Wafer polishing equipment

Abstract

To provide a wafer polishing apparatus that offers superior precision on the polished surface of the wafer after polishing, while also achieving higher productivity. [Solution] The wafer polishing apparatus of the present invention comprises a base plate 1, 3, a carrier 5, polishing bodies 7, 9, and a polishing liquid supply means 11 for interposing a polishing liquid 19 between the wafer W and the polishing bodies 7, 9. The base plate 1, 3 and the polishing bodies 7, 9 have circular holes 1a, 7a, 9a, and 3a formed in the same circular shape as the axis O1. The polishing liquid supply means 11 is configured to supply the polishing liquid 19 to the inner edges of the polishing bodies 7, 9 on the side of the circular holes 1a, 7a, 9a, and 3a.

Description

Technical Field

[0001] The present invention relates to a wafer polishing apparatus that can be used as a lapping machine, a polishing machine, or the like.

Background Art

[0002] An example of a conventional wafer polishing apparatus is disclosed in Patent Document 1. This wafer polishing apparatus includes a surface plate, a carrier, a polishing body, and a polishing liquid supply means. The surface plate has a fixing surface extending in a direction orthogonal to the axis, and is rotated around the axis. In this wafer polishing apparatus, the surface plate consists of a lower surface plate whose lower fixing surface as the fixing surface faces upward, and an upper surface plate whose upper fixing surface as the fixing surface faces downward.

[0003] The carrier is provided between the lower surface plate and the upper surface plate, and holds one or more plate-shaped wafers rotatably relative to the lower surface plate and the upper surface plate. The polishing body consists of a lower polishing body fixed to the lower fixing surface and an upper polishing body fixed to the upper fixing surface. The lower polishing body and the upper polishing body clamp the wafer under a predetermined surface pressure. The polishing surface of the lower polishing body abuts against the lower surface to be polished, which is the lower surface of the wafer, and the polishing surface of the upper polishing body abuts against the upper surface to be polished, which is the upper surface of the wafer. As the lower polishing body and the upper polishing body, lapping plates having a polishing layer, polishing pads, or the like are employed. The polishing liquid supply means interposes a polishing liquid between the lower surface to be polished of the wafer and the polishing surface of the lower polishing body, and between the upper surface to be polished of the wafer and the polishing surface of the upper polishing body. The polishing liquid may or may not contain abrasive grains.

[0004] In this wafer polishing apparatus, one or more wafers are held by the carrier, and the lower and upper surfaces to be polished of each wafer can be polished simultaneously in the presence of the polishing liquid. Therefore, if this wafer polishing apparatus is used as, for example, a lapping machine, both surfaces of the wafer can be polished in a short time, and thus high productivity can be exhibited.

Prior Art Literature

Patent Literature

[0005] [Patent Document 1] Patent No. 6885492 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, according to the inventor's test results, conventional wafer polishing equipment does not achieve sufficient precision on the polished surface of the wafer after polishing when the platen is rotated at high speed to achieve higher productivity. As wafer diameters increase and efficiency increases, the size of wafer polishing equipment tends to increase, making it extremely important to perform stable, high-precision processing with wafer polishing equipment.

[0007] This invention has been made in view of the above-mentioned conventional circumstances, and aims to solve the problem of providing a wafer polishing apparatus that can achieve higher productivity while maintaining excellent accuracy of the polished surface of the wafer after polishing. [Means for solving the problem]

[0008] The inventor conducted various studies to determine why conventional wafer polishing equipment could not polish the surface to be polished with high precision when operating at high speeds. The inventor concluded that the reason lay in the position where the polishing liquid was interposed between the wafer and the polishing body by the polishing liquid supply means, and that in conventional wafer polishing equipment, this position was inappropriate, resulting in uneven replacement of the polishing body. Based on this, the inventor completed the present invention.

[0009] The wafer polishing apparatus of the present invention comprises a platen having a fixed surface extending in a direction perpendicular to the axis and rotating around the axis, a carrier that holds a flat wafer so as to be rotatable relative to the platen, a polishing body fixed to the fixed surface and polishing the wafer under a predetermined surface pressure, and a polishing liquid supply means for interposing a polishing liquid between the wafer and the polishing body, The surface plate and the polishing body have circular holes formed in them that are coaxial with the axis. The polishing liquid supply means is characterized in that it is configured to supply the polishing liquid to the inner edge of the circular hole side of the polishing body.

[0010] In the wafer polishing apparatus of the present invention, a circular hole is formed in the base plate and the polishing body, which is coaxial with the axis. This circular hole is sometimes unavoidably necessary for the placement of a sun gear or the like when the base plate and polishing body rotate around the axis. In such a wafer polishing apparatus, the carrier is positioned in the area on the outer circumference of the base plate, relative to the circular hole. In this wafer polishing apparatus, the polishing fluid supply means supplies the polishing fluid to the inner edge of the polishing body on the side of the circular hole. Therefore, the polishing fluid easily moves uniformly from its inner edge to the surface of the wafer to be polished and the polishing surface of the polishing body due to the centrifugal force of the base plate. As a result, even when the base plate is rotated at high speed, the surface of the polishing body changes uniformly, and the accuracy of the polished surface of the wafer after polishing is improved.

[0011] Therefore, the wafer polishing apparatus of the present invention can achieve higher productivity while maintaining excellent accuracy of the polished surface of the wafer after polishing.

[0012] The polishing plate may consist of a lower platen with a lower circular hole formed therein and a lower fixed surface facing upward, and an upper platen with an upper circular hole formed therein and an upper fixed surface facing downward. A carrier may be provided between the lower and upper platens. Furthermore, the polishing body may consist of a lower polishing body fixed to the lower fixed surface and an upper polishing body fixed to the upper fixed surface. Preferably, the polishing fluid supply means is configured to supply polishing fluid to the inner edge of the upper polishing body on the side with the upper circular hole and to the inner edge of the lower polishing body on the side with the lower circular hole. In this case, the lower and upper polishing surfaces of each wafer can be polished simultaneously. Therefore, this wafer polishing apparatus can polish both sides of a wafer uniformly in a short time and can exhibit higher productivity.

[0013] The polishing fluid supply means is preferably positioned on the upper platen and includes a tray for storing the polishing fluid and an inner edge supply passage for supplying the polishing fluid in the tray to the inner edge on the upper circular hole side via the upper platen. In this case, it becomes possible to easily supply the polishing fluid to the inner edge on the upper circular hole side and the inner edge on the lower circular hole side, and the structure of the polishing fluid supply means is simplified.

[0014] It is preferable that the upper circular hole has a larger diameter than the lower circular hole. In this case, it becomes possible to supply an appropriate amount of polishing fluid to the inner edge of the upper circular hole while also supplying an appropriate amount to the inner edge of the lower circular hole. The difference between the inner diameter of the upper circular hole and the inner diameter of the lower circular hole is appropriately set depending on the size of the lower and upper platen, the rotation speed, the viscosity of the polishing fluid, etc.

[0015] If the abrasive body does not contain abrasive particles, the polishing solution will contain abrasive particles. If the abrasive body does contain abrasive particles, the polishing solution may or may not contain abrasive particles. [Effects of the Invention]

[0016] According to the wafer polishing apparatus of the present invention, it is possible to achieve higher productivity while maintaining excellent accuracy of the polished surface of the wafer after polishing. [Brief explanation of the drawing]

[0017] [Figure 1] Figure 1 is a schematic cross-sectional view of the wafer polishing apparatus of Example 1. [Figure 2] Figure 2 is an enlarged schematic cross-sectional view of the main part of the wafer polishing apparatus of Example 1. [Figure 3] Figure 3 is a graph showing the relationship between the difference between the inner diameter of the lower circular hole and the inner diameter of the upper circular hole, the cumulative processing time, and the removal efficiency for the wafer polishing apparatus of Example 1. [Figure 4] Figure 4 is a graph showing the relationship between the difference between the inner diameter of the lower circular hole and the inner diameter of the upper circular hole, the cumulative processing time, and TTV for the wafer polishing apparatus of Example 1. [Figure 5] Figure 5 is an enlarged schematic cross-sectional view of the main part of the wafer polishing apparatus of Example 2. [Figure 6] Figure 6 is an enlarged schematic cross-sectional view of the main part of a comparative example wafer polishing apparatus. MODE FOR CARRYING OUT THE INVENTION

[0018] Hereinafter, Examples 1 and 2 embodying the present invention will be described together with comparative examples with reference to the drawings.

[0019] (Example 1) The wafer polishing apparatus of Example 1 is a double-sided wafer polishing apparatus including a lower surface plate, an upper surface plate, a plurality of carriers, a first lapping plate, a second lapping plate, and a polishing liquid supply apparatus, as shown in FIG. 1 and FIG. 2. In Example 1, this wafer polishing apparatus is used as a lapping machine.

[0020] The lower surface plate has an annular shape formed with a lower circular hole that is coaxial with the first axis O1 and has a circular shape. A fixing surface extending in a direction perpendicular to the first axis O1 is formed on the upper surface of the lower surface plate, and the first lapping plate serving as a lower polishing body is fixed to the fixing surface. The first lapping plate also has an annular shape formed with a first circular hole aligned with the lower circular hole 1a.

[0021] The upper surface plate also has an annular shape formed with an upper circular hole that is coaxial with the first axis O1 and has a circular shape. A fixing surface extending in a direction perpendicular to the first axis O1 is also formed on the lower surface of the upper surface plate, and the second lapping plate serving as an upper polishing body is provided on the fixing surface. The second lapping plate also has an annular shape formed with a second circular hole aligned with the upper circular hole 3a.

[0022] The lower surface plate and the upper surface plate are each provided with a rotation shaft (not shown), and these rotation shafts are independently rotated around the first axis O1 at a predetermined speed by a driving device. In addition, the lower surface plate and the upper surface plate can approach and separate from each other. The first lapping plate and the second lapping plate extend horizontally in a direction perpendicular to the first axis O1 and face each other.

[0023] The carrier 5 is provided between the lower platen 1 and the upper platen 3, more specifically between the first lap plate 7 and the second lap plate 9. The carrier 5 is provided with a drive force transmission mechanism (not shown), and the carrier 5 is rotated relative to the lower platen 1 and the upper platen 3 at a predetermined speed around a second axis O2 parallel to the first axis O1 by the drive force transmission mechanism.

[0024] The carrier 5 extends horizontally in a direction perpendicular to the second axis O2, and faces both the first lap plate 7 and the second lap plate 9. The carrier 5 is provided with multiple fixing parts 5a. A wafer W can be mounted on each fixing part 5a.

[0025] Each wafer W is made of SiC. The Si side of the SiC is the lower polishing surface W1, and the C side of the SiC is the upper polishing surface W2. The lower polishing surface W1 of wafer W faces the polishing surface 7b of the first lap plate 7, and the upper polishing surface W2 faces the polishing surface 9b of the second lap plate 9. Alternatively, the C side of the SiC may be used as the lower polishing surface W1, and the Si side of the SiC may be used as the upper polishing surface W2.

[0026] An annular receiving tray 15 is positioned on the upper platen 3. The receiving tray 15 is also rotatable around the first axis O1 along with the upper platen 3. Multiple nozzles 17 face the receiving tray 15, and each nozzle 17 is connected to a pump and a tank (not shown). Therefore, polishing fluid 19 in the tank is supplied into the receiving tray 15 from each nozzle 17. Multiple supply holes 15a are formed in the receiving tray 15, and a tube 21 extending up to the upper platen 3 is connected to each supply hole 15a. Multiple communication holes 11a and openings 11b that communicate with the tube 21 are provided through the upper platen 3 and the second lap plate 9.

[0027] In the wafer polishing apparatus of Embodiment 1, in addition to the communication holes 11a and openings 11b, an inner edge supply passage 11c that communicates with the tube 21 is also recessed in the upper platen 3. The inner edge supply passage 11c extends radially to the upper circular hole 3a of the upper platen 3 and connects to the inner edge of the upper circular hole 3a and the inner edge of the second circular hole 9a of the second lap plate 9. The tank, pump, each nozzle 17, receiving tray 15, each supply hole 15a, each tube 21, each communication hole 11a, each opening 11b, and the inner edge supply passage 11c correspond to the polishing fluid supply means 11.

[0028] Meanwhile, the following steps were taken to obtain the first and second wrap plates 7 and 9. <Preparation process> First, we prepared the following countless fixed abrasive grains, countless metallic aggregates, and free abrasive grains. Fixed abrasive grain: Diamond (SD3000 (D50: 5μm)) Aggregate: Dendritic powder made of Cu (Specific surface area: 450-5000 cm²) 2 Spherical powder consisting of ( / g), Sn (specific surface area: 350-1000 cm²) 2 / g) Polishing solution (lapping solution): An aqueous solution containing 1% by mass of Al2O3 (average particle size: 3 μm) as free abrasive particles.

[0029] <Mixed molding process> 70% by mass of dendritic powder made of Cu and 30% by mass of spherical powder made of Sn were placed in a container, and fixed abrasive grains were added and mixed so that the concentration in the abrasive layer was 75 (fixed abrasive grain content was 18.75% by volume), and a molded body of a predetermined shape was formed in a mold.

[0030] <Crimping process> Place the molded body into the crimping mold and apply a unit pressure of 2 tons / cm². 2 The aggregates were then pressed and crimped together. This formed a polished layer. The polished layer was fixed to the upper surface of the plate body, forming the first and second lap plates 7 and 9.

[0031] Machining tests were conducted under the following conditions to evaluate the removal efficiency of the workpiece W (μm / min), the difference between the maximum and minimum thickness of the workpiece W (TTV (Total Thickness Variation)) (μm), and the surface roughness Ra (nm) of the workpiece W. For the lower platen 1 and the first lap plate 7, the inner diameter D1 of the lower circular hole 1a and the first circular hole 7a was maintained. For the upper platen 3 and the second lap plate 9, the inner diameter D2 of the upper circular hole 3a and the second circular hole 9a was set to be equal to D1, D1-2 (mm), D1-10 (mm), and D1-20 (mm).

[0032] <Processing conditions> Wrap plate dimensions: Outer diameter 240 x Width 20 (mm) Workpiece: SiC wafers (4-inch x 3 sheets) Lower platen rotation speed: 60 rpm Upper plate rotation speed: 120 rpm Unit pressure: 200 gr / cm² 2 Workpiece rotation conditions: accompanying rotation Polishing solution (lapping solution): 50cc / min Processing time: 60 minutes x 3 times (total 180 minutes)

[0033] When the wafer polishing apparatus is activated, the lower platen 1 and the upper platen 3 move closer together, and each wafer W and the first and second lap plates 7 and 9 are pressurized to a predetermined surface pressure. Then, the drive unit 13 is driven, and the lower platen 1, the upper platen 3, and each carrier 5 rotate. As a result, the lower polishing surface W1 of each wafer W and the polishing surface 7b of the first lap plate 7 move relative to each other at a predetermined speed, polishing the lower polishing surface W1, and the upper polishing surface W2 of each wafer W and the polishing surface 9b of the second lap plate 9 move relative to each other at a predetermined speed, polishing the upper polishing surface W2. Thus, the polishing of the lower polishing surface W1 and the upper polishing surface W2 are completed simultaneously.

[0034] During this time, in the wafer polishing apparatus of Example 1, the polishing liquid 19 in the receiving tray 15 is supplied between the first lap plate 7 and the second lap plate 9 through each supply hole 15a, each tube 21, each communication hole 11a and each opening 11b, and also through each supply hole 15a, each tube 21 and the inner edge supply passage 11c.

[0035] More specifically, the polishing fluid 19 passing through each communication hole 11a and each opening 11b is supplied between the polishing surface 9b of the second lap plate 9 and the upper polishing surface W1 of the wafer W, as indicated by the white arrows. The polishing fluid 19 supplied to the upper surface of the carrier 5 and the upper polishing surface W2 of the wafer W is supplied radially outward from the carrier 5 by centrifugal force due to the rotation of the carrier 5 around its second axis O2, and also supplied radially outward from the upper platen 3 by centrifugal force due to the rotation of the upper platen 3 around its first axis O1.

[0036] Furthermore, the polishing liquid 19 supplied between the polishing surface 9b of the second lap plate 9 and the upper polishing surface W1 of the wafer W is supplied through the gap between the carriers 5 and the lower polishing surface W1 of the first lap plate 7 and the wafer W. The polishing liquid 19 supplied to the lower surface of the carrier 5 and the lower polishing surface W1 of the wafer W is supplied radially outward from the carrier 5 by centrifugal force due to the rotation of the carrier 5 around its second axis O2, and also supplied radially outward from the lower platen 3 by centrifugal force due to the rotation of the lower platen 1 around its first axis O1.

[0037] In particular, even if the inner diameter difference between the two holes is 0 to 20 mm, the polishing fluid 19 that has passed through the inner edge supply passage 11c reaches the inner edges of the upper circular hole 3a and the second circular hole 9a, and then, due to the centrifugal force caused by the rotation of the upper platen 3 around the first axis O1, it is supplied from the inner edge of the second circular hole 9a between the polishing surface 9b of the second lap plate 9 and the upper polished surface W2 of the wafer W.

[0038] Furthermore, the polishing fluid 19 that reaches the inner edges of the upper hole 3a and the second hole 9a also reaches the inner edges of the first hole 7a and the lower hole 1a, and is supplied from the inner edge of the first hole 7a between the polishing surface 7b of the first lap plate 7 and the lower polishing surface W1 of the wafer W by the centrifugal force caused by the rotation of the lower platen 3 around the first axis O1.

[0039] Thus, in this wafer polishing apparatus, the polishing liquid 19 moves uniformly between the polishing surface 9b of the second lap plate 9 and the upper polishing surface W2 of the wafer W, and between the polishing surface 7b of the first lap plate 7 and the lower polishing surface W1 of the wafer W. For this reason, even when the lower platen 1, the upper platen 3, and each carrier 5 are rotated at high speed, the changes in the polishing surfaces 7b and 9b of the first and second lap plates 7 and 9 become uniform, and the accuracy of the lower polishing surface W1 and upper polishing surface W2 of the wafer W after polishing is high.

[0040] In this wafer polishing apparatus, the relationship between cumulative processing time and removal efficiency is shown in Figure 3, and the relationship between cumulative processing time and TTV is shown in Figure 4. Furthermore, Table 1 shows the difference in surface roughness Ra due to the inner diameter difference (inner diameter D2 - inner diameter D1), which is the difference between the inner diameter D1 of the lower circular hole 1a of the lower platen 1 and the first circular hole 7a of the first lap plate 7, and the inner diameter D2 of the upper circular hole 3a of the upper platen 3 and the second circular hole 9a of the second lap plate 9.

[0041] [Table 1]

[0042] As shown in Figures 3 and 4 and Table 1, the wafer polishing apparatus of Example 1 shows excellent accuracy of the lower polished surface W1 and upper polished surface W2 of the wafer W after polishing.

[0043] Therefore, it can be seen that the wafer polishing apparatus of Example 1 provides excellent accuracy to the lower polished surface W1 and upper polished surface W2 of the wafer W after polishing, as well as achieving higher productivity.

[0044] Upon closer examination, it was found that when the inner diameter difference is 0 mm, the removal efficiency is lower and the TTV worsens with increasing processing time compared to when the inner diameter difference is 2 mm or 10 mm. This is thought to be because, when the inner diameter difference is 0 mm, the change in surface texture on the inner circumference is not promoted, making it easier for the polished surfaces 7b and 9b of the first and second lap plates 7 and 9 to become uneven.

[0045] Furthermore, when the inner diameter difference is 20 mm, the removal efficiency is almost the same as when the inner diameter difference is 2 mm or 10 mm, but the TTV is slightly worse. This is thought to be because, when the inner diameter difference is 20 mm, the wafer W is not sandwiched on the upper inner circumference side, causing the wafer W to move around and worsening the TTV.

[0046] On the other hand, when the inner diameter difference is 2 mm or 10 mm, the processing efficiency is higher and more stable compared to other inner diameter differences, and the TTV also shows a stable and small value. This is thought to be because the polishing fluid is properly supplied to the inner circumference as well, so the entire polishing surface 7b, 9b of the first and second lapping plates 7, 9 is uniformly replaced, and the area where the wafer W is not sandwiched is small, resulting in less movement of the wafer W and enabling high-precision lapping.

[0047] Therefore, it is preferable that the upper circular hole 3a has a larger diameter than the lower circular hole 1a. Furthermore, it is preferable that the inner diameter difference be between 2 and 10 mm under the above machining conditions. Under other machining conditions, the size of the lower platen 1 and upper platen 3, the rotational speed, the viscosity of the polishing fluid 19, etc., are appropriately designed.

[0048] (Example 2) As shown in Figure 5, the wafer polishing apparatus of Example 2 has an inner diameter difference of 0 mm, and the inner edge supply passage 11d communicating with the tube 21 extends radially to the upper circular hole 3a of the upper platen 3. However, it bends downward before reaching the inner edges of the upper circular hole 3a and the second circular hole 9a of the second lap plate 9, and connects to the inner edges of the upper circular hole 3a and the second circular hole 9a of the second lap plate 9. The other configurations are the same as those of the wafer polishing apparatus of Example 1, so the same reference numerals are used for the same components and detailed descriptions are omitted.

[0049] In this wafer polishing apparatus, under the same processing conditions as the wafer polishing apparatus of Example 1, the polishing liquid 19 flows downward to the inner edges of the upper circular hole 3a and the second circular hole 9a. After this, the polishing liquid 19 is supplied from the inner edge of the second circular hole 9a to the polishing surface 9b of the second lap plate 9 and the upper polished surface W2 of the wafer W by centrifugal force due to the rotation of the upper platen 3 around the first axis O1.

[0050] Furthermore, the polishing fluid 19 that reaches the inner edges of the upper circular hole 3a and the second circular hole 9a, although the amount is less than that of the wafer polishing apparatus in Example 1 due to the difference in inner diameter of 0 mm, also reaches the inner edges of the first circular hole 7a and the lower circular hole 1a, and is supplied from the inner edge of the first circular hole 7a between the polishing surface 7b of the first lap plate 7 and the lower polishing surface W1 of the wafer W by the centrifugal force caused by the rotation of the lower platen 3 around the first axis O1.

[0051] Thus, this wafer polishing apparatus produces the same effects and advantages as the wafer polishing apparatus of Example 1.

[0052] (Comparative example) The wafer polishing apparatus of the comparative example is a known one, as shown in Figure 6. This wafer polishing apparatus has an inner diameter difference of 0 mm and does not have the inner edge supply passage 11c of Example 1 or the inner edge supply passage 11d of Example 2. The upper platen 3 and the second lap plate 9 are provided with only a plurality of communication holes 11a and openings 11b that communicate with the tube 21. The innermost opening 11b is located about 20 to 40 mm outside the inner circumference of the second lap plate 3. The other configurations are the same as those of the wafer polishing apparatuses of Examples 1 and 2, so the same reference numerals are used for the same components and detailed descriptions are omitted.

[0053] In this wafer polishing apparatus, under the same processing conditions as the wafer polishing apparatus of Example 1, the polishing liquid 19 has difficulty reaching the inner edges of the upper circular hole 3a and the second circular hole 9a. This is because, when the lower platen 1, the upper platen 3, and each carrier 5 are rotated at high speed, the polishing liquid 19 is easily discharged outside the second lap plate 9 by the peripheral speed of the upper platen 3 before it can act on the polishing surface 9b of the second lap plate 9.

[0054] Therefore, in this wafer polishing apparatus, it becomes difficult to change the inner circumference of the polishing surface 9b of the second lap plate 9 and the polishing surface 7b of the first lap plate 7, resulting in inaccuracies in the lower polished surface W1 and upper polished surface W2 of the wafer W after polishing.

[0055] Although the present invention has been described above in reference to Examples 1 and 2, it goes without saying that the present invention is not limited to Examples 1 and 2, and can be applied with appropriate modifications without departing from its spirit.

[0056] For example, in the above embodiments 1 and 2, the present invention was applied to a double-sided wafer polishing apparatus capable of polishing both sides of the wafer W, but it is also possible to apply the present invention to a single-sided wafer polishing apparatus capable of polishing only one side of the wafer W.

[0057] Furthermore, in Examples 1 and 2 above, the wafer polishing apparatus of the present invention was a lapping machine, but it can also be a polishing machine.

[0058] Furthermore, in Examples 1 and 2 above, an aqueous polishing solution containing Al2O3 as free abrasive particles was used as the polishing solution, but in the present invention, other polishing solutions can also be used.

[0059] Furthermore, while the above-mentioned Examples 1 and 2 used a lapping plate with a polishing layer containing fixed diamond abrasive grains, it is also possible to use an abrasive body with a polishing layer containing other types of abrasive grains.

[0060] Furthermore, in the above-described examples 1 and 2, the holding portion that holds the fixed abrasive grains has countless aggregates made of metal, and each aggregate is intertwined with others while forming pores between them without being bonded or joined to one another. However, the holding portion that holds the fixed abrasive grains may be made of metal or resin.

[0061] The inner edge supply channel 11c may be formed as a groove or as a hole. [Industrial applicability]

[0062] This invention can be used in lapping machines, polishing machines, and the like. [Explanation of Symbols]

[0063] O1…1st axis center 1b, 3b…Fixed surface 1, 3...Surface plate (1...Lower surface plate, 3...Upper surface plate) W...wafer 5…Carrier 7, 9… Polishing bodies (7… Lower polishing body, 1st lapping plate, 9… Upper polishing body, 2nd lapping plate) 19… Polishing liquid (lapping liquid) 11...Polishing liquid supply means 1a, 3a... circular hole (1a... lower circular hole, 3a... upper circular hole) 15... Saucer 11c, 11d... Inner edge supply channels

Claims

1. A wafer polishing apparatus comprising: a platen having a fixed surface extending in a direction perpendicular to the axis and rotatable about the axis; a carrier that holds a flat wafer relative to the platen so as to be rotatable relative to the platen; a polishing body fixed to the fixed surface and polishing the wafer under a predetermined surface pressure; and a polishing liquid supply means for interposing a polishing liquid between the wafer and the polishing body, The surface plate and the polishing body have circular holes formed in them that are coaxial with the axis. The wafer polishing apparatus is characterized in that the polishing liquid supply means is configured to supply the polishing liquid to the inner edge of the circular hole side of the polishing body.

2. The aforementioned mounting plate consists of a lower mounting plate having a lower circular hole as the circular hole and a lower fixing surface facing upward, and an upper mounting plate having an upper circular hole as the circular hole and an upper fixing surface facing downward. The carrier is provided between the lower platen and the upper platen. The abrasive body consists of a lower abrasive body fixed to the lower fixed surface and an upper abrasive body fixed to the upper fixed surface. The wafer polishing apparatus according to claim 1, wherein the polishing liquid supply means is configured to supply the polishing liquid to the inner edge on the upper circular hole side of the upper polishing body and to the inner edge on the lower circular hole side of the lower polishing body.

3. The wafer polishing apparatus according to claim 2, wherein the polishing liquid supply means is disposed on the upper platen and includes a receiving tray for storing the polishing liquid and an inner edge supply passage for supplying the polishing liquid in the receiving tray to the inner edge on the upper circular hole side via the upper platen.

4. The wafer polishing apparatus according to claim 3, wherein the upper circular hole has a larger diameter than the lower circular hole.

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