Support substrate

Abstract

To provide a support substrate that can be bonded to a wafer with sufficient strength and that enables alignment of a processing apparatus by observing the wafer through the support substrate.SOLUTION: A support substrate fixed to a wafer via an adhesive member comprises a first surface facing the wafer, a second surface opposite to the first surface, and an outer peripheral surface connecting the first surface and the second surface. The first surface includes one or both of a recess and one of a roughened surface portion and a smooth surface portion. Preferably, the first surface has the recess, and the recess is formed in a region including a central portion of the first surface. More preferably, a bottom surface of the recess has a planar region overlapping the central portion of the first surface, and the planar region of the first surface is parallel to the second surface.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a support substrate that can support a wafer by being fixed to the wafer via an adhesive member. [Background technology]

[0002] In the manufacturing process of device chips to be mounted on electronic devices, the front side of a wafer is first partitioned by a plurality of mutually intersecting planned division lines (streets). Then, devices such as ICs (Integrated Circuits), LSIs (Large Scale Integration), power devices, and LEDs (Light Emitting Diodes) are formed in each of the partitioned areas. The wafer is then ground from the back side to thin it, and divided along the planned division lines to obtain a plurality of device chips, each equipped with a device.

[0003] When thinning a wafer from the backside, a grinding device equipped with an annular grinding wheel, a polishing device equipped with a disk-shaped polishing pad, or the like is used. When dividing a wafer, a cutting device equipped with an annular cutting blade, or the like is used. In recent years, there has been a remarkable trend toward miniaturization and weight reduction of various electronic devices equipped with device chips, and extremely thin device chips are required. Furthermore, thin device chips can efficiently remove heat generated by the device.

[0004] When a wafer is thinned by a grinding machine, it tends to bend easily like paper. This makes it difficult to transport the wafer to the location where the next process is performed. Therefore, the wafer is attached to a support substrate made of a material such as glass with an adhesive member, and the support substrate supports the wafer (see Patent Document 1). When the wafer is supported by the support substrate, the wafer continues to be supported by the support substrate even after it is ground and thinned, making it easier to handle the wafer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-134231 Summary of the Invention [Problem to be solved by the invention]

[0006] When a wafer attached to and supported by a support substrate is subjected to processing such as grinding, a processing load exceeding the adhesive strength between the support substrate and the wafer may be applied to the wafer. In this case, the wafer may peel off from the support substrate during processing. Therefore, there is a demand for improving the adhesive strength between the support substrate and the wafer.

[0007] One method for increasing the adhesive strength is to increase the amount of adhesive material disposed between the support substrate and the wafer. However, when the adhesive material is sandwiched between the support substrate and the wafer, the adhesive material is pushed out toward the outer periphery of the support substrate, causing the adhesive material to spill out from between the support substrate and the wafer. Increasing the amount of adhesive material also increases the amount of adhesive material that spills out from between the support substrate and the wafer. Therefore, simply increasing the amount of adhesive material used does not leave enough adhesive material in a position that contributes to adhesion.

[0008] Furthermore, since the adhesive material leaks out of the region sandwiched between the support substrate and the wafer, the thickness of the adhesive material near the outer edge of this region becomes thinner than that of the central portion. Therefore, when the adhesive material is cured to form a bonding layer, the thickness of the bonded substrate formed is not uniform. In other words, the wafer is supported by the support substrate in a curved state. When the wafer is processed, the processing results are affected by this curvature.

[0009] Another method for increasing adhesive strength is to roughen the top surface of the support substrate. However, a roughened surface scatters light and has low transparency. In processing equipment, it is sometimes desirable to observe the surface of a wafer on which devices and other components are formed through the support substrate for alignment purposes. If the transparency of the support substrate is reduced by roughening the top surface, alignment will be hindered.

[0010] The present invention has been made in consideration of such problems, and its object is to provide a support substrate that can be bonded to a wafer with sufficient strength, and that allows alignment of a processing device to be performed by observing the wafer through the support substrate. [Means for solving the problem]

[0011] According to one aspect of the present invention, there is provided a support substrate that is fixed to a wafer via an adhesive member, the support substrate having a first surface facing the wafer, a second surface opposite the first surface, and an outer peripheral surface connecting the first surface and the second surface, the first surface having a recess and one or both of a rough surface portion and a smooth surface portion.

[0012] Preferably, the first surface has the recess, and the recess is formed in a region including the center of the first surface. More preferably, the bottom surface of the recess has a flat region overlapping the center of the first surface, and the flat region of the first surface is parallel to the second surface. Or, more preferably, the inner wall surface of the recess is a conical surface that is inclined from the center of the first surface to the outer edge of the recess.

[0013] Alternatively, preferably, the first surface has the recess, and the recess is formed in the outer periphery of the first surface along the outer periphery surface, and the recess is formed in an annular shape so as to surround the central portion of the first surface.

[0014] Alternatively, preferably, the first surface has the rough surface portion and the smooth surface portion, and the rough surface portion is formed on the outer periphery of the first surface along the outer periphery.More preferably, the rough surface portion is formed in an annular shape so as to surround the central portion of the first surface.

[0015] Alternatively, preferably, the first surface has the rough surface portion and the smooth surface portion, and the rough surface portion is formed on the first surface in a position and shape that allows it to face the planned dividing line set on the wafer through the adhesive member when the wafer is fixed to the support substrate. [Effects of the Invention]

[0016] A support substrate according to one embodiment of the present invention has a recessed portion and one or both of a roughened surface portion and a smooth surface portion on a first surface facing a wafer, and therefore, when the support substrate is attached to a wafer via an adhesive member, the adhesive member comes into contact with the recessed portion or the roughened surface portion.

[0017] When a recess is formed on the first surface of the wafer, an adhesive material enters the recess, and the wall surface of the recess generates resistance to the force applied to the adhesive material, etc. This makes it less likely for the wafer to peel off. Furthermore, when attaching the wafer to the support substrate, the recess prevents the adhesive material from spilling out from between the support substrate and the wafer. In addition, in areas of the first surface of the wafer that do not have a recess, there are no elements in the support substrate that hinder the passage of light. Furthermore, there are no elements on the inner wall surface of the recess that reduce transparency. Therefore, alignment can be performed by observing the surface of the wafer through the support substrate.

[0018] Furthermore, when a rough surface portion is formed on the first surface of the wafer, the adhesive member adheres relatively strongly to the rough surface portion, making it less likely for the wafer to peel off when force is applied to the adhesive member, etc. Furthermore, in the smooth surface portion of the first surface of the wafer, there are no elements on the support substrate that impede the progression of light. Therefore, alignment can be performed by observing the surface of the wafer through the smooth surface portion of the support substrate.

[0019] Therefore, one aspect of the present invention provides a support substrate that can be bonded to a wafer with sufficient strength, and that allows alignment of a processing device to be performed by observing the wafer through the support substrate. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1(A) is a perspective view schematically showing the front surface side of a wafer supported by a support substrate, and FIG. 1(B) is a perspective view schematically showing the back surface side of the wafer. [Figure 2] FIG. 2(A) is a perspective view that schematically shows how a support substrate is fixed to a wafer via an adhesive member, and FIG. 2(B) is a perspective view that schematically shows the wafer and support substrate that are integrated via an adhesive member (bonding layer). [Figure 3] FIG. 1 is a perspective view schematically showing how a wafer supported by a support substrate is thinned by grinding from the back surface side. [Figure 4] FIG. 1 is a perspective view schematically showing how a wafer supported by a support substrate is cut and divided. [Figure 5] FIG. 5(A) is a perspective view that schematically shows a support substrate according to a first example, and FIG. 5(B) is a cross-sectional view that schematically shows the support substrate according to the first example. [Figure 6] FIG. 6(A) is a perspective view that schematically shows a support substrate according to the second example, and FIG. 6(B) is a cross-sectional view that schematically shows the support substrate according to the second example. [Figure 7] FIG. 7(A) is a perspective view that schematically shows a support substrate according to the third example, and FIG. 7(B) is a cross-sectional view that schematically shows the support substrate according to the third example. [Figure 8] FIG. 8(A) is a perspective view that schematically shows a support substrate according to the fourth example, and FIG. 8(B) is a cross-sectional view that schematically shows the support substrate according to the fourth example. [Figure 9] FIG. 9(A) is a cross-sectional view schematically showing a support substrate according to a first modified example, and FIG. 9(B) is a cross-sectional view schematically showing a support substrate according to a second modified example. DETAILED DESCRIPTION OF THE INVENTION

[0021] An embodiment according to one aspect of the present invention will be described below with reference to the accompanying drawings. First, a configuration example of a wafer supported by a support substrate according to this embodiment will be described. Fig. 1(A) is a perspective view schematically showing the front surface 11a side of a wafer 11, and Fig. 1(B) is a perspective view schematically showing the back surface 11b side of the wafer 11.

[0022] For example, the wafer 11 is a wafer made of a semiconductor such as silicon, and has a front surface 11a and a back surface 11b that are generally parallel to each other. However, there are no limitations on the material, shape, structure, size, etc. of the wafer 11. The wafer 11 may also be a substrate made of a semiconductor other than silicon (GaAs, SiC, InP, GaN, etc.), sapphire, glass, ceramics, resin, metal, etc.

[0023] 1(A), the wafer 11 is partitioned into a plurality of rectangular regions by a plurality of dividing lines (streets) 13 arranged in a grid pattern so as to intersect with one another. Devices 15 such as ICs (Integrated Circuits) and LSIs (Large Scale Integrations) are formed in each of the regions partitioned by the dividing lines 13. However, there are no limitations on the type, number, shape, structure, size, arrangement, etc. of the devices 15, and the wafer 11 does not necessarily have to have any devices 15 formed thereon.

[0024] The central portion of the front surface 11a of the wafer 11 where the devices 15 are formed is called a device region 17. The outer peripheral portion surrounding the device region 17 of the front surface 11a of the wafer 11 is called an outer peripheral excess region 19.

[0025] Furthermore, a cutout called a notch 21 indicating the crystal orientation of the wafer 11 is formed on the outer peripheral surface 11c of the wafer 11. Alternatively, a cut portion called an orientation flat is formed on the outer peripheral surface 11c of the wafer 11 instead of the notch 21. When the devices 15 are formed, the planned dividing lines 13 are set with reference to the notch 21, and the formation positions of the devices 15 are determined.

[0026] The wafer 11 is ground from the back surface 11b side to be thinned, and then divided along the planned division lines 13. This produces a plurality of device chips, each equipped with a device 15. The wafer 11 is fixed and supported in advance on a support substrate to facilitate handling after thinning. FIG. 2(A) is a perspective view that schematically shows how the support substrate 31 is fixed to the wafer 11 via an adhesive member 33, and FIG. 2(B) is a perspective view that schematically shows the wafer 11 and the support substrate 31 integrated together via the adhesive member 33 (bonding layer 37).

[0027] The support substrate 31 is preferably formed to have the same planar shape and thickness as the wafer 11. Alternatively, the support substrate 31 is preferably equal to or larger in size than the wafer 11 in order to properly support the wafer 11. The support substrate 31 may be formed of a semiconductor material such as silicon, and is preferably formed of a transparent material such as glass or resin. The support substrate 31 desirably has a thickness of 500 μm or more in order to stably support the wafer 11, but the thickness is not limited to this.

[0028] The support substrate 31 has a first surface (front surface) 31a facing the wafer 11, a second surface (back surface) 31b opposite the first surface 31a, and an outer peripheral surface 31c connecting the first surface 31a and the second surface 31b.

[0029] In order to perform the thinning process described below on the wafer 11 with high precision, the first surface 31a and the second surface 31b of the support substrate 31 are required to have a certain level of flatness or more, except for areas where predetermined structures are to be formed. For example, the support substrate 31 preferably has thickness uniformity that is the same as or greater than that of the wafer 11. Furthermore, the first surface 31a and the second surface 31b of the support substrate 31 preferably have flatness that is the same as or greater than that of the front surface 11a and the back surface 11b of the wafer 11. The support substrate 31 will be described in detail below.

[0030] The adhesive member 33 used to fix the wafer 11 to the support substrate 31 may be an epoxy-based, acrylic-based, silicone-based, or polyimide-based adhesive, a thermoplastic resin, a thermosetting resin, or an ultraviolet-curable resin. However, the adhesive member 33 is not limited to these. The adhesive member 33 is a liquid resin with a certain fluidity before being cured, and is cured by ultraviolet light, heat, the passage of time, or the like. The cured adhesive member 33 functions as a bonding layer 37. The thickness of the bonding layer 37 may be approximately 1 μm to 200 μm, and is preferably 100 μm.

[0031] 2(A), the support substrate 31 is placed on a flat surface with the first surface 31a facing upward and the second surface 31b facing downward. Then, a liquid adhesive material 33 is supplied to the first surface 31a exposed above the support substrate 31. Thereafter, the wafer 11 is placed above the support substrate 31 with the back surface 11b to be processed facing upward and the front surface 11a facing the first surface 31a of the support substrate 31, and the wafer 11 and the support substrate 31 are brought relatively close to each other.

[0032] When the downward-facing first surface 31a of the wafer 11 comes into contact with the adhesive member 33 and the wafer 11 and the support substrate 31 are further brought closer, the adhesive member 33 is pushed out toward the outer periphery of the wafer 11 (the outer periphery of the support substrate 31). At this time, the entire surface 11a of the wafer 11 comes into contact with the adhesive member 33, and the supply amount of the adhesive member 33 is determined so that the adhesive member 33 can provide sufficient adhesive strength when it is solidified into a bonding layer 37.

[0033] Thereafter, when heat or ultraviolet light is supplied to the liquid adhesive member 33 through the support substrate 31 or the like, the adhesive member 33 hardens to form a bonding layer 37, and the wafer 11 is fixed to the support substrate 31 via the adhesive member 33 (bonding layer 37). Fig. 2(B) is a perspective view schematically showing the wafer 11 and support substrate 31 integrated via the adhesive member 33 (bonding layer 37). When the wafer 11 is integrated with the support substrate 31 via the adhesive member 33, a bonded substrate 35 is formed.

[0034] The bonded substrate 35 is transported to a grinding device or the like that thins the wafer 11. In the grinding device or the like, the wafer 11 that has become a part of the bonded substrate 35 is thinned. FIG. 3 is a perspective view that schematically shows how the wafer 11 is ground in the grinding device 2. In FIG. 3, the adhesive member 33 (bonding layer 37) of the bonded substrate 35 is omitted. The grinding device 2 includes a chuck table (holding table) 4 that holds the wafer 11 (bonded substrate 35), and a grinding unit 6 that grinds the wafer 11 held by the chuck table 4.

[0035] The chuck table 4 has a suction path (not shown) inside, and one end of this suction path is connected to a suction source (not shown) such as an ejector. A porous member (not shown) is exposed on the upper surface of the chuck table 4, and the other end of the suction path is connected to this porous member. The diameter of the porous member is approximately the same as the diameter of the support substrate 31. The upper surface of the chuck table 4 becomes the holding surface 4a. When the support substrate 31 that supports the wafer 11 is placed on the holding surface 4a and the suction source is operated, the support substrate 31 is sucked and held on the chuck table 4.

[0036] The holding surface 4a is a conical surface with an extremely small inclination, with the center at the apex. The chuck table 4 is connected to a rotation drive source such as a motor (not shown), and can rotate around a table rotation axis 4d that is approximately perpendicular to the holding surface 4a.

[0037] The grinding device 2 includes a grinding unit 6 that grinds a workpiece held by a chuck table 4. The grinding unit 6 is supported by a lifting mechanism (not shown) and can be raised and lowered. The grinding unit 6 includes a spindle 8 that is approximately perpendicular to the holding surface 4a, and a rotation drive mechanism (not shown) such as a motor (not shown) is connected to the upper end of the spindle 8. When the rotation drive mechanism is operated, the spindle 8 rotates around a rotation axis 8a.

[0038] The upper surface of a disk-shaped wheel mount 10 is connected to the lower end of the spindle 8. A grinding wheel 12 is fixed to the wheel mount 10. The grinding wheel 12 has an annular wheel base 14. The wheel base 14 is made of a metal such as aluminum, and has a diameter corresponding to the diameter of the wafer 11.

[0039] A plurality of grinding wheels 16 are arranged in an annular shape on the outer periphery of the lower surface (bottom surface) of the wheel base 14. Each grinding wheel 16 is formed by mixing abrasive grains such as diamond or cBN (cubic boron nitride) with a binder such as vitrified or resinoid, and then sintering the mixture.

[0040] The wheel mount 10 is provided with a plurality of grinding wheel fixing holes that penetrate vertically, and the wheel base 14 is formed with fastening holes into which fasteners 18 such as bolts are tightened. The grinding wheel 12 is fixed to the wheel mount 10 by passing the fasteners 18 through the grinding wheel fixing holes and tightening the fasteners 18 into the fastening holes.

[0041] When the wafer 11 is ground to be thinned, the bonded substrate 35 is placed on the holding surface 4a of the chuck table 4. At this time, the second surface 31b of the support substrate 31 faces the holding surface 4a, and the back surface 11b of the wafer 11 is exposed upward. Then, the support substrate 31 is suction-held by the chuck table 4 from the second surface 31b side.

[0042] Thereafter, the rotary drive source connected to the spindle 8 is operated to rotate the spindle 8 around the rotation axis 8a, which rotates the grinding wheel 12 and moves the grinding stone 16 along the rotational orbit. Also, the chuck table 4 is rotated around the table rotation axis 4d.

[0043] Then, the grinding unit 6 is lowered, and the bottom surface of the grinding wheel 16 moving on the rotational orbit is brought into contact with the surface to be ground (back surface 11b) of the wafer 11. The wafer 11 is then ground, and gradually becomes thinner. At this time, the thickness of the wafer 11 is monitored, and when the wafer 11 reaches a predetermined thickness, the lowering of the grinding unit 6 is stopped. Then, the wafer 11 having the predetermined thickness is obtained.

[0044] While the wafer 11 is being ground from the back surface 11b side, the devices 15 formed on the front surface 11a are protected by the support substrate 31. Therefore, the support substrate 31 also functions as a protective member. Furthermore, since the support substrate 31 sufficiently supports the ground and thinned wafer 11, the wafer 11 can be thinned to a thickness of 10 μm or less by grinding.

[0045] Thereafter, the bonded substrate 35 is transported to a processing device or the like that divides the wafers 11. Then, the wafers 11 that have become part of the bonded substrate 35 are divided along the planned division lines 13. The wafers 11 are divided using a processing device such as a cutting device equipped with an annular cutting blade or a laser processing device that can focus a laser beam to perform laser processing on the workpiece. The following describes an example in which a cutting device is used.

[0046] 4 is a perspective view schematically showing how the wafer 11 is cut by the cutting device 20. In FIG. 4, the bonding layer 37 (adhesive member 33) of the bonded substrate 35 is omitted. The cutting device 20 is provided with a chuck table (not shown) that can suction-hold the workpiece. The chuck table provided in the cutting device 20 is configured similarly to the chuck table 4 of the grinding device 2 described in FIG. 3, and therefore description thereof will be omitted. However, the holding surface of the chuck table provided in the cutting device 20 is configured as a flat surface.

[0047] The cutting unit 22 has an annular cutting blade 28, and cuts the workpiece with the cutting blade 28. The cutting unit 22 has a spindle housing 24 that rotatably accommodates the base end side of a spindle (not shown) that forms a rotation axis parallel to the holding surface of the chuck table.

[0048] A rotary drive source such as a motor that rotates the spindle is housed inside the spindle housing 24, and operating this rotary drive source causes the spindle to rotate. An annular cutting blade 28 is fixed to the tip of the spindle. The cutting blade 28 can be rotated by rotating the spindle. The cutting blade 28 has a grinding wheel portion that includes a circular binder made of a metal material, a resin material, or the like, and abrasive grains made of diamond or the like dispersed and fixed in the binder.

[0049] When a workpiece is cut with the cutting blade 28, cutting chips and processing heat are generated from the grinding wheel and the workpiece. Therefore, while the workpiece is being cut with the cutting blade 28, processing water (cutting water) made of pure water or the like is supplied to the cutting blade 28 and the workpiece. The cutting water removes cutting chips and processing heat.

[0050] 4, the cutting unit 22 further includes a blade cover 26 that covers the cutting blade 28, and a processing water supply nozzle 32 connected to the blade cover 26. In addition, a processing water injection nozzle (not shown) that injects processing water onto the cutting blade 28 is provided inside the blade cover 26.

[0051] Machining water is supplied to the cutting blade 28 from a machining water supply nozzle 32 or the like. The blade cover 26 incorporates a liquid supply path whose end communicates with the machining water supply nozzle 32 or the like, and is provided with a connection part 30 at the start point of the liquid supply path. Machining water is supplied to the connection part 30 from the outside.

[0052] When being carried into the cutting device 20, the wafer 11 (bonded substrate 35) may be integrated with the dicing tape 23 and a ring frame 25 made of metal or the like. That is, as shown in Fig. 4, the wafer 11 supported on the support substrate 31, the dicing tape 23, and the ring frame 25 may be integrated to form a frame unit 27. Then, the wafer 11 may be cut while being included in the frame unit 27.

[0053] When cutting the wafer 11, the wafer 11 supported on the support substrate 31 is held by suction on a chuck table (not shown) of the cutting device 20. Then, the cutting unit 22 is lowered to a predetermined height while rotating the cutting blade 28. Then, the chuck table and the cutting unit 22 are moved relatively along the planned division line 13, and the cutting edge of the rotating cutting blade 28 is caused to cut into the planned division line 13 (see FIG. 1(A)). Then, the wafer 11 is cut along the planned division line 13.

[0054] Then, in the cutting device 20, the wafer 11 is cut along the division lines 13, and cutting grooves 13a are formed in the wafer 11. When the cutting grooves 13a are formed along all of the division lines 13 of the wafer 11, the wafer 11 is divided into individual chips.

[0055] The cutting device 20 is equipped with an imaging unit (not shown) that can image the front surface 11a side of the wafer 11 through the support substrate 31. In the cutting device 20, the imaging unit images the front surface 11a of the wafer 11, and the positions of the planned dividing lines 13 are detected. This allows the alignment work to be performed. The alignment work is performed before the wafer 11 is cut by the cutting blade 28.

[0056] The wafer 11 can be cut by positioning the lowest end of the cutting edge of the cutting blade 28 at a position lower than the surface 11a, which is the lowest end of the wafer 11, and cutting the wafer 11 with the cutting blade 28. The cut and individual wafers 11 continue to be supported collectively on the support substrate 31.

[0057] The chips formed by dividing the wafer 11 are finally peeled off from the support substrate 31. When peeling off the chips, it is preferable to carry out a process to reduce the adhesive strength of the adhesive member 33 (bonding layer 37) in advance. Here, the process to reduce the adhesive strength of the adhesive member 33 needs to be carried out by a method suited to the properties of the adhesive member 33.

[0058] For example, if the adhesive member 33 is made of a thermoplastic resin, the adhesive strength can be reduced by heating the adhesive member 33. Alternatively, if the adhesive member 33 is made of a UV-curable resin, the adhesive member 33 can be irradiated with ultraviolet light through the support substrate 31. In this case, the support substrate 31 needs to be made of a material that transmits ultraviolet light. The process for reducing the adhesive strength of the adhesive member 33 is not limited to these, and other methods may also be used.

[0059] However, when processing such as grinding or cutting is performed on the wafer 11 attached to and supported by the support substrate 31, a processing load that exceeds the adhesive strength between the support substrate 31 and the wafer 11 may occur. In this case, the wafer 11 may peel off from the support substrate 31 during processing. Therefore, there is a demand for improving the adhesive strength between the support substrate 31 and the wafer 11 by the adhesive member 33.

[0060] One method for increasing the adhesive strength is to increase the amount of adhesive member 33 disposed between the support substrate 31 and the wafer 11. However, when the adhesive member 33 is sandwiched between the support substrate 31 and the wafer 11, the adhesive member 33 is pushed out toward the outer periphery of the support substrate 31, causing the adhesive member 33 to spill out from between the support substrate 31 and the wafer 11. Therefore, it is not easy to make the adhesive member 33 thicker simply by increasing the amount of adhesive member 33 used.

[0061] Furthermore, since the adhesive member 33 leaks out of the region sandwiched between the support substrate 31 and the wafer 11, the thickness of the adhesive member 33 near the outer edge of this region becomes thinner than that of the central portion. Therefore, when the adhesive member 33 is cured to form the bonding layer 37, the thickness of the formed bonded substrate 35 is not uniform, that is, the wafer 11 is supported by the support substrate 31 in a curved state. When the wafer 11 is processed, the processing results are affected by this curvature.

[0062] Another method for increasing adhesive strength is to roughen the upper surface (first surface 31a) of the support substrate 31. However, a roughened surface scatters light, which reduces the transparency of the support substrate 31. As described above, in some processing devices (e.g., cutting device 20), it is sometimes desirable to observe the front surface 11a of the wafer 11, on which devices 15 and the like are formed, through the support substrate 31 for alignment purposes. If the transparency of the support substrate 31 is reduced by roughening the upper surface (first surface 31a) of the support substrate 31, alignment will be hindered.

[0063] Therefore, a support substrate 31 according to the present embodiment, which will be described below, is provided. The support substrate 31 according to the present embodiment can be bonded to the wafer 11 with sufficient strength. Furthermore, alignment can be performed by observing the wafer 11 through this support substrate 31. The support substrate 31 according to the present embodiment will be described below.

[0064] 5(A) is a perspective view schematically showing the support substrate 41, 31 according to the first example, and FIG. 5(B) is a cross-sectional view schematically showing the support substrate 41, 31 according to the first example. The support substrate 41, 31 has a first surface 41a, 31a facing the wafer 11, a second surface 41b, 31b opposite the first surface 41a, 31a, and an outer peripheral surface 41c, 31c connecting the first surface 41a, 31a and the second surface 41b, 31b.

[0065] The first surface 41a of the support substrate 41 according to this embodiment has a recess 45. In particular, in the support substrate 41 according to the first example shown in FIGS. 5(A) and 5(B), the recess 45 is formed in a region including the central portion 43 of the first surface 41a. Typically, the outer edge of the recess 45 is circular. It is preferable that the center of the recess 45 coincides with the center of the first surface 41a of the support substrate 41.

[0066] Although there are no particular limitations on the position of the outer edge of the recess 45, it is preferable that the position be determined so that it overlaps with the outer peripheral surface 11c of the wafer 11 when the wafer 11 is attached to the support substrate 41, or so that it is located more inward than the outer peripheral surface 11c of the wafer 11 when observed from above. The inner surface of the recess 45 slopes gently and continuously from the outer edge to the central portion 43 of the first surface 41a. The inner surface of the recess 45 has a high degree of flatness.

[0067] When bonding the wafer 11 to the support substrate 41, the liquid adhesive member 33 is supplied to the recess 45 formed on the first surface 41a of the support substrate 41 in an amount that exceeds the capacity of the recess 45. In this state, the wafer 11 is placed on the support substrate 41 with the adhesive member 33 interposed therebetween, and the adhesive member 33 is sandwiched between the support substrate 41 and the wafer 11. Then, the adhesive member 33 is pushed and spread in the region between the support substrate 41 and the wafer 11 toward the periphery of the region.

[0068] Here, the inner surface of the recess 45 gradually rises from the center to the outer edge, and the slope becomes steeper as it approaches the outer edge. Therefore, the adhesive member 33 being pushed outward along the inner surface of the recess 45 is more restricted in its progress as it approaches the outer edge of the recess 45.

[0069] For example, if no recesses 45 are formed on the first surface 41a of the support substrate 41 and the first surface 41a is flat, the adhesive member 33 sandwiched between the support substrate 41 and the wafer 11 advances smoothly on the first surface 41a toward the outer periphery. Therefore, the adhesive member 33 easily slips out from between the wafer 11 and the support substrate 41, making it difficult to retain a large amount of the adhesive member 33 between the wafer 11 and the support substrate 41. In other words, it is difficult to form a thick bonding layer 37 (adhesive member 33) between the wafer 11 and the support substrate 41.

[0070] Furthermore, in this case, the progress of the adhesive member 33 sandwiched between the support substrate 41 and the wafer 11 is not suppressed, and therefore, in the region close to the outer peripheral surface 41c of the support substrate 41, the adhesive member 33 is unlikely to remain between the support substrate 41 and the wafer 11 in an amount sufficient to form a bonding layer 37 with a sufficient thickness. Therefore, the bonding layer 37 formed by hardening the adhesive member 33 is likely to be thick in the region overlapping with the central portion 43 of the first surface 41a of the support substrate 41 and is likely to be thin near the outer peripheral surface 41c of the support substrate 41. In other words, the thickness of the bonding layer 37 is likely to be non-uniform, and the wafer 11 supported by the bonding layer 37 is likely to be distorted or curved.

[0071] In contrast, the support substrate 41 according to this embodiment has a recess 45 formed on the first surface 41a, which makes it difficult for the adhesive member 33 to slip out from between the wafer 11 and the support substrate 41. That is, it is easy to retain a large amount of adhesive member 33 between the wafer 11 and the support substrate 41. When the adhesive member 33 is cured while a large amount of adhesive member 33 remains between the wafer 11 and the support substrate 41, a thick bonding layer 37 (adhesive member 33) can be formed. When the thick bonding layer 37 (adhesive member 33) is formed between the wafer 11 and the support substrate 41, the wafer 11 and the support substrate 41 are firmly bonded together.

[0072] From this viewpoint, the shape of recess 45 is preferably determined so that the height near the center is lower than the outer edge by 25% to 50% of the planned thickness of bonding layer 37. For example, if the planned thickness of bonding layer 37 is 100 μm, recess 45 is preferably deeper near the center than the outer edge by 25 μm to 50 μm. However, the depth of recess 45 is not limited to this.

[0073] When the support substrate 41 has a recess 45, the distance between the front surface 11a (lower surface) of the wafer 11 and the first surface 41a (upper surface) of the support substrate 41 is large in a region overlapping with the central portion 43 of the first surface 41a of the support substrate 41 and is small near the outer peripheral surface 41c of the support substrate 41. In other words, this distance is large in a region where the adhesive member 33 is likely to remain and is small in a region where the adhesive member 33 is unlikely to remain.

[0074] Therefore, in each region between the support substrate 41 and the wafer 11, the adhesive member 33 is disposed in an amount appropriate for filling the gap. Therefore, when the adhesive member 33 is cured to form the bonding layer 37 and the support substrate 41 and the wafer 11 are integrated to form the bonded substrate 35, the total thickness of the support substrate 41 and the bonding layer 37 (adhesive member 33) becomes uniform throughout the bonded substrate 35. Therefore, each portion of the wafer 11 is supported uniformly, making it less likely that the wafer 11 will be distorted or warped.

[0075] The thickness of the adhesive member 33 before hardening is about 3 μm smaller near the outer edge of the region between the support substrate 41 and the wafer 11 than near the center of the region. From this perspective, the shape of the recess 45 is preferably determined so that the depth near the center is about 3 μm lower than the outer edge. However, the depth of the recess 45 is not limited to this.

[0076] Furthermore, in the case where a recess 45 is formed in the support substrate 41, when the adhesive member 33 is cured, the bonding layer 37 is formed in a shape that follows the shape of the inner surface of the recess 45. At this time, the bonding layer 37 (adhesive member 33) is fitted into the recess 45.

[0077] Therefore, for example, when a force acts on the wafer 11 in a direction along the front surface 11a (a direction along the second surface 31b of the support substrate) during processing of the wafer 11 and the force is also applied to the bonding layer 37, the force applied to the bonding layer 37 is received by the recess 45. In other words, the wall surface of the recess 45 generates a resistance force against the force applied to the bonding layer 37. That is, the recess 45 suppresses movement of the bonding layer 37 that would cause it to peel off from the support substrate 41.

[0078] 5(A) and 5(B) is formed in the support substrate 41, the support substrate 41 and the wafer 11 are firmly fixed together, and the wafer 11 is less likely to peel off from the support substrate 41. The inner surface of the recess 45 may have high flatness, and in this case, when observing the surface 11a of the wafer 11 through the support substrate 41 in the bonded substrate 35 for the purpose of alignment or the like, the inner surface of the recess 45 does not obstruct the observation.

[0079] Next, a second example of the support substrate 31 according to this embodiment will be described. Fig. 6(A) is a perspective view schematically showing the support substrate 51, 31 according to the second example, and Fig. 6(B) is a cross-sectional view schematically showing the support substrate 51, 31 according to the second example. The support substrate 51, 31 has a first surface 51a, 31a facing the wafer 11, a second surface 51b, 31b opposite the first surface 51a, 31a, and an outer peripheral surface 51c, 31c connecting the first surface 51a, 31a and the second surface 51b, 31b.

[0080] The first surface 51a of the support substrate 51 according to the second example has a recess 55. In particular, in the support substrate 51 shown in FIGS. 6(A) and 6(B), the recess 55 is formed in the outer periphery of the first surface 51a along the outer periphery 51c. More specifically, the recess 55 is formed in an annular shape so as to surround the central portion 53 of the first surface 51a. Typically, the recess 55 is continuous without interruption along the outer periphery 51c. However, the recess 55 may be interrupted, and the inside and outside of the recess 55 on the first surface 51a may be connected.

[0081] Although there is no particular limitation on the position where the recess 55 is formed, it is preferable that the recess 55 is formed in the support substrate 51 at a position that overlaps with the peripheral excess region 19 (see FIG. 1(A)) of the wafer 11 when the wafer 11 is attached to the support substrate 51. However, the position where the recess 55 is formed is not limited to this.

[0082] When the wafer 11 is bonded to the support substrate 51, the liquid adhesive member 33 is supplied to the support substrate 51 in an area inside the recess 55 of the first surface 51a. In this state, the wafer 11 is placed on the support substrate 51 with the adhesive member 33 interposed therebetween, and the adhesive member 33 is sandwiched between the support substrate 51 and the wafer 11. Then, the adhesive member 33 is pushed and spread between the support substrate 51 and the wafer 11 toward the outer edge.

[0083] At this time, the adhesive material 33 reaches the recess 55 before reaching the outer edge and accumulates in the recess 55. Therefore, even if a sufficient amount of adhesive material 33 is supplied to the support substrate 51 for the purpose of forming a thick bonding layer 37, the adhesive material 33 is unlikely to protrude to the outside from between the support substrate 51 and the wafer 11. In other words, the amount of adhesive material 33 lost can be reduced, and the adhesive material 33 can be supplied to the support substrate 51 in a sufficient amount to suppress unevenness in the thickness of the bonding layer 37 due to the loss of the adhesive material 33.

[0084] Furthermore, when the support substrate 51 has a larger diameter than the wafer 11, the recess 55 may be formed in the support substrate 51 at a position that does not overlap with the wafer 11. In this case, the adhesive member 33 sandwiched and spread between the support substrate 51 and the wafer 11 protrudes outside the wafer 11 and then enters the recess 55. Therefore, the adhesive member 33 is less likely to reach the outer peripheral surface 51c of the support substrate 51 and fall off.

[0085] Then, when the adhesive member 33 is hardened while it is in the recess 55 of the support substrate 51, a bonding layer 37 can be formed that is in the recess 55. In this case, when a force parallel to the front surface 11a of the wafer 11 is applied to the wafer 11 during processing of the wafer 11, the wall surface of the recess 55 generates a resistance to this force, and therefore the support substrate 51 and the adhesive member 33 (bonding layer 37) are less likely to peel off.

[0086] The width of the recess 55 is preferably 1.0 mm or more and 2.0 mm or less, and the depth of the recess 55 is preferably 500 μm or more so as to be able to accommodate a sufficient amount of adhesive member 33. However, the size of each part of the recess 55 is not limited to this. In this case, precision is not required for the depth of the recess 55, and therefore the recess 55 can be formed in the support substrate 51 by low-cost, low-precision machining.

[0087] Furthermore, when the bonded substrate 35 is carried into the processing device (cutting device 20) and the wafer 11 is processed (cut), the front surface 11a of the wafer 11 can be observed through the area of the support substrate 51 where the recesses 55 are not formed. In other words, alignment can be performed without any problems in the processing device.

[0088] 6(A) and 6(B) show the case where one recess 55 is formed in the support substrate 51, but the number of recesses 55 is not limited to one. That is, another recess may be formed on the first surface 51a of the support substrate 51 outside or inside the recess 55, or three or more recesses may be formed in the support substrate 51. Also, while FIG. 6(A) shows the case where the recess 55 is circular, the shape of the recess 55 is not limited to circular. That is, the recess 55 may be formed on the first surface 51a in a shape such as a sine wave, a rectangular wave, or a triangular wave, and it is preferable that the recess 55 be formed on the first surface 51a in a shape and arrangement that surrounds the central portion 53 of the first surface 51a.

[0089] Support substrate 51 having recessed portion 55 is manufactured, for example, by processing a circular substrate. For example, the circular substrate is placed on the chuck table of cutting device 20 described in Fig. 4, and cutting blade 28 is positioned above the position on the upper surface of the circular substrate where recessed portion 55 is planned to be formed. Cutting unit 22 is then lowered while rotating cutting blade 28. Then, cutting blade 28 cuts into the circular substrate from above.

[0090] Thereafter, when the chuck table is rotated once around the rotation axis perpendicular to the holding surface, the cutting blade 28 cuts the circular substrate all the way around to form the recesses 55. That is, the support substrate 51 having the recesses 55 formed therein is manufactured. However, the manufacturing method of the support substrate 51 is not limited to this.

[0091] Next, a third example of the support substrate 31 according to this embodiment will be described. Fig. 7(A) is a perspective view schematically showing the support substrate 61, 31 according to the third example, and Fig. 7(B) is a cross-sectional view schematically showing the support substrate 61, 31 according to the third example. The support substrate 61, 31 has a first surface 61a, 31a facing the wafer 11, a second surface 61b, 31b opposite the first surface 61a, 31a, and an outer peripheral surface 61c, 31c connecting the first surface 61a, 31a and the second surface 61b, 31b.

[0092] The first surface 61a of the support substrate 61 according to this embodiment has a rough surface portion 65 and a smooth surface portion 63. For example, the entire area of the first surface 61a that is not the rough surface portion 65 is the smooth surface portion 63. In particular, in the support substrate 61 according to the third example shown in FIGS. 7(A) and 7(B), the rough surface portion 65 is formed on the outer periphery of the first surface 61a along the outer periphery 61c of the support substrate 61.

[0093] The rough surface portion 65 is formed in an annular shape so as to surround the smooth surface portion 63 formed in the center of the first surface 61a. However, the rough surface portion 65 does not have to be formed in the outermost peripheral portion of the first surface 61a; smooth surface portions 63 may also be formed further outside the rough surface portion 65. Typically, the rough surface portion 65 is continuous and uninterrupted along the outer peripheral surface 61c. However, the rough surface portion 65 may be interrupted. That is, the rough surface portion 65 may be formed in each of multiple, mutually separated, arc-shaped regions that overlap the outer peripheral portion of the first surface 61a. Furthermore, when smooth surface portions 63 are formed on both the inside and outside of the rough surface portion 65 of the first surface 61a, the inner and outer smooth surface portions 63 may be connected between the adjacent arc-shaped rough surface portions 65.

[0094] Although there is no particular limitation on the position where the rough surface portion 65 is formed, it is preferable that the rough surface portion 65 is formed on the support substrate 51 at a position that overlaps with the peripheral excess region 19 (see FIG. 1(A)) of the wafer 11 when the wafer 11 is attached to the support substrate 51. However, the position where the rough surface portion 65 is formed is not limited to this.

[0095] The rough surface portion 65 is rougher and less flat than the smooth surface portion 63. The maximum height (Ry) indicating the surface roughness of the smooth surface portion 63 is smaller than the maximum height of the rough surface portion 65. Furthermore, for example, the surface roughness (Ra) of the rough surface portion 65 is 0.01 or more and 1.00 or less, and the surface roughness (Ra) of the smooth surface portion 63 is less than 0.01. However, the roughnesses of the rough surface portion 65 and the smooth surface portion 63 are not limited to these.

[0096] When the wafer 11 is bonded to the support substrate 61, the liquid adhesive member 33 is supplied to the support substrate 61 in an area inside the rough surface portion 65 of the first surface 61a. In this state, the wafer 11 is placed on the support substrate 61 with the adhesive member 33 interposed therebetween, and the adhesive member 33 is sandwiched between the support substrate 61 and the wafer 11. Then, the adhesive member 33 is pressed and spread between the support substrate 61 and the wafer 11 toward the outer circumferential surface 61c.

[0097] At this time, the adhesive member 33 reaches the rough surface portion 65 before reaching the outer peripheral surface 61c. The adhesive member 33 before hardening penetrates into the minute irregularities formed in the rough surface portion 65. Therefore, when the adhesive member 33 is hardened in this state, a bonding layer 37 that penetrates into these minute irregularities can be formed. The contact area between the rough surface portion 65 and the bonding layer 37 is wide, and the bonding layer 37 adheres strongly to the rough surface portion 65. Therefore, when a force is applied to the wafer 11 during processing of the wafer 11, the support substrate 61 and the adhesive member 33 (bonding layer 37) are unlikely to peel off.

[0098] Furthermore, since the rough surface portion 65 can suppress the progression of the adhesive member 33, the adhesive member 33 can also be suppressed from coming off, and unevenness in the thickness of the bonding layer 37 due to this coming off is less likely to occur. Furthermore, when the bonded substrate 35 is carried into a processing device (cutting device 20) and the wafer 11 is processed (cut), the front surface 11a of the wafer 11 can be observed through the smooth surface portion 63 of the support substrate 61. In other words, alignment can be performed without any problems in the processing device.

[0099] The support substrate 61 having the rough surface portion 65 is manufactured, for example, by processing a circular substrate. For example, the circular substrate is placed on the chuck table of the cutting device 20 described in FIG. 4, and the cutting blade 28 is positioned above the position on the upper surface of the circular substrate where the rough surface portion 65 is to be formed. The cutting unit 22 is then lowered while rotating the cutting blade 28. At this time, the height of the cutting unit 22 is adjusted so that the lowest end of the cutting edge of the cutting blade 28 is approximately at the same height as the first surface 61a of the support substrate 61.

[0100] As a result, the first surface 61a is roughened in the area where the cutting edge of the rotating cutting blade 28 comes into contact, forming a rough surface portion 65. Thereafter, when the chuck table is rotated once around the rotation axis perpendicular to the holding surface, the cutting blade 28 roughens the first surface 61a over the entire circumference, forming the rough surface portion 65. The area surrounded by the rough surface portion 65 then becomes a smooth surface portion 63. In other words, a support substrate 61 is manufactured in which the rough surface portion 65 and the smooth surface portion 63 are formed. However, the method for manufacturing the support substrate 61 is not limited to this.

[0101] Next, a fourth example of the support substrate 31 according to this embodiment will be described. Fig. 8(A) is a perspective view schematically showing the support substrate 71, 31 according to the fourth example, and Fig. 8(B) is a cross-sectional view schematically showing the support substrate 71, 31 according to the fourth example. The support substrate 71, 31 has a first surface 71a, 31a facing the wafer 11, a second surface 71b, 31b opposite the first surface 71a, 31a, and an outer peripheral surface 71c, 31c connecting the first surface 71a, 31a and the second surface 71b, 31b.

[0102] 8(A) and 8(B) show a first surface 71a of a support substrate 71 according to a fourth example, which has a rough surface portion 75 and a smooth surface portion 73. In particular, in the support substrate 71 according to the fourth example, the rough surface portion 75 is formed on the first surface 71a in a position and shape that allows it to face the planned dividing line 13 set on the wafer 11 through the adhesive member 33 (bonding layer 37) when the wafer 11 is fixed to the support substrate 71.

[0103] The properties of the rough surface portion 75 and the smooth surface portion 73 of the support substrate 71 according to the fourth example are similar to the properties of the rough surface portion 65 and the smooth surface portion 63 of the support substrate 61 according to the third example described above. When the wafer 11 is attached to the support substrate 71 via the adhesive member 33 (bonding layer 37), the adhesive member 33 is less likely to peel off from the support substrate 71 due to the strong adhesion between the rough surface portion 75 and the adhesive member 33. In particular, the support substrate 71 according to the fourth example has the rough surface portion 75 arranged not only in the peripheral region but also in the central region, so that the adhesive member 33 (bonding layer 37) is less likely to peel off over the entire first surface 71a.

[0104] When the support substrate 71 according to the fourth example and the wafer 11 are integrated, the orientations of the support substrate 71 and the wafer 11 are adjusted so that the rough surface portion 75 of the support substrate 71 overlaps the planned dividing lines 13 of the wafer 11. When the support substrate 71 and the wafer 11 whose orientations have been adjusted in this manner are integrated, the smooth surface portion 73 of the support substrate 71 overlaps the devices 15 formed on the wafer 11. Therefore, the devices 15 on the wafer 11 can be observed through the smooth surface portion 73, and the positions of various patterns constituting the devices 15 can be identified and alignment can be performed.

[0105] In order to easily align the orientation of the wafer 11 with the support substrate 71, a notch or the like corresponding to the notch 21 of the wafer 11 may be formed in the outer peripheral surface 71c of the support substrate 71. This notch or the like may be formed in the support substrate 71 at a position that overlaps with the notch 21 of the wafer 11 when the orientation of the support substrate 71 is appropriately aligned with the orientation of the wafer 11. In this case, by adjusting the orientation of the wafer 11 so that the notch 21 of the wafer 11 overlaps with this notch or the like and then bonding the wafer 11 to the support substrate 71, the smooth surface portion 73 of the support substrate 71 and the device 15 of the wafer 11 overlap.

[0106] However, since there is a limit to the accuracy with which the orientation of the wafer 11 can be aligned with the support substrate 71, it is preferable that the rough surface portion 75 be formed on the support substrate 71 in a shape that corresponds to the alignment accuracy of the wafer 11. For example, the width of the rough surface portion 75 is preferably narrower than the width of the planned dividing lines 13 of the wafer 11, and more preferably about 10 μm narrower than the width of the planned dividing lines 13. In this case, even if a typical amount of misalignment occurs in the positional relationship between the wafer 11 and the support substrate 71, the device 15 and the rough surface portion 75 will not overlap. Therefore, the alignment operation is not hindered by the rough surface portion 75.

[0107] As described above, the support substrate 31 according to this embodiment has the recessed portions 45, 55 and one or both of the rough surface portions 65, 75 and the smooth surface portions 63, 73 on the first surface 31a facing the wafer 11. Therefore, when the support substrate 31 is attached to the wafer 11 via the adhesive member 33, the adhesive member 33 comes into contact with the recessed portions 45, 55 or the rough surface portions 65, 75.

[0108] When recesses 45, 55 are formed on the first surface 31a of the wafer, the adhesive member 33 enters the recesses 45, 55, and the wall surfaces of the recesses 45, 55 generate resistance to the force acting on the adhesive member 33 in the direction along the second surface 31b of the support substrate 31 (the front surface 11a of the wafer 11). Therefore, peeling of the wafer 11 is less likely to occur.

[0109] Furthermore, the recesses 45, 55 prevent the adhesive member 33 from spilling out from between the support substrate 31 and the wafer 11 when the wafer 11 is attached to the support substrate 31. In areas of the support substrate 31 without the recesses 45, 55, there is no element that obstructs the progression of light. The inner walls of the recesses 45, 55 are flat. Therefore, the surface 11a of the wafer 11 can be observed through the corresponding areas of the support substrate 31 to perform alignment.

[0110] Furthermore, when rough surface portions 65, 75 are formed on the front surface 11a of the wafer 11, the adhesive member 33 adheres relatively strongly to the rough surface portions 65, 75. Therefore, when a force is applied to the adhesive member 33 in a direction along the second surface 31b (front surface 11a of the wafer 11) of the support substrate 31, peeling of the wafer 11 is unlikely to occur. Note that, in the smooth surface portions 63, 73, the support substrate 31 has no elements that impede the propagation of light. Therefore, alignment can be performed by observing the front surface 11a of the wafer 11 through the smooth surface portions 63, 73 of the support substrate 31.

[0111] The present invention is not limited to the above-described embodiment, and various modifications can be made. For example, in the above-described embodiment, the support substrates 41 and 31 have recesses 45 on the first surfaces 41a and 31a, respectively, as shown in Fig. 5, and the inner walls of the recesses 45 have a gradual slope that changes from the central portion 43 of the first surfaces 41a and 31a to the outer edges of the recesses 45. However, one aspect of the present invention is not limited to this.

[0112] Fig. 9(A) is a cross-sectional view schematically showing a support substrate 91 according to a first modified example. The support substrate 91 shown in Fig. 9(A) has a first surface 91a facing the wafer 11, a second surface 91b opposite the first surface 91a, and an outer peripheral surface 91c connecting the first surface 91a and the second surface 91b. The first surface 91a of the support substrate 91 has a recess 95, which is formed in a region including a central portion 97 of the first surface 91a.

[0113] 9(A) , the inner wall of the recess 95 of the support substrate 91 is inclined at a certain angle from the central portion 97 of the first surface 91a to the outer edge of the recess 95. In other words, the inner wall surface of the recess 95 is a conical surface having an apex at the central portion 97 of the first surface 91a. Even in this case, when the adhesive member 33 is supplied to the recess 95, the adhesive member 33 is sandwiched between the support substrate 91 and the wafer 11, and the adhesive member 33 is cured to integrate the support substrate 91 and the wafer 11, the recess 95 generates resistance to the force applied to the wafer 11, etc. Therefore, the adhesive member 33 (bonding layer 37) is unlikely to peel off from the support substrate 91.

[0114] 9(B) is a cross-sectional view schematically showing a support substrate 101 according to a second modified example. The support substrate 101 shown in FIG. 9(B) has a first surface 101a facing the wafer 11, a second surface 101b opposite the first surface 101a, and an outer peripheral surface 101c connecting the first surface 101a and the second surface 101b. The first surface 101a of the support substrate 101 has a recess 105, which is formed in a region including the center of the first surface 101a.

[0115] 9(B) is composed of a flat area 107 with no inclination located near the center of the first surface 101a and an inclined surface 109 surrounding the flat area 107. In this case as well, when the adhesive member 33 is supplied to the recessed portion 105, the adhesive member 33 is sandwiched between the support substrate 101 and the wafer 11, and the adhesive member 33 is cured to integrate the support substrate 101 and the wafer 11, the recessed portion 105 generates resistance to the force applied to the wafer 11, etc. Therefore, the adhesive member 33 (bonding layer 37) is unlikely to peel off from the support substrate 101.

[0116] As described above, the thickness of the adhesive member 33 tends to be thin near the outer edge of the region between the support substrate 101 and the wafer 11. This tendency for the thickness of the adhesive member 33 to decrease toward the outer edge of this region is constant regardless of the sizes of the wafer 11 and the support substrate 101. More specifically, this decrease in thickness occurs significantly in an annular region about 10 mm wide inward from the outer edge of this region. Conversely, the thickness of the adhesive member 33 is constant at a position 10 mm or more inward from the outer edge of the region between the support substrate 101 and the wafer 11.

[0117] Therefore, it is preferable that the flat region 107 is formed on the support substrate 101 at a position facing a region 10 mm or more inward from the outer periphery of the front surface 11a of the wafer 11 when the wafer 11 is attached to the support substrate 101. It is also preferable that the inclined surface 109 is formed on the support substrate 101 at a position facing a ring-shaped region up to 10 mm from the outer periphery of the front surface 11a of the wafer 11.

[0118] The inclined surface 109 is formed so that the difference in height between its inner and outer edges is about 3 μm, and the inclination from the inner edge to the outer edge may be constant throughout, or may be a curved surface with an inconstant inclination. Furthermore, the inclined surface 109 may be formed in a stepped shape consisting of a plurality of flat portions and vertical portions.

[0119] 5(A) and 5(B) show a case where the recess 45 is formed in the support substrate 41 such that the outer edge of the recess 45 is connected to the outer peripheral surface 41c of the support substrate 41. However, one aspect of the present invention is not limited to this. That is, when the recess is formed on the first surface of the support substrate, the outer edge of the recess does not need to be connected to the outer peripheral surface of the support substrate.

[0120] 9(A) and 9(B), in the support substrate 91, 101 according to one embodiment of the present invention, a flat portion 93, 103 may be left on the first surface 91a, 101a between the outer edge of the recess 95, 105 and the outer peripheral surface 91c, 101c. The size and formation position of the flat portion 93, 103 may be determined to correspond to the size and shape of the wafer 11 to be attached to the support substrate 91, 101, for example.

[0121] Finally, in the above embodiment, the recesses 45, 55 and one of the rough surface portions 65, 75 and the smooth surface portions 63, 73 are formed on the first surface 31a of the support substrate 31 facing the wafer 11. However, one aspect of the present invention is not limited to this. The first surface 31a of the support substrate 31 may have both the recesses 45, 55, the rough surface portions 65, 75, and the smooth surface portions 63, 73 formed thereon.

[0122] In addition, the structures, methods, etc. according to the above-described embodiments can be modified as appropriate without departing from the scope of the object of the present invention. [Explanation of symbols]

[0123] 2 Grinding equipment 4 Chuck table 4a Holding surface 4d table rotation axis 6 Grinding Unit 8 spindles 8a Rotation axis 10. Wheel mount 12 Grinding wheels 14 Wheel base 16 Grinding Wheel 18 Fixtures 20 Cutting equipment 22 Cutting unit 24 Spindle housing 26 Blade cover 28 Cutting Blade 30 Connection 32 Processing water supply nozzle 11 wafers 11a surface 11b Back side 11c Outer surface 13 Planned division line 13a cutting groove 15 devices 17 Device Area 19 Surplus outer area 21 notches 23 Dicing tape 25 ring frame 27 Frame Unit 31,41,51,61,71,91,101 Support substrate 31a,41a,51a,61a,71a,91a,101a 1st page 31b,41b,51b,61b,71b,91b,101b 2nd side 31c,41c,51c,61c,71c,91c,101c Outer surface 33 Adhesive material 35 Bonded substrate 37 Bonding layer 43,53,97 central part 45,55,95,105 recess 63,73 Smooth surface part 65,75 Rough surface area 93,103 Flat area 107 Planar area 109 Slope

Claims

1. A support substrate fixed to a wafer via an adhesive member, a first surface facing the wafer, a second surface opposite the first surface, and an outer peripheral surface connecting the first surface and the second surface; The first surface of the support substrate has a recess and one or both of a rough surface portion and a smooth surface portion.

2. the first surface has the recess; The support substrate according to claim 1 , wherein the recess is formed in a region including a central portion of the first surface.

3. a bottom surface of the recessed portion having a flat area overlapping the central portion of the first surface; The support substrate according to claim 2 , wherein the planar region of the first surface is parallel to the second surface.

4. 3. The support substrate according to claim 2, wherein the inner wall surface of the recess is a conical surface that is inclined from the center of the first surface to the outer edge of the recess.

5. the first surface has the recess; The support substrate according to claim 1 , wherein the recess is formed in the outer periphery of the first surface along the outer periphery.

6. The support substrate according to claim 5 , wherein the recess is formed in a ring shape so as to surround the center of the first surface.

7. the first surface has the rough surface portion and the smooth surface portion, The support substrate according to claim 1 , wherein the rough surface portion is formed on the outer periphery of the first surface along the outer periphery.

8. The support substrate according to claim 7 , wherein the rough surface portion is formed in an annular shape so as to surround a central portion of the first surface.

9. the first surface has the rough surface portion and the smooth surface portion, The support substrate according to claim 1, characterized in that the rough surface portion is formed on the first surface in a position and shape that allows it to face the planned dividing line set on the wafer through the adhesive member when the wafer is fixed to the support substrate.

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