Wafer grinding method and wafer grinding device

Abstract

The present invention provides a wafer polishing method for polishing a wafer using a polishing apparatus. The wafer polishing method includes: obtaining in-plane thickness distribution information about a wafer to be polished or a wafer that has been subjected to the same processing as the wafer to be polished; determining, based on the in-plane thickness distribution information, a pressure difference between a pressure Pc applied to the central portion of the wafer to be polished by introducing gas into the central region of a space portion of a polishing head and a pressure Pe applied to the outer periphery of the wafer to be polished by introducing gas into the outer periphery of the space portion; determining one of the pressures Pc and Pe, and determining the other pressure based on the determined pressure and the pressure difference; determining a pressure Pg applied downward from the head body of the polishing head by pressing the lower surface of the second annular member of the polishing pad based on a set value Pr of the contact pressure applied to the lower surface of the polishing pad by contact with the polishing pad during polishing; and polishing the lower surface of the wafer to be polished by bringing the lower surface into contact with the polishing pad while the determined Pg, Pc, and Pe are applied.

Description

[0001] This application claims priority based on Japanese Patent Application No. 2020-151460, filed on September 9, 2020, the entire contents of which are expressly incorporated herein by reference. Technical Field

[0002] The present invention relates to a wafer grinding method and a wafer grinding device. Background Art

[0003] Among the devices for grinding the surface of a wafer, there are single-sided grinding devices for grinding a single side of the wafer and double-sided grinding devices for grinding both sides of the wafer. In the single-sided grinding device, the grinding target surface of the wafer held by a grinding head is usually pushed against a grinding pad attached to a platform while the grinding head and the platform are rotated respectively so that the grinding target surface of the wafer contacts the grinding pad. By supplying an abrasive between the grinding target surface and the grinding pad in such contact, the grinding target surface of the wafer can be ground (for example, with reference to Japanese Patent Application Laid-Open No. 2006-263903 (all of which are specifically cited herein as disclosed)).

[0004] When polishing wafers using a single-side polishing device, as described in paragraph 0007 of Japanese Patent Application Laid-Open No. 2006-263903, a retaining ring is provided to hold the wafer being polished for stable polishing. However, simply providing a retaining ring is insufficient to improve polishing stability during wafer polishing. Appropriately setting polishing conditions can help improve polishing stability. However, finding these polishing conditions has traditionally required extensive trial and error. Summary of the Invention

[0005] An object of one aspect of the present invention is to easily set appropriate polishing conditions and perform stable wafer polishing.

[0006] A technical solution of the present invention relates to a wafer grinding method (hereinafter simply referred to as "grinding method"), which is a wafer grinding method for grinding a wafer using a grinding device, the grinding device comprising a grinding head and a grinding pad, the grinding head comprising a head main body, a first annular component, a plate-shaped component, a diaphragm, and a second annular component, the first annular component being located below the head main body and having an opening, the plate-shaped component sealing the upper surface side opening of the first annular component, the diaphragm sealing the lower surface side opening of the first annular component, the second annular component being located below the diaphragm and holding the grinding target wafer, the grinding pad being in contact with the lower surface of the grinding target wafer and the lower surface of the second annular component during grinding; the opening of the first annular component is sealed by the plate-shaped component and the diaphragm to form a space portion, the space portion comprising a central area and a peripheral area separated from the central area. Domain; the wafer grinding method includes: obtaining in-plane thickness distribution information about the grinding object wafer or the wafer subjected to the same processing as the grinding object wafer; determining the pressure difference between the pressure Pc applied to the central part of the grinding object wafer by introducing gas into the above-mentioned central area and the pressure Pe applied to the peripheral part of the grinding object wafer by introducing gas into the above-mentioned peripheral area based on the above-mentioned in-plane thickness distribution information; determining the pressure of one of Pc and Pe, and determining the pressure of the other based on the determined pressure and the above-mentioned pressure difference; determining the pressure Pg applied downward from the above-mentioned head main body by pushing the above-mentioned head main body based on the set value Pr of the contact pressure applied to the lower surface of the above-mentioned second annular component by contact with the above-mentioned grinding pad during grinding; and grinding by bringing the lower surface of the grinding object wafer into contact with the above-mentioned grinding pad in a state where the above-mentioned determined Pg, Pc and Pe are applied.

[0007] In one embodiment, the polishing method may include determining Pg based on a ratio Pr / Pt of Pr to a reference value Pt of the contact pressure applied to the lower surface of the second annular member and a ratio Pe / Pc of Pe to Pc.

[0008] In one embodiment, the polishing method may further include determining Pg by calculating Pg based on a relationship equation among the ratio Pr / Pt, the ratio Pe / Pc, and Pg.

[0009] In one embodiment, the above relational expression can be represented by the following formula A. In formula A, R, X, Y, Z, a, and b are each an independent positive number.

[0010] (Formula A)

[0011] Pr / Pt=-RX(Pe / Pc)+Y(Pg / Pc)+Z((Pe / Pc)-a)((Pg / Pc)-b)

[0012] In one embodiment, the ratio Pr / Pt can be in the range of 0.8 to 1.2.

[0013] One technical solution of the present invention relates to a method for manufacturing a wafer, comprising: polishing a surface of a wafer to be polished by the above-mentioned wafer polishing method to form a polished surface.

[0014] In one embodiment, the wafer may be a semiconductor wafer.

[0015] In one embodiment, the semiconductor wafer may be a silicon wafer.

[0016] A technical solution of the present invention relates to a wafer grinding device, comprising a grinding section and a grinding condition determining section; the grinding section comprises a grinding head and a grinding pad, the grinding head comprises a head main body, a first annular component, a plate-shaped component, a diaphragm, and a second annular component, the first annular component is located below the head main body and has an opening, the plate-shaped component closes the upper surface side opening of the first annular component, the diaphragm closes the lower surface side opening of the first annular component, the second annular component is located below the diaphragm and holds the grinding object wafer, when the grinding pad is grinding, the lower surface of the grinding object wafer and the lower surface of the second annular component are in contact with it; the opening of the first annular component is closed by the plate-shaped component and the diaphragm to form a space portion, the space portion has a central area and a peripheral area separated from the central area; the grinding strip The component determination unit determines the pressure difference between the pressure Pc applied to the central portion of the polishing target wafer by introducing gas into the above-mentioned central region and the pressure Pe applied to the peripheral portion of the polishing target wafer by introducing gas into the above-mentioned peripheral region based on the in-plane thickness distribution information obtained about the polishing target wafer or the wafer subjected to the same processing as the polishing target wafer; determines the pressure of one of Pc and Pe, and determines the pressure of the other based on the determined pressure and the above-mentioned pressure difference; determines the pressure Pg applied downward from the above-mentioned head main body by pushing the above-mentioned head main body based on the set value Pr of the contact pressure applied to the lower surface of the above-mentioned second annular component by contact with the above-mentioned polishing pad during polishing; the above-mentioned polishing unit performs polishing by bringing the lower surface of the polishing target wafer into contact with the above-mentioned polishing pad in a state where the above-mentioned determined Pg, Pc and Pe are applied.

[0017] In one embodiment, the polishing condition determination unit may determine Pg based on a ratio Pr / Pt of Pr to a reference value Pt of the contact pressure applied to the lower surface of the second annular member and a ratio Pe / Pc of Pe to Pc.

[0018] In one embodiment, the polishing condition determination unit can determine Pg by calculating Pg based on a relational expression among the ratio Pr / Pt, the ratio Pe / Pc, and Pg.

[0019] In one embodiment, the above relationship can be the above-mentioned equation A.

[0020] In one embodiment, the ratio Pr / Pt can be in the range of 0.8 to 1.2.

[0021] In one embodiment, the wafer may be a semiconductor wafer.

[0022] In one embodiment, the semiconductor wafer may be a silicon wafer.

[0023] According to a technical solution of the present invention, a wafer can be polished with high stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic cross-sectional view showing an example of a polishing head.

[0025] Figure 2 yes Figure 1 A partial enlarged view of the grinding head is shown.

[0026] Figure 3 It is a plan view showing an example of the positional relationship between the space portion and the second annular member.

[0027] Figure 4A It is a schematic cross-sectional view showing an example of a plate-shaped member.

[0028] Figure 4B It is a schematic cross-sectional view showing an example of a plate-shaped member.

[0029] Figure 5A An example of the cross-sectional shape of a partition that partitions the central region and the outer peripheral region of the space portion of the polishing head is shown.

[0030] Figure 5B An example of the cross-sectional shape of a partition that partitions the central region and the outer peripheral region of the space portion of the polishing head is shown.

[0031] Figure 5C An example of the cross-sectional shape of a partition that partitions the central region and the outer peripheral region of the space portion of the polishing head is shown.

[0032] Figure 5D An example of the cross-sectional shape of a partition that partitions the central region and the outer peripheral region of the space portion of the polishing head is shown.

[0033] Figure 5E An example of the cross-sectional shape of a partition that partitions the central region and the outer peripheral region of the space portion of the polishing head is shown.

[0034] Figure 5F An example of the cross-sectional shape of a partition that partitions the central region and the outer peripheral region of the space portion of the polishing head is shown.

[0035] Figure 6 This is an explanatory diagram regarding the pressure applied to the diaphragm from the space portion of the polishing head.

[0036] Figure 7 This is a schematic cross-sectional view showing an example of a polishing device.

[0037] Figure 8 This is a flowchart showing an example of a polishing method.

[0038] Figure 9 This is an example of a graph showing the correlation between the polishing amount difference between the polishing amount of the wafer periphery and the polishing amount of the wafer center during polishing and the pressure difference (Pe-Pc).

[0039] Figure 10 This is an example of a graph showing the correlation between the polishing rate at the center of the wafer and Pc.

[0040] Figure 11 This is a schematic diagram showing the structure of an example of a wafer polishing apparatus.

[0041] Figure 12 This is a graph showing the distribution of the polishing amount within the surface to be polished of a wafer under different polishing conditions. DETAILED DESCRIPTION

[0042] [Wafer polishing method]

[0043] One technical solution of the present invention relates to a wafer polishing method for polishing a wafer using a polishing device. The polishing device comprises a polishing head and a polishing pad. The polishing head comprises a head body, a first annular member, a plate-shaped member, a diaphragm, and a second annular member. The first annular member is located below the head body and has an opening. The plate-shaped member seals the upper surface opening of the first annular member. The diaphragm seals the lower surface opening of the first annular member. The second annular member is located below the diaphragm and holds the wafer to be polished. The polishing pad contacts the lower surface of the wafer to be polished and the lower surface of the second annular member during polishing. The space formed by the opening of the first annular member being sealed by the plate-shaped member and the diaphragm comprises a central region and a peripheral region separated from the central region. The wafer grinding method includes: obtaining in-plane thickness distribution information about a wafer to be ground or a wafer subjected to the same processing as the wafer to be ground; determining the pressure difference between Pc and Pe based on the in-plane thickness distribution information, wherein Pc is the pressure applied to the central portion of the wafer to be ground by introducing gas into the central region, and Pe is the pressure applied to the peripheral portion of the wafer to be ground by introducing gas into the peripheral region; determining the pressure of one of Pc and Pe, and determining the pressure of the other based on the determined pressure and the pressure difference; determining Pg based on Pr, wherein Pr is a set value of the contact pressure applied to the lower surface of the second annular component by contacting with the grinding pad during grinding, and Pg is the pressure applied downward from the head main body by pushing the head main body; and grinding is performed by bringing the lower surface of the wafer to be ground into contact with the grinding pad in a state where the determined Pg, Pc and Pe are applied.

[0044] The wafer polishing method described above is described in more detail below. In the present invention and this specification, terms such as "lower surface," "lower side," and "upper surface" refer to the "lower surface," "lower side," and "upper surface" when the polishing head is in a state where polishing is being performed. Below, one embodiment of the present invention is described based on the accompanying drawings. However, the embodiments shown in the drawings are illustrative only and the present invention is not limited to these embodiments. In the drawings, identical components are denoted by the same reference numerals.

[0045] <Grinding device>

[0046] The polishing device at least includes a polishing head and a polishing pad.

[0047] (Grinding head)

[0048] The polishing head included in the polishing device comprises: a head body; a first annular member located below the head body and having an opening; a plate-shaped member that closes the upper surface opening of the first annular member; a diaphragm that closes the lower surface opening of the first annular member; and a second annular member located below the diaphragm and that holds the wafer to be polished. Furthermore, the space formed by the opening of the first annular member being closed by the plate-shaped member and the diaphragm comprises a central region and a peripheral region separated from the central region. By using a polishing head having such a central region and peripheral regions, the polishing surface pressure acting on the peripheral portion and the polishing surface pressure acting on the central portion of the wafer's polishing surface can be independently controlled.

[0049] Figure 1 This is a schematic cross-sectional view showing an example of a polishing head included in a polishing apparatus that can be used in the above-mentioned polishing method.

[0050] exist Figure 1 In the polishing head 10 , a first annular member 12 is connected to a head body 11 .

[0051] The first annular member 12 is located below the head body 11 and has an opening.

[0052] The upper surface side opening of the first annular member 12 is closed by a plate-shaped member 16 .

[0053] The lower surface of the first annular member 12 is covered with a diaphragm 14. The diaphragm 14 closes the lower surface side opening of the first annular member.

[0054] Furthermore, a backing pad 15 is attached to the lower surface of the diaphragm 14 .

[0055] The diaphragm 14 has a separator 19. As a result, the opening of the first annular member 12 is closed by the plate member 16 and the diaphragm 14, and a space having a central region 17A and an outer peripheral region 17B is formed on the back side of the diaphragm 14. The outer peripheral region 17B is separated from the central region 17A by the separator 19.

[0056] Gas is introduced into the central region 17A from the gas introduction path 18A, and gas is introduced into the peripheral region 17B from the gas introduction path 18B, whose gas introduction amount can be controlled independently of the gas introduction path 18A. This allows the diaphragm 14 to swell and press the wafer W via the backing pad 15 .

[0057] Figure 2 yes Figure 1 A partial enlarged view of the grinding head is shown.

[0058] The second annular member 13 holds the wafer W at its opening. The inner peripheral end region of the second annular member 13 is located vertically below the outer peripheral end of the outer peripheral region 17B of the space portion. The inner peripheral end region refers to the inner peripheral end and its surrounding area. That is, if the direction toward the center of the opening of the second annular member 13 is referred to as the inner side, and the other direction is referred to as the outer side, then the inner peripheral end of the second annular member 13 is located inward of the outer peripheral end of the outer peripheral region 17B of the space portion. In addition, the separator 19 is located inward of the inner peripheral end of the second annular member 13. Figure 3 It is a plan view showing an example of the positional relationship between the space portion and the second annular member 13 .

[0059] Furthermore, the polishing head 10 includes an outer peripheral region 17B, which is an independent space separated from the central region 17A by a partition. For example, by varying the amount of gas introduced from the gas introduction path 18A to the central region 17A and the amount of gas introduced from the gas introduction path 18B to the outer peripheral region 17B, the polishing surface pressure applied to the outer periphery of the polishing surface w1 of the wafer W below the outer peripheral region 17B and the polishing surface pressure applied to the central portion of the polishing surface w1 of the wafer W below the central region 17A can be independently controlled.

[0060] The polishing head has the above-described structure, and thereby can easily control the polishing surface pressure applied to the outer peripheral portion of the surface to be polished of the wafer.

[0061] Next, each component constituting the polishing head will be further described.

[0062] As the first annular member 12 , an annular ring made of a rigid material such as stainless steel (SUS) that is generally used in a polishing head of a single-side polishing apparatus can be used.

[0063] The head body 11 to which the first annular member 12 is attached may be a structure commonly used in a polishing head of a single-side polishing apparatus (for example, a head body made of SUS). The first annular member 12 can be attached to the head body 11 by a known method such as bolting.

[0064] The opening portion on the lower surface side of the first annular component 12 is covered and sealed by the diaphragm 14. From the viewpoint of preventing positional deviation when the diaphragm bulges, it is preferred to also cover the annular lower surface of the first annular component with the diaphragm. In addition, it is also preferred to cover the annular lower surface of the first annular component with the diaphragm from the viewpoint of inhibiting the abrasive from being mixed into the opening portion of the first annular component. The diaphragm 14 can be bonded to the annular lower surface of the first annular component 12 by a known method such as using an adhesive. In addition, it is also preferred to cover the diaphragm 14 as Figure 1 and Figure 2The first annular member 12 is fitted over the side of the first annular member 14 in the manner shown in FIG. 1 . In this way, the lower surface side opening of the first annular member 12 is closed. Furthermore, the upper surface side opening of the first annular member 12 is closed by the plate-shaped member 16. In this way, the opening of the first annular member 12 is closed to form a space portion. In one embodiment, from the perspective of being able to accurately control the in-plane distribution of the grinding surface pressure applied to the grinding object surface of the wafer W, the height of the space portion (in other words, the distance between the lower surface of the plate-shaped member 16 and the upper surface of the diaphragm 14) is preferably a value of about 3.5 to 5.5 mm, which is a state in which no gas is introduced into the space portion in order to bulge the diaphragm. The height of the space portion can be adjusted, for example, by means of the size of the partition described later.

[0065] A film made of an elastic material such as rubber can be used as the diaphragm 14. Examples of rubber include fluororubber. The thickness of the diaphragm 14 is not particularly limited and can be, for example, approximately 0.5 to 2 mm.

[0066] The plate-like member 16 can be, for example, a disc-shaped plate and can be mounted on the head body 11 by a known method such as bolt fixing. The plate-like member 16 is provided with a through hole forming a part of the gas introduction path 18A for introducing gas into the central area of the space portion and a through hole forming a part of the gas introduction path 18B for introducing gas into the peripheral area of the space portion. Figure 1 In the figure, there is shown a method in which one gas inlet path is provided for introducing gas into the central area of the space portion and one gas inlet path is provided for introducing gas into the peripheral area, but more than two gas inlet paths can be provided at any position, and the number and position of each gas inlet path are not limited to the method shown in the figure.

[0067] The diaphragm 14 has a separator 19. The opening of the first annular member 12 is closed by the plate member 16 and the diaphragm 14 to form a space, and the space is divided into a central area 17A and an outer peripheral area 17B by the separator 19. As an example, the separator 19 can be attached to the plate member 16 by inserting the annular member (separator 19) into a circular groove provided on the plate member 16. As an example of the plate member 16, Figure 4A and Figure 4B As shown, a configuration including a first plate-shaped member 16A having a recess and a second plate-shaped member 16B disposed in the recess, with an annular groove G, can be employed. The second plate-shaped member 16B can be attached to the first plate-shaped member 16A by known methods such as bolt fastening. A recess g for inserting a separator having an L-shaped cross-section, such as that described later, can be provided at any position within the annular groove G, depending on the shape of the separator.

[0068] exist Figures 5A to 5F1 shows an example of a cross-sectional shape of the separator 19. In the figure, the dotted line portion indicates the connection portion with the plate-shaped member 16, and the arrow indicates the center direction of the first annular member 12. In one embodiment, the separator 19 can be Figure 5A and Figure 5B In another embodiment, the partition 19 can be formed as shown in FIG. Figure 5C As shown in FIG. 1 , the separator 19 may have an I-shaped cross-section. Figure 5D and Figure 5E In another embodiment, the partition 19 can be formed as shown in FIG. Figure 5F As shown, the separator 19 has a T-shaped cross-section. The separator 19 can be made of, for example, resin, metal, or the like, formed into a desired shape. The separator 19 preferably has a thickness sufficient to maintain its shape when pressure is applied by gas introduced into the space; this thickness can be, for example, approximately 0.5 to 1.5 mm.

[0069] It is also possible to adopt a method in which the separator 19 and the diaphragm 14 are made as separate parts and the two parts are fixed with an adhesive or the like, but it is preferable that the separator 19 and the diaphragm 14 are integrally formed. This is based on the following reasons. If a gap occurs between the separator 19 and the diaphragm 14, ventilation can occur between the central area 17A and the peripheral area 17B separated by the separator 19. In contrast, if the separator 19 and the diaphragm 14 are integrally formed into one part, such ventilation does not occur and the central area 17A and the peripheral area 17B can be separated by the separator 19. In addition, it is not easy to evenly adhere the separator 19 and the diaphragm 14 made as separate parts in the circumferential direction, and the uniformity of the pressure applied to the wafer may decrease when the pasting state is uneven. Alternatively, in the case where the diaphragm is bulged due to the adhesive, it is possible that the grinding surface is pressed differently on the bulged part and on other parts. From the above viewpoints, it is preferable to integrally form the separator 19 and the diaphragm 14. As a separator 19, such as Figure 5A and Figure 5B As shown in the figure, the cross-sectional shape of the L-shaped or Figure 5C In the case of a relatively simple shape such as the one having an I-shaped cross-section as shown, molding is easy regardless of whether the separator 19 and the diaphragm 14 are integrally molded or not.

[0070] Figure 6This diagram illustrates the pressure applied to the diaphragm from the space. In the polishing head described above, the space formed by sealing the opening of the first annular member is divided into a central region 17A and a peripheral region 17B. The pressure applied to the central portion of the wafer W located below the central portion of the diaphragm 14 during polishing, caused by the introduction of gas into the central region 17A to cause the central portion of the diaphragm 14 to bulge, is referred to as Pc, and the pressure applied to the peripheral portion of the wafer W located below the peripheral portion of the diaphragm 14, caused by the introduction of gas into the peripheral region 17B to cause the peripheral portion of the diaphragm 14 to bulge, is referred to as Pe. The magnitudes of pressures Pc and Pe can be independently controlled by adjusting the amount of gas introduced into each region of the space. Pc and Pe will be described further below.

[0071] A backing pad 15 is bonded to the lower surface of the diaphragm 14. The backing pad 15 can be bonded to the lower surface of the diaphragm 14 using a known method, such as an adhesive. While the outer periphery of the lower surface of the diaphragm 14 can be in direct contact with the annular upper surface of the second annular member 13, it is preferred that the backing pad 15 be sandwiched between the outer periphery of the lower surface of the diaphragm 14 and the annular upper surface of the second annular member 13 to prevent peeling and undulation of the backing pad 15. The backing pad 15 can be a disc-shaped plate made of a material, such as foamed polyurethane, that exhibits adsorption properties due to the surface tension of water when it is present. This allows the backing pad 15, which contains water, to hold the wafer W.

[0072] The second annular component 13 is a component for holding the wafer W at its opening, and is also referred to as a retainer, a retaining ring, etc. The second annular component 13 can be, for example, an annular component made of glass epoxy resin. The second annular component 13 can be bonded to the backing pad 15 by a known method such as using an adhesive. In the above-mentioned grinding head, the inner peripheral end area of the second annular component (specifically, the inner peripheral area of the annular upper surface of the second annular component) is located vertically below the outer peripheral end of the outer peripheral area of the space portion formed by closing the opening of the first annular component 12. As a result, the grinding surface w1 of the wafer W can be ground without the outer peripheral portion of the grinding target surface w1 of the wafer W being located vertically below the outer peripheral end of the space portion. For example, by arranging a second annular member having an inner diameter smaller than that of the first annular member concentrically with the first annular member, the inner peripheral end region of the second annular member can be arranged vertically below the outer peripheral end of the space portion formed by closing the opening portion of the first annular member. From the viewpoint of facilitating the control of the grinding surface pressure applied to the outer peripheral portion of the grinding target surface of the wafer, it is preferred that the width ( Figure 1The area of approximately 8 to 25 mm ("d") in the space portion is located below the outer peripheral area 17B of the space portion. The thickness of the second annular member 13 can be determined based on the thickness of the wafer W to be polished. Furthermore, the diameter of the opening of the second annular member 13 can also be determined based on the diameter of the wafer W to be polished. The second annular member 13 can be made of a material commonly used in a retaining ring of a polishing head.

[0073] The lower surface of the second annular member 13 contacts the polishing pad 41 during polishing. The second annular member is pressed downward by the pressure control mechanism (not shown) pressing the head body 11 during polishing (pressure Pg described in detail later; see Figure 1 ), the weight of the head body 11 and the weight of the first annular component 12 apply pressure. If the contact pressure applied to the lower surface of the second annular component 13 by contact with the polishing pad 41 during polishing is too large, wear or degradation of the second annular component 13 may occur. On the other hand, when the above-mentioned contact pressure is too small, the chip W may fall off during polishing. Due to such a phenomenon, the stability of the polishing process is reduced, but in the above-mentioned polishing method, by determining Pg as described in detail later, it is easy to set appropriate polishing conditions, and as a result, it is possible to reduce the wear or degradation of the second annular component 13 and / or prevent the chip from falling off.

[0074] Various semiconductor wafers such as silicon wafers can be cited as the polishing target wafer W. As is well known, a semiconductor wafer is a wafer having a disk shape.

[0075] (Structural Example of Polishing Device)

[0076] The polishing apparatus that can be used in the above-mentioned polishing method includes the above-mentioned polishing head and polishing pad, and may further include a platform for supporting the polishing pad. Figure 7 1 is a schematic cross-sectional view showing an example of the grinding device. While the grinding head 10 and the platform 42 are rotated separately by means of a rotating mechanism (not shown), the grinding target surface of the wafer W is brought into contact with the grinding pad 41 attached to the platform 42. The grinding agent 61 discharged from the grinding agent supply mechanism 60 is supplied between the grinding target surface of the wafer W and the grinding pad 41 to grind the grinding target surface of the wafer W. As the grinding agent, the grinding slurry commonly used in CMP (Chemical Mechanical Polishing) can be used. Regarding the details of the thickness, material, etc. of the grinding pad 41, known techniques related to the grinding process of the wafer can be applied. As the grinding pad 41, for example, a commercially available product can be used. The grinding device used in the above-mentioned grinding method can have the same structure as a conventional single-sided grinding device, except that it has a grinding pad and the grinding head described above.

[0077] <Determination of grinding conditions>

[0078] In order to improve the stability of the grinding process of the grinding of wafer, it is desirable to set the contact pressure applied to the lower surface of the second annular component by contacting with the grinding pad to an appropriate value when grinding. This is because, as previously described, by properly controlling the above-mentioned grinding pressure, the wear or deterioration of the second annular component can be alleviated and / or the wafer can be prevented from falling off when grinding. In addition, the above-mentioned contact pressure is an appropriate value. Specifically, in grinding, the above-mentioned contact pressure is maintained at a constant value or the variation of the above-mentioned contact pressure is reduced, thus the amount of grinding of the wafer periphery can also be suppressed to vary. This also helps to improve the stability of the grinding process during the grinding of wafer. For example, by in grinding, Pg, Pc and Pe are constantly maintained at the value of setting and grinding is carried out, thus the contact pressure applied to the lower surface of the second annular component by contacting with the grinding pad can be maintained at a constant value or its variation is reduced when grinding. Thus, the amount of grinding of the wafer periphery can be suppressed to vary.

[0079] Please refer to the following as appropriate Figure 8 The flowchart shown in FIG. 1 illustrates a method for determining the polishing conditions in the polishing method. However, the following description is for illustrative purposes only, and the polishing method is not limited to the illustrative description.

[0080] (Obtaining wafer in-plane thickness distribution information)

[0081] In the above-mentioned grinding method, as described above, the opening portion of the first annular member is closed by the plate-shaped member and the diaphragm to form a space portion having a central area and a peripheral area separated from the central area. By separating the central area and the peripheral area in this way, the pressure Pc and the pressure Pe can be controlled independently of each other. If Pc and Pe can be controlled independently, the in-plane grinding amount can be changed according to the in-plane thickness distribution of the grinding object surface of the wafer. This is preferable in terms of being able to provide a wafer with excellent in-plane uniformity of wafer thickness, for example. In order to set the Pc and Pe, in the above-mentioned grinding method, the in-plane thickness distribution information ( Figure 8In S1). The in-plane thickness distribution information can be, for example, information related to the difference in thickness between the central portion of the wafer and the peripheral portion of the wafer. The central portion related to the wafer refers to a portion of the area including the center of the wafer, and the peripheral portion refers to the area surrounding the central portion. This is also the same for the central portion and the peripheral portion related to the diaphragm described above. The thickness of the wafer can be measured by a known thickness measurement method, either contact or non-contact. Here, the thickness of the central portion can be the value of the thickness at one point in the central portion, or it can be the arithmetic average of the thicknesses at two or more points in the central portion. This is also the same for the thickness of the peripheral portion. In one embodiment, the in-plane thickness distribution information can be obtained by measuring the thickness of the wafer to be polished itself. In another embodiment, the in-plane thickness distribution information can be obtained by measuring the thickness of a wafer that has been subjected to the same processing as the wafer to be polished. Here, "wafer subjected to the same processing" refers to a wafer that has been subjected to the same process up to the point of polishing under the same conditions in the above-mentioned polishing method. However, regarding "same conditions", differences that usually occur in the wafer manufacturing process are allowed. For example, when polishing multiple wafers that have undergone the same processing, in-plane thickness distribution information can be obtained for a portion of the multiple wafers, and the obtained in-plane thickness distribution information can be used to determine the polishing conditions for the multiple wafers. The number of wafers in the portion can be one or two or more. In the case of two or more wafers, the in-plane thickness distribution information can be obtained by, for example, taking the arithmetic mean of the measured values obtained for the two or more wafers.

[0082] (Determination of the pressure difference between Pc and Pe, determination of Pc and Pe)

[0083] After obtaining the above-mentioned in-plane thickness distribution information, the pressure difference (Pc) between the pressure applied to the central portion of the polishing target wafer by introducing gas into the central region of the space portion formed by closing the opening portion of the first annular member and the pressure Pe applied to the peripheral portion of the polishing target wafer by introducing gas into the peripheral region of the space portion is determined based on the obtained in-plane thickness distribution information. Figure 8 Specifically, the pressure difference can be a pressure difference (Pe-Pc) or a pressure difference (Pc-Pe), preferably a pressure difference (Pe-Pc).

[0084] According to the research of the inventors of the present invention, the greater the pressure difference (Pe-Pc), the more the polishing amount of the wafer periphery during the polishing process can be made greater than the polishing amount of the wafer center. Figure 9This is an example of a graph showing the correlation between the grinding amount difference between the grinding amount of the outer periphery of the wafer and the grinding amount of the central part of the wafer during grinding and the pressure difference (Pe-Pc). Here, the grinding amount is the thickness of the portion removed by grinding, and can be calculated as the difference in wafer thickness before and after grinding (wafer thickness before grinding - wafer thickness after grinding). In the figure, "au" represents an arbitrary unit. The grinding amount difference between the grinding amount of the outer periphery of the wafer and the grinding amount of the central part of the wafer during grinding is taken on the vertical axis, and the pressure difference (Pe-Pc) is taken on the horizontal axis. A graph is prepared, and the measured values are linearly approximated by the least squares method to obtain an approximate straight line of y=cx+d (c and d are independent positive numbers). The square of the correlation coefficient R of the approximate straight line is 2 =0.96, confirming a high correlation.

[0085] As described above, the difference in grinding amount between the periphery of the wafer and the center of the wafer can be controlled by means of the pressure difference between Pe and Pc. On the other hand, it is preferable that, in the previously obtained in-plane thickness distribution information of the wafer, when the thickness of the periphery of the wafer is thicker than that of the center of the wafer, the greater the difference in thickness, the more the grinding amount of the periphery is increased compared to the center in order to improve the in-plane uniformity of the thickness of the wafer after grinding. For example, based on the difference in thickness between the periphery of the wafer and the center of the wafer, a desired grinding amount difference can be determined in order to improve the in-plane uniformity of the thickness of the wafer after grinding, and based on the determined grinding amount difference, the grinding amount difference can be used. Figure 9 The pressure difference (Pe-Pc) is determined based on the correlation relationship shown (e.g., an approximate straight line).

[0086] If the pressure difference is obtained as described above, one of the pressures Pe and Pc to be applied during polishing is determined, and the other pressure (Pc) can also be determined based on the pressure difference. Figure 8 For example, by determining the polishing time t taking into account the production volume and the polishing amount target value B taking into account the ideal value of the wafer thickness corresponding to the application, the polishing rate A can be calculated according to the relationship: A×t=B. The polishing rate is the polishing amount per unit time. According to the research of the inventors of the present invention, the higher the pressure Pc, the greater the polishing amount per unit time (i.e., the higher the polishing rate). In this regard, Figure 10 This is an example of a graph showing the correlation between the polishing rate and Pc at the center of the wafer. The vertical axis is the polishing rate, and the horizontal axis is Pc. The graph is made, and the measured values are linearly approximated using the least squares method to obtain an approximate straight line of y = ex + f (e and f are independent positive numbers). The square of the correlation coefficient of this approximate straight line is R2 = 0.95, confirming a high correlation. For example, using Figure 10The correlation (e.g., approximate straight line) shown above can be used to calculate and determine Pc from the polishing rate A value determined by the above relationship. Once Pc is determined in this way, Pe can be calculated and determined from the pressure difference value determined above and the determined Pc.

[0087] (Determination of Pg)

[0088] As previously described, by determining the pressure difference between Pc and Pe based on the in-plane thickness distribution information of the wafer, Pc and Pe can be set to appropriate values for polishing. As described above, this is preferred, for example, in terms of improving the in-plane uniformity of the wafer thickness after polishing. On the other hand, as previously described, in terms of improving the stability of the polishing process, it is desirable that the contact pressure applied to the lower surface of the second annular component by contact with the polishing pad during polishing is an appropriate value. This contact pressure is affected by the pressure Pg applied downward from the head body by the push head body. Therefore, it is preferred to determine the polishing conditions so that Pg can be set to an appropriate value. In this regard, in the above-mentioned polishing method, the pressure Pg applied downward from the head body by the push head body is determined based on the set value Pr of the contact pressure applied to the lower surface of the second annular component. By determining Pg in this way, Pg can be set to an appropriate value. As a result, the contact pressure applied to the lower surface of the second annular component by contact with the polishing pad during polishing can be set to an appropriate value.

[0089] The above-mentioned Pr can be said to be a value equivalent to or close to the contact pressure actually applied to the lower surface of the second annular member by contact with the polishing pad during polishing. In one embodiment, Pr can be determined empirically or by preliminary experiments. In this case, Pr can be determined empirically or by preliminary experiments, for example, as the contact pressure applied to the lower surface of the second annular member by contact with the polishing pad during polishing, to a value that is unlikely to cause adverse polishing conditions. Examples of adverse polishing conditions include the falling off of the wafer during polishing and damage to components of the polishing device.

[0090] In one embodiment, when determining Pr, a reference value Pt ( Figure 8 (S4). Pt can be considered a benchmark or target value for Pr. For specific methods of determining Pt, refer to the previous description regarding Pr determination. The ratio of Pr to Pt, Pr / Pt, can be, for example, in the range of 0.8 to 1.2.

[0091] Determination of Pg ( Figure 8In the embodiment of the present invention, S5) can be performed based on Pr. In addition, the contact pressure applied to the lower surface of the second annular component by contact with the polishing pad during polishing is affected by the pressure Pg applied downward from the head body by the push head body, and can also be affected by the pressure Pc applied to the central part of the polishing object wafer and the pressure Pe applied to the peripheral part of the polishing object wafer. Therefore, it is preferable to also consider Pc and Pe when determining Pg based on Pr. For example, determining Pg based on Pr can be performed based on the ratio Pr / Pt and the ratio Pe / Pc of Pe to Pc. As a specific example of the determination method, a method for calculating Pg based on the relationship between the ratio Pr / Pt, the ratio Pe / Pc and Pg can be cited. As a relationship formula, for example, the following formula A can be cited. In formula A, coefficients R, X, Y, Z, a and b are respectively independent positive numbers. The coefficients in formula A can be experimentally obtained in one method. In one embodiment, for example, Pr can be calculated from the pressure by varying Pc, Pe, and Pg, and Pr / Pt, Pe / Pc, and Pg / Pc can be calculated. The coefficients in Formula A can be determined by multivariate regression analysis of Pr / Pt, Pe / Pc, and Pg / Pc. The pressure calculation can be performed, for example, by simulation using FEM (Finite Element Method) or the like, depending on the structure of the polishing head.

[0092] (Formula A)

[0093] Pr / Pt=-RX(Pe / Pc)+Y(Pg / Pc)+Z((Pe / Pc)-a)((Pg / Pc)-b)

[0094] In one embodiment, Formula A can be the following Formula A-1.

[0095] (Formula A-1)

[0096] Pr / Pt=-0.3282-0.2087(Pe / Pc)+0.7947(Pg / Pc)+0.0293((Pe / Pc)-0.9)((Pg / Pc)-2.1)

[0097] Based on the above, Pg, Pc, and Pe can be determined.

[0098] As described above, in the polishing method, appropriate polishing conditions can be easily determined without repeating much trial and error.

[0099] <Implementation of Grinding>

[0100] In the polishing method, the lower surface of the wafer to be polished is brought into contact with the polishing pad while the determined Pg, Pc, and Pe are applied. Figure 8, S6). Except for the fact that grinding is performed under the condition that the determined Pg, Pc and Pe are applied, known techniques related to wafer grinding can be applied. The grinding object wafer can be, for example, a semiconductor wafer. The semiconductor wafer can be, for example, a silicon wafer (preferably a single crystal silicon wafer). For example, a silicon wafer can be produced by the following method. A single crystal ingot is pulled out by the Czochralski process, and the produced ingot is cut to obtain a block. The obtained block is sliced to make a wafer. Silicon wafers can be produced by performing various processing on the wafer. As the above-mentioned processing, chamfering processing, flattening processing (polishing, grinding, lapping) and the like can be cited. The above-mentioned grinding method is suitable as a grinding method in the final process of these wafer processing, that is, the fine grinding process.

[0101] [Wafer Manufacturing Method]

[0102] One aspect of the present invention relates to a wafer manufacturing method (hereinafter also simply referred to as a "manufacturing method") that includes polishing a surface of a wafer to be polished by a polishing method to form a polished surface.

[0103] Regarding the wafer polishing in the above-mentioned manufacturing method, the polishing method is as described above. Regarding the manufactured wafer and the various steps performed for wafer manufacturing, reference can be made to the above-mentioned description related to the polishing method, and known techniques can also be applied.

[0104] [Wafer polishing equipment]

[0105] One embodiment of the present invention relates to a wafer polishing apparatus (hereinafter, also simply referred to as a "polishing apparatus").

[0106] The polishing device includes a polishing unit and a polishing condition determination unit.

[0107] The above-mentioned grinding part has a grinding head and a grinding pad. The above-mentioned grinding head has a head body, a first annular component, a plate-shaped component, a diaphragm, and a second annular component. The above-mentioned first annular component is located below the above-mentioned head body and has an opening. The above-mentioned plate-shaped component closes the upper surface side opening of the above-mentioned first annular component, and the above-mentioned diaphragm closes the lower surface side opening of the above-mentioned first annular component. The above-mentioned second annular component is located below the above-mentioned diaphragm and holds the grinding object wafer. The above-mentioned grinding pad contacts the lower surface of the grinding object wafer and the lower surface of the above-mentioned second annular component during grinding. The space portion formed by the opening of the above-mentioned first annular component being closed by the above-mentioned plate-shaped component and the above-mentioned diaphragm has a central area and a peripheral area separated from the central area.

[0108] Regarding the polishing unit, reference can be made to the above description regarding the polishing apparatus that can be used in the polishing method. The polishing unit performs polishing by bringing the lower surface of the wafer to be polished into contact with the polishing pad while applying the Pg, Pc, and Pe conditions determined by the polishing condition determination unit. The wafer polishing and the wafer to be polished are those described above in connection with the polishing method.

[0109] The grinding condition determination unit included in the above-mentioned grinding device determines the pressure difference between the pressure Pc applied to the central part of the grinding object wafer by introducing gas into the above-mentioned central area and the pressure Pe applied to the peripheral part of the grinding object wafer by introducing gas into the above-mentioned peripheral area based on the in-plane thickness distribution information obtained about the grinding object wafer or the wafer subjected to the same processing as the grinding object wafer; determines the pressure of one of Pc and Pe, and determines the pressure of the other based on the determined pressure and the above-mentioned pressure difference; determines the pressure Pg applied downward from the above-mentioned head main body by pushing the above-mentioned head main body based on the set value Pr of the contact pressure applied to the lower surface of the above-mentioned second annular component by contact with the above-mentioned grinding pad during grinding.

[0110] The polishing condition determination unit can determine Pg based on the ratio Pr / Pt of Pr and a reference value Pt of the contact pressure applied to the lower surface of the second annular member, and the ratio Pe / Pc of Pe and Pc. Pg can be determined by calculating Pg from a relationship between the ratio Pr / Pt, the ratio Pe / Pc, and Pg. The relationship can be exemplified by the aforementioned equation A, which may be the aforementioned equation A-1.

[0111] The various determinations performed by the polishing condition determination unit are as described above with respect to the polishing method.

[0112] Figure 11 : is a schematic diagram showing the structure of an example of the above-mentioned grinding device. Figure 11 In the embodiment, the wafer polishing apparatus 1 includes a polishing condition determination unit 2 and a polishing unit 3. Regarding the polishing head 10, the polishing pad 41, and the platen 42 included in the polishing unit 3, reference can be made to the above description.

[0113] The grinding condition determination unit 2 includes an in-plane thickness distribution information input unit 201 and a determination unit 202. The in-plane thickness distribution information input unit 201 inputs in-plane thickness distribution information obtained about the grinding target wafer or a wafer subjected to the same processing as the grinding target wafer. The wafer grinding device 1 can also include a wafer thickness measuring unit (not shown). The introduction of the measurement target wafer into the wafer thickness measuring unit can be performed manually or automatically. For example, the grinding process can be automated so that the grinding target wafer before being introduced into the grinding unit 3 is introduced into the wafer thickness measuring unit. The determination unit 202 receives or takes out the in-plane thickness distribution information from the in-plane thickness distribution information input unit 201, and determines Pg, Pc and Pe as described above. The determination can be performed using known calculation software. In the calculation software, for example, the calculation of the pressure difference (Pe-Pc) based on the correlation (such as the approximate curve) described above, the determination of Pc based on the relationship, the calculation of Pe based on Pc and the pressure difference (Pe-Pc), the structural analysis of stress-displacement based on FEM or the calculation of Pt or Pr based on the force balance formula, and the calculation of Pg based on Formula A are performed.

[0114] In one embodiment, the polishing unit 1 can receive or retrieve the values of Pg, Pc, and Pe from the determination unit 10. The polishing unit 1 can determine the pressing conditions of the head body and the conditions for introducing gas into the central and peripheral regions of the space, thereby applying Pg, Pc, and Pe to perform polishing. Furthermore, in one embodiment, the determination unit 10 can determine the pressing conditions and / or gas introduction conditions using, for example, known calculation software, and information related to the determined conditions can be transmitted to or retrieved from the determination unit 10.

[0115] In the wafer grinding device, the grinding condition determination unit and the grinding unit can be connected by wireless or wired communication means. This is also the same for the wafer thickness measuring unit and the grinding condition determination unit. Figure 11 2 shows an example of a wafer polishing apparatus in which one polishing condition determination unit includes one polishing unit. However, the wafer polishing apparatus is not limited to this example. For example, one polishing condition determination unit and two or more polishing units may be connected via wireless or wired communication means.

[0116] Example

[0117] Hereinafter, the present invention will be described based on the examples. However, the present invention is not limited to the embodiments shown in the examples. Hereinafter, the grinding surface pressure and the contact pressure are calculated by pressure calculation (finite element method) using ABAQUS manufactured by Dassault Systèmes.

[0118] exist Figure 1In the structural analytical model of the polishing head having the structure shown, Pr was calculated by pressure calculation with changes in Pc, Pe, and Pg through FEM simulation, and Pr / Pt, Pe / Pc, and Pg / Pc were calculated. The various coefficients in Formula A were then determined by multivariate regression analysis of Pr / Pt, Pe / Pc, and Pg / Pc. Specifically, with Pr / Pt on the vertical axis and Pg / Pc on the horizontal axis, a graph showing the relationship between Pr / Pt and Pg / Pc was created for the cases of Pe / Pc = 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, and 1.6. The above-described Formula A-1 (the square of the correlation coefficient R of the approximate straight line) was determined as the relationship between Pr / Pt, Pe / Pc, and Pg / Pc obtained by multivariate regression analysis of all 80 data points in the graph. 2 =0.99).

[0119] Table 1 is a table summarizing the relationship between grinding conditions and the possibility of stable grinding based on the pressure calculation (finite element method) using ABAQUS made by Dassault Systemes and the findings obtained experimentally. In the table, "WF shedding" means that the wafer falls off during grinding, and "excessive wear" means that excessive wear of the second annular component occurs. "Good" means that these do not occur and stable grinding can be achieved. For example, the result of determining Pg as a constant value without being based on Pr is that when Pg is set to a value such as Pg / Pc=1.2 or Pg / Pc=3.0, the wafer falls off during grinding or excessive wear of the second annular component occurs, and the stability of the grinding process decreases. In addition, as shown in Table 1, in the case of Pg / Pc=2.2, although it is "good" in the range of Pe / Pc values of 1.0 to 1.6, excessive wear of the second annular component occurs in the range of 0.2 to 0.8, and the stability of the grinding process decreases. That is, as a result of determining Pg as a constant value without taking Pr into account, when Pg is set to a value such as Pg / Pc=2.2, excessive wear of the second annular member may occur.

[0120] In contrast, according to the above-described polishing method, for example, by determining Pc and Pe as described above, and using Formula A-1 to determine Pg so that Pr / Pt is within the range of 0.8 to 1.2, the polishing conditions (Pc, Pe, and Pg during polishing) are set. This prevents wafer dropout and excessive wear of the second annular member during polishing, allowing wafer polishing to be performed with high stability. Furthermore, the polishing conditions can be easily determined, for example, by following the process described above, without extensive trial and error.

[0121] Furthermore, by maintaining Pg, Pc, and Pe constant at set values during polishing, the contact pressure applied to the lower surface of the second annular member by contact with the polishing pad during polishing can be maintained constant or its variation can be reduced. This can suppress fluctuations in the amount of polishing on the outer periphery of the wafer.

[0122] [Table 1]

[0123]

[0124] Figure 12 This is a graph showing the distribution of the polishing amount within the surface to be polished of a wafer under different polishing conditions. Figure 12 The grinding amount of each part in the surface shown is Pe / Pc is 1, for the following (1) to (3):

[0125] (1) Pr / Pt = 0.5, Pg / Pc = 1.2

[0126] (2) Pr / Pt = 1.0, Pg / Pc = 1.9

[0127] (3) Pr / Pt = 1.8, Pg / Pc = 3.0

[0128] In such a case where Pr (specifically, Pr / Pt) and Pg (specifically, Pg / Pc) are different, they are calculated using the Preston formula.

[0129] As explained above, the difference in the amount of polishing between the wafer periphery and the wafer center can be controlled by the pressure difference between Pe and Pc. Figure 12The results shown show that, while Pe and Pc remain constant, Pr changes due to differences in Pg, resulting in a change in the amount of polishing applied to the wafer's periphery. Specifically, the greater the Pg, the greater the amount of polishing applied to the wafer's periphery, while the smaller the Pg, the less the amount of polishing applied to the wafer's periphery. For example, regarding the in-plane uniformity of the wafer's thickness after polishing, as previously described, if the thickness of the periphery of the wafer being polished is thicker than that of the central portion, the greater the difference in thickness, the more the amount of polishing applied to the periphery compared to the central portion. In other words, if the difference in thickness between the periphery and central portions of the wafer being polished is small, the difference in the amount of polishing applied to the central portion and the periphery is preferably smaller to improve the in-plane uniformity of the wafer's thickness after polishing. Thus, when polishing wafers of varying shapes, it is preferable to appropriately set the polishing conditions based on the shape of the wafer being polished. In this regard, according to the above-mentioned grinding method, Pg, Pc and Pe can be determined as appropriate values that can achieve the desired grinding amount corresponding to the shape of each chip based on the in-plane thickness distribution information obtained about the grinding object chip or the chip that has been subjected to the same processing as the grinding object chip, and this determination can be easily performed without much trial and error.

[0130] One aspect of the present invention is applicable in the technical field of semiconductor wafers such as silicon wafers.

Claims

1. A wafer grinding method, wherein a wafer is ground using a grinding device, characterized in that: The polishing device comprises a polishing head and a polishing pad. The polishing head comprises a head body, a first annular component, a plate-shaped component, a diaphragm, and a second annular component. The first annular component is located below the head body and has an opening. The plate-shaped component seals the upper surface opening of the first annular component. The diaphragm seals the lower surface opening of the first annular component. The second annular component is located below the diaphragm and holds the wafer to be polished. The polishing pad is in contact with the lower surface of the wafer to be polished and the lower surface of the second annular member during polishing. The space formed by the opening of the first annular member being closed by the plate-shaped member and the diaphragm comprises a central region and an outer peripheral region separated from the central region. The wafer grinding method comprises: Acquiring in-plane thickness distribution information about a wafer to be polished or a wafer that has been subjected to the same processing as the wafer to be polished; Based on the in-plane thickness distribution information, determining a pressure difference between Pc and Pe, where Pc is the pressure applied to the central portion of the wafer to be polished by introducing gas into the central region, and Pe is the pressure applied to the peripheral portion of the wafer to be polished by introducing gas into the peripheral region; Determine the pressure of one of Pc and Pe, and determine the pressure of the other based on the determined pressure and the aforementioned pressure difference; Determining Pg based on Pr, wherein Pr is a set value of the contact pressure applied to the lower surface of the second annular member by contact with the polishing pad during polishing, and Pg is a pressure applied downward from the head body by pushing the head body; Polishing is performed by bringing the lower surface of the wafer to be polished into contact with the polishing pad while the determined Pg, Pc, and Pe are applied.

2. The wafer polishing method according to claim 1, wherein: include: The Pg is determined based on the ratio Pr / Pt of the Pr and Pt and the ratio Pe / Pc of the Pe and Pc, wherein the Pt is a reference value of the contact pressure applied to the lower surface of the second annular member.

3. The wafer polishing method according to claim 2, wherein: The method further includes calculating Pg based on a relationship between the ratio Pr / Pt, the ratio Pe / Pc and Pg, thereby determining Pg.

4. The wafer polishing method according to claim 3, wherein: The aforementioned relationship is the following formula A: (Formula A) Pr / Pt=-R-X(Pe / Pc)+Y(Pg / Pc)+Z((Pe / Pc)-a)((Pg / Pc)-b) R, X, Y, Z, a, and b are each independent positive numbers.

5. The wafer polishing method according to any one of claims 2 to 4, wherein: The ratio Pr / Pt is in the range of 0.8 to 1.

2.

6. A method for manufacturing a wafer, characterized in that: include: The surface of a wafer to be polished is polished by the wafer polishing method according to any one of claims 1 to 5 to form a polished surface.

7. The method for manufacturing a wafer according to claim 6, wherein: The aforementioned wafer is a semiconductor wafer.

8. The method for manufacturing a wafer according to claim 7, wherein: The aforementioned semiconductor wafer is a silicon wafer.

9. A wafer grinding device, characterized in that: including a grinding section and a grinding condition determination section, The polishing part has a polishing head and a polishing pad. The polishing head comprises a head body, a first annular component, a plate-shaped component, a diaphragm, and a second annular component. The first annular component is located below the head body and has an opening. The plate-shaped component seals the upper surface opening of the first annular component. The diaphragm seals the lower surface opening of the first annular component. The second annular component is located below the diaphragm and holds the wafer to be polished. The polishing pad is in contact with the lower surface of the wafer to be polished and the lower surface of the second annular member during polishing. The space formed by the opening of the first annular member being closed by the plate-shaped member and the diaphragm comprises a central region and an outer peripheral region separated from the central region. The grinding condition determination unit is configured as follows: determining, based on in-plane thickness distribution information obtained for a wafer to be polished or a wafer subjected to the same processing as the wafer to be polished, a pressure difference between Pc and Pe, where Pc is the pressure applied to the central portion of the wafer to be polished by introducing gas into the central region and Pe is the pressure applied to the peripheral portion of the wafer to be polished by introducing gas into the peripheral region; Determine the pressure of one of Pc and Pe, and determine the pressure of the other based on the determined pressure and the aforementioned pressure difference; Determining Pg based on Pr, wherein Pr is a set value of the contact pressure applied to the lower surface of the second annular member by contact with the polishing pad during polishing, and Pg is a pressure applied downward from the head body by pushing the head body; The polishing section performs polishing by bringing the lower surface of the wafer to be polished into contact with the polishing pad in a state where the determined Pg, Pc, and Pe are applied.

10. The wafer polishing apparatus according to claim 9, wherein: The polishing condition determination unit determines Pg based on a ratio Pr / Pt of Pr and Pt and a ratio Pe / Pc of Pe and Pc, wherein Pt is a reference value of a contact pressure applied to the lower surface of the second annular member.

11. The wafer polishing apparatus according to claim 10, wherein: The polishing condition determination unit determines Pg by calculating Pg based on a relational expression among the ratio Pr / Pt, the ratio Pe / Pc, and Pg.

12. The wafer polishing apparatus according to claim 11, wherein: The aforementioned relationship is the following formula A: (Formula A) Pr / Pt=-R-X(Pe / Pc)+Y(Pg / Pc)+Z((Pe / Pc)-a)((Pg / Pc)-b) R, X, Y, Z, a, and b are each independent positive numbers.

13. The wafer polishing apparatus according to any one of claims 10 to 12, wherein: The ratio Pr / Pt is in the range of 0.8 to 1.

2.

14. The wafer polishing apparatus according to any one of claims 9 to 12, wherein: The aforementioned wafer is a semiconductor wafer.

15. The wafer polishing apparatus according to claim 13, wherein: The aforementioned wafer is a semiconductor wafer.

16. The wafer grinding apparatus according to claim 14, wherein: The aforementioned semiconductor wafer is a silicon wafer.

17. The wafer grinding apparatus according to claim 15, wherein: The aforementioned semiconductor wafer is a silicon wafer.

Images