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

Abstract

To provide a two-zone membrane head capable of both controlling a polishing amount of an outer peripheral portion on the polishing target surface of workpiece and suppressing local fluctuations of the polishing amount on the polishing target surface.SOLUTION: A polishing head 1A has: a blocking member that blocks an upper surface-side opening of an opening part in a first annular member 11, the blocking member comprising an upper disk-shaped member 10a and a lower disc-shaped member 10b; and a second annular member 12 that has an opening part to hold workpiece W to be polished. A space formed by the opening part of the first annular member 11 being blocked by the blocking member and a membrane 13 is partitioned into an inside space 16a and an outside space 16b by an annular partitioning wall 15A having an upper annular connection section joined to the blocking member and a lower annular connection section joined to the membrane 13. An inner diameter of the lower annular connection section of the annular partitioning wall is greater than an inner diameter of the second annular member 12, and an outer circumferential area for an installation position of the workpiece W to be polished is positioned vertically below the upper annular connection section of the annular partitioning wall.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Devices for polishing the surface of a workpiece such as a semiconductor wafer include single-sided polishing devices that polish one side of the workpiece, and double-sided polishing devices that polish both sides of the workpiece. In single-sided polishing devices, the surface to be polished of the workpiece held by the polishing head is usually pressed against a polishing pad attached to a platen while the polishing head and platen are rotated to bring the surface to be polished of the workpiece into sliding contact with the polishing pad. By supplying an abrasive between the surface to be polished and the polishing pad that are in sliding contact with each other in this way, the surface to be polished of the workpiece can be polished.

[0003] In the above-mentioned single-sided polishing apparatus, a rubber chuck method is known as a method for pressing a workpiece held by a polishing head against a polishing pad (see Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] WO2020 / 202682 [Patent Document 2] Patent No. 4833355 specification Summary of the Invention [Problem to be solved by the invention]

[0005] In a rubber chuck type polishing head, the workpiece can be pressed by inflating the membrane (called a rubber film in Patent Document 2) by introducing a gas such as air into the space behind the membrane.

[0006] In the polishing head described in Patent Document 1, the above space is divided into two spaces, and the amount of gas introduced into each space is adjusted, thereby making it possible to independently control the polishing surface pressure applied to the outer circumferential region of the polishing target surface of the workpiece and the polishing surface pressure applied to the central portion (see paragraph 0009 of Patent Document 1, etc.). Patent Document 2 also discloses a polishing head in which the above space is divided into two spaces (see FIG. 1 of Patent Document 2, etc.). Hereinafter, a polishing head in which the space behind the membrane is divided into two spaces is referred to as a two-zone membrane head. When the present inventor studied the two-zone membrane head described in Patent Document 1 and the two-zone membrane head described in Patent Document 2, it was found that it is difficult to simultaneously control the polishing amount of the outer circumferential region of the polishing target surface of the workpiece and suppress localized fluctuations in the polishing amount on the polishing target surface.

[0007] One aspect of the present invention aims to provide a two-zone membrane head that can simultaneously control the amount of polishing in the peripheral region of the workpiece surface to be polished and suppress localized fluctuations in the amount of polishing on the surface to be polished. [Means for solving the problem]

[0008] One aspect of the present invention is A first annular member; a blocking member that blocks an upper opening of the opening of the first annular member; A membrane that closes a lower opening of the opening of the first annular member; a second annular member located below the membrane and having an opening for holding a workpiece to be polished; having The direction toward the center of the opening of the first annular member is defined as the inside, and the other direction is defined as the outside. a space formed by closing the opening of the first annular member with the closing member and the membrane is divided into an inner space and an outer space by an annular partition wall having an upper annular connecting portion connected to the closing member and a lower annular connecting portion connected to the membrane; The inner diameter of the lower annular connection portion of the annular partition wall is greater than the inner diameter of the second annular member; and a polishing head, the outer peripheral area of ​​which is located at a position where a workpiece to be polished is placed, being vertically below the upper annular connection portion of the annular partition wall; Regarding.

[0009] According to the polishing head (two-zone membrane head) of the above-mentioned embodiment of the present invention, it is possible to simultaneously control the polishing amount of the peripheral region of the polishing target surface of the workpiece and suppress the local variation in the polishing amount on the polishing target surface. The present inventor's speculation on this point is as follows.

[0010] When a workpiece is polished using the polishing head shown in WO2020 / 202682 (Patent Document 1), the peripheral region of the surface to be polished of the workpiece is located vertically below the connection between the membrane and the partition that separates the space behind the membrane (see, for example, FIG. 1 of Patent Document 1). Although the pressure applied vertically downward from the two spaces separated by the partition can be controlled by the amount of gas introduced into each region, it is not easy to control the pressure applied vertically downward from the partition, and it is usually smaller than the pressure applied vertically downward from each of the two spaces. This is thought to be the reason why localized fluctuations in the polishing amount (specifically, localized reductions in the polishing amount vertically downward from the connection) are likely to occur in the workpiece polished using the polishing head shown in WO2020 / 202682 (Patent Document 1). In contrast, in the polishing head according to one aspect of the present invention, the inner diameter of the lower annular connecting part, which is the connecting part of the membrane of the annular partition wall separating the two spaces, is larger than the inner diameter of the second annular member. Therefore, when polishing is performed using the polishing head, the second annular member is located vertically below the lower annular connecting part, and the outer peripheral region of the surface to be polished of the workpiece is not located vertically below the lower annular connecting part. The inventor believes that this is the reason why the polishing head can be used to polish the surface to be polished of the workpiece while suppressing a local decrease in the amount of polishing vertically below the connecting part. In addition, in the polishing head according to one aspect of the present invention, the outer peripheral region of the installation position of the workpiece to be polished is located vertically below the upper annular connection part of the connection part of the annular partition wall, and the inner diameter of the lower annular connection part is larger than the inner diameter of the second annular member, so that the second annular member is located vertically below the lower annular connection part. In contrast, in the polishing head shown in FIG. 1 of Japanese Patent No. 4833355 (Patent Document 2), the inner diameter of the connection part with the partition membrane is smaller than the inner diameter of the second annular member. Compared to the polishing head having such a configuration, the polishing head according to one aspect of the present invention can more effectively control the pressure applied downward from the outer space by adjusting the amount of gas introduced into the outer space partitioned by the annular partition wall, and as a result, the inventors have speculated that the polishing amount of the outer peripheral region of the surface to be polished of the workpiece can be easily controlled by adjusting the amount of gas introduced into the outer space. Note that the present invention is not limited to the speculation of the inventor in this specification.

[0011] In one embodiment, the annular partition wall may include a cross-sectional shape that is selected from the group consisting of an inclined shape and a horizontal shape, and an area including an inner peripheral edge of the second annular member and an outer peripheral edge of a placement position for a workpiece to be polished may be located vertically below at least a portion of the side shape.

[0012] In one form, the obstruction member may include an upper disk-shaped member and a lower disk-shaped member having an outer diameter smaller than that of the upper disk-shaped member, and the annular partition wall may have an upper annular connecting portion connected to a side of the lower disk-shaped member.

[0013] In one form, the polishing head can further include a back pad between the membrane and the second annular member.

[0014] In one embodiment, the polishing head can have an introduction passage for introducing a gas into the inner space and an introduction passage for introducing a gas into the outer space.

[0015] One aspect of the present invention is The polishing head; A polishing pad; A platen supporting the polishing pad; The present invention relates to a polishing apparatus having a

[0016] One aspect of the present invention relates to a method for manufacturing a semiconductor wafer, which includes polishing a surface of a semiconductor wafer to be polished by the above-mentioned polishing apparatus to form a polished surface. Effect of the Invention

[0017] According to one aspect of the present invention, it is possible to provide a two-zone membrane head that can simultaneously control the amount of polishing in the peripheral region of the workpiece surface to be polished and suppress localized fluctuations in the amount of polishing on the surface to be polished. [Brief description of the drawings]

[0018] [Figure 1] 1 is a schematic cross-sectional view showing an example of a polishing head according to an embodiment of the present invention. [Diagram 2] 2 is an explanatory diagram of a connection portion of an annular partition wall 15A in the polishing head 1A shown in FIG. 1. [Diagram 3] 2 is an explanatory diagram of a connection portion of an annular partition wall 15A in the polishing head 1A shown in FIG. 1. [Figure 4] 4 is an explanatory diagram of the inner wall surface of the annular partition wall and the upper surface of the membrane. FIG. [Diagram 5] 1 is a schematic cross-sectional view showing an example of a polishing head according to an embodiment of the present invention. [Figure 6] 1 is a schematic cross-sectional view showing an example of a polishing head according to an embodiment of the present invention. [Figure 7] 1 is a schematic cross-sectional view showing an example of a polishing head according to an embodiment of the present invention. [Figure 8] 1 is a schematic cross-sectional view showing an example of a polishing apparatus according to an embodiment of the present invention. [Figure 9] 1 is a graph in which the difference in polishing amount is plotted against the polishing pressure Pe for Example 1, Example 2, Comparative Example 1, and Comparative Example 2. [Figure 10] 1 shows a graph in which ESFQR is plotted against the polishing pressure Pe for Example 1, Example 2, Comparative Example 1, and Comparative Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] [Polishing head] A polishing head according to one aspect of the present invention includes a first annular member, a blocking member blocking the upper opening of the opening of the first annular member, a membrane blocking 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, the direction toward the center of the opening of the first annular member is the inside, and the other direction is the outside, and a space formed by blocking the opening of the first annular member with the blocking member and the membrane is divided into an inner space and an outer space by an annular partition wall whose upper annular connecting part is connected to the blocking member and whose lower annular connecting part is connected to the membrane, and the inner diameter of the lower annular connecting part of the annular partition wall is larger than the inner diameter of the second annular member, and the outer peripheral area of ​​the installation position of the workpiece to be polished is located vertically below the upper annular connecting part of the annular partition wall. The polishing head will be described in more detail below. In the present invention and this specification, the terms "lower surface", "lower", "upper surface", "upper part", "lower part", and the like refer to the "lower surface", "lower surface", "upper surface", "upper part", "lower part", and the like when the polishing head is placed in a state where a polishing process is performed. In the present invention and this specification, "inclined" and "horizontal" refer to the case where the polishing head is inclined with respect to the horizontal direction when placed in a state where a polishing process is performed, and the case where the polishing head is parallel to the horizontal direction is called "horizontal". 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 planar shape of the opening can be circular. In the following, the present invention will be described based on the drawings, but the embodiment shown in the drawings is an example, and the present invention is not limited to such an embodiment. In addition, the same parts in the drawings are given the same symbols.

[0020] FIG. 1 and FIG. 5 to FIG. 7 are schematic cross-sectional views showing an example of a polishing head according to one embodiment of the present invention. The polishing head 1A in FIG. 1, the polishing head 1B in FIG. 5, the polishing head 1C in FIG. 6, and the polishing head 1D in FIG. 7 may be collectively referred to as the polishing head 1. The annular partition wall 15A in FIG. 1, the annular partition wall 15B in FIG. 5, the annular partition wall 15C in FIG. 6, and the annular partition wall 15D in FIG. 7 may be collectively referred to as the annular partition wall 15. In each of FIG. 1 and FIG. 5 to FIG. 7, the head body is omitted. The head body is located above the parts shown in each of FIG. 1 and FIG. 5 to FIG. 7, and the parts shown in each of the figures are attached to the head body by a known method such as bolt fastening.

[0021] In each of FIG. 1 and FIG. 5 to FIG. 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, and the inner diameter of the upper surface is the same as the outer 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 the opening is also cylindrical. This point is the same for the second annular member 12 described later. In the present invention and this specification, the term "same value" is used to include a case where the two are completely the same as each other and a case where an error that may occur unavoidably during manufacturing is included. This point is also the same for terms related to the shape of a cylinder, etc. As the first annular member 11, an annular ring made of a rigid material such as stainless steel (SUS) that is usually used in the polishing head of a single-sided polishing device can be used.

[0022] The lower surface of the first annular member 11 is covered with a membrane 13. The membrane 13 may close at least the lower opening of the first annular member 11, but from the viewpoint of suppressing displacement when the membrane 13 expands and suppressing the abrasive from being mixed into the opening of the first annular member 11, it is preferable that the entire annular lower surface of the first annular member 11 is also covered with the membrane 13. The membrane 13 can be bonded to the annular lower surface of the first annular member 11 by a known method such as using an adhesive. In addition, as shown in each of FIG. 1 and FIG. 5 to FIG. 7, it is also preferable to bond the membrane 13 to cover a part or the entire side surface of the first annular member 11. As the membrane 13, a film made of an elastic material such as rubber can be used. As the rubber, for example, fluororubber can be mentioned. The thickness of the membrane 13 is not particularly limited, and can be, for example, about 0.5 to 2 mm.

[0023] In each of FIG. 1 and FIG. 5 to FIG. 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 a known method such as using an adhesive. Although it is possible for the outer peripheral region of the lower surface of the membrane 13 to be in direct contact with the annular upper surface of the second annular member 12, from the viewpoint of suppressing the occurrence of 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 disk-shaped plate made of a material (e.g., polyurethane foam, etc.) that exhibits adsorptivity when it contains water due to the surface tension of water can be used. This allows the back pad 14 containing water to hold the workpiece during polishing.

[0024] In each of Figs. 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 disk-shaped member 10a and a lower disk-shaped member 10b. The lower disk-shaped member 10b is a disk-shaped member having an outer diameter smaller than that of the upper disk-shaped member 10a. The upper disk-shaped member 10a and the lower disk-shaped member 10b can be disk-shaped flat plates having the same upper and lower outer diameters, and can be arranged, for example, in a concentric shape. In each of Figs. 1 and 5 to 7, the upper disk-shaped member 10a and the lower disk-shaped member 10b are separate members and are fixed by any means (for example, a method of providing a recess on one side and a protrusion on the other side and fitting the protrusion into the recess, bolting, bonding with an adhesive, etc.). However, the polishing head according to one embodiment of the present invention is not limited to such a configuration, and the blocking member may be a member in which an upper disk-shaped portion and a lower disk-shaped portion having an outer diameter smaller than that of the upper disk-shaped portion are integrally molded. The material constituting the blocking member is not particularly limited. In each of Figs. 1 and 5 to 7, W indicates a workpiece installation position. When a gas is introduced into the space surrounded by the first annular member 11, the membrane 13, and the blocking member during polishing of the workpiece, the membrane 14 expands, and the workpiece installed at the workpiece installation position W is pressed through the back pad 14 to be polished.

[0025] In each of FIG. 1 and FIG. 5 to FIG. 7, the space surrounded by the first annular member 11, the membrane 13, and the blocking 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. An example of the rubber is fluororubber. 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 at the center of the blocking member, and into the outer space 16b from a gas introduction passage 17b that penetrates the upper disc-shaped member 10a at the outer peripheral region of the blocking member, with the gas introduction amount being controlled independently. When polishing a workpiece, for example, by changing the amount of gas introduced from the gas introduction path 17a into the inner space 16a and the amount of gas introduced from the gas introduction path 17b into the outer space 16b, the polishing surface pressure applied to the outer peripheral region of the surface of the workpiece to be polished below the outer space 16b can be controlled independently of the polishing surface pressure applied to the central part of the surface of the workpiece to be polished below the inner space 16a. Note that, although there is one gas introduction path 17a and one gas introduction path 17b in each of Figs. 1 and 5 to 7, this is not limited to the embodiment, and two or more gas introduction paths 17a can be provided, and two or more gas introduction paths 17b can be provided.

[0026] In each of Fig. 1 and Fig. 5 to Fig. 7, a second annular member 12 is disposed below the membrane 13 via a back pad 14. The second annular member 12 is an annular member having an opening for holding a workpiece to be polished. Such an annular member is generally also called a retainer, a retainer ring, a template, etc. The second annular member 12 can be an annular member made of a material (e.g., glass epoxy) that is usually used for annular members called retainers of polishing heads, etc.

[0027] FIG. 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 FIG. upperis connected to the blocking member, and the lower annular connection part C lower is connected to the membrane 13. In detail, the upper annular connection part C upper is connected to the side surface of the lower disc-shaped member 10b of the blocking member, and the lower annular connection part C lower is connected to the upper surface of the membrane 13. Examples of the connection means include known methods such as using an adhesive, integral molding, and fitting a convex part into a concave part. If the inner diameter of the lower annular connection part of the annular partition wall is called d1 and the inner diameter of the second annular member is called d2, in the polishing head according to one embodiment of the present invention, the inner diameter d1 of the lower annular connection part of the annular partition wall is larger than the inner diameter d2 of the second annular member. That is, the relationship of "d1>d2" is satisfied. Therefore, when polishing the workpiece, the second annular member is located vertically below the lower annular connection part of the annular partition wall, and the outer peripheral region of the surface to be polished of the workpiece is not located. In contrast, in the polishing head shown in WO2020 / 202682 (Patent Document 1) shown above, the outer peripheral region of the surface to be polished of the workpiece is located vertically below the connection part of the partition (see, for example, FIG. 1 of Patent Document 1). As described above, this is thought to be the reason why localized fluctuations in the amount of polishing (specifically, localized decreases in the amount of polishing vertically below the connection part) are likely to occur in the workpiece polished using the polishing head illustrated in WO2020 / 202682 (Patent Document 1). In contrast, the inventor believes that the polishing head according to one embodiment of the present invention can suppress localized decreases in the amount of polishing vertically below the connection part and polish the surface of the workpiece to be polished by satisfying the relationship "d1>d2". If d2 is 100%, d1 is more than 100%, preferably more than 102%, and more preferably 103% or more. If d2 is 100%, d1 can be, for example, 120% or less or 110% or less, or can exceed the values ​​exemplified herein.

[0028] FIG. 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 FIG. upperThe upper annular connection part C is connected to the side of the lower disk-shaped member 10b of the blocking member. In FIG. 3, the two dotted lines indicate the upper annular connection part C upper As shown by these two dotted lines, the upper annular connection part C upper The outer peripheral region of the workpiece to be polished is located vertically below the outer peripheral end of the annular partition wall 15. Here, the "outer peripheral region" refers to a portion of the region extending from the outer peripheral end toward the inside in the radial direction. upper are connected to the side surface of the lower disc-shaped member 10b of the blocking member, the upper annular connecting portion C upper The vertically downward portion of the lower disk-shaped member 10b is also the vertically downward portion of the side surface of the lower disk-shaped member 10b. upper can be connected to the lower surface of the lower disc-shaped member 10b or the lower surface of the upper disc-shaped member 10a. In this case, the upper annular connection part C upper The vertically downward part is the upper annular connection part C upper The upper annular joint C is the vertically downward part of the inner circumferential edge of the upperLet the inner diameter of the opening be d3 and the outer diameter of the installation position W of the workpiece to be polished be d4. Then, d3 is smaller than d4. That is, the relationship "d3 < d4" is satisfied. As described above, in the polishing head according to one aspect of the present invention, for the connection portion of the annular partition wall, the outer peripheral region of the installation position of the workpiece to be polished is located vertically below the upper annular connection portion, and the inner diameter of the lower annular connection portion is larger than the inner diameter of the second annular member. Compared with the polishing head shown in FIG. 1 of Japanese Patent No. 4833355 (Patent Document 2), the present inventor believes that by adjusting the amount of gas introduced into the outer space partitioned by the annular partition wall, it is possible to more effectively control the pressure applied downward from the outer space. As a result, the present inventor推测 that it becomes possible to easily control the polishing amount of the outer peripheral region of the polishing target surface of the workpiece by adjusting the amount of gas introduced into the outer space. Taking d4 as 100%, d3 is less than 100%, preferably 95% or less, and more preferably 90% or less. Further, from the viewpoint of making the change in the polishing amount of the outer peripheral region of the polishing target surface of the workpiece with respect to the change in the amount of gas introduced into the outer space larger, taking d4 as 100%, d3 is preferably 40% or more, more preferably 50% or more, still more preferably 60% or more, even more preferably 70% or more, and even more preferably 80% or more.

[0029] It should be noted that the word "推测" in the translation is a more literal rendering of the Chinese word which might be better translated as "speculate" or "infer" in a more natural English context for a more polished translation. Also, the text seems to have some minor grammar or expression issues in the original Chinese which are carried over in this translation for the sake of strict adherence to the rules.Regarding the annular partition wall, it is preferable that the cross-sectional shape of the annular partition wall at least partially includes a side shape selected from the group consisting of an inclined shape and a horizontal shape, and more preferably, an area including the inner peripheral end of the second annular member and the outer peripheral end of the installation position of the workpiece to be polished is located vertically below at least a part of such a side shape. Having such a configuration can lead to at least a part of the inner wall surface of the annular partition wall coming into contact with the upper surface of the membrane when gas is introduced into the outer space during polishing. This can contribute to making it easier to control the amount of polishing within the surface 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 space and the inner space. The polishing head has a configuration in which at least a part 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, for example, by at least a part of the upper surface of the membrane coming into contact with the inner wall surface of the partition wall when gas is introduced only into the outer space without introducing gas into the inner space. FIG. 4 is an explanatory diagram of the inner wall surface of the annular partition wall and the upper surface of the membrane. In FIG. inner indicates the inner wall surface of the annular partition wall 15A, and 13 upper indicates the upper surface of the membrane 13.

[0030] As a specific example of the cross-sectional shape, in the example shown in FIG. 1, the cross-sectional shape of the annular partition wall 15A includes a horizontal shape at the top and bottom, and the lower horizontal shape is followed by an inclined shape. In the example shown in FIG. 5, the cross-sectional shape of the annular partition wall 15B is inclined. In the example shown in FIG. 6, the cross-sectional shape of the annular partition wall 15C includes a horizontal shape. In the example shown in FIG. 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 FIG. 1, by introducing gas into the outer space 16b during polishing, a part or all of the inner wall surface of the part whose cross-sectional shape is the lower horizontal shape can be brought into contact with the upper surface of the membrane 13. In the example shown in FIG. 5, by introducing gas into the outer space 16b during polishing, a part or all of the inner wall surface of the annular partition wall 15B whose cross-sectional shape is inclined can be brought into contact with the upper surface of the membrane 13. In the example shown in Fig. 6, by introducing gas into outer space 16b during polishing, a part or all of the inner wall surface of the portion having a horizontal cross section can be brought into contact with the upper surface of membrane 13. In the example shown in Fig. 7, by introducing gas into outer space 16b during polishing, a part or all of the inner wall surface of the portion having a horizontal cross section can be brought into contact with the upper surface of membrane 13.

[0031] [Polishing equipment, manufacturing method for semiconductor wafers] One aspect of the present invention relates to a polishing apparatus having the above-mentioned polishing head, a polishing pad, and a platen that supports the polishing pad.

[0032] Another aspect of the present invention relates to a method for manufacturing a semiconductor wafer, the method including polishing a surface of a semiconductor wafer to be polished by the above-mentioned polishing apparatus to form a polished surface.

[0033] FIG. 8 is a schematic cross-sectional view showing an example of a polishing apparatus according to one embodiment of the present invention. The polishing apparatus 50 shown in FIG. 8 includes the polishing head 1A shown in FIG. 1. As in FIG. 1, the head body of the polishing head is omitted. The polishing apparatus 50 is a rubber chuck type single-sided polishing apparatus, and the polishing head 1A and the surface plate 42 are rotated by a rotation mechanism (not shown), respectively, to bring the surface of the workpiece Wa to be polished, which is set at the installation position W of the polishing head 1A, into sliding contact with the polishing pad 41 attached on the surface 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 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 includes the polishing head according to one embodiment of the present invention. In addition, the above-mentioned semiconductor wafer manufacturing method can be applied to a known technique related to a manufacturing method of a semiconductor wafer having a polished surface, except that the method includes forming a polished surface by polishing the surface of a semiconductor wafer to be polished using a polishing apparatus according to one embodiment of the present invention. 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 single crystal silicon ingot is cut to obtain a block. A single crystal silicon ingot can be grown by a known method such as the CZ method (Czochralski method) or the FZ method (Floating Zone method). The obtained block is sliced ​​to obtain a wafer. The wafer is subjected to various processes to manufacture a silicon wafer. Examples of the processes include chamfering and flattening (lapping, grinding, polishing). The above-mentioned polishing apparatus can be suitably used, for example, in the final polishing process, which is the final process of these wafer processes. EXAMPLES

[0034] Hereinafter, the present invention will be described 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 from the gas introduction passage 17b into the outer space 16b and the outer peripheral region of the membrane 13 swells. The polishing pressure Pc is the pressure applied downward from the central portion of the membrane 13 when gas is introduced from the gas introduction passage 17a into the inner space 16a and the central portion of the membrane 13 swells. The polishing pressures Pe and Pc are experimental values.

[0035] [Polishing head] The polishing head of Example 1 (rubber chuck type two-zone membrane head) is a polishing head having the configuration shown in FIG. 1, and the inner diameter d1 of the lower annular connection portion of the annular partition wall, the inner diameter d2 of the second annular member, the opening inner diameter d3 of the upper annular connection portion of the annular partition wall, and the outer diameter d4 of the installation position of the workpiece to be polished are the values shown in Table 1. The polishing head of Example 2 is a polishing head having the same configuration as the polishing head of Example 1 except that d3 is the value shown in Table 1. In the polishing heads of Example 1 and Example 2, the inner diameter d1 of the lower annular connection portion C of the annular partition wall 15A lower is larger than the inner diameter d2 of the second annular member, and the outer peripheral region of the installation position W of the workpiece to be polished is located vertically below the upper annular connection portion C of the annular partition wall 15A. upper Regarding the polishing heads of Example 1 and Example 2, when gas is introduced only into the outer space without introducing gas into the inner space, it was confirmed that at least a part of the inner wall surface of the partition wall (specifically, a part or all of the inner wall surface of the portion having a lower horizontal cross-sectional shape) contacts the upper surface of the membrane. The polishing heads of Comparative Example 1 and Comparative Example 2 are polishing heads having the same configuration as the polishing head of Example 1 except that d1 and d3 are the values shown in Table 1. In the polishing head of Comparative Example 1, the inner diameter d1 of the lower annular connection portion C of the annular partition wall 15A lower is smaller than the inner diameter d2 of the second annular member (d1 < d2). Therefore, during polishing, the lower annular connection portion C of the annular partition wall 15A lowerA second annular member 12 is located vertically below it. In the polishing head of Comparative Example 2, the lower annular connection part C of the annular partition wall 15A lower has an inner diameter d1 that is approximately equal to the inner diameter d2 of the second annular member, but satisfies the relationship "d1 < d2". Therefore, during polishing, the second annular member 12 is located vertically below the lower annular connection part C of the annular partition wall 15A. lower A second annular member 12 is located vertically below it.

[0036]

Table 1

[0037] [Polishing Process of Silicon Wafer] In the following polishing process, a single-sided polishing process was performed on a plurality of silicon wafers that were cut out from the same single-crystal silicon ingot under the same cutting conditions and subjected to various processing treatments under the same conditions, as the final finishing polishing process for each of them.

[0038] As the polishing apparatus of Example 1, a polishing apparatus having the configuration shown in FIG. 8 including the polishing head of Example 1 was prepared, and a single-sided polishing process of a silicon wafer was performed in this polishing apparatus. A single-sided polishing process was performed on three silicon wafers under the following polishing conditions, respectively. Pc = 10 kPa Pe = 8 kPa, 10 kPa or 12 kPa

[0039] The polishing apparatus of Example 2 is the same as the polishing apparatus of Example 1 except that the polishing head is the polishing head of the example. In this polishing apparatus, a single-sided polishing process was performed on three silicon wafers by the method described for Example 1, respectively. Similarly for Comparative Example 1 and Comparative Example 2, using the polishing heads of the respective comparative examples as the polishing heads, a single-sided polishing process was performed on three silicon wafers by the method described for Example 1, respectively.

[0040] [Evaluation of Change in Polishing Amount due to Change in Polishing Pressure Pe] The silicon wafers polished in Example 1, Example 2, Comparative Example 1, and Comparative Example 2 were measured using a geometric measurement system WaferSight manufactured by KLA-Tencor as a measuring device. (i) the wafer thickness at the wafer center (referred to as the "wafer center thickness"); and (ii) The arithmetic average of the wafer thickness at 72 equally spaced locations around the entire circumference, 10 mm inward in the radial direction from the outer periphery of the wafer (referred to as the "wafer outer circumference thickness"). asked for. For each silicon wafer subjected to polishing, the polishing amount difference was calculated as "polishing amount difference = wafer center thickness - wafer outer periphery thickness". Figure 9 shows a graph in which the polishing amount difference is plotted against the polishing pressure Pe for Example 1, Example 2, Comparative Example 1, and Comparative Example 2. As shown in the graph of Figure 9, in Comparative Example 2, the degree of change in the value of the polishing amount difference relative to the change in the value of the polishing pressure Pe was smaller than those of Example 1, Example 2, and Comparative Example 1.

[0041] [Evaluation of polishing volume fluctuation] For the silicon wafers polished in Example 1, Example 2, Comparative Example 1, and Comparative Example 2, the ESFQR, which is an index of the flatness of the peripheral region of the wafer, was obtained using a geometric measurement system WaferSight manufactured by KLA-Tencor as a measuring device. The ESFQR is E dge s It flatness f ront reference least s q uare rESFQR is an abbreviation of the ange (an abbreviation formed by connecting underlined letters). In the above-mentioned measuring device, a site is set in the outer peripheral region of the surface of the polished wafer, and the site is radially divided into a plurality of sectors, and ESFQR is obtained as a value obtained by adding the maximum displacement from the best-fit surface at the site to the minimum displacement. The sector division conditions were 72 sectors, Length 15 mm, and Width 5°. FIG. 10 shows a graph in which ESFQR is plotted against the polishing pressure Pe for Example 1, Example 2, Comparative Example 1, and Comparative Example 2. As shown in the graph in FIG. 10, in Comparative Example 1, the value of ESFQR was larger than that of Example 1, Example 2, and Comparative Example 2 at each Pe (i.e., the flatness of the outer peripheral region of the polished wafer was low). The reason why the flatness of the outer peripheral region was low in the wafer polished by the polishing apparatus of Comparative Example 1 is believed to be that, in the polishing apparatus of Comparative Example 1, the outer peripheral region of the surface of the wafer to be polished is located below the lower annular connecting portion of the annular partition wall, and therefore it was not easy to control the polishing pressure applied below the lower annular connecting portion.

[0042] From the above results, it can be confirmed that, according to the polishing process using the polishing apparatus of Example 1 and Example 2, the amount of polishing in the peripheral region of the workpiece surface to be polished can be controlled by changing the polishing pressure Pe, and it is also possible to suppress localized fluctuations in the amount of polishing on the surface to be polished. [Industrial Applicability]

[0043] One aspect of the present invention is useful in the field of semiconductor wafers such as silicon wafers.

Claims

1. A first annular member; a closing member that closes an upper opening of the opening of the first annular member; a membrane that closes a lower opening of the opening of the first annular member; a second annular member located below the membrane and having an opening for holding a workpiece to be polished; having The direction toward the center of the opening of the first annular member is defined as the inside, and the other direction is defined as the outside. a space formed by closing an opening of a first annular member with the closing member and the membrane is divided into an inner space and an outer space by an annular partition wall having an upper annular connecting portion connected to the closing member and a lower annular connecting portion connected to the membrane by using an adhesive, by integral molding, or by fitting a protrusion into a recess; The inner diameter of the lower annular connection portion of the annular partition wall is greater than the inner diameter of the second annular member; and A polishing head, in which an outer peripheral area of ​​a placement position of a workpiece to be polished is located vertically below the upper annular connection portion of the annular partition wall.

2. The annular partition wall has a cross-sectional shape having a side shape selected from the group consisting of an inclined shape and a horizontal shape; and The polishing head according to claim 1 , wherein an area including an inner peripheral edge of the second annular member and an outer peripheral edge of a position where a workpiece to be polished is placed is located vertically below at least a portion of the side surface shape.

3. The blocking 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, 3. The polishing head according to claim 1, wherein the annular partition wall has an upper annular connecting portion connected to a side surface of the lower disk-shaped member.

4. The polishing head of any one of claims 1 to 3, further comprising a back pad between the membrane and the second annular member.

5. An introduction path for introducing a gas into the internal space; An introduction path for introducing a gas into the outer space; The polishing head according to any one of claims 1 to 4, comprising:

6. A polishing head described in any one of claims 1 to 5, wherein the inner diameter of the lower annular connection portion of the annular partition wall is more than 102% and not more than 120%, when the inner diameter of the second annular member is 100%.

7. A polishing head according to any one of claims 1 to 6, A polishing pad; a platen supporting the polishing pad; A polishing apparatus having

8. A method for manufacturing a semiconductor wafer, comprising: polishing a surface of a semiconductor wafer to be polished by the polishing apparatus according to claim 7 to form a polished surface.

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