Processing methods

Abstract

To separate a support base and a workpiece when the workpiece is caused to adhere to the support base via a resin sheet without using an adhesive layer between the workpiece and the resin sheet.SOLUTION: A machining method includes: bringing a first side which is not provided with an adhesive layer, and a second surface which is not provided with an adhesive layer, into close contact with a workpiece, and a support base, respectively, so as to form a workpiece unit where the workpiece, the resin sheet, and the support base are integrated; machining the workpiece in the workpiece unit; positioning a focal point of a laser beam having a wavelength that passes through the workpiece or the support base at a boundary between the resin sheet and the support base; irradiating an outer periphery of an overlapping area of the resin sheet and the support base with a laser beam to form a reduced-fixing-force region in which a fixing force for fixing the resin sheet to the support base is reduced; and separating the workpiece unit into the workpiece and the support base with the resin sheet, starting at the first region as a starting point.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a processing method for processing a workpiece integrated with a support base via a resin sheet.

Background Art

[0002] When manufacturing a semiconductor device chip, for example, first, a workpiece is created by forming a plurality of devices such as ICs (Integrated Circuits) on the surface side of a silicon single crystal substrate (i.e., a wafer). Next, after grinding the back surface side of the workpiece to thin it, the workpiece is divided into individual devices.

[0003] However, the workpiece during or after grinding is likely to warp or crack. Therefore, a technique is known in which a support base thicker than the thinned workpiece is attached to the surface side of the workpiece, and then the back surface side of the workpiece is ground (see, for example, Patent Document 1).

[0004] In recent years, in some cases, the workpiece is attached to the support base via a thin resin sheet formed of resin between the workpiece and the support base. However, after grinding, it is necessary to peel the workpiece from the support base.

[0005] For example, when using a resin sheet having a laminated structure of an adhesive layer and a base material layer, where the adhesive layer contains an ultraviolet-curable adhesive and is provided on the resin base material layer, irradiating the adhesive layer with ultraviolet light can reduce the adhesive force of the adhesive layer. Therefore, after ultraviolet irradiation, the workpiece can be easily peeled from the support base.

[0006] However, when using a resin sheet having a resin base material layer but no adhesive and attaching the workpiece to the support base by thermocompression bonding, it is impossible to reduce the adhesive force by ultraviolet irradiation, so it becomes difficult to separate the workpiece from the support base.

Prior Art Documents

Patent Documents

[0007] [Patent Document 1] Japanese Patent Publication No. 2004-207606 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] This invention has been made in view of the aforementioned problems, and aims to separate the workpiece from the support base when the workpiece is attached to the support base via a resin sheet without using an adhesive layer between the workpiece and the resin sheet. [Means for solving the problem]

[0009] According to one aspect of the present invention, a processing method for processing a workpiece integrated with a support base via a resin sheet, comprising: a workpiece unit formation step of forming a workpiece unit in which the workpiece, the resin sheet, and the support base are integrated by adhering a first surface of the resin sheet, which does not have an adhesive layer containing an adhesive, to the workpiece, and adhering a second surface of the resin sheet, which is located on the opposite side of the first surface and does not have an adhesive layer, to the support base; and a processing step of processing the workpiece in the workpiece unit after the workpiece unit formation step, and processing A processing method is provided, comprising: a laser beam irradiation step in which, after the first step, the focal point of a first laser beam having a wavelength that penetrates the workpiece, or the focal point of a second laser beam having a wavelength that penetrates the support base, is positioned at the boundary between the resin sheet and the support base, and the first laser beam or the second laser beam is irradiated onto the outer periphery of the overlapping region of the resin sheet and the support base to form a fixing force reduction region in which the fixing force fixing the resin sheet and the support base is reduced; and a separation step in which, after the laser beam irradiation step, the workpiece unit is separated into the support base and the workpiece with the resin sheet attached, starting from the fixing force reduction region.

[0010] Preferably, in the laser beam irradiation step, the second laser beam is irradiated onto the workpiece unit such that the second laser beam passes over the support base side of the workpiece unit before reaching the workpiece.

[0011] Preferably, in the machining step, the workpiece is ground using a grinding wheel in which a plurality of grinding wheels are arranged in a ring shape on one face of an annular base. [Effects of the Invention]

[0012] In one aspect of the present invention, a workpiece unit is formed by adhering a first surface of the resin sheet, which does not have an adhesive layer, to the workpiece, and adhering a second surface of the resin sheet, which is located on the opposite side of the first surface and does not have an adhesive layer, to the support base, thereby attaching the workpiece and the support base via the resin sheet.

[0013] At this time, the ambient gas (e.g., air) of the workspace is removed from the boundary between the resin sheet and the support base, so the support base is pressed against the resin sheet by atmospheric pressure via the resin sheet.

[0014] In the laser beam irradiation step, if a region of reduced fixing force is formed at the boundary between the resin sheet and the support base, and on the outer periphery of the overlapping area between the resin sheet and the support base, the region of reduced fixing force functions as a gap into which air can enter.

[0015] Furthermore, by separating the workpiece unit into a support base and a workpiece with a resin sheet, starting from the region where the fixing force is reduced, the support base can be easily separated from the workpiece with the resin sheet compared to when the region where the fixing force is reduced is not formed. In other words, the support base and the workpiece can be separated. [Brief explanation of the drawing]

[0016] [Figure 1] This is a flowchart illustrating the processing method for working with a workpiece. [Figure 2]FIG. 2(A) is a top view of the workpiece, the resin sheet, and the support base, and FIG. 2(B) is a cross-sectional view taken along line AA of FIG. 2(A). [Figure 3] It is a partial cross-sectional side view showing the step of forming the workpiece unit. [Figure 4] It is a diagram showing the grinding step. [Figure 5] It is a diagram showing the laser beam irradiation step. [Figure 6] It is a cross-sectional view of the workpiece unit showing the fixing force reduction region. [Figure 7] It is a top view of the workpiece unit showing the fixing force reduction region. [Figure 8] It is a diagram showing the separation step. [Figure 9] It is a side view showing the step of forming the workpiece unit according to the second embodiment. [Figure 10] FIG. 10(A) is a diagram showing a state in which the workpiece unit is held in an upside-down state, and FIG. 10(B) is a diagram showing the laser beam irradiation step according to the third embodiment.

MODE FOR CARRYING OUT THE INVENTION

[0017] An embodiment according to an aspect of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a flowchart of a processing method for processing the workpiece 11 according to the first embodiment (see FIG. 2(A)). Therefore, first, the workpiece 11 and the like will be described with reference to FIGS. 2(A) and 2(B).

[0018] FIG. 2(A) is a top view of the workpiece 11, the resin sheet 13, and the support base 15, and FIG. 2(B) is a cross-sectional view taken along line AA of FIG. 2(A). The workpiece 11 has a disk-shaped substrate formed of Si (silicon).

[0019] On the surface 11a side and the back surface 11b side of the outer peripheral portion of the workpiece 11, chamfered portions (also referred to as bevel portions) are formed over the entire circumferential direction of the workpiece 11. In FIGS. 2(B) and the like, the chamfered portions are omitted.

[0020] However, there are no restrictions on the wafer's material, shape, structure, size, etc. The workpiece 11 may have a disc-shaped substrate formed from a single crystal of a semiconductor material such as GaAs, InP, GaN, or SiC, or it may have a disc-shaped substrate formed from sapphire, glass, ceramics, metal, etc. The shape of the substrate may not be a disc, and may be a rectangular plate.

[0021] The surface 11a of the workpiece 11 is divided into multiple rectangular regions by a plurality of streets (planned division lines) (not shown) arranged in a grid pattern so as to intersect each other. Devices such as ICs (Integrated Circuits) are formed in each region divided by the plurality of streets.

[0022] There are no restrictions on the type, quantity, shape, structure, size, or arrangement of the devices or device chips. The workpiece 11 does not need to have device chips on it.

[0023] The first surface 13a of a thin resin sheet 13 is attached to the surface 11a of the workpiece 11 by heat-pressing without the use of an adhesive. The resin sheet 13 in this embodiment is circular in shape and has approximately the same size as the workpiece 11.

[0024] The resin sheet 13 has a predetermined thickness of, for example, 80 μm to 200 μm (e.g., 100 μm). The first surface 13a of the resin sheet 13 is not provided with an adhesive layer containing an adhesive. In this embodiment, the adhesive refers to a semi-solid, viscous layer formed from, for example, a rubber-based, acrylic-based, silicone-based, or urethane-based material.

[0025] The resin sheet 13 has a base layer formed of a thermoplastic resin. The thermoplastic resin can be selected from, for example, the following materials. (Note that the parentheses and numbers within them are added for ease of understanding.)

[0026] (1) Acrylic resin, (2) Methacrylic resin, (3) Vinyl resin, (4) Polyacetal, (5) Natural rubber, (6) Butyl rubber, (7) Isoprene rubber, (8) Chloroprene rubber, (9) Polyolefins such as polyethylene, polypropylene, poly(4-methyl-1-pentene), poly(1-butene), (10) Polyesters such as polyethylene terephthalate, polybutylene terephthalate, (11) Polyamides such as nylon-6, nylon-66, polymetaxylene adipamide, (12) Polyacrylate, (13) Polymethacrylate, (14) Polyvinyl chloride, (15) Polyetherimide, (16) Polyacrylonitrile, (17) Polycarbonate, ( 18) Polystyrene, (19) Polysulfone, (20) Polyethersulfone, (21) Polyphenylene, (22) Etherpolybutadiene resin, (23) Polycarbonate resin, (24) Thermoplastic polyimide resin, (25) Thermoplastic polyurethane resin, (26) Phenoxy resin, (27) Polyamideimide resin, (28) Fluororesin, (29) Ethylene-unsaturated carboxylic acid copolymer, (30) Ethylene-vinyl acetate copolymer, (31) Ionomer, (32) Ethylene-vinyl acetate-maleic anhydride terpolymer, (33) Ethylene-vinyl acetate copolymer saponified resin, (34) Ethylene-vinyl alcohol copolymer, etc. One or more resins selected from these.

[0027] Examples of unsaturated carboxylic acids that make up the above-mentioned ethylene-unsaturated carboxylic acid copolymer include acrylic acid, methacrylic acid, maleic acid, itaconic acid, monomethyl maleate, monoethyl maleate, maleic anhydride, and itaconic anhydride.

[0028] Furthermore, ethylene-unsaturated carboxylic acid copolymers include not only binary copolymers of ethylene and unsaturated carboxylic acids, but also polypolymers in which other monomers are copolymerized. Examples of other monomers that may be copolymerized in ethylene-unsaturated carboxylic acid copolymers include vinyl esters such as vinyl acetate and vinyl propionate, and unsaturated carboxylic acid esters such as methyl acrylate, ethyl acrylate, isobutyl acrylate, n-butyl acrylate, methyl methacrylate, isobutyl methacrylate, dimethyl maleate, and diethyl maleate.

[0029] Polyolefins such as polyethylene and polypropylene, or polystyrene, are preferred as the base layer. When using these materials, the softening point of the resin sheet 13 is set to a predetermined temperature of 70°C to 120°C, or a predetermined temperature of 80°C to 100°C. The thickness of the resin sheet 13 is set to a predetermined value of 80 μm to 200 μm (for example, 100 μm).

[0030] The first surface 13a of the resin sheet 13 has the base material layer exposed and no adhesive layer is provided. As described above, the first surface 13a is in contact with the surface 11a of the workpiece 11. The second surface 13b, located on the opposite side of the first surface 13a, also does not have an adhesive layer.

[0031] In other words, the base material layer is exposed on the second surface 13b of the resin sheet 13 in this embodiment. The second surface 13b is in contact with the surface 15a of the circular support base 15.

[0032] The support base 15 has a diameter approximately equal to the diameter of the workpiece 11 and is made of glass, ceramics, metal, or resin. The support base 15 has higher rigidity than the thinned workpiece 11 and has a predetermined thickness of 0.1 mm to 1.5 mm.

[0033] In the workpiece unit formation step S10 (see Figure 1), the workpiece 11 and the support base 15 are attached via the resin sheet 13 to form a disc-shaped workpiece unit 17 (see Figure 3) in which the workpiece 11, the resin sheet 13, and the support base 15 are integrated.

[0034] Figure 3 is a partial cross-sectional side view showing the workpiece unit formation step S10 in which the workpiece unit 17 is formed. In the workpiece unit formation step S10, the workpiece 11 and the support base 15 are bonded together via the resin sheet 13 by heat compression using the bonding device 2.

[0035] The bonding device 2 has a disc-shaped chuck table 4. The chuck table 4 includes a circular holding surface 4a that suction-holds the back surface 15b of the support base 15. Negative pressure is transmitted to the holding surface 4a from a suction source (not shown), such as a vacuum pump.

[0036] A disc-shaped pressing body 6, which has a larger diameter than the support base 15, is provided above the chuck table 4. The pressing body 6 is made of a metal such as stainless steel. The lower surface 6a of the pressing body 6 is substantially flat and is covered with a release agent such as PTFE (polytetrafluoroethylene).

[0037] Inside the pressing body 6 is a heating element (not shown) that generates heat when an electric current is applied. The pressing body 6 is connected to a ball screw type vertical movement mechanism (not shown) that moves the pressing body 6 in the vertical direction, and the pressing body 6 is movable along the Z-axis direction (vertical direction).

[0038] In the workpiece unit formation step S10, for example, first, the resin sheet 13 is placed on the surface 15a of the support base 15 while the back surface 15b of the support base 15 is held in place by suction with the holding surface 4a, and then the workpiece 11 is placed on the resin sheet 13.

[0039] At this time, the surface 15a of the support base 15 and the second surface 13b of the resin sheet 13 come into contact, and the first surface 13a of the resin sheet 13 comes into contact with the surface 11a of the workpiece 11. Also, the back surface 11b of the workpiece 11 is exposed upwards.

[0040] Next, with the lower surface 6a of the pressing body 6, which has been heated to a predetermined temperature, in close contact with the back surface 11b, the workpiece 11 is pressed downwards. For example, the pressing body 6 is heated to a predetermined temperature of 80°C to 100°C, and the workpiece 11 is pressed downwards for about 30 seconds at a predetermined pressure of 0.2 MPa to 0.8 MPa.

[0041] The heat from the pressing body 6 is also transferred to the resin sheet 13, and the resin sheet 13, softened by the heating, adheres closely to the surface 11a of the workpiece 11 and the surface 15a of the support base 15, respectively. Furthermore, the heating and pressing process removes almost all of the air near the boundary between surface 11a and the first surface 13a, and also removes almost all of the air near the boundary between surface 15a and the second surface 13b.

[0042] After heating and pressing, when the pressing body 6 is raised and separated from the workpiece 11, the workpiece 11, the resin sheet 13, and the support base 15 are cooled, and the workpiece 11 and the resin sheet 13, and the resin sheet 13 and the support base 15 are pressed against each other by atmospheric pressure.

[0043] In this way, the workpiece 11 and the support base 15 are integrated via the resin sheet 13, forming a workpiece unit 17. After the workpiece unit formation step S10, the workpiece 11 is processed (processing step S20).

[0044] In this embodiment, as shown in Figure 4, the back surface 11b of the workpiece 11 is ground (processed) by the grinding device 8. The grinding device 8 has a disc-shaped chuck table 10. The chuck table 10 has a disc-shaped frame 12 made of ceramics.

[0045] A disc-shaped recess is formed on the upper surface of the frame 12. A suction passage (not shown) for transmitting negative pressure is formed at the bottom of the recess, and a suction source (not shown), such as a vacuum pump, is connected to this passage.

[0046] A porous plate 14, made of porous ceramics, is fixed to the recess of the frame 12. The lower surface of the porous plate 14 is approximately flat, but the upper surface of the porous plate 14 is conical in shape, with the center slightly protruding (for example, 20 μm) compared to the outer edge. Note that in Figure 4, the amount of protrusion at the center of the upper surface of the porous plate 14 is exaggerated for illustrative purposes.

[0047] The upper surface of the frame 12 and the upper surface of the porous plate 14 are formed to be substantially flush, forming a substantially circular holding surface 10a. When the suction source is activated, negative pressure is generated on the upper surface of the porous plate 14, and the workpiece unit 17 placed on the holding surface 10a is held in place by suction on the holding surface 10a, conforming to the shape of the holding surface 10a.

[0048] A cylindrical rotating shaft 16 is connected to the lower part of the chuck table 10. In Figure 4, the rotating shaft 16 is shown by a dashed line. The rotating shaft 16 is tilted by a small angle such that a part of the holding surface 10a is approximately parallel to a plane perpendicular to the Z-axis (for example, the horizontal plane).

[0049] Furthermore, the chuck table 10 is rotatably supported by a table base 18. The tilt of the table base 18 is adjusted by a tilt adjustment mechanism (not shown) that supports the table base 18.

[0050] A grinding unit 20 is provided above the chuck table 10. The grinding unit 20 is configured to be movable along the Z-axis direction by a ball screw type moving mechanism (not shown).

[0051] The grinding unit 20 has a cylindrical spindle housing (not shown). A portion of a cylindrical spindle 22, whose longitudinal portion is aligned along the Z-axis, is rotatably housed in the spindle housing.

[0052] A motor (not shown) for rotating the spindle 22 is provided near the upper end of the spindle 22. The lower end of the spindle 22 protrudes below the lower end of the spindle housing, and a disc-shaped wheel mount 24 is fixed to this lower end.

[0053] A grinding wheel 26, which has approximately the same diameter as the wheel mount 24, is mounted on the underside of the wheel mount 24. The grinding wheel 26 has an annular wheel base (base) 28 made of a metal material such as an aluminum alloy.

[0054] Multiple grinding wheels 30 are arranged in an annular pattern at approximately equal intervals along the circumferential direction of the wheel base 28 on the lower surface (one surface) 28a of the wheel base 28. The lower surfaces of the multiple grinding wheels 30 are at approximately the same height in the Z-axis direction. When the spindle 22 rotates, the lower surfaces of the multiple grinding wheels 30 form a grinding surface 30a for grinding the workpiece 11.

[0055] Figure 4 shows a grinding step as an example of the processing step S20. In the grinding step, first, the back surface 15b of the support base 15 is held by the holding surface 10a using suction. Next, the chuck table 10 is rotated at a predetermined speed (e.g., 300 rpm), and the grinding wheel 26 is rotated at a predetermined speed (e.g., 4000 rpm).

[0056] Furthermore, while supplying grinding fluid (not shown), such as pure water, to multiple grinding wheels 30 from the center side of the grinding wheel 26 at a flow rate of 4.0 L / min, the grinding unit 20 is lowered at a predetermined speed (for example, 0.4 μm / s).

[0057] The arc-shaped region on the back surface 11b, which is positioned approximately parallel to the grinding surface 30a, is ground by the grinding surface 30a. However, as the chuck table 10 rotates, the entire back surface 11b is ground, and the workpiece 11 is uniformly thinned.

[0058] For example, in processing step S20, the workpiece 11 is thinned until its thickness reaches a predetermined value of 20 μm to 100 μm. When thinning the workpiece 11 to the predetermined value in processing step S20, the process may be completed not only by grinding with a single grinding wheel 26, but also by sequentially performing rough grinding, finish grinding, and polishing.

[0059] After the processing step S20, in order to separate the support base 15 from the workpiece 11 and the resin sheet 13, the focusing point P of the laser beam L1 (see Figure 5) is positioned on the outer periphery 13c (see Figure 6) of the overlapping region of the resin sheet 13 and the support base 15 at the boundary 19 between the resin sheet 13 and the support base 15.

[0060] By irradiating with this laser beam (first laser beam) L1, a region of reduced fixing force 21 (see Figures 6 and 7) is formed in which the fixing force fixing the resin sheet 13 and the support base 15 is reduced (laser beam irradiation step S30).

[0061] In the laser beam irradiation step S30, a laser processing device 32 (see Figure 5) is used. As shown in Figure 5, the laser processing device 32 has a disc-shaped chuck table 34. The chuck table 34 has a disc-shaped frame 36 made of a metal such as stainless steel.

[0062] A disc-shaped recess is formed on the upper surface of the frame 36. A suction passage for transmitting negative pressure is formed at the bottom of the recess, and a suction source (not shown), such as a vacuum pump, is connected to this passage.

[0063] A porous plate 38 made of porous ceramics is fixed to the recess of the frame 36. The upper surface of the porous plate 38 is substantially flat, and the upper surface of the frame 36 and the upper surface of the porous plate 38 are substantially flush, forming a circular holding surface 34a.

[0064] When the suction source is activated, negative pressure is generated on the upper surface of the porous plate 38, and the workpiece unit 17 placed on the holding surface 34a is held in place by suction from the holding surface 34a. The chuck table 34 is configured to be movable along the X-axis and Y-axis directions by a ball screw type moving mechanism (not shown).

[0065] A laser beam irradiation unit 40 is provided above the chuck table 34. The laser beam irradiation unit 40 has a laser beam generation unit (not shown). The laser beam generation unit includes a laser oscillator.

[0066] The laser oscillator has a laser medium such as Nd:YAG or Nd:YVO4. After being emitted from the laser oscillator, the laser beam L1 passes through a predetermined optical system and is irradiated from the irradiation head 42 toward the holding surface 34a along the Z-axis.

[0067] The laser beam L1 irradiated onto the holding surface 34a is pulsed (i.e., has a predetermined repetition frequency) and has a wavelength that penetrates the workpiece 11.

[0068] Figure 5 shows the laser beam irradiation step S30. In the laser beam irradiation step S30, first, the back surface 15b of the support base 15 is held by the holding surface 34a through suction. At this time, the back surface 11b of the workpiece 11 is exposed upward.

[0069] Next, the position of the focusing lens (not shown) of the irradiation head 42 in the Z-axis direction is adjusted so that the focusing point P is located at the boundary 19 (see Figure 6) between the resin sheet 13 and the support base 15. Then, the laser beam L1 is irradiated from the irradiation head 42, and the chuck table 34 is moved by a predetermined amount along the X-axis direction at a predetermined processing feed rate (see arrow in Figure 5).

[0070] As a result, multiphoton absorption occurs at the boundary 19 between the resin sheet 13 and the support base 15 along the movement path of the focal point P, and a damage layer is formed on the second surface 13b of the resin sheet 13 and the surface 15a of the support base 15.

[0071] After relatively moving the focusing point P along the X-axis from the inner end 13c1 to the outer end 13c2 of the outer periphery 13c of the overlapping area of ​​the resin sheet 13 and the support base 15, as shown in Figure 6, the chuck table 34 is moved along the Y-axis by a predetermined index amount.

[0072] Then, similarly, the focusing point P is moved relative to the inner end 13c1 and the outer end 13c2. This is repeated multiple times to form a fixing force reduction region 21 on the outer periphery 13c of the resin sheet 13 and the support base 15.

[0073] Figure 6 is a cross-sectional view of the workpiece unit 17 showing the fixing force reduction region 21. In Figure 6, the fixing force reduction region 21 is shown for convenience by multiple dashed circles. However, the multiple circles only show a rough outline of the movement trajectory of the focusing point P.

[0074] Figure 7 is a top view of the workpiece unit 17 showing the fixing force reduction region 21. In this embodiment, the fixing force reduction region 21 has a substantially square shape with dimensions of 3.0 mm in length and 3.0 mm in width. However, the shape and size of the fixing force reduction region 21 are not particularly limited as long as it reaches the outer edge 13c2 of the outer periphery 13c of the overlapping area of ​​the resin sheet 13 and the support base 15.

[0075] An example of the processing conditions used in the laser beam irradiation step S30 is shown below.

[0076] Wavelength: 1064nm Machining feed rate: 200 mm / s Indexing feed amount: 10 μm (i.e., index amount) Repetition frequency: 50kHz Average output: 4.0W Spot diameter at focusing point P: 1.0 μm

[0077] After the laser beam irradiation step S30, the workpiece unit 17 is separated into the workpiece 11 with the resin sheet 13 attached and the support base 15 using the peeling device 44 shown in Figure 8 (separation step S40). Figure 8 shows the separation step S40.

[0078] The peeling device 44 has a disc-shaped chuck table 46. The chuck table 46, like the chuck table 34 described above, has a metal frame and a porous plate. The holding surface 46a of the chuck table 46 is substantially flat. The chuck table 46 is configured to be movable along the X-axis direction by a ball screw type moving mechanism (not shown).

[0079] A gripping unit 48 is provided above the chuck table 46 to grip one end of the ribbon-shaped release tape 23. The gripping unit 48 is configured to be movable along the Z-axis and X-axis directions by a ball screw type moving mechanism (not shown).

[0080] The gripping unit 48 has an L-shaped first claw portion 50 in side view. The first claw portion 50 includes an upright portion 50a and a bottom portion 50b. Above the bottom portion 50b, a second claw portion 52 is provided so as to be movable along the height direction of the upright portion 50a.

[0081] In separation step S40, first, one of the multiple diameters of the support base 15, which includes the fixing force reduction region 21 in a plan view, is made approximately parallel to the X-axis direction of the peeling device 44. Then, with one end of the peeling tape 23 being gripped by the bottom 50b of the first claw portion 50 and the second claw portion 52, the other end of the peeling tape 23 is attached to a part of the outer circumference of the back surface 15b located near the fixing force reduction region 21.

[0082] After attachment, the gripping unit 48 is gradually raised along the Z-axis direction, allowing the atmospheric gas (e.g., air) to spread throughout almost the entire area between surface 15a and second surface 13b, starting from the fixing force reduction region 21, thereby peeling the support base 15 from the thinned workpiece 11 and resin sheet 13. In this way, the support base 15 can be separated starting from the fixing force reduction region 21.

[0083] The fixing force reduction region 21 functions as a gap into which air can enter between the resin sheet 13 and the support base 15. Therefore, compared to the case where the fixing force reduction region 21 is not formed, the workpiece unit 17 can be easily separated into the workpiece 11 with the resin sheet 13 and the support base 15. In other words, the support base 15 and the workpiece 11 can be separated.

[0084] The gripping unit 48 rises, for example, until the support base 15 is completely separated from the resin sheet 13. In this case, the support base 15, suspended by the gripping unit 48 via the release tape 23, is transported to a collection box (not shown) as the gripping unit 48 moves in the X-axis direction.

[0085] The gripping unit 48 may also release the release tape 23 after expanding the area where the fixing force between the support base 15 and the resin sheet 13 is reduced, starting from the fixing force reduction area 21, by lifting the support base 15.

[0086] In this case, the support base 15 is returned to the resin sheet 13 with the fixing force between it and the resin sheet 13 sufficiently reduced. Next, the support base 15 is transported to a collection box (not shown) with its back surface 15b side held in place by a transport mechanism (not shown) having a disc-shaped suction part that generates negative pressure.

[0087] (Second Embodiment) Next, a second embodiment will be described with reference to Figure 9. Figure 9 is a diagram showing the workpiece unit formation step S10 according to the second embodiment. In the second embodiment, a circular and thin-film resin sheet 13 is formed by heating and pressing a solid thermoplastic resin such as powder, lump, granules, film, or string. This is the difference from the first embodiment.

[0088] In the workpiece unit formation step S10, the bonding device 2 is also used. Specifically, first, the back surface 15b of the support base 15 is held in place by suction on the holding surface 4a, and then the lump of thermoplastic resin 25 is placed on the surface 15a of the support base 15.

[0089] Although the thickness of the block 25 is greater than that of the resin sheet 13 shown in Figure 2(B), the area of ​​the block 25 when viewed from above is smaller than that of the resin sheet 13. After placing the block 25 on the surface 15a, the workpiece 11 is pressed with a predetermined pressure using the heated pressing body 6, as described above.

[0090] The mass 25, softened by heating, spreads out almost uniformly, becoming a resin sheet 13, and adheres closely to the surface 11a of the workpiece 11 and the surface 15a of the support base 15, respectively. After pressing for a predetermined time, the pressing body 6 is raised. In this way, the workpiece unit 17 is formed.

[0091] Alternatively, instead of a solid thermoplastic resin, a liquid thermoplastic resin may be supplied to the surface 15a of the support base 15, and a circular, thin-film resin sheet 13 may be formed in the same manner.

[0092] (Third Embodiment) Next, a third embodiment will be described with reference to Figures 10(A) and 10(B). In the third embodiment, the support base 15' is entirely made of glass that is transparent to visible light and infrared rays, from the front surface 15a' to the back surface 15b'.

[0093] In the third embodiment, after the processing step S20, with the workpiece unit 17 inverted, the back surface 11b of the workpiece 11 is held by suction on the holding surface 34a of the chuck table 34 of the laser processing device 32.

[0094] At this time, the back surface 15b' of the support base 15' is exposed upward. Figure 10(A) shows how the workpiece unit 17 of the first embodiment shown in Figure 5 is held in place by suction in an inverted state.

[0095] In this state, when a pulsed laser beam (second laser beam) L2 is irradiated from the irradiation head 42, the support base 15' is positioned above the workpiece 11, so the laser beam L2 is irradiated onto the workpiece 11 in such a way that it passes through the support base 15' before reaching the workpiece 11.

[0096] Figure 10(B) shows the laser beam irradiation step S30 according to the third embodiment. In the third embodiment, the wavelength of the laser beam L2 is 1064 nm, the same as in the first embodiment, but the wavelength of the laser beam L2 may be different from 1064 nm as long as it can penetrate the support base 15'.

[0097] In the third embodiment, as in the first embodiment, the focusing point P of the laser beam L2 is positioned at the boundary 19 between the surface 15a' of the support base 15' and the second surface 13b of the resin sheet 13, and the laser beam L2 is irradiated onto the resin sheet 13 and the outer periphery 13c of the support base 15.

[0098] As a result, a region 21 is formed on the outer periphery 13c of the resin sheet 13 and the support base 15' where the fixing force fixing the resin sheet 13 and the support base 15' is reduced. In the third embodiment, compared to the first embodiment, the influence of the laser beam L2 on devices located near the surface 11a of the workpiece 11 can be reduced.

[0099] In addition, the third embodiment can also form a fixing force reduction region 21 even when a film, layer, etc., made of a material that the laser beam L2 cannot penetrate (for example, metal) is provided on the back surface 11b side of the workpiece 11.

[0100] Furthermore, the structures, methods, etc., according to the above embodiments can be modified as appropriate without departing from the scope of the object of the present invention. For example, the processing performed on the workpiece 11 in processing step S20 is not limited to the grinding and polishing described above.

[0101] In machining step S20, the workpiece 11 may be subjected to cutting with a cutting tool. Furthermore, the polishing performed on the workpiece 11 in machining step S20 may be CMP (Chemical Mechanical Polishing) using a slurry (i.e., wet polishing), or it may be dry polishing without using a slurry.

[0102] Alternatively, in separation step S40, instead of using the peeling device 44, the support bases 15, 15' may be separated by an operator manually lifting them from the resin sheet 13 using a blade, spatula, scraper, etc.

[0103] Even when performed manually, slightly lifting the support bases 15 and 15' allows the atmospheric gas to naturally spread from the area of ​​reduced fixing force 21, automatically separating the support bases 15 and 15' from the resin sheet 13.

[0104] After separating the support bases 15 and 15', the resin sheet 13 may be peeled off the workpiece 11. Alternatively, the workpiece 11 may be placed in the opening of an annular frame (not shown) made of metal, and after attaching a circular tape (not shown) to the back surface 11b of the workpiece 11 and one side of the annular frame, the resin sheet 13 may be peeled off from the front surface 11a. [Explanation of symbols]

[0105] 2: Bonding device, 4: Chuck table, 4a: Holding surface, 6: Pressing body, 6a: Bottom surface 8: Grinding device, 10: Chuck table, 10a: Holding surface 11: Workpiece, 11a: Front surface, 11b: Back surface 12: Frame, 14: Porous plate, 16: Rotating axis, 18: Table base 13: Resin sheet, 13a: First surface, 13b: Second surface 13c: Outer edge, 13c1: Inner edge, 13c2: Outer edge 15,15´: Support base, 15a,15a´: Front side, 15b,15b´: Back side 17: Workpiece Unit 19: Boundary, 21: Fixed force reduction area 23: Release tape, 25: Clump 20: Grinding unit, 22: Spindle, 24: Wheel mount 26: Grinding wheel, 28: Wheel base (base), 28a: Bottom surface (one side) 30: grinding wheel, 30a: grinding surface 32: Laser processing device, 34: Chuck table, 34a: Holding surface 36: Frame, 38: Porous board 40: Laser beam irradiation unit, 42: Irradiation head 44: Peeling device, 46: Chuck table, 46a: Holding surface 48: Gripping unit, 50: First claw portion, 50a: Upright portion, 50b: Bottom portion, 52: Second claw portion L1: Laser beam (first laser beam) L2: Laser beam (second laser beam) P: Focus point S10: Workpiece unit formation step S20: Machining step S30: Laser beam irradiation step S40: Separation step

Claims

1. A processing method for processing a workpiece that is integrated with a support base via a resin sheet, A workpiece unit forming step, in which the workpiece and the support base are bonded together via the resin sheet by adhering the first surface of the resin sheet, which does not have an adhesive layer containing an adhesive, to the workpiece, and adhering the second surface of the resin sheet, which is located on the opposite side of the first surface and does not have an adhesive layer, to the support base, thereby forming a workpiece unit in which the workpiece, the resin sheet, and the support base are integrated; After the workpiece unit formation step, a processing step is performed to process the workpiece in the workpiece unit, A laser beam irradiation step is performed after the processing step, in which the focal point of a first laser beam having a wavelength that penetrates the workpiece, or the focal point of a second laser beam having a wavelength that penetrates the support base, is positioned at the boundary between the resin sheet and the support base, and the first laser beam or the second laser beam is irradiated onto the outer periphery of the overlapping region of the resin sheet and the support base, thereby forming a region of reduced fixing force in which the fixing force fixing the resin sheet and the support base is reduced. After the laser beam irradiation step, a separation step is performed to separate the workpiece unit into the support base and the workpiece with the resin sheet attached, starting from the region where the fixing force is reduced. A processing method characterized by comprising the following:

2. The processing method according to claim 1, characterized in that, in the laser beam irradiation step, the second laser beam is irradiated onto the workpiece unit such that the second laser beam passes through the support base side of the workpiece unit before reaching the workpiece.

3. The machining method according to claim 1 or 2, characterized in that the machining step involves grinding the workpiece using a grinding wheel in which a plurality of grinding wheels are arranged in a ring shape on one surface of an annular base.

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