holding table

Abstract

The present application provides a holding stage capable of easily and reliably holding a wafer having a recess. The holding stage holds a wafer having a recess and an annular outer peripheral portion surrounding the recess, wherein the holding stage has a base and a holding portion protruding from an upper surface of the base and inserted into the recess of the wafer, the base has an annular groove provided in a region corresponding to the outer peripheral portion of the wafer and a support member provided inside the groove, the support member changes from a softened state to a hardened state or from the hardened state to the softened state by energy application, the recess of the wafer is held by the holding portion, and the outer peripheral portion of the wafer is supported by the support member in the hardened state.

Description

Technical Field

[0001] This invention relates to a holding stage for holding a wafer with a recess. Background Technology

[0002] In the manufacturing process of a device chip, a wafer is used, which has device regions on its front side, each formed within multiple regions divided by predetermined dicing lines (spacers) arranged in a grid pattern, and the remaining peripheral region surrounding the device regions. The wafer is diced along the predetermined dicing lines to obtain multiple device chips, each containing a device. These device chips are then assembled into various electronic devices such as mobile phones and personal computers.

[0003] In wafer dicing, for example, a cutting device is used. The cutting device has a holding table for holding the workpiece and a cutting unit equipped with an annular cutting tool for cutting the workpiece. The wafer is held by the holding table, and the cutting tool is rotated and cut into the wafer, thereby cutting and dicing the wafer.

[0004] Furthermore, in recent years, with the miniaturization of electronic devices, there is a demand for thinner chip designs. Therefore, wafer thinning is sometimes performed before wafer dicing. For example, a grinding apparatus is used in wafer thinning. The grinding apparatus has a holding table for holding the workpiece and a grinding unit equipped with grinding wheels having multiple grinding tools. The wafer is held by the holding table, and while the holding table and grinding wheels are rotated, the grinding tools are brought into contact with the back side of the wafer, thereby grinding the back side of the wafer and thinning it.

[0005] When a wafer is thinned by grinding, its rigidity decreases, making it prone to breakage during subsequent wafer processing (wafer transport, machining, cleaning, etc.). Therefore, a method has been proposed to thin only the central portion of the back side of the wafer that overlaps with the device area (see Patent Document 1). When this method is used, the outer periphery of the wafer remains thick without being thinned, thus suppressing the decrease in wafer rigidity and preventing wafer breakage.

[0006] When only the central portion of the wafer is ground as described above, a wafer with a recess formed on the back side and an annular outer periphery surrounding the recess is obtained. Furthermore, when the wafer is finally divided into multiple device chips, the unthinned outer periphery of the wafer is removed first. For example, the wafer is held by a holding stage of a cutting device, and a cutting tool is used to cut the boundary region between the recess and the outer periphery of the wafer in an annular shape, thereby separating the outer periphery from the wafer (see Patent Document 2).

[0007] Patent Document 1: Japanese Patent Application Publication No. 2007-19379

[0008] Patent Document 2: Japanese Patent Application Publication No. 2007-59829

[0009] When processing a wafer with a recess using a cutting device or similar processing apparatus, the wafer is held in place by a holding stage. For example, the wafer is positioned on the holding stage such that it is inserted into the recess of the wafer onto the upper surface (holding surface) of the holding stage. Thus, the bottom surface of the recess of the wafer is held in place by the holding stage.

[0010] At this point, the outer periphery of the wafer is positioned outside the holding surface of the holding stage and is not supported by the holding surface. Therefore, the wafer is not adequately fixed relative to the holding stage, which can easily lead to machining defects. For example, when the wafer is cut with a cutting tool, vibration (wobbling) occurs at the outer periphery of the wafer, sometimes resulting in defects (chipping) or breakage on the wafer.

[0011] Therefore, in holding wafers with recesses, a holding stage is sometimes used, which has a cylindrical base (stadium) and a holding portion protruding upward from the center of the base. When using this holding stage, the recess of the wafer is supported by the holding portion, and the outer periphery of the wafer is supported by the base. As a result, the wafer is reliably fixed to the holding stage, and machining defects are less likely to occur.

[0012] However, when there is a discrepancy between the depth of the wafer's recess and the protrusion (height) of the chuck stage's holding portion, the wafer's recess and outer periphery cannot be properly supported. Therefore, the protrusion of the holding portion of the chuck stage needs to be strictly adjusted according to the depth of the wafer's recess. However, the depth of the recess varies for each wafer, so the protrusion of the holding portion of the chuck stage needs to be changed whenever the wafer being processed is changed. This complicates the preparation of the holding stage and reduces wafer processing efficiency. Summary of the Invention

[0013] The present invention was made in view of this problem, and its object is to provide a holding stage that can easily and reliably hold a wafer with a recess.

[0014] According to one aspect of the invention, a holding stage is provided for holding a wafer having a recess and an annular outer periphery surrounding the recess, wherein the holding stage has: a base; and a holding portion protruding from the upper surface of the base and inserted into the recess of the wafer, the base having: an annular groove disposed in a region corresponding to the outer periphery of the wafer; and a support member disposed inside the groove, which changes from a softened state to a hardened state or from a hardened state to a softened state by the application of energy, the holding portion holding the recess of the wafer, and the support member in a hardened state supporting the outer periphery of the wafer.

[0015] In addition, it is preferable that the support component is a component that changes into a liquid state when heated in a solidified state.

[0016] In one embodiment of the holding stage of the present invention, a support member whose hardness changes by applying energy is used as the component supporting the outer periphery of the wafer. Furthermore, by deforming the support member according to the depth of the recess in the wafer, various wafers with different recess depths can be supported. Thus, a holding stage capable of easily holding wafers with recesses is realized.

[0017] Furthermore, in one embodiment of the holding stage of the present invention, the recess of the wafer is held by a holding portion, and the outer periphery of the wafer is supported by a support member. Therefore, the wafer is reliably held by the holding stage, and wafer positional displacement is less likely to occur. Attached Figure Description

[0018] Figure 1 This is a perspective view showing the cutting device.

[0019] Figure 2 (A) is a perspective view showing the front side of the wafer. Figure 2 (B) is a perspective view showing the back side of the wafer.

[0020] Figure 3 (A) is a perspective view showing a wafer supported by a frame. Figure 3 (B) is a cross-sectional view showing the wafer supported by a frame.

[0021] Figure 4 (A) is a perspective view showing the holding table. Figure 4 (B) is an enlarged sectional view showing a portion of the worktable.

[0022] Figure 5 This is a cross-sectional view showing the holding stage used to hold the wafer.

[0023] Figure 6 This is an enlarged cross-sectional view showing a portion of a wafer held by a holding stage.

[0024] Label Explanation

[0025] 11: Wafer; 11a: Front (First Surface); 11b: Back (Second Surface); 13: Dividing Line (Separation Channel); 15: Device; 17a: Device Area; 17b: Remaining Peripheral Area; 19: Recess; 19a: Bottom Surface; 19b: Side Surface (Inner Wall); 21: Peripheral Area; 23: Strip; 25: Frame; 25a: Opening; 2: Cutting Device; 4: Base; 4a, 4b, 4c: Openings; 6: Cartridge Mount (Cartridge Lift); 8: Cartridge; 10: Moving Unit (Moving Mechanism); 12: Dustproof and Dripproof Cover; 14: Moving Worktable; 16: Holding Worktable (Chuck Worktable); 16a: Holding Surface; 18: Fixture; 20: Support Structure; 22: Moving Unit (Moving Mechanism) 24: Guide rail; 26: Moving plate; 28: Ball screw; 30: Guide rail; 32: Moving plate; 34: Ball screw; 36: Pulse motor; 38: Machining unit (cutting unit); 40: Housing; 42: Cutting tool; 44: Imaging unit (camera); 46: Cleaning unit; 48: Holding table (rotary table); 50: Fixture; 52: Nozzle; 60: Base (base, frame); 60a: Upper surface; 60b: Flow path; 62: Holding part; 62a: Upper surface; 62b: Recess (groove); 64: Holding component; 64a: Upper surface; 66: Groove; 66a, 66b: Side (inner wall); 68: Support component; 70: Suction source; 72: Energy imparting unit. Detailed Implementation

[0026] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. First, a structural example of a machining apparatus capable of carrying the holding table of this embodiment will be described. Figure 1 This is a perspective view showing the cutting device 2 that performs cutting operations on the workpiece. Additionally, in Figure 1 In this diagram, the X-axis (machining feed direction, first horizontal direction, forward / backward direction) and the Y-axis (indexing feed direction, second horizontal direction, left / right direction) are perpendicular to each other. Additionally, the Z-axis (vertical direction, up / down direction, height direction) is perpendicular to both the X-axis and Y-axis.

[0027] The cutting device 2 has a base 4 that supports or houses the various components constituting the cutting device 2. A rectangular opening 4a is provided at the front corner of the base 4, and a box-mounted platform (box lifter) 6 is provided inside the opening 4a. A lifting mechanism (not shown) is connected to the box-mounted platform 6, which causes the box-mounted platform 6 to move up and down along the Z-axis.

[0028] A box 8, which holds multiple workpieces that are the objects of machining by the cutting device 2, is placed on the upper surface of the box mounting stage 6. Figure 1In the diagram, the outline of box 8 is shown using a double-dotted line. For example, a disc-shaped wafer 11 is housed in box 8 as a workpiece.

[0029] Figure 2 (A) is a perspective view showing the front side of chip 11. Figure 2 (B) is a perspective view showing the back side of the wafer 11. For example, the wafer 11 is a disk-shaped substrate formed of semiconductors such as silicon, having a front side (first side) 11a and a back side (second side) 11b that are substantially parallel to each other.

[0030] The chip 11 is divided into multiple rectangular regions by multiple predetermined dividing lines (spacers) 13 arranged in a grid pattern in an intersecting manner. Furthermore, devices 15 such as IC (Integrated Circuit), LSI (Large Scale Integration), LED (Light Emitting Diode), and MEMS (Micro Electro Mechanical Systems) are formed in the multiple regions divided by the predetermined dividing lines 13.

[0031] The wafer 11 has a generally circular device region 17a on the front side 11a, on which a plurality of devices 15 are formed, and an annular peripheral remaining region 17b surrounding the device region 17a. The peripheral remaining region 17b corresponds to an annular region of a predetermined width (e.g., about 2 mm) including the outer periphery of the front side 11a. Figure 2 In (A), the boundary between device region 17a and the remaining peripheral region 17b is shown by a double-dotted line.

[0032] Furthermore, there are no restrictions on the material, shape, structure, or size of the wafer 11. For example, the wafer 11 can be a substrate formed from semiconductors other than silicon (GaAs, InP, GaN, SiC, etc.), glass, ceramics, resin, metal, etc. Additionally, there are no restrictions on the type, quantity, shape, structure, size, or arrangement of the devices 15.

[0033] The wafer 11 is divided into a grid pattern along the predetermined dividing line 13, thereby manufacturing multiple device chips, each having a device 15. Furthermore, when the wafer 11 is divided after a thinning process, thinned device chips are obtained.

[0034] In the thinning of wafer 11, for example, a grinding apparatus is used. The grinding apparatus has a holding stage (chuck stage) for holding wafer 11 and a grinding unit equipped with grinding wheels having multiple grinding tools. While holding wafer 11 using the holding stage and rotating the holding stage and grinding wheels respectively, the grinding tools are brought into contact with the back side 11b side of wafer 11, thereby grinding the back side 11b side of wafer 11 to thin wafer 11.

[0035] Here, if the entire back side 11b of the wafer 11 is ground, the wafer 11 will be thinned as a whole, reducing its rigidity. This will make the wafer 11 more susceptible to breakage during subsequent processing (wafer 11 transport, processing, cleaning, etc.). Therefore, the thinning process (grinding) is preferably performed only on the central portion of the back side 11b of the wafer 11.

[0036] When only the central portion of chip 11 is thinned, such as Figure 2 As shown in (B), a circular recess 19 is formed in the center of the back surface 11b of the wafer 11. Furthermore, the recess 19 is positioned corresponding to the device region 17a. For example, the diameter of the recess 19 is set to be approximately the same as the diameter of the device region 17a, and the recess 19 is formed at a position overlapping with the device region 17a.

[0037] The recess 19 has a circular bottom surface 19a that is substantially parallel to the front side 11a and back side 11b of the wafer 11, and an annular side surface (inner wall) 19b that is substantially perpendicular to the bottom surface 19a and connected to the back side 11b and the bottom surface 19a. In addition, an outer peripheral portion 21 of the wafer 11 that has not undergone thinning (grinding) remains around the recess 19, and the outer peripheral portion 21 surrounds the recess 19.

[0038] As described above, when only the central portion of the wafer 11 is thinned, the outer periphery 21 of the wafer 11 remains thick, suppressing the reduction in the rigidity of the wafer 11 and thus making it less prone to breakage. That is, the unthinned outer periphery 21 of the wafer 11 functions as a reinforcement portion (reinforcement region) to strengthen the wafer 11.

[0039] The wafer 11 with the recess 19 is passed through the cutting device 2 (see reference). Figure 1 The wafer 11 is cut along the predetermined dividing line 13 and divided into multiple device chips. Furthermore, when the wafer 11 is processed by the cutting device 2, the wafer 11 is first supported by a ring-shaped frame.

[0040] Figure 3 (A) is a perspective view showing the wafer 11 supported by the frame 25. Figure 3(B) is a cross-sectional view showing the wafer 11 supported by the frame 25. A strip 23, large enough to cover the entire back side 11b of the wafer 11, is attached to the back side 11b of the wafer 11. For example, a circular strip 23 with a diameter larger than the wafer 11 is attached in such a way that it covers the back side 11b of the wafer 11.

[0041] As for section 23, a flexible film having a circular substrate and an adhesive layer (paste layer) disposed on the substrate can be used. For example, the substrate is formed of resins such as polyolefin, polyvinyl chloride, and polyethylene terephthalate, and the adhesive layer is formed of adhesives such as epoxy, acrylic, or rubber-based adhesives. In addition, an ultraviolet-curing resin that cures by ultraviolet radiation can also be used in the adhesive layer.

[0042] Strip 23 is attached along the contour of the back side 11b of wafer 11. That is, as... Figure 3 As shown in (B), the strip 23 is attached along the bottom surface 19a and side surface 19b of the recess 19 and the back surface (lower surface) of the outer peripheral portion 21. Additionally, in Figure 3 In (B), an example is shown where there is a slight gap between the wafer 11 and the strip 23 on the outer periphery of the bottom surface 19a of the recess 19, but the strip 23 can be attached in a way that is close to the entire area of ​​the bottom surface 19a and the side surface 19b.

[0043] A ring-shaped frame 25 made of a metal such as SUS (stainless steel) is attached to the outer periphery of the belt 23. A circular opening 25a is provided in the center of the frame 25 to accommodate the wafer 11. The wafer 11 is attached to the center of the belt 23 exposed inside the opening 25a. Thus, the wafer 11 is supported by the frame 25 via the belt 23. The wafer 11, supported by the frame 25, is then stored in the box 8 (see reference). Figure 1 )middle.

[0044] A rectangular opening 4b, extending along the X-axis, is provided on the side of the base 4, located beside the opening 4a. A ball screw-type moving unit (moving mechanism) 10 is provided inside the opening 4b. The upper part of the moving unit 10 is covered by a pleated dustproof and drip-proof cover 12 and a plate-shaped moving worktable 14.

[0045] A holding stage (chuck stage) 16 for holding the wafer 11 is provided on the moving stage 14. The upper surface of the holding stage 16 forms a holding surface 16a for holding the wafer 11. The detailed structure of the holding stage 16 will be described later (see [reference]). Figure 4 (A) In addition, multiple clamps 18 are provided around the worktable 16 to hold and fix the frame 25 supporting the wafer 11.

[0046] The moving unit 10 moves the holding table 16 together with the moving table 14 along the X-axis. In addition, a rotary drive source (not shown) such as an electric motor is connected to the holding table 16, and the rotary drive source rotates the holding table 16 about a rotation axis that is approximately parallel to the Z-axis.

[0047] A support structure 20 is provided in the area of ​​the base 4 adjacent to the opening 4b. The upper part of the support structure 20 is arranged along the Y-axis direction in a manner that overlaps with the opening 4b. In addition, a ball screw type moving unit (moving mechanism) 22 is provided on the front surface side of the upper part of the support structure 20.

[0048] The moving unit 22 has a pair of guide rails 24 fixed to the front surface of the support structure 20. The pair of guide rails 24 are arranged parallel to each other along the Y-axis direction. In addition, a flat moving plate 26 is mounted on the pair of guide rails 24 in a state that allows it to slide along the guide rails 24 in the Y-axis direction.

[0049] A nut portion (not shown) is provided on the back side (rear surface side) of the movable plate 26. A ball screw 28, which is arranged substantially parallel to the guide rail 24, is screwed into this nut portion. In addition, a pulse motor (not shown) is connected to one end of the ball screw 28. When the ball screw 28 is rotated by the pulse motor, the movable plate 26 moves along the guide rail 24 in the Y-axis direction.

[0050] A pair of guide rails 30 arranged parallel to each other along the Z-axis are fixed on the front side (front surface side) of the movable plate 26. In addition, a flat movable plate 32 is mounted on the pair of guide rails 30 in a state that allows it to slide along the guide rails 30 in the Z-axis direction.

[0051] A nut portion (not shown) is provided on the back side (rear surface side) of the movable plate 32. A ball screw 34, which is arranged substantially parallel to the guide rail 30, is screwed into this nut portion. In addition, a pulse motor 36 is connected to one end of the ball screw 34. When the ball screw 34 is rotated by the pulse motor 36, the movable plate 32 moves along the guide rail 30 in the Z-axis direction.

[0052] A processing unit (cutting unit) 38 for cutting wafer 11 is fixed to the lower part of the moving plate 32. The processing unit 38 has a cylindrical housing 40, in which a cylindrical spindle (not shown) arranged along the Y-axis is housed. The front end (one end) of the spindle is exposed outside the housing 40, and a rotation drive source (not shown) such as an electric motor for rotating the spindle is connected to the base end (the other end) of the spindle.

[0053] A ring-shaped cutting tool 42 is mounted at the front end of the spindle. The cutting tool 42 is a machining tool that cuts into the wafer 11 to cut it. It is formed by fixing abrasive grains made of diamond, cubic boron nitride (cBN), etc., with a bonding material. In addition, there are no restrictions on the materials of the abrasive grains and bonding material, or the grain size of the abrasive grains, etc., and they are appropriately selected according to the material of the wafer 11 and the cutting process.

[0054] As a cutting tool 42, for example, a hub-type cutting tool (hub tool) is used. A hub tool is constructed by integrating an annular base made of metal or the like and an annular cutting edge formed along the outer periphery of the base. As the cutting edge of the hub tool, for example, an electroformed abrasive is used, which is formed by fixing abrasive grains using a bonding material such as nickel plating.

[0055] On the other hand, as the cutting tool 42, a washer-type cutting tool (washer tool) can also be used. A washer tool is a ring-shaped cutting edge formed by fixing abrasive grains using a bonding material made of metal, ceramic, resin, etc.

[0056] The cutting tool 42, mounted on the processing unit 38, is moved by the moving unit 22. This allows for adjustment of the position of the cutting tool 42 in the Y-axis direction or its depth of cut into the wafer 11.

[0057] An imaging unit (camera) 44 is provided adjacent to the processing unit 38 to capture images of the wafer 11 held by the holding stage 16. The images obtained by the imaging unit 44 capturing images of the wafer 11 held by the holding stage 16 are used for alignment of the wafer 11 with the processing unit 38, etc.

[0058] An opening 4c, defining a cylindrical cleaning space (cleaning chamber), is provided on the side opposite to the opening 4a of the opening 4b. A cleaning unit 46 for cleaning the wafer 11 is provided inside the opening 4c. The cleaning unit 46 has a holding stage (rotary stage) 48 for holding the wafer 11. A rotation drive source (not shown), such as a motor, is connected to the holding stage 48 to rotate the holding stage 48 about a rotation axis approximately parallel to the Z-axis. Furthermore, multiple clamps 50 are provided around the holding stage 48 to hold and fix the frame 25 supporting the wafer 11.

[0059] A nozzle 52 is disposed above the holding stage 48 to provide cleaning fluid (e.g., a mixture of water and air) to the wafer 11 held by the holding stage 48. The holding stage 48 holding the wafer 11 is rotated while fluid is supplied from the nozzle 52 to the wafer 11, thereby cleaning the wafer 11.

[0060] When processing the wafer 11 using the cutting device 2, the wafer 11, housed in the cassette 8, is first transported to the holding table 16 via a conveying mechanism (not shown), where it is held. The frame 25 is then secured by multiple clamps 18. Simultaneously, a liquid such as pure water (cutting fluid) is supplied to the wafer 11, causing the cutting tool 42 mounted on the processing unit 38 to rotate and cut into the wafer 11. This process cuts the wafer 11.

[0061] The processed wafer 11 is transported to the cleaning unit 46 via a conveying mechanism (not shown) for cleaning. Then, the wafer 11 is transported and stored in the box 8 via the conveying mechanism (not shown).

[0062] Next, an example of the structure of the holding table 16 mounted on the cutting device 2 will be described. Figure 4 (A) is a perspective view showing the holding table 16. The holding table 16 is capable of holding a recess 19 (see reference). Figure 2 (B) and Figure 3 The (B)) wafer 11 is held in a holding stage.

[0063] The holding worktable 16 has a disc-shaped base (base, frame) 60 made of glass, ceramic, metal, resin, etc. A cylindrical holding part 62 protruding upward from the upper surface 60a of the base 60 is provided at the center of the base 60. In addition, the holding part 62 can be integrated with the base 60, or it can be formed independently relative to the base 60 and fixed to the upper surface 60a side of the base 60.

[0064] A cylindrical recess (groove) 62b is provided at the center of the upper surface 62a side of the retaining part 62, and a disc-shaped retaining member 64 is embedded in the recess 62b. The retaining member 64 is a component formed of a porous material such as porous ceramic, and contains a hole (suction path) inside that connects the upper surface of the retaining member 64 to the lower surface.

[0065] The retaining component 64 is held via the flow path 60b provided on the base 60 (see reference). Figure 5 Valves (not shown), etc., and suction sources 70 such as injectors (see reference). Figure 5 The upper surface 64a of the holding member 64 forms a circular attraction surface for attracting the wafer 11. Furthermore, the upper surface 62a of the holding part 62 and the upper surface 64a of the holding member 64 are disposed on approximately the same plane, forming the holding surface 16a of the holding stage 16.

[0066] An annular groove 66 is provided in the region outside the retaining portion 62 on the upper surface 60a side of the base 60. For example, the groove 66 is formed with a predetermined width along the outer periphery of the retaining portion 62 in a manner adjacent to the retaining portion 62, surrounding the retaining portion 62.

[0067] Figure 4 (B) is an enlarged cross-sectional view showing a portion of the holding table 16. The groove 66 includes an annular side surface (inner wall) 66a located radially inside the base 60 and an annular side surface (inner wall) 66b located radially outside the base 60. For example, side surface 66a is formed on approximately the same plane as the side surface of the holding part 62. In addition, side surface 66b is formed in a curved shape. Specifically, side surface 66b is formed in an upwardly convex shape such that the slope gradually decreases from the bottom of the groove 66 toward the upper surface 60a of the base 60.

[0068] Inside the slot 66, there is a peripheral portion 21 for the wafer 11 (see reference). Figure 5 Support member 68 provides support. Support member 68 is a component whose hardness changes through the application of energy. Further details about support member 68 will be described later.

[0069] Figure 5 This is a cross-sectional view showing a holding stage 16 for holding wafer 11. The holding portion 62 of the holding stage 16 is formed to a size that allows insertion into the recess 19 of wafer 11. For example, the diameter of the holding portion 62 is set to be smaller than the diameter of the recess 19 of wafer 11. Furthermore, a groove 66 is provided in a region corresponding to the outer periphery 21 of wafer 11. For example, the outer diameter of the groove 66 (the diameter of the upper end of the side surface 66b) is set to be greater than or equal to the diameter of wafer 11, and the width of the groove 66 is set to be greater than or equal to the width of the outer periphery 21 of wafer 11. Additionally, the position of the groove 66 is set such that when wafer 11 is positioned above the holding stage 16, the outer periphery 21 of wafer 11 overlaps with the groove 66.

[0070] The wafer 11 is positioned on the holding stage 16 with its back surface 11b facing the holding surface 16a. At this time, the wafer 11 is positioned such that its upper surface 62a of the holding portion 62 is inserted into the recess 19 and embedded therein. Thus, the bottom surface 19a of the recess 19 of the wafer 11 is supported by the holding surface 16a via the band 23. Furthermore, when a negative pressure from the attraction source 70 is applied to the upper surface 64a of the holding member 64, the bottom surface 19a of the recess 19 of the wafer 11 is attracted and held by the holding portion 62 via the band 23.

[0071] Furthermore, the lower surface of the outer periphery 21 of the wafer 11 is inserted into the groove 66 provided in the base 60. As a result, the strip 23 attached to the lower surface of the outer periphery 21 of the wafer 11 comes into contact with the support member 68 filling the groove 66.

[0072] Figure 6 This is an enlarged cross-sectional view showing a portion of the wafer 11 held by the holding stage 16. Here, the support member 68 is a member that changes from a softened state (unhardened state) to a hardened state by being hardened by the application of a specified energy.

[0073] For example, the support member 68 is formed of a material that, before being energized, is in a fluid and freely deformable state, and when energized, solidifies to fix its shape. Specifically, the support member 68 is formed of a material that hardens upon irradiation by electromagnetic waves (visible light, infrared light, ultraviolet light, microwaves, etc.).

[0074] For example, as the support component 68, an ultraviolet-curing resin that hardens upon exposure to ultraviolet light, a visible-light-curing resin that hardens upon exposure to visible light, or a thermosetting resin that hardens upon heating can be used. Alternatively, as the support component 68, a material that hardens upon application of ultrasound (such as anti-Pd2L2) can be used.

[0075] When the wafer 11 is placed on the holding stage 16, the support member 68 is maintained in an unhardened state (non-hardened state, softened state), that is, a state that can be deformed by external force. Furthermore, when the outer periphery 21 of the wafer 11 is inserted into the slot 66, the support member 68 deforms according to the position (height) of the outer periphery 21 of the wafer 11. As a result, the tape 23 attached to the outer periphery 21 of the wafer 11 is embedded in the support member 68.

[0076] In addition, such as Figure 6 As shown, when the wafer 11 is held by the stage 16, a portion of the strip 23 contacts the side surface 66b of the groove 66. Therefore, it is preferable that the side surface 66b is formed as a curved surface. This prevents the application of localized forces to the strip 23 and reduces the likelihood of damage to the strip 23.

[0077] Next, a predetermined energy is applied to the support member 68 to harden it. For example, an energy-applying unit 72 is provided below the holding table 16 to apply the predetermined energy to the support member 68. When energy is applied to the support member 68 by the energy-applying unit 72, the support member 68 hardens and solidifies while in contact with the belt 23.

[0078] The type of energy supplied to the support member 68 by the energy supply unit 72 is determined according to the properties of the support member 68. For example, if the support member 68 is an ultraviolet-curing resin, an ultraviolet light source (lamp) is used as the energy supply unit 72, and ultraviolet light is supplied to the support member 68 through the base 60. Alternatively, if the support member 68 is a visible light-curing resin, a visible light source (lamp) is used as the energy supply unit 72, and visible light is supplied to the support member 68 through the base 60.

[0079] Furthermore, when the support member 68 is made of thermosetting resin, a heater such as an infrared lamp is used as an energy imparting unit 72 to heat the support member 68. Alternatively, when the support member 68 is a member that hardens by ultrasonic waves, an ultrasonic oscillator that emits ultrasonic waves is used as an energy imparting unit 72 to irradiate the support member 68 with ultrasonic waves.

[0080] When the support member 68 is cured, the outer periphery 21 of the wafer 11 is supported from below by the support member 68 through the belt 23. As a result, the recess 19 of the wafer 11 is held by the holding part 62, and the outer periphery 21 of the wafer 11 is supported by the cured support member 68. Thus, the entire wafer 11 is reliably fixed to the holding stage 16.

[0081] Furthermore, the position (height) of the outer peripheral portion 21 of the wafer 11 held by the stage 16 varies depending on the depth of the recess 19 of the wafer 11. Specifically, the deeper the recess 19 of the wafer 11, the more the bottom surface 19a of the recess 19 is positioned on the front side 11a of the wafer 11, and the more the back side 11b of the wafer 11 (the lower surface of the outer peripheral portion 21) is disposed at the bottom. Therefore, the distance (height difference) between the lower surface of the outer peripheral portion 21 of the wafer 11 and the bottom surface of the groove 66 varies depending on the depth of the recess 19.

[0082] Here, when the support member 68 is used as described above, when the wafer 11 is placed on the holding stage 16, the unhardened support member 68 deforms according to the depth of the recess 19 to maintain the wafer 11 in a flat (unbent) state. Then, when energy is applied to the support member 68, the support member 68 hardens in the state of being deformed according to the depth of the recess 19, and supports the outer periphery 21 of the wafer 11.

[0083] That is, the support member 68 functions as a support member whose thickness can vary according to the depth of the recess 19 of the wafer 11. Therefore, the holding stage 16 can hold various wafers 11 with different recess 19 depths. As a result, it is not necessary to adjust the height (protrusion amount) of the holding part 62 according to the depth of the recess 19 of the wafer 11, and wafers 11 with recesses 19 can be held easily.

[0084] The wafer 11, held by the stage 16, is mounted on the processing unit 38 (see reference). Figure 1 The cutting tool 42 performs cutting. For example, the cutting tool 42 is used to cut along the predetermined dividing line 13 (see reference). Figure 2 (A)) Divide the wafer 11 to obtain multiple device chips, each having a device 15.

[0085] When dicing the wafer 11, the annular outer peripheral portion 21 is first removed from the wafer 11. Specifically, the positions of the holding stage 16 and the cutting tool 42 are adjusted such that the cutting tool 42 is positioned directly above the outer peripheral portion of the recess 19 of the wafer 11. Next, the cutting tool 42 is rotated and lowered so that it cuts into the outer peripheral portion of the recess 19 of the wafer 11. The amount of descent of the cutting tool 42 is set so that the lower end of the cutting tool 42 reaches the belt 23.

[0086] Furthermore, while the cutting tool 42 is cutting into the wafer 11, the rotation of the cutting tool 42 is maintained, causing the holding table 16 to rotate. As a result, the wafer 11 is cut and severed in a ring shape along the outer periphery of the recess 19. Consequently, the ring-shaped outer periphery 21 is separated from the wafer 11. The outer periphery 21 separated from the wafer 11 is then peeled off and removed from the tape 23.

[0087] Then, the wafer 11, with the outer periphery 21 removed, is moved along the predetermined dividing line 13 (see reference). Figure 2 The wafer 11 is cut into thinner central portions (A). This results in the thinning of the wafer 11 into multiple device chips, thus obtaining thinner device chips.

[0088] When the outer periphery 21 of the wafer 11 is removed before dividing the wafer 11 into multiple device chips as described above, it is possible to prevent the cutting tool 42 from contacting the outer periphery 21 of the wafer 11 when the wafer 11 is subsequently cut along the predetermined dividing line 13. As a result, the cutting of the wafer 11 can be carried out smoothly.

[0089] Furthermore, the preferred support member 68 is a reversible member that changes from a hardened state (non-softened state) to a softened state through a prescribed process. In this case, when or after the processed wafer 11 is transferred from the holding table 16, the support member 68 can be softened and restored to its pre-hardened state, allowing it to be reused as a support for the next wafer.

[0090] As described above, in the holding stage 16 of this embodiment, a support member 68 whose hardness varies with the application of energy is used as the component supporting the outer periphery 21 of the wafer 11. Furthermore, the support member 68 is deformed according to the depth of the recess 19 of the wafer 11, thereby enabling the support of various wafers 11 with different recess depths. Thus, a holding stage 16 is realized that can easily hold wafers 11 having recesses 19.

[0091] Furthermore, in the holding stage 16, the recess 19 of the wafer 11 is held by the holding part 62, and the outer peripheral portion 21 of the wafer 11 is supported by the support member 68. As a result, the wafer 11 is reliably held by the holding stage 16, and it is not easy for the wafer 11 to shift position.

[0092] Furthermore, in the above embodiment, the case where the support member 68 changes from a softened state (non-hardened state) to a hardened state by the application of energy has been described. However, the support member 68 may also be a member that changes from a hardened state (non-softened state) to a softened state by the application of energy.

[0093] In this case, while the wafer 11 is held by the stage 16, the hardened support member 68 is heated by the energy-applying unit 72, causing the support member 68 to soften. Then, while the tape 23 attached to the outer periphery 21 of the wafer 11 is in contact with the support member 68, heating of the support member 68 is stopped, allowing it to cool. As a result, the softened support member 68 hardens, and the outer periphery 21 of the wafer 11 is supported by the support member 68 through the tape 23.

[0094] For example, thermoplastic resins or waxes such as polyethylene, polypropylene, polyvinyl chloride, polystyrene, acrylic acid, polyacetal, and polytetrafluoroethylene can be used as the support component 68. In this case, by heating the solidified support component 68, it can be changed into a liquid state. Alternatively, by cooling the liquid support component 68, it can be solidified.

[0095] Alternatively, an electroviscous fluid (ER fluid) whose viscosity can be reversibly changed by the application of voltage can also be used as the support component 68. For example, an electroviscous fluid is generated by dispersing particles formed of aluminosilicates in an insulating oil such as silicone oil.

[0096] Furthermore, there are no restrictions on the device on which the holding table 16 is mounted. For example, the holding table 16 can also be mounted on a machining device other than a cutting device (grinding device, polishing device, laser processing device, etc.) or a cleaning device.

[0097] The grinding apparatus has a processing unit (grinding unit) for grinding the wafer 11. The grinding unit has a spindle, and an annular grinding wheel with multiple grinding tools is mounted at the front end of the spindle. The wafer 11 is held by a holding table 16 provided in the grinding apparatus, and the grinding tools rotate while contacting the wafer 11, thereby grinding the wafer 11.

[0098] The polishing apparatus includes a processing unit (polishing unit) for polishing the wafer 11. The polishing unit has a spindle, and a disc-shaped polishing pad is mounted on the front end of the spindle. The wafer 11 is held by a holding stage 16 provided in the polishing apparatus, and the polishing pad rotates while contacting the wafer 11, thereby polishing the wafer 11.

[0099] The laser processing apparatus includes a processing unit (laser irradiation unit) that irradiates a laser beam used for processing the wafer 11. For example, the laser irradiation unit includes a laser oscillator that pulses to produce a laser of a predetermined wavelength and a concentrator that focuses the laser beam oscillated from the laser oscillator. The wafer 11 is held by a holding stage 16 provided in the laser processing apparatus, and the laser beam is irradiated onto the wafer from the laser irradiation unit, thereby performing laser processing on the wafer 11.

[0100] The cleaning apparatus includes nozzles that provide fluid (such as pure water) for cleaning the wafer 11. The wafer 11 is held by a holding stage 16 provided in the cleaning apparatus, and fluid is supplied to the wafer 11 from the nozzles while the holding stage 16 is rotated, thereby cleaning the wafer 11.

[0101] In addition, the structure and method of the above embodiments can be appropriately modified and implemented as long as they do not depart from the scope of the purpose of the present invention.

Claims

1. A holding stage for holding a wafer having a recess and an annular outer periphery surrounding the recess, characterized in that, The holding table has the following features: Base; and A retaining portion protrudes from the upper surface of the base and inserts into the recess of the wafer. The base has: An annular groove is disposed in a region corresponding to the outer periphery of the wafer; and The supporting component, located inside the groove, changes from a softened state to a hardened state or vice versa through the application of energy. When the wafer is positioned on the holding stage, the support member is in a softened state; when the wafer's outer periphery is supported by the support member, the support member is in a hardened state. The retaining part holds the recess of the wafer, and the supporting member in a hardened state supports the outer periphery of the wafer.

2. The holding table according to claim 1, characterized in that, The support component is a part that changes into a liquid state when heated in a solidified state.

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