Wafer processing method and holding table

Abstract

The present invention provides a wafer processing method and a holding stage that suppresses a decrease in production efficiency and damage to a device. The method includes the following steps: a preparation step of preparing a holding stage including a holding portion having a holding surface corresponding to a central concave portion of a wafer and an annular convex portion support portion having an annular support surface surrounding the holding surface and lower than the holding surface, the height difference between the holding surface and the annular support surface being formed to be at least a value of the depth of the central concave portion; a sheet arrangement step of arranging a sheet on the back surface of the wafer; a holding step of holding the back surface side of the wafer using the holding stage; a cutting step of cutting the wafer with a cutting tool on the holding portion until the sheet is reached, and cutting the annular convex portion from the wafer; and an annular convex portion removal step of removing the annular convex portion from the sheet by cutting the annular convex portion supported by the annular convex portion support portion from the wafer with the cutting tool.

Description

TECHNICAL FIELD

[0001] The present application relates to a wafer processing method and a holding stage, the wafer being formed with a central recess on the back surface and having a ring-shaped protrusion around the central recess. BACKGROUND

[0002] A processing method in which only a central portion corresponding to a device is thinned and an outer periphery is left as the original wafer thickness, thereby improving the handling property of the thinned wafer, is widely used (for example, refer to Patent Literature 1).

[0003] In the processing method shown in Patent Literature 1, after a wafer formed with a central recess on the back surface and having a ring-shaped protrusion around the central recess is finally divided into individual device chips, the individual device chips are picked up from the sheet.

[0004] In the case where the wafer having the ring-shaped protrusion is cut by a cutting tool, a cutting tool having a blade tip overhang amount corresponding to only the thickness of the ring-shaped protrusion of the wafer is used, and the fixing member of the cutting tool is prevented from contacting the ring-shaped protrusion to damage the wafer.

[0005] However, compared with the case where the thinned wafer is cut, in the case where the wafer having the ring-shaped protrusion is cut by a cutting tool, a large blade tip overhang amount of the cutting tool is required, and it is possible that the processing feed speed cannot be improved, and tool bending progression and the like occur. That is, in the case where the wafer having the ring-shaped protrusion is cut by a cutting tool, the time required to divide the wafer into individual devices becomes long and the production efficiency is reduced, and when the wafer is divided into individual devices in a short time, it is possible that the tool bending progression occurs to damage the devices.

[0006] On the other hand, in the case where the wafer is divided into device chips by expanding the sheet from the modified layer formed in the inside of the wafer by irradiating a laser beam, in order to divide the ring-shaped protrusion having a thick thickness by expansion as well, it is necessary to form the modified layer more in the thickness direction than the central portion.

[0007] Therefore, an apparatus in which a partition groove is formed in advance between the ring-shaped protrusion and the central recess before being divided into individual device chips, and the ring-shaped protrusion is removed from the sheet has also been proposed (for example, refer to Patent Literature 2).

[0008] Patent Literature 1: Japanese Patent Application Laid-Open No. 2007-019461

[0009] Patent Literature 2: Japanese Patent Application Laid-Open No. 2014-170822

[0010] However, in the device shown in Patent Document 2, if the sheet remains adhered to the annular protrusion in a local area, the annular protrusion can sometimes break when the annular protrusion is removed from the sheet. The broken annular protrusion must be removed from the sheet by handwork, which not only takes effort but also can damage the device due to the broken pieces. Thus, in the device shown in Patent Document 2, the production efficiency is reduced and the device can be damaged. SUMMARY

[0011] Therefore, an object of the present application is to provide a wafer processing method and a holding stage capable of suppressing reduction in production efficiency and damage to a device.

[0012] According to the present application, there is provided a wafer processing method for a wafer formed with a central recess on a back surface and having an annular protrusion around the central recess, the wafer processing method comprising: a preparation step of preparing a holding stage including a holding portion having a holding surface corresponding to the central recess and an annular protrusion support portion having an annular support surface around the holding surface and lower than the holding surface, a height difference between the holding surface and the annular support surface being formed to be at least a value of a depth of the central recess, the depth of the central recess being a depth from an upper surface of the annular protrusion of the wafer to a bottom surface of the central recess; a sheet arrangement step of arranging a sheet on the back surface of the wafer; a holding step of holding the back surface side of the wafer with the holding stage through the sheet; a cutting step of cutting the wafer with a cutting tool on the holding portion until the sheet is reached and relatively moving the holding stage with respect to the cutting tool to cut the annular protrusion of the wafer from the wafer; and an annular protrusion removal step of pulverizing the annular protrusion supported by the annular protrusion support portion by cutting the annular protrusion with the cutting tool to remove the annular protrusion from the sheet.

[0013] Preferably, the holding stage is formed with a holding surface suction passage having a holding surface suction hole on the holding surface and one end of which communicates with the holding surface suction hole and the other end of which is connected to a suction source via a valve, and a support surface suction passage having a support surface suction hole on the annular support surface and one end of which communicates with the support surface suction hole and the other end of which is connected to the suction source via a valve, in the cutting step, the wafer is suction-held by the holding portion, and in the annular protrusion removal step, the annular protrusion is suction-held by the annular protrusion support portion.

[0014] Preferably, in the cutting step, the cutting tool is cut into the wafer in a state where a part in a thickness direction of the cutting tool is placed on the holding surface and a remaining part in the thickness direction of the cutting tool is projected to an outside of the holding surface.

[0015] According to another aspect of the present invention, a holding stage is provided for holding a wafer in the above-described processing method, wherein the holding stage has: a holding portion including a holding surface corresponding to the central recess; and an annular protrusion support portion including an annular support surface surrounding the holding surface and lower than the holding surface, the height difference between the holding surface and the annular support surface being at least equal to or greater than the depth of the central recess, the depth of the central recess being the depth from the upper surface of the annular protrusion of the wafer to the bottom surface of the central recess.

[0016] Preferably, the holding worktable is formed with: a holding surface suction path having a holding surface suction hole on the holding surface, one end of which is connected to the holding surface suction hole and the other end of which is connected to a suction source via a valve; and a support surface suction path having a support surface suction hole on the annular support surface, one end of which is connected to the support surface suction hole and the other end of which is connected to a suction source via a valve.

[0017] This invention can suppress the reduction in production efficiency and the damage to devices. Attached Figure Description

[0018] Figure 1 This is a perspective view showing a structural example of a cutting device having an embodiment for holding a worktable.

[0019] Figure 2 Is as Figure 1 A perspective view of the wafer being processed by the cutting device shown.

[0020] Figure 3 It is along Figure 2 A sectional view along line III-III.

[0021] Figure 4 It is shown schematically. Figure 1 A front view of the main parts of the cutting device shown.

[0022] Figure 5 This is a perspective view showing an example of the structure of the holding table according to the embodiment.

[0023] Figure 6 This is a flowchart illustrating the processing method of the embodiment.

[0024] Figure 7 yes Figure 6 A perspective view of the wafer after the sheet arrangement steps of the processing method shown.

[0025] Figure 8 It is shown Figure 6 A cross-sectional view of the holding steps of the processing method shown.

[0026] Figure 9 It is shown Figure 6A cross-sectional view of the cutting step of the processing method shown.

[0027] Figure 10 is a cross-sectional view showing a state in which the annular protrusion is attracted and held to the annular support surface in the annular protrusion removal step of the processing method shown. Figure 6

[0028] Figure 11 is a cross-sectional view showing a state in which the annular protrusion is removed in the annular protrusion removal step of the processing method shown. Figure 6

[0029] Figure 12 is a cross-sectional view showing a state in which the annular protrusion is removed in the annular protrusion removal step of the processing method shown. Figure 6

[0030] Figure 13 is a cross-sectional view of the cutting step of the processing method of the modified example of the embodiment.

[0031] Figure 14 is a cross-sectional view showing a state in which the annular protrusion is attracted and held to the annular support surface in the annular protrusion removal step of the processing method of the modified example of the embodiment.

[0032] Figure 15 is a cross-sectional view showing a state in which the annular protrusion is removed in the annular protrusion removal step of the processing method of the modified example of the embodiment.

[0033] Explanation of Reference Numerals

[0034] 10: holding stage; 11: holding surface; 14: holding portion; 15: annular protrusion support portion; 16: annular support surface; 17: height difference; 18: holding surface attraction path; 19: support surface attraction path; 21-1, 21-2: cutting tool; 142: fine hole (holding surface attraction hole); 151: support surface attraction groove (support surface attraction hole); 181, 191: attraction source; 182, 192: valve; 200: wafer; 207: back surface; 210: central concave portion; 214: bottom surface; 215: annular protrusion; 217: value of depth; 221: sheet; 1001: preparation step; 1002: sheet arrangement step; 1003: holding step; 1004: cutting step; 1005: annular protrusion removal step. DETAILED DESCRIPTION

[0035] ​​​Hereinafter, embodiments of the present application will be described in detail with reference to the accompanying drawings. The present application is not limited to the following embodiments. In addition, among the structural elements described in the following, structural elements having substantially the same function will be given the same reference numerals, and repeated explanation will be omitted. Furthermore, the structures described in the following can be appropriately combined. In addition, various omissions, substitutions, or alterations of the structures can be made without departing from the spirit of the present application.

[0036] A holding table according to an embodiment of the present application will be described with reference to the drawings. Figure 1 is a perspective view showing a structure example of a cutting apparatus having the holding table according to the embodiment. Figure 2 is a perspective view showing a structure example of a cutting apparatus having the holding table according to the embodiment. Figure 1 is a perspective view showing a wafer as a processing object of the cutting apparatus shown in Figure 3 is a sectional view along the line III-III in Figure 2 Figure 4 is a front view schematically showing a main part of the cutting apparatus shown in Figure 1 Figure 5 is a perspective view showing a structure example of a holding table according to the embodiment.

[0037] (Processed object)

[0038] The holding table 10 according to the embodiment constitutes a cutting apparatus 1 shown in Figure 1 Figure 1 The cutting apparatus 1 shown in Figure 2 is a processing apparatus that performs cutting processing on a wafer 200 shown in Figure 2 The wafer 200 is a wafer such as a semiconductor wafer or an optical device wafer that has a circular plate shape with silicon, sapphire, or gallium arsenide as a substrate 201. As shown in

[0039] In addition, as shown in Figure 3 Figure 2 ​​​​The wafer 200 shown is a so-called TAIKO (registered trademark) wafer in which a central recess 210 is formed on the back surface 207 side of the front surface 202 and a ring-shaped protrusion 215 is provided around the central recess 210, so that the central portion is thinned and a thick-walled portion is formed in the outer peripheral portion. The central recess 210 is provided on the back surface 207 side of the device region 203, at a position corresponding to the device region 203. In the embodiment, the planar shape of the central recess 210 is formed in a circular shape. The ring-shaped protrusion 215 is provided on the back surface 207 side of the outer peripheral remaining region 204, at a position corresponding to the outer peripheral remaining region 204. In the embodiment, the ring-shaped protrusion 215 is formed in a circular ring shape coaxial with the central recess 210. In this way, in the wafer 200 of the embodiment, the position at which the central recess 210 is provided corresponds to a position overlapping in the thickness direction of the wafer 200.

[0040] The wafer 200 has the central recess 210 and the ring-shaped protrusion 215, and the front surface 202 side is formed in the same plane in the range of the device region 203 and the ring-shaped protrusion 215, and the back surface 207 side has the circular-shaped central recess 210 formed in the center. The wafer 200 is formed so that the thickness of the device region 203 is thinner than the thickness of the outer peripheral remaining region 204.

[0041] In addition, in the embodiment, as shown in Figure 3 the central recess 210 has a first circular recess 211 and a second circular recess 212. The planar shapes of the first circular recess 211 and the second circular recess 212 are formed in a circular shape, the diameter of the first circular recess 211 is formed to be larger than the diameter of the second circular recess 212, and the first circular recess 211 and the second circular recess 212 are coaxially arranged with each other. In addition, in the embodiment, the thickness of the substrate 201 at the bottom surface 213 of the first circular recess 211 is formed to be thicker than the thickness of the substrate 201 at the bottom surface 214 of the second circular recess 212. In addition, the bottom surface 214 of the second circular recess 212 is the bottom surface of the central recess 210.

[0042] In addition, in the embodiment, the wafer 200 has a metal film 216 formed in the range of the bottom surface 213 of the first circular recess 211, the bottom surface 214 of the second circular recess 212, the inner peripheral surface of the ring-shaped protrusion 215, and the inner edge portion of the back surface 207 side of the ring-shaped protrusion 215 (i.e., on the back surface 207 side) of the central recess 210, but in the present application, the metal film 216 can not be formed.

[0043] In one embodiment, the wafer 200 with the above structure, while maintaining a certain thickness, undergoes rough grinding on the back surface 207 side of the device region 203 to form a first circular recess 211, and fine grinding on the bottom surface 213 of the first circular recess 211 to form a second circular recess 212. In another embodiment, after forming the first circular recess 211 and the second circular recess 212, the wafer 200 is etched (wet etched) as needed to form a metal film 216 on the back surface 207 side. Alternatively, in this invention, the wafer 200 may undergo rough grinding to form the first circular recess 211, and fine grinding to form the second circular recess 212, without forming the metal film 216.

[0044] In the implementation method, such as Figure 1 As shown, a sheet 221, which is a circular plate with a diameter larger than the outer diameter of the wafer 200, is attached to the back surface 207 side of the wafer 200, and an annular frame 220 is attached to its outer edge, thereby supporting the wafer 200 within the opening 222 of the annular frame 220. If the type of wafer 200 is different, at least the inner diameter of the circular recesses 211 and 212 of the central recess 210 and the value 217 of the depth of the central recess 210 will be different. Furthermore, the value 217 of the depth of the central recess 210 refers to the depth from the upper surface of the annular protrusion 215 (i.e., the surface on the back surface 207 side) to the bottom surface 214 of the central recess 210. In this embodiment, the value 217 of the depth of the central recess 210 refers to the depth from the surface of the metal film 216 formed on the back surface 207 of the annular protrusion 215 to the bottom surface 214 of the central recess 210.

[0045] (Cutting device)

[0046] Next, the cutting device 1 will be described. Figure 1 The cutting device 1 shown is a processing device that uses a holding table 10 to hold the wafer 200 and uses a cutting tool 21 to cut (equivalent to machining) the outer edge of the central recess 210 over its entire circumference, thereby removing the annular protrusion 215 from the wafer 200. Figure 1 As shown, the cutting device 1 includes: a holding stage 10 that holds a wafer 200 using a holding surface 11; a cutting unit 20 that cuts the wafer 200 held by the holding stage 10 using a cutting tool 21; an imaging unit 30 that images the wafer 200 held by the holding stage 10; and a control unit 100.

[0047] In addition, such as Figure 1As shown, the cutting apparatus 1 has a moving unit 40 that relatively moves the holding table 10 and the cutting unit 20. The moving unit 40 has an X-axis moving unit 41 that is a machining feed unit that feeds the holding table 10 in a machining feed direction that is parallel to the horizontal direction, a Y-axis moving unit 42 that is an indexing feed unit that moves the cutting unit 20 in an indexing feed direction that is parallel to the horizontal direction and perpendicular to the X-axis direction, a Z-axis moving unit 43 that moves the cutting unit 20 in a plunge feed direction that is parallel to the vertical direction perpendicular to the Y-axis direction and the holding surface 11, and a rotational moving unit 44 that rotates the holding table 10 about an axis that is parallel to the Z-axis direction. That is, the moving unit 40 relatively moves the holding table 10 and the cutting unit 20 in the X-axis direction, the Y-axis direction, and the Z-axis direction. As shown in FIG. 1, the cutting apparatus 1 has a wafer transfer unit 30 that transfers the wafer 200 between the holding table 10 and a wafer cassette 50. The wafer transfer unit 30 has a wafer cassette transfer unit 31 that transfers the wafer 200 between the holding table 10 and the wafer cassette 50, and a wafer transfer robot 32 that transfers the wafer 200 between the holding table 10 and the wafer cassette transfer unit 31. Figure 1 and Figure 4 As shown, the cutting apparatus 1 is a so-called face-to-face type double-axis cutting apparatus having two cutting units 20 (i.e., a two-spindle cutting machine)

[0048] The X-axis moving unit 41 moves the holding table 10 together with the rotational moving unit 44 in the machining feed direction that is the X-axis direction, thereby relatively machining feeding the holding table 10 and the cutting unit 20 in the X-axis direction.

[0049] The X-axis moving unit 41 moves the holding table 10 in the X-axis direction within a range of a wafer in / out area 4 in which the wafer 200 is carried in and out and a machining area 5 in which the wafer 200 held by the holding table 10 is machined by the cutting unit 20. The Y-axis moving unit 42 moves the cutting unit 20 in the indexing feed direction that is the Y-axis direction, thereby relatively indexing feeding the holding table 10 and the cutting unit 20 in the Y-axis direction. The Z-axis moving unit 43 moves the cutting unit 20 in the plunge feed direction that is the Z-axis direction, thereby relatively plunge feeding the holding table 10 and the cutting unit 20 in the Z-axis direction.

[0050] The X-axis moving unit 41, the Y-axis moving unit 42, and the Z-axis moving unit 43 have a publicly known ball screw that is rotatably provided about an axis, a publicly known motor that rotates the ball screw about the axis, and a publicly known guide rail that supports the holding table 10 or the cutting unit 20 so as to be movable in the X-axis direction, the Y-axis direction, or the Z-axis direction.

[0051] The holding table 10 is in a disc shape and holds the wafer 200 on the holding surface 11. In addition, the holding table 10 is provided so as to be movable in the X-axis direction within a range of the wafer in / out area 4 and the machining area 5 by the X-axis moving unit 41 and so as to be rotatable about an axis that is parallel to the Z-axis direction by the rotational moving unit 44. In addition, as shown in FIG. 1, the holding table 10 is provided so as to be movable in the Y-axis direction within a range of the wafer in / out area 4 and the machining area 5 by the Y-axis moving unit 42. Figure 1As shown, a plurality of clamping ring frames 220 are provided around the holding worktable 10. The structure of the holding worktable 10 will be described later.

[0052] The cutting unit 20 is a machining unit with a spindle 23 on which a cutting tool 21 for cutting the wafer 200 held by the holding table 10 is detachably mounted. The cutting unit 20 is configured to be movable relative to the wafer 200 held by the holding table 10 in the Y-axis direction via the Y-axis moving unit 42, and to be movable relative to the wafer 200 held by the holding table 10 in the Z-axis direction via the Z-axis moving unit 43.

[0053] like Figure 1 As shown, the cutting unit 20 is mounted on the portal frame 3, which is erected from the main body 2, via the Y-axis moving unit 42 and the Z-axis moving unit 43. The cutting unit 20 can position the cutting tool 21 at any position on the holding surface 11 of the holding table 10 via the Y-axis moving unit 42 and the Z-axis moving unit 43.

[0054] like Figure 1 As shown, the cutting unit 20 includes: a cutting tool 21; a spindle housing 22, which is configured to move freely along the Y-axis and Z-axis directions via a Y-axis moving unit 42 and a Z-axis moving unit 43; a spindle 23, which is mounted on the spindle housing 22 in a manner that allows it to rotate about its axis and is rotated by a motor (not shown), and the cutting tool 21 is mounted at the front end of the spindle 23; and a cutting water nozzle, which provides cutting water to the cutting tool 21.

[0055] The cutting tool 21 is an extremely thin, annular cutting tool with a generally ring-shaped design. In an embodiment, as... Figure 4 As shown, the cutting tool 21 is a so-called washer tool consisting only of an annular cutting edge 24 for cutting the wafer 200. The cutting edge 24 is formed to a predetermined thickness by fixing abrasive grains such as diamond or CBN (Cubic Boron Nitride) with a bonding material such as metal or resin. Alternatively, in this invention, the cutting tool 21 may also be a hub tool, which has a cutting edge 24 and an annular circular base with the cutting edge 24 disposed on its outer periphery.

[0056] In addition, the axes of the cutting tool 21 and the spindle 23 of the cutting unit 20 are parallel to the Y-axis direction.

[0057] Hereinafter, the end of the reference numerals of the respective structural elements of one of the cutting units 20 (hereinafter, indicated by the reference numeral 20-1) is marked with the reference numeral "-1" to be described, and the end of the reference numerals of the respective structural elements of the other of the cutting units 20 (hereinafter, indicated by the reference numeral 20-2) is marked with the reference numeral "-2" to be described. In the embodiment, as shown in FIG. 1, the thickness 25-1 of the cutting edge 24-1 of the cutting tool 21-1 of the cutting unit 20-1 is thinner than the thickness 25-2 of the cutting edge 24-2 of the cutting tool 21-2 of the cutting unit 20-2. Thus, in the embodiment, the thicknesses 25-1, 25-2 of the cutting edges 24-1, 24-2 of the cutting tools 21-1, 21-2 of the cutting units 20-1, 20-2 are different from each other. Figure 4

[0058] The photographing unit 30 is fixed to the cutting unit 20 in a manner of moving integrally with the cutting unit 20. The photographing unit 30 has a photographing element that photographs a region to be divided of the wafer 200 held by the holding stage 10 before cutting. The photographing element is, for example, a CCD (Charge-Coupled Device) photographing element or a CMOS (Complementary MOS) photographing element. The photographing unit 30 photographs the wafer 200 held by the holding stage 10 to obtain an image for performing alignment and the like of aligning the wafer 200 and the cutting tools 21-1, 21-2, and outputs the obtained image to the control unit 100.

[0059] In addition, the cutting apparatus 1 has an X-axis direction position detecting unit (not shown) for detecting the position of the holding stage 10 in the X-axis direction, a Y-axis direction position detecting unit (not shown) for detecting the position of the cutting unit 20 in the Y-axis direction, and a Z-axis direction position detecting unit for detecting the position of the cutting unit 20 in the Z-axis direction. The X-axis direction position detecting unit and the Y-axis direction position detecting unit can be constituted by a linear scale and a reading head parallel to the X-axis direction or the Y-axis direction. The Z-axis direction position detecting unit detects the position of the cutting unit 20 in the Z-axis direction using the pulse of a motor. The X-axis direction position detecting unit, the Y-axis direction position detecting unit, and the Z-axis direction position detecting unit output the positions of the holding stage 10 in the X-axis direction, the cutting unit 20 in the Y-axis direction, or the cutting unit 20 in the Z-axis direction to the control unit 100. In addition, in the embodiment, the positions of the holding stage 10 and the cutting unit 20 of the cutting apparatus 1 in the X-axis direction, the Y-axis direction, and the Z-axis direction are determined based on a predetermined origin position (not shown).

[0060] ​Further, the cutting apparatus 1 has a cassette elevator 50 that places a cassette 51 that houses the wafer 200 before and after cutting and moves the cassette 51 in the Z-axis direction, a cleaning unit 52 that cleans the wafer 200 after cutting, and a conveyance unit (not shown) that takes out and puts in the wafer 200 with respect to the cassette 51 and conveys the wafer 200.

[0061] The control unit 100 controls each of the above-described units of the cutting apparatus 1 to cause the cutting apparatus 1 to perform a processing operation on the wafer 200. Further, the control unit 100 is a computer that has an arithmetic processing device having a microprocessor like a CPU (central processing unit), a storage device having a memory like a ROM (read only memory) or a RAM (random access memory), and an input / output interface device. The arithmetic processing device of the control unit 100 performs an arithmetic process according to a computer program stored in the storage device and outputs a control signal for controlling the cutting apparatus 1 to the above-described structural elements of the cutting apparatus 1 via the input / output interface device.

[0062] Further, the control unit 100 is connected to a display unit constituted by a liquid crystal display device or the like that displays a state or an image or the like of the processing operation and an input unit used when an operator registers processing content information or the like. The input unit is constituted by at least one of a touch panel provided to the display unit and an external input device like a keyboard.

[0063] (Holding stage)

[0064] Next, the holding stage 10 will be described. Figure 5 The illustrated holding stage 10 is provided on a disc-shaped stage base 13 that moves in the X-axis direction together with the rotary movement unit 44 by the X-axis movement unit 41. In the processing method of the embodiment, the holding stage 10 holds the wafer 200.

[0065] As Figure 4 and Figure 5As shown, the holding stage 10 has a holding portion 14 and a ring-shaped convex portion support portion 15. The holding portion 14 is formed in a disc shape with a diameter slightly smaller than the central recessed portion 210 of the wafer 200, and an upper surface of the holding portion 14 is a holding surface 11 that holds the wafer 200 in parallel with the horizontal direction. Thus, the holding stage 10 includes the holding surface 11 with a diameter slightly smaller than the central recessed portion 210 of the wafer 200. The holding surface 11 intrudes into the central recessed portion 210 of the wafer 200 via the sheet 221, holds a bottom surface 214 of the central recessed portion 210, and thereby holds the wafer 200. In the present application, the case where the holding surface 11 is formed to have a diameter slightly smaller than the central recessed portion 210 of the wafer 200 is referred to as the holding surface 11 corresponding to the central recessed portion 210.

[0066] The holding portion 14 has a ring-shaped porous member 141 formed of a ring-shaped porous ceramic or the like at an outer edge portion. An upper surface of the ring-shaped porous member 141 is formed in the same plane as the holding surface 11 to constitute the holding surface 11. The ring-shaped porous member 141 is composed of a porous material having a plurality of fine pores 142. The fine pores 142 correspond to the holding surface suction holes in the technical solution. Thus, the holding stage 10 has the fine pores 142 as the holding surface suction holes on the holding surface 11.

[0067] The ring-shaped convex portion support portion 15 is formed in a circular ring shape with an inner diameter equal to an outer diameter of the holding portion 14, and is fixed to an outer periphery of the holding portion 14 on the inner side so as to surround the holding surface 11. An upper surface of the ring-shaped convex portion support portion 15 is a ring-shaped support surface 16 that is parallel to the horizontal direction and can support the ring-shaped convex portion 215 of the wafer 200. That is, the ring-shaped convex portion support portion 15 includes the ring-shaped support surface 16.

[0068] The ring-shaped convex portion support portion 15 has a thickness thinner than that of the holding portion 14. The ring-shaped convex portion support portion 15 is fixed at a position where a lower surface thereof is in the same plane as a lower surface of the holding portion 14. Thus, the ring-shaped support surface 16 of the ring-shaped convex portion support portion 15 is disposed at a position lower than the holding surface 11. In the embodiment, a difference 17 in height between the holding surface 11 and the ring-shaped support surface 16 of the holding stage 10 is formed to be at least a value 217 equal to or greater than a depth of the central recessed portion 210.

[0069] Further, the ring-shaped convex portion support portion 15 is provided with support surface suction holes, i.e., support surface suction grooves 151, recessed from the ring-shaped support surface 16 at an outer edge portion in the entire circumferential range. Thus, the holding stage 10 has the support surface suction grooves 151 as the support surface suction holes on the ring-shaped support surface 16. The support surface suction grooves 151 are formed in a circular shape coaxially disposed with the ring-shaped convex portion support portion 15, and in the embodiment, two support surface suction grooves 151 are formed at positions coaxial with each other, and the two support surface suction grooves 151 are communicated with each other by a communication passage 152 (shown) provided in the ring-shaped convex portion support portion 15. Figure 8 As shown, the holding stage 10 has a holding portion 14 and a ring-shaped convex portion support portion 15. The holding portion 14 is formed in a disc shape with a diameter slightly smaller than the central recessed portion 210 of the wafer 200, and an upper surface of the holding portion 14 is a holding surface 11 that holds the wafer 200 in parallel with the horizontal direction. Thus, the holding stage 10 includes the holding surface 11 with a diameter slightly smaller than the central recessed portion 210 of the wafer 200. The holding surface 11 intrudes into the central recessed portion 210 of the wafer 200 via the sheet 221, holds a bottom surface 214 of the central recessed portion 210, and thereby holds the wafer 200. In the present application, the case where the holding surface 11 is formed to have a diameter slightly smaller than the central recessed portion 210 of the wafer 200 is referred to as the holding surface 11 corresponding to the central recessed portion 210.

[0066] The holding portion 14 has a ring-shaped porous member 141 formed of a ring-shaped porous ceramic or the like at an outer edge portion. An upper surface of the ring-shaped porous member 141 is formed in the same plane as the holding surface 11 to constitute the holding surface 11. The ring-shaped porous member 141 is composed of a porous material having a plurality of fine pores 142. The fine pores 142 correspond to the holding surface suction holes in the technical solution. Thus, the holding stage 10 has the fine pores 142 as the holding surface suction holes on the holding surface 11.

[0067] The ring-shaped convex portion support portion 15 is formed in a circular ring shape with an inner diameter equal to an outer diameter of the holding portion 14, and is fixed to an outer periphery of the holding portion 14 on the inner side so as to surround the holding surface 11. An upper surface of the ring-shaped convex portion support portion 15 is a ring-shaped support surface 16 that is parallel to the horizontal direction and can support the ring-shaped convex portion 215 of the wafer 200. That is, the ring-shaped convex portion support portion 15 includes the ring-shaped support surface 16.

[0068] The ring-shaped convex portion support portion 15 has a thickness thinner than that of the holding portion 14. The ring-shaped convex portion support portion 15 is fixed at a position where a lower surface thereof is in the same plane as a lower surface of the holding portion 14. Thus, the ring-shaped support surface 16 of the ring-shaped convex portion support portion 15 is disposed at a position lower than the holding surface 11. In the embodiment, a difference 17 in height between the holding surface 11 and the ring-shaped support surface 16 of the holding stage 10 is formed to be at least a value 217 equal to or greater than a depth of the central recessed portion 210.

[0069] Further, the ring-shaped convex portion support portion 15 is provided with support surface suction holes, i.e., support surface suction grooves 151, recessed from the ring-shaped support surface 16 at an outer edge portion in the entire circumferential range. Thus, the holding stage 10 has the support surface suction grooves 151 as the support surface suction holes on the ring-shaped support surface 16. The support surface suction grooves 151 are formed in a circular shape coaxially disposed with the ring-shaped convex portion support portion 15, and in the embodiment, two support surface suction grooves 151 are formed at positions coaxial with each other, and the two support surface suction grooves 151 are communicated with each other by a communication passage 152 (shown) provided in the ring-shaped convex portion support portion 15. Figure 8 As shown, the holding stage 10 has a holding portion 14 and a ring-shaped convex portion support portion 15. The holding portion 14 is formed in a disc shape with a diameter slightly smaller than the central recessed portion 210 of the wafer 200, and an upper surface of the holding portion 14 is a holding surface 11 that holds the wafer 200 in parallel with the horizontal direction. Thus, the holding stage 10 includes the holding surface 11 with a diameter slightly smaller than the central recessed portion 210 of the wafer 200. The holding surface 11 intrudes into the central recessed portion 210 of the wafer 200 via the sheet 221, holds a bottom surface 214 of the central recessed portion 210, and thereby holds the wafer 200. In the present application, the case where the holding surface 11 is formed to have a diameter slightly smaller than the central recessed portion 210 of the wafer 200 is referred to as the holding surface 11 corresponding to the central recessed portion 210.

[0066] The holding portion 14 has a ring-shaped porous member 141 formed of a ring-shaped porous ceramic or the like at an outer edge portion. An upper surface of the ring-shaped porous member 141 is formed in the same plane as the holding surface 11 to constitute the holding surface 11. The ring-shaped porous member 141 is composed of a porous material having a plurality of fine pores 142. The fine pores 142 correspond to the holding surface suction holes in the technical solution. Thus, the holding stage 10 has the fine pores 142 as the holding surface suction holes on the holding surface 11.

[0067] The ring-shaped convex portion support portion

[0070] Further, the holding stage 10 is formed with a holding surface suction path 18 and a support surface suction path 19. The holding surface suction path 18 is a passage that penetrates the holding portion 14, one end of which communicates with the fine hole 142 of the annular porous member 141, and the other end of which is connected to the suction source 181 via a valve 182. The support surface suction path 19 is a passage that penetrates the annular convex portion support portion 15, one end of which communicates with the support surface suction groove 151, and the other end of which is connected to the suction source 191 via a valve 192.

[0071] By opening the valve 182 and suctioning the fine hole 142 with the suction source 281, the holding stage 10 suction-holds the bottom surface 214 of the central concave portion 210 on the back surface 207 side of the wafer 200 placed on the holding surface 11 through the sheet 221. Further, by opening the valve 192 and suctioning the support surface suction groove 151 with the suction source 191, the holding stage 10 suction-holds the annular convex portion 215 cut off from the wafer 200 through the sheet 221 to the annular support surface 16.

[0072] (Machining method)

[0073] Next, the machining method of the embodiment will be described with reference to the drawings. Figure 6 is a flowchart showing the flow of the machining method of the embodiment. The machining method of the embodiment is a machining method of the above-described wafer 200, and is a machining method of removing the annular convex portion 215 from the wafer 200. The machining method includes the machining operation of the above-described cutting device 1. As shown in Figure 6 the machining method of the embodiment has a preparation step 1001, a sheet provision step 1002, a holding step 1003, a cutting step 1004, and an annular convex portion removal step 1005.

[0074] (Preparation step)

[0075] The preparation step 1001 is a step of preparing the above-described holding stage 10. In the embodiment, in the preparation step 1001, an operator of the cutting device 1 or the like prepares the holding stage 10 in which the diameter of the holding portion 14 is smaller than the inner diameter of the second circular concave portion 212 of the central concave portion 210 of the wafer 200 as a machining target, and the height difference 17 is equal to or greater than the depth value 217 of the central concave portion 210, based on the inner diameter of the circular concave portions 211, 212 of the central concave portion 210 of the wafer 200 as a machining target and the depth value 217 of the central concave portion 210, and installs the prepared holding stage 10 to the stage base 13.

[0076] (Sheet provision step)

[0077] Figure 7 isFigure 6 A perspective view of the wafer after the sheet disposing step of the processing method shown. The sheet disposing step 1002 is a step of disposing a sheet 221 on the back surface 207 of the wafer 200. In the sheet disposing step 1002, a known mounter adheres the circular plate-shaped sheet 221 having a larger diameter than the outer diameter of the wafer 200 to the back surface 207 side of the wafer 200 and adheres the annular frame 220 to the outer edge portion of the sheet 221, as shown in Figure 7 The wafer 200 is supported inside the opening 222 of the annular frame 220, as shown.

[0078] (Holding Step)

[0079] Figure 8 is a cross-sectional view showing the holding step of the processing method shown. In addition, Figure 6 is a cross-sectional view showing the holding step of the processing method shown. In addition, Figure 8 The metal film 216 is omitted in the holding step 1003. The holding step 1003 is a step of holding the back surface 207 side of the wafer 200 with the holding stage 10 through the sheet 221. In the embodiment, in the holding step 1003, the control unit 100 of the cutting apparatus 1 receives the processing content information registered by the operator, sets the cassette 51 in which a plurality of wafers 200 before cutting processing are accommodated in the cassette elevator 50, and starts the processing operation when the control unit 100 receives the start instruction of the processing operation from the operator.

[0080] In the embodiment, in the holding step 1003, the control unit 100 of the cutting apparatus 1 controls the conveyance unit to take out one wafer 200 from the cassette 51, causes the holding portion 14 of the holding stage 10 positioned in the carry-in and carry-out region 4 to intrude into the central recessed portion 210, and places the back surface 207 side of the device region 203 on the holding surface 11 through the sheet 221. In the embodiment, in the holding step 1003, as shown in Figure 8 In the embodiment, in the holding step 1003, the control unit 100 of the cutting apparatus 1 opens the valve 182 in the state that the valve 192 is closed, attracts the fine holes 142 of the annular porous member 141 by the suction source 181, and holds the back surface 207 side of the device region 203 of the wafer 200 on the holding surface 11 through the sheet 221. At this time, in the embodiment, in the holding step 1003, the cutting apparatus 1 does not grip the annular frame 220 with the jig portion 12.

[0081] (Cutting Step)

[0082] Figure 9 is a cross-sectional view showing the cutting step of the processing method shown. In addition, Figure 6 is a cross-sectional view showing the cutting step of the processing method shown. In addition, Figure 9The metal film 216 is omitted. The cutting-off step 1004 is a step of cutting the cutting tool 21-1 into the wafer 200 on the holding portion 14 until reaching the sheet 221, relatively moving the holding table 10 with respect to the cutting tool 21-1 to cut off the annular protrusion 215 of the wafer 200 from the wafer 200.

[0083] In the embodiment, in the cutting-off step 1004, the cutting device 1 rotates the spindle 23 around the axis to rotate the cutting tools 21-1, 21-2, moves the holding table 10 from the carry-in and carry-out area 4 toward the machining area 5 below the imaging unit 30 by the X-axis moving unit 41 and the moving unit 40, and performs imaging of the wafer 200 held by the holding table 10 by the imaging unit 30, thereby performing alignment.

[0084] In the embodiment, in the cutting-off step 1004, the cutting device 1 supplies cutting water to the cutting tool 21-1 of the thinner one of the pair of cutting tools 21-1, 21-2, relatively moves the cutting unit 20-1 and the holding table 10 by the moving unit 40 according to the machining content information, cuts the cutting tool 21-1 into the outer edge portion of the second circular recess 212 of the central recess 210 until reaching the sheet 221 as shown, and rotates the holding table 10 around the axis. Figure 9 In the embodiment, in the cutting-off step 1004, the cutting tool 21-1 is cut into the wafer 200 with a part of the thickness direction of the cutting tool 21-1 resting on (positioned on) the holding surface 11 and the remaining part of the thickness direction of the cutting tool 21-1 protruding outward beyond the outer edge of the holding surface 11.

[0085] In addition, in the embodiment, in the cutting-off step 1004, after the cutting device 1 positions the cutting tool 21-1 of the cutting unit 20-1 above the outer edge portion of the second circular recess 212 of the central recess 210 of the wafer 200 held by the holding table 10, the cutting unit 20-1 is lowered until the cutting tool 21-1 cuts into the sheet 221, and the annular protrusion 215 is cut off from the wafer 200 in the entire circumferential range by the so-called chopper cut of rotating the holding table 10 around the axis at least once by the rotation moving unit 44. In the embodiment, in the cutting-off step 1004, when the cutting device 1 cuts off the annular protrusion 215 from the wafer 200 in the entire circumferential range, the cutting unit 20-1 is raised and the cutting tool 21-1 is retracted from the wafer 200 held by the holding table 10. In this way, in the cutting-off step 1004, the wafer 200 is held by the holding table 10 by attraction by the holding portion 14, that is, is held by attraction on the holding surface 11 of the holding portion 14 of the holding table 10 through the sheet 221, and is not held by attraction by the annular support surface 16 of the annular protrusion support portion 15 of the holding table 10.

[0086] In addition, in the embodiment, in the cutting step 1004, the annular protrusion 215 is cut off from the wafer 200 by so-called cleaving, but the present application is not limited to cleaving. For example, the present application can be such that, in the cutting step 1004, after the cutting device 1 positions the lower end of the cutting tool 21-1 of the cutting unit 20-1 at a position where the cutting tool 21-1 is aligned with the outer edge portion of the second circular recess 212 of the central recess 210 of the wafer 200 held by the holding stage 10 in the X-axis direction at the height of the cut-in sheet 221, the holding stage 10 is moved in the X-axis direction toward the cutting tool 21-1, the cutting tool 21-1 is cut into the wafer 200 up to the cut-in sheet 221, the holding stage 10 is rotated at least one revolution around the axis by the rotation moving unit 44, and thus the annular protrusion 215 is cut off from the wafer 200 in the entire circumferential range.

[0087] (Removal step of annular protrusion)

[0088] Figure 10 is a cross-sectional view showing a state in which the annular protrusion is attracted and held to the annular support surface in the removal step of annular protrusion of the processing method shown in Figure 6 Figure 11 is a cross-sectional view showing a state in which the cutting tool is cut into the annular protrusion in the removal step of annular protrusion of the processing method shown in Figure 6 Figure 12 is a cross-sectional view showing a state after the annular protrusion is removed in the removal step of annular protrusion of the processing method shown in Figure 6 Figure 10 , Figure 11 and Figure 12 omit the metal film 216.

[0089] The removal step 1005 of the annular protrusion is a step of performing pulverization by cutting the annular protrusion 215 supported by the annular protrusion support 15 cut off from the wafer 200 by the cutting step 1004 with the cutting tool 21-2, and thus removing the annular protrusion 215 from the cut-in sheet 221. In the embodiment, in the removal step 1005 of the annular protrusion, the control unit 100 of the cutting device 1 opens the valve 192, as shown in Figure 10 annular support surface 16 with the cut-in sheet 221 interposed by the suction source 291, and the annular frame 220 is gripped by the gripper portion 12.

[0090] ​​​In the embodiment, in the annular protrusion removal step 1005, the cutting device 1 supplies cutting water to the thicker one of the pair of cutting tools 21-1, 21-2, and moves the cutting unit 20-2 and the holding table 10 relatively by the moving unit 40 according to the machining content information, as shown in FIG. 10, to cut the cutting tool 21-2 into the inner edge portion of the annular protrusion 215 up to the sheet 221 on the annular support surface 16, and rotates the holding table 10 around the axis. Figure 11 In the embodiment, in the annular protrusion removal step 1005, after the cutting device 1 cuts the cutting tool 21-2 into the sheet 221, the cutting device 1 temporarily retreats the cutting tool 21-2 from the holding table 10, and moves the cutting unit 20-2 in the Y-axis direction to cut the cutting tool 21-2 into the outer peripheral side of the annular protrusion 215. The cutting device 1 cuts the cutting tool 21-2 into the outer peripheral side of the annular protrusion 215 up to the sheet 221 on the annular support surface 16, and rotates the holding table 10 around the axis. Thus, in the embodiment, in the annular protrusion removal step 1005, as shown in FIG. 10, the cutting device 1 repeatedly performs the operation of cutting the cutting tool 21-2 into the annular protrusion 215 up to the sheet 221 and the operation of moving the cutting unit 20 in the Y-axis direction until the annular protrusion 215 is entirely cut and crushed from the sheet 221. Figure 12

[0091] In addition, in the embodiment, in the annular protrusion removal step 1005, the cutting device 1 repeatedly performs the operation of cutting the cutting tool 21-2 into the annular protrusion 215 up to the sheet 221 and the operation of moving the cutting unit 20 in the Y-axis direction until the annular protrusion 215 is entirely cut and crushed, but the present application is not limited thereto, as shown in FIG. 11, and the cutting tool 21-2 that cuts the annular protrusion 215 up to the sheet 221 on the annular support surface 16 can be moved in the Y-axis direction to the outer peripheral side of the annular protrusion 215 while rotating the holding table 10 around the axis to cut and crush the annular protrusion 215 entirely. Figure 11

[0092] ​​In addition, in the embodiment, in the annular protrusion removing step 1005, the annular protrusion 215 is cut and crushed by so-called cleaving cutting, like the cutting-off step 1004. However, the present application is not limited to the cleaving cutting. For example, in the annular protrusion removing step 1005, the cutting device 1 can position the lower end of the cutting tool 21-2 of the cutting unit 20-2 at a position where the cutting tool 21-2 is arranged in the X-axis direction at the height of the cut-in sheet 221 and at a position where the annular protrusion 215 held by the holding table 10 is arranged in the X-axis direction, and then move the holding table 10 in the direction of approaching the cutting tool 21-2 along the X-axis direction, and cut the annular protrusion 215 with the cutting tool 21-2 until the cut-in sheet 221, and rotate the holding table 10 at least one revolution around the axis by the rotation moving unit 44, and cut and crush the annular protrusion 215.

[0093] In the embodiment, in the annular protrusion removing step 1005, when the cutting device 1 cuts and crushes the annular protrusion 215 as a whole, the cutting unit 20-2 is raised, and the cutting tool 21-2 is retracted from the wafer 200 held by the holding table 10. In this way, in the annular protrusion removing step 1005, the annular protrusion 215 is held by the holding table 10 by the annular protrusion support portion 15, that is, is held by the annular support surface 16 of the annular protrusion support portion 15 of the holding table 10 through the cut-in sheet 221.

[0094] Then, the cutting device 1 moves the holding table 10 from the processing area 5 toward the carry-in and carry-out area 4, stops the movement of the holding table 10 in the carry-in and carry-out area 4, closes the valves 182, 192 to stop the holding table 10 from holding the wafer 200, and releases the clamping of the annular frame 220 by the clamp portion 12. The control unit 100 of the cutting device 1 controls the conveyance unit to carry the wafer 200 from which the annular protrusion 215 is removed to the cleaning unit 52, and after cleaning by the cleaning unit 52, the wafer 200 is stored in the cassette 51. The cutting device 1 repeatedly performs the holding step 1003, the cutting-off step 1004, and the annular protrusion removing step 1005, and sequentially removes the annular protrusion 215 from the wafers 200 in the cassette 51, and when the annular protrusion 215 is removed from all the wafers 200 in the cassette 51, the processing operation is ended. In addition, the wafer 200 from which the annular protrusion 215 is removed is divided into individual devices 206.

[0095] As explained above, in the processing method of the embodiment, after the ring-shaped protrusion 215 is cut off from the wafer 200 by the cutting tool 21-1 in the cutting step 1004, the ring-shaped protrusion 215 is crushed by cutting with the cutting tool 21-2 in the ring-shaped protrusion removal step 1005, and thus the ring-shaped protrusion 215 is removed from the sheet 221. Therefore, in the processing method of the embodiment, when the wafer 200 is divided into individual devices 206, the wafer 200 from which the ring-shaped protrusion 215 has been cut off is divided into individual devices 206, and thus the amount by which the cutting tool is protruded when divided into individual devices 206 can be suppressed, the reduction in the processing feed rate can be suppressed, and the possibility of tool bending progress can be suppressed.

[0096] In addition, in the processing method of the embodiment, after the ring-shaped protrusion 215 is cut off from the wafer 200 by the cutting tool 21-1 in the cutting step 1004, the ring-shaped protrusion 215 is crushed by cutting with the cutting tool 21-2 in the ring-shaped protrusion removal step 1005, and thus the ring-shaped protrusion 215 is removed from the sheet 221. Therefore, in the processing method of the embodiment, when the wafer 200 is divided into individual devices 206, the wafer 200 from which the ring-shaped protrusion 215 has been cut off is divided into individual devices 206, and thus the amount by which the cutting tool is protruded when divided into individual devices 206 can be suppressed, the reduction in the processing feed rate can be suppressed, and the possibility of tool bending progress can be suppressed.

[0097] As a result, the processing method of the embodiment has an effect of being able to suppress the reduction in the production efficiency of each divided device 206 and the damage to the device 206.

[0098] In addition, in the processing method of the embodiment, in the cutting step 1004, the wafer 200 is held by the holding surface 11 of the holding portion 14, and the ring-shaped protrusion 215 is not held by the ring-shaped holding surface 16 of the ring-shaped protrusion support portion 15, and thus the suction force does not act on the ring-shaped protrusion 215 that is partially cut off halfway through cutting off the ring-shaped protrusion 215, and the like, and thus the ring-shaped protrusion 215 can be suppressed from being broken or the like.

[0099] In addition, in the processing method of the embodiment, in the cutting step 1004, the wafer 200 is held by the holding surface 11 of the holding portion 14, and the ring-shaped protrusion 215 is not held by the ring-shaped holding surface 16 of the ring-shaped protrusion support portion 15, and thus the suction force does not act on the ring-shaped protrusion 215 that is partially cut off halfway through cutting off the ring-shaped protrusion 215, and the like, and thus the ring-shaped protrusion 215 can be suppressed from being broken or the like.

[0100] In addition, in the processing method of the embodiment, in the cutting step 1004, the cutting tool 21-1 is cut into the wafer 200 in a state where a part in the thickness direction of the cutting tool 21-1 is placed on the holding surface 11 and the remaining part in the thickness direction of the cutting tool 21-1 is projected to the outside of the holding surface 11, and thus the annular protrusion 215 can be cut off from the wafer 200.

[0101] The holding stage 10 of the embodiment has a holding portion 14 including the holding surface 11 corresponding to the central recess 210, and an annular protrusion support portion 15 including an annular support surface 16 surrounding the holding surface 11 and being lower than the holding surface 11, the height difference 17 between the holding surface 11 and the annular support surface 16 being formed to be at least a value 217 equal to or more than the depth of the central recess 210 of the wafer 200, and thus after the annular protrusion 215 is cut off from the wafer 200 held by the holding surface 11 by the cutting tool 21-1, the annular protrusion 215 held by the annular support surface 16 can be cut and crushed by the cutting tool 21-2 to be removed from the sheet 221. As a result, the holding stage 10 functions to suppress the reduction of the production efficiency of each divided device 206 and the damage of the device 206.

[0102] In addition, the holding stage 10 forms the fine hole 142 of the annular porous member 141 connected to the suction source 181 via the valve 182 on the holding surface 11, and forms the support surface suction groove 151 connected to the suction source 191 via the valve 192 on the annular support surface 16, and thus the wafer 200 can be held by suction on the holding surface 11, and the annular protrusion 215 can be held by suction on the annular support surface 16.

[0103] (Modified Example)

[0104] A processing method of a modified example of the embodiment will be described with reference to the drawings. Figure 13 is a cross-sectional view showing a cutting step of the processing method of the modified example of the embodiment. Figure 14 is a cross-sectional view showing a state in which the annular protrusion is held by suction on the annular support surface in the annular protrusion removal step of the processing method of the modified example of the embodiment. Figure 15 is a cross-sectional view showing a state in which the cutting tool is cut into the annular protrusion in the annular protrusion removal step of the processing method of the modified example of the embodiment. In addition, in Figure 13 , Figure 14 and Figure 15 , the metal film 216 is omitted, and the same reference numerals are assigned to the same parts as those of the embodiment, and the description is omitted.

[0105] In the processing method of the modified example, in the cutting step 1004, as shown in Figure 13As shown, the cutting tool 21-1 is inserted into the wafer 200 in a state where the thickness direction of the cutting tool 21-1 is entirely placed on (positioned on) the holding surface 11, and the outer edge portion of the second circular recess 212 of the central recess 210 of the wafer 200 is cut, thereby separating the annular protrusion 215 from the wafer 200.

[0106] In addition, in the processing method of the modified example, in the annular protrusion removal step 1005, when the annular protrusion 215 separated from the wafer 200 is held on the annular support surface 16 of the cutting device 1 with the sheet 221 interposed therebetween and the annular frame 220 is gripped by the jig portion 12, as shown by a broken line in Figure 14 As shown, the outer edge portion of the second circular recess 212 of the central recess 210 connected to the annular protrusion 215 is located on the holding surface 11 with the sheet 221 interposed therebetween.

[0107] In the processing method of the modified example, in the annular protrusion removal step 1005, the cutting device 1 supplies the cutting tool 21-2 with cutting water, and the cutting unit 20-2 and the holding table 10 are relatively moved by the moving unit 40 according to the processing content information, as shown by a broken line in Figure 15 The cutting tool 21-2 is caused to cut into the outer edge portion of the second circular recess 212 of the central recess 210 on the holding surface 11 until the sheet 221 on the annular support surface 16, and the holding table 10 is caused to rotate around the axis, and then, as shown by a solid line in Figure 15 The cutting tool 21-2 is caused to cut into the inner edge portion of the annular protrusion 215 until the sheet 221 on the annular support surface 16, and the holding table 10 is caused to rotate around the axis.

[0108] In the processing method of the modified example, in the annular protrusion removal step 1005, the same as in the embodiment, the operation of causing the cutting tool 21-2 of the cutting device 1 to cut into the outer edge portion of the second circular recess 212 of the central recess 210 on the holding surface 11 or the annular protrusion 215 until the sheet 221 and the operation of moving the cutting unit 20 in the Y-axis direction are repeated until the annular protrusion 215 is entirely cut from the sheet 221 and is crushed. In addition, in the processing method of the modified example, in the annular protrusion removal step 1005, the same as in the embodiment, the cutting tool 21-2 that cuts into the inner edge portion of the annular protrusion 215 is moved to the outer peripheral side of the annular protrusion 215 in the Y-axis direction while the holding table 10 is rotated around the axis, thereby cutting the entire annular protrusion 215 and crushing it.

[0109] In addition, in the processing method of the modified example, in the cutting step 1004 and the annular protrusion removal step 1005, as in the embodiment, the outer edge portion of the second circular recess 212 of the central recess 210 is cut or the annular protrusion 215 is cut and crushed by so-called cleaving cutting. However, in the present application, it is also possible that, after the cutting device 1 positions the lower end of the cutting tool 21-2 of the cutting unit 20-2 at a position at which the cutting tool 21-2 is aligned with the outer edge portion of the second circular recess 212 of the central recess 210 or the annular protrusion 215 of the wafer 200 held by the holding table 10 in the X-axis direction and cuts into the sheet 221, the holding table 10 is moved in the X-axis direction toward the cutting tool 21-2, the cutting tool 21-2 cuts into the outer edge portion of the second circular recess 212 of the central recess 210 or the annular protrusion 215 of the wafer 200 until the cutting tool 21-2 cuts into the sheet 221, the holding table 10 is rotated at least one revolution around the axis by the rotation moving unit 44, and the outer edge portion of the second circular recess 212 of the central recess 210 is cut or the annular protrusion 215 is cut and crushed.

[0110] In the processing method of the modified example, after the annular protrusion 215 is cut from the wafer 200 by the cutting tool 21-1 in the cutting step 1004, the annular protrusion 215 is cut and crushed by the cutting tool 21-2 in the annular protrusion removal step 1005, and thus the annular protrusion 215 is removed from the sheet 221, and as in the embodiment, the effect of being able to suppress a decrease in the production efficiency of each of the divided devices 206 and damage to the devices 206 is exerted.

[0111] In addition, the present application is not limited to the above-described embodiment and modified example. That is, various modifications can be made within the scope of the gist of the present application and implemented.

Claims

1. A wafer processing method of a wafer formed with a central recess on a back surface and having a ring-shaped protrusion around the central recess, wherein the wafer processing method has the steps of: a preparation step of preparing a holding stage including a holding portion having a holding surface corresponding to the central recess and a ring-shaped protrusion support portion having a ring-shaped support surface around the holding surface and lower than the holding surface, a height difference between the holding surface and the ring-shaped support surface being formed at least above a value of a depth of the central recess, the depth of the central recess being a depth from an upper surface of the ring-shaped protrusion of the wafer to a bottom surface of the central recess; a sheet arrangement step of arranging a sheet on the back surface of the wafer; a holding step of holding the back surface side of the wafer with the holding stage through the sheet; a cutting step of cutting the wafer with a cutting tool on the holding portion until reaching the sheet and relatively moving the holding stage with respect to the cutting tool to cut off the ring-shaped protrusion of the wafer from the wafer; and a ring-shaped protrusion removal step of pulverizing the ring-shaped protrusion supported by the ring-shaped protrusion support portion by cutting the ring-shaped protrusion with the cutting tool to remove the ring-shaped protrusion from the sheet.

2. The wafer processing method according to claim 1, wherein the holding stage is formed with: a holding surface suction passage having a holding surface suction hole on the holding surface and one end communicating with the holding surface suction hole and the other end connected to a suction source via a valve; and a support surface suction passage having a support surface suction hole on the ring-shaped support surface and one end communicating with the support surface suction hole and the other end connected to the suction source, in the cutting step, the wafer is suction-held by the holding portion, and in the ring-shaped protrusion removal step, the ring-shaped protrusion is suction-held by the ring-shaped protrusion support portion.

3. The wafer processing method according to claim 1 or 2, wherein in the cutting step, the wafer is cut in a state where a part in a thickness direction of the cutting tool is placed on the holding surface and a remaining part in the thickness direction of the cutting tool is projected to an outside of the holding surface.

4. A holding stage holding a wafer in the wafer processing method according to claim 1, wherein the holding stage has: a holding portion including a holding surface corresponding to the central recess; and a ring-shaped protrusion support portion including a ring-shaped support surface around the holding surface and lower than the holding surface, a height difference between the holding surface and the ring-shaped support surface being formed at least above a value of a depth of the central recess, the depth of the central recess being a depth from an upper surface of the ring-shaped protrusion of the wafer to a bottom surface of the central recess.

5. The holding stage according to claim 4, wherein the holding stage is formed with: a holding surface suction passage having a holding surface suction hole on the holding surface and one end communicating with the holding surface suction hole and the other end connected to a suction source via a valve; and a support surface suction passage having a support surface suction hole on the ring-shaped support surface and one end communicating with the support surface suction hole and the other end connected to the suction source. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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