 6, by introducing gas into the outer space 16b during polishing, part or all of the inner wall surface of the portion with a horizontal cross-sectional shape can be brought into contact with the upper surface of the membrane 13. In the example shown in Figure 7, by introducing gas into the outer space 16b during polishing, part or all of the inner wall surface of the portion with a horizontal cross-sectional shape can be brought into contact with the upper surface of the membrane 13.

[0023] [Polishing equipment, semiconductor wafer manufacturing method] One aspect of the present invention relates to a polishing apparatus having the polishing head, a polishing pad, and a base plate for supporting the polishing pad.

[0024] Furthermore, one aspect of the present invention relates to a method for manufacturing a semiconductor wafer, which includes polishing the surface of a semiconductor wafer to be polished using the polishing apparatus described above to form a polished surface.

[0025] Figure 8 is a schematic cross-sectional view showing an example of a polishing apparatus according to one aspect of the present invention. The polishing apparatus 50 shown in Figure 8 is equipped with a polishing head 1A shown in Figure 1. As with Figure 1, the head body of the polishing head is not shown. The polishing apparatus 50 is a rubber chuck type single-sided polishing apparatus, in which the polishing head 1A and the base plate 42 are rotated by a rotation mechanism (not shown), and the surface to be polished of the workpiece Wa, which is installed at the installation position W of the polishing head 1A, is brought into sliding contact with the polishing pad 41 attached to the base plate 42. The polishing agent 61 discharged from the polishing agent supply mechanism 60 is supplied between the lower surface of the workpiece Wa, which is the surface to be polished of the workpiece Wa, and the polishing pad 41, and the surface to be polished of the workpiece Wa is polished. As the polishing agent, a polishing slurry that is normally used in CMP (Chemical Mechanical Polishing) can be used. The above polishing apparatus can have the same configuration as a normal single-sided polishing apparatus except that it is equipped with a polishing head according to one aspect of the present invention. Furthermore, regarding the method for manufacturing the semiconductor wafer described above, prior art relating to the method for manufacturing a semiconductor wafer having a polished surface can be applied, except that it includes polishing the surface of the semiconductor wafer to be polished using a polishing apparatus according to one aspect of the present invention to form a polished surface. The wafer to be polished can be, for example, a silicon wafer (preferably a single-crystal silicon wafer). For example, a silicon wafer can be manufactured by the following method: A block is obtained by cutting a single-crystal silicon ingot. The single-crystal silicon ingot can be grown by known methods such as the CZ method (Czochralski method) or the FZ method (Floating Zone method). The obtained block is sliced ​​to make a wafer. A silicon wafer can be manufactured by applying various processes to this wafer. Examples of the above processes include chamfering and planarization (lapping, grinding, polishing). The polishing apparatus described above can be suitably used, for example, in the final polishing process, which is the final step in these wafer processing steps. [Examples]

[0026] The present invention will be described below based on examples. However, the present invention is not limited to the embodiments shown in the examples. The polishing pressure Pe described below is the pressure applied downward from the outer peripheral region of the membrane 13 when gas is introduced into the outer space 16b from the gas introduction passage 17b and the outer peripheral region of the membrane 13 expands, and the polishing pressure Pc is the pressure applied downward from the central part of the membrane 13 when gas is introduced into the inner space 16a from the gas introduction passage 17a and the central part of the membrane 13 expands. The polishing pressures Pe and Pc are experimental values. The shape of the surface to be polished on the silicon wafer described below is concave.

[0027] [Polishing head] The polishing head of Example 1 (a two-zone membrane head with a rubber chuck) is a polishing head with the configuration shown in Figure 1, wherein the inner diameter d1 of the lower annular connection part of the annular partition wall is 320 mm, the inner diameter d2 of the second annular member is 301 mm, and the inner diameter d3 of the opening of the upper annular connection part of the annular partition wall is 100 mm (therefore the upper annular connection part C upper Radius RC upper It is 50mm. The polishing head of Example 2 is located at the upper annular connection part C of the annular partition wall. upper Radius RC upper It has the same configuration as the polishing head of Example 1, except that the length is 100 mm. The polishing head of Example 3 is located at the upper annular connection part C of the annular partition wall. upper Radius RC upper It has the same configuration as the polishing head of Example 1, except that the length is 135 mm. The polishing head of Comparative Example 1 has an annular connection part C at the upper part of the annular partition wall. upper Radius RC upper It has the same configuration as the polishing head of Example 1, except that the length is 30 mm. The polishing head of Comparative Example 2 has an annular connection part C at the top of the annular partition wall. upper Radius RC upper It has the same configuration as the polishing head of Example 1, except that the length is 145 mm.

[0028] [Silicon wafer polishing process 1] In polishing process 1, multiple silicon wafers (300 mm in diameter) cut from single-crystal silicon ingots and subjected to various processing treatments were each polished on one side using the polishing heads of the examples and comparative examples as the final finishing polishing process. The inflection positions, obtained by taking the first derivative of the cross-sectional shape profile of the polishing surface of the multiple silicon wafers, were located more than 100 mm outside the center of the polishing surface of the silicon wafer. The GBIR was measured for the silicon wafers to be polished before the polishing process. GBIR (Global Backside Ideal Range) is the difference between the maximum and minimum values ​​of the thickness (distance from the back surface reference plane) when the wafer is adsorbed and fixed. The smaller the GBIR value after polishing, the less in-plane variation in the amount of polishing on the polishing surface of the workpiece and the higher the in-plane uniformity of the amount of polishing.

[0029] For polishing treatment 1, a polishing apparatus with the configuration shown in Figure 8, including the polishing heads for the examples and comparative examples, was prepared. A single-sided polishing treatment of silicon wafers was performed using this apparatus under the following polishing conditions. The GBIR of each silicon wafer after polishing was measured. Pc = 10kPa Pe = 12kPa

[0030] [Silicon wafer polishing process 2] In polishing process 2, multiple silicon wafers (300 mm in diameter) cut from single-crystal silicon ingots and subjected to various processing treatments were each subjected to single-sided polishing using the polishing heads of the examples and comparative examples as the final finishing polishing process. The inflection positions, obtained by taking the first derivative of the cross-sectional shape profile of the polishing surface of the multiple silicon wafers, were located more than 100 mm inward from the center of the polishing surface of the silicon wafer. GBIR was measured for the silicon wafers to be polished before the polishing process.

[0031] For polishing process 2, a polishing apparatus with the configuration shown in Figure 8, including the polishing heads for the examples and comparative examples, was prepared. Using this apparatus, one side of the silicon wafer was polished under the following polishing conditions. The GBIR of each silicon wafer after polishing was measured. Pc = 10kPa Pe = 12kPa

[0032] Figure 9 shows a graph plotting the GBIR values ​​before and after polishing for silicon wafers that underwent polishing treatment 1 using each of the polishing heads in the examples and comparative examples. Figure 10 shows a graph plotting the GBIR values ​​before and after polishing for silicon wafers that underwent polishing treatment 2 using each of the polishing heads in the examples and comparative examples. In the polishing heads of Examples 1-3, Comparative Example 1, and Comparative Example 2, the upper annular connection portion C upper Radius RC upper The GBIR values ​​are set with the radius R of the workpiece to be polished (radius Rw of the silicon wafer to be polished) as 100%, as follows: Example 1: 33%, Example 2: 67%, Example 3: 90%, Comparative Example 1: 20%, Comparative Example 2: 97%. From the graphs shown in Figure 9 and Figure 10, it can be confirmed that when polishing is performed using the polishing heads of Examples 1 to 3, the GBIR value is smaller compared to when polishing is performed using the polishing heads of Comparative Example 1 or Comparative Example 2, meaning that the in-plane uniformity of the polishing amount is higher. Also, from the graph shown in Figure 9, in polishing treatment 1, the upper annular connection part C is the same as in Examples 1 to 3. upper Radius RC upper The larger the value, the higher the in-plane uniformity of the polishing amount. On the other hand, the graph in Figure 10 shows that in polishing treatment 2, the upper annular connection part C upper Radius RC upper The smaller the value, the higher the in-plane uniformity of the polishing amount can be confirmed. [Industrial applicability]

[0033] One aspect of the present invention is useful in the field of semiconductor wafers such as silicon wafers.

Claims

1. A first annular member and A closing member that closes the upper opening of the opening of the first annular member, A membrane that closes the lower side opening of the opening of the first annular member, A second annular member located below the membrane and having an opening for holding the workpiece to be polished, It has, The direction toward the center of the opening of the first annular member is considered the inside, and the other direction is considered the outside. The space formed when the opening of the first annular member is closed by the closing member and the membrane is divided into an inner space and an outer space by an annular partition wall, the upper annular connecting portion of which is connected to the closing member and the lower annular connecting portion of which is connected to the membrane. The inner diameter of the lower annular connection portion of the aforementioned annular partition wall is larger than the inner diameter of the second annular member. The radius of the upper annular connection portion of the aforementioned annular partition wall is 33% to 90% of the radius of the installation position of the workpiece to be polished, with the radius being 100%, and A polishing head in which, when gas is introduced into the outer space, at least a portion of the inner wall surface of the annular partition wall comes into contact with the upper surface of the membrane.

2. The polishing head according to claim 1, wherein the shape of the surface of the workpiece to be polished is concave.

3. The aforementioned annular partition wall includes a side shape selected from the group consisting of inclined shapes and horizontal shapes in its cross-sectional shape, The polishing head according to claim 1, wherein a region including the inner circumferential end of the second annular member and the outer circumferential end of the installation position of the workpiece to be polished is located vertically below at least a portion of the side shape.

4. The closing member includes an upper disc-shaped member and a lower disc-shaped member having a smaller outer diameter than the upper disc-shaped member. The polishing head according to claim 1, wherein the annular partition wall has an upper annular connecting portion connected to the side surface of the lower disc-shaped member.

5. The polishing head according to claim 1, further comprising a back pad between the membrane and the second annular member.

6. An introduction passage for introducing gas into the aforementioned inner space, An introduction passage for introducing gas into the aforementioned outer space, The polishing head according to claim 1, further comprising the following:

7. The shape of the surface of the workpiece to be polished is concave. The aforementioned annular partition wall includes a cross-sectional shape selected from the group consisting of inclined shapes and horizontal shapes, A region including the inner circumferential end of the second annular member and the outer circumferential end of the installation position of the workpiece to be polished is located vertically below at least a portion of the aforementioned side shape. The closing member includes an upper disc-shaped member and a lower disc-shaped member having a smaller outer diameter than the upper disc-shaped member. The annular partition wall has an upper annular connecting portion connected to the side surface of the lower disc-shaped member, A back pad is further provided between the membrane and the second annular member. An introduction passage for introducing gas into the aforementioned inner space, An introduction passage for introducing gas into the aforementioned outer space, The polishing head according to claim 1, further comprising the following:

8. The polishing head according to claim 1, wherein, if the inner diameter of the second annular member is 100%, the inner diameter of the lower annular connection portion of the annular partition wall is greater than 102%.

9. A polishing head according to any one of claims 1 to 8, Polishing pad and A surface plate that supports the polishing pad, A polishing device having the following features.

10. A method for manufacturing a semiconductor wafer, comprising polishing the surface of a semiconductor wafer to be polished using the polishing apparatus described in claim 9 to form a polished surface.

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