Working preparation method, and working method, each for workpiece

Abstract

To propose a new technique for a working method for thinning a tabular workpiece in which an outer peripheral groove is formed at an outer peripheral edge of a surface.SOLUTION: A working method is provided which includes: an adhesion material laying step of laying an adhesion material on a surface of a support substrate; an opposition step of opposing a tabular workpiece in which an outer peripheral groove is formed at an outer peripheral edge of a surface to the adhesion material; a pressurizing step of pressurizing the adhesion material with the surface of the workpiece, pushing and expanding the adhesion material between the workpiece and the support substrate and filling the outer peripheral groove with the adhesion material; a laminate formation step of solidifying the adhesion material with external stimuli and forming a laminate; a holding step of holding the laminate on the side of the support substrate with a holding table and exposing a rear surface of the workpiece; and a grinding step of grinding the rear surface of the workpiece with an abrasive grindstone and thinning the workpiece to a predetermined thickness.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a method for processing a plate-like object, and more particularly to a method for grinding a plate-like object to thin it to a predetermined thickness. [Background technology]

[0002] When thinning a plate-like workpiece such as a semiconductor wafer, the rigidity of the workpiece decreases significantly as the workpiece is thinned, causing cracks, deflection, etc. during transportation and processing. To prevent this problem, a process is known in which the workpiece is bonded to a rigid support substrate (support substrate) and then ground (see, for example, Patent Document 1).

[0003] Furthermore, as the thickness of the workpiece decreases, the R-shape of the edge of the workpiece becomes knife-edge-shaped, which makes edge chipping more likely to occur. To prevent this problem, a process known as edge trimming is known in which a cutting blade is used to cut a circumferential groove into the outer periphery of the workpiece before bonding it to a support substrate (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-207606 [Patent Document 2] Japanese Patent Application Laid-Open No. 2000-173961 [Patent Document 3] Japanese Patent Publication No. 2023-180023 [Patent Document 4] Japanese Patent Publication No. 2022-051112 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-described processing method, the workpiece is fixed to the surface of a support substrate using a liquid resin as a fixing material and then ground to a predetermined thickness. However, when the edge-trimmed workpiece is thinned by grinding from the side without the circumferential groove, the outer periphery of the workpiece cracks and the scrap material scatters (edge ​​chipping). The scrap material scattered inside the equipment adheres to the equipment due to the grinding water supplied during processing, making it difficult to remove.

[0006] To address these issues, mechanisms for recovering scrap materials (see, for example, Patent Document 3) and methods for grinding scrap materials while crushing them by attaching an ultrasonic unit (see, for example, Patent Document 4) are known. However, in addition to the problem of the device configuration becoming complicated, these methods cannot prevent the generation of scrap materials, which is the root cause of the problem in the first place.

[0007] In view of the above problems, the present invention proposes a novel technique for thinning a plate-shaped workpiece having an outer peripheral groove formed on the outer peripheral edge of its surface. [Means for solving the problem]

[0008] The problem to be solved by the present invention is as described above, and the means for solving this problem will now be described.

[0009] According to one aspect of the present invention, a method for preparing a workpiece for processing includes an adhesive material laying step of laying an adhesive material on the surface of a support substrate; a facing step of bringing a plate-shaped workpiece having a peripheral groove formed on the outer peripheral edge of its surface into contact with the adhesive material; a pressing step of pressing the adhesive material against the surface of the workpiece and spreading the adhesive material between the workpiece and the support substrate to fill the peripheral groove with the adhesive material; and a laminate formation step of solidifying the adhesive material using an external stimulus to form a laminate.

[0010] According to one aspect of the present invention, in order to form the peripheral groove on the peripheral edge portion of the surface of the workpiece, a trimming step is provided in which a portion of the edge of the peripheral edge portion of the workpiece is removed to form the peripheral groove.

[0011] According to one aspect of the present invention, the adhesive material contains abrasive grains.

[0012] According to one aspect of the present invention, the processing method includes an adhesive material laying step of laying an adhesive material on the surface of a support substrate; a facing step of bringing a plate-shaped workpiece having a peripheral groove formed on the outer peripheral edge of its surface into contact with the adhesive material; a pressing step of pressing the adhesive material against the surface of the workpiece and spreading the adhesive material between the workpiece and the support substrate to fill the peripheral groove with the adhesive material; a laminate formation step of solidifying the adhesive material by an external stimulus to form a laminate; a holding step of holding the support substrate side of the laminate on a holding table to expose the back surface of the workpiece; and a grinding step of grinding the back surface of the workpiece with a grinding wheel to thin the workpiece to a predetermined thickness.

[0013] According to one aspect of the present invention, the grinding step thins the workpiece to the extent that the adhesive material is ground away. [Effects of the Invention]

[0014] The present invention provides the following effects. That is, according to one aspect of the present invention, by filling the outer circumferential groove with adhesive material to eliminate gaps, the outer circumferential edge portion can be reinforced so that it is supported by the adhesive material, thereby preventing the outer circumferential edge portion from breaking into large scraps and scattering.

[0015] Furthermore, according to one aspect of the present invention, by grinding the surface of the adhesive material that is exposed after the workpiece is thinned, even if the grinding wheel is prone to being dulled, it is possible to dress (sharpen) the grinding wheel using the abrasive grains contained in the adhesive material. [Brief explanation of the drawings]

[0016] [Figure 1] Schematic diagram of a press-shaping device used to prepare a workpiece for processing. [Figure 2] (A) is a diagram showing an overview of a wafer, which is an example of a workpiece, and (B) is a diagram explaining edge trimming. [Figure 3] 3 is a flowchart of a processing preparation method according to the present invention. [Figure 4] 1A is a diagram illustrating the adhesive material laying step, and FIG. 1B is a diagram illustrating the pressing step. [Figure 5] 1A is a diagram illustrating a laminate formation step, and FIG. 1B is a diagram illustrating the laminate. [Figure 6] (A) is a diagram showing the holding step, and (B) is a diagram showing the grinding step. [Figure 7] 1A is a diagram illustrating how the workpiece is thinned, and FIG. 1B is a diagram illustrating the laminate after the grinding step. [Figure 8] 10A and 10B are diagrams for explaining a problem that occurs when the present invention is not used; DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a diagram showing an outline of the configuration of a pressure shaping device used to prepare a workpiece for processing. Fig. 1 shows how, in the pressure shaping device 1, a wafer W, which is a workpiece, is brought into contact with an adhesive material (resin 25) laid on the upper surface of a support substrate 31.

[0018] The pressure shaping device 1 is configured to include a table 2, a holding means 4 (holding pad), a lifting means 6, an ultraviolet light irradiation means 5, a resin supply means 3, and a control device 7 for controlling various operating parts.

[0019] The table 2 has a horizontal upper surface 2a and is configured to transmit ultraviolet light, and is made of a transparent material such as glass. A suction groove that leads to a suction source (not shown) is formed on the horizontal upper surface 2a, and by generating negative pressure on the upper surface 2a, the upper surface 2a is configured to function as a suction holding surface.

[0020] The holding means 4 is disposed above the horizontal upper surface 2a of the table 2, and its horizontal lower surface 4a has suction grooves formed therein that communicate with a suction source (not shown), and by generating negative pressure on the lower surface 4a, the lower surface 4a is configured as a suction holding surface. The lower surface 4a suction-holds the back surface (upper surface) of the wafer W, which is the workpiece, and exposes the front surface (lower surface).

[0021] The holding means 4 is fixed to the underside of the lifting base 61 of the lifting means 6, and moves up and down together with the lifting base 61. The lifting means 6 has an actuator (not shown), and the lifting base 61 moves up and down by operating the actuator.

[0022] The ultraviolet light irradiation means 5 is disposed below the table 2 and has a light source 5a for emitting ultraviolet light. As will be described in detail later, the ultraviolet light passes through the table 2 and the support substrate 31 and solidifies the resin 25.

[0023] The resin supply means 3 has a supply nozzle 3a for supplying liquid resin 25 onto the upper surface of the support substrate 31 or the like placed on the table 2. The supply nozzle 3a is configured to be movable by an actuator (not shown), and can be positioned at a supply position where the supply nozzle 3a is positioned at the center of the table 2, and at a retracted position where the supply nozzle 3a is away from the table 2. The supply nozzle 3a is connected to a resin supply source (not shown), and can supply a predetermined amount of resin 25 onto the upper surface of the support substrate 31 or the like.

[0024] 2A, the wafer W, which is the workpiece, is disk-shaped and has a chamfered portion Wm formed at its edge, which becomes the outer periphery Wg. The surface Wa of the wafer W is configured as a device surface where devices are formed in each region defined by, for example, orthogonal dividing lines.

[0025] When the back surface Wb of the wafer W is thinned, the R-shape of the chamfered portion Wm of the edge becomes a knife-edge shape, which makes edge chipping more likely to occur. For this reason, as shown in Fig. 2(B), for example, edge trimming is performed by using a processing device 52 equipped with a cutting blade 50 to trim a part of the outer periphery of the front surface Wa of the wafer W, thereby forming an outer periphery groove G on the outer periphery of the front surface Wa.

[0026] Specifically, the back surface Wb side of the wafer W is held by suction on a holding table 54, and a cutting blade 50 is cut into the outer peripheral edge Wg on the front surface Wa side of the wafer W, and the holding table 54 is rotated 360 degrees to form a stepped outer peripheral groove G that is continuous in the circumferential direction.

[0027] The edge trimming of the workpiece described above can be incorporated as a trimming step into the preparatory method for preparing a workpiece for processing according to the present invention.

[0028] The peripheral groove G shown in FIG. 2(B) is formed by edge trimming using a cutting blade 50, but may also be formed by laser ablation processing, for example, and is not particularly limited.

[0029] The wafer W as the workpiece may be a silicon wafer, or may be, for example, a plate made of glass material or a composite wafer made of a plurality of wafers, etc. The shape of the workpiece may be a disk or a rectangle.

[0030] Next, a processing preparation method including each step of the flowchart shown in FIG. 3 will be described.

[0031] <Adhesive material laying step> As shown in FIG. 4(A), this is a step of laying a resin 25, which is an adhesive material, on the surface of a support substrate 31.

[0032] Specifically, a plate-shaped support substrate 31 is placed on the horizontal upper surface 2a of the table 2. The support substrate 31 is made of a transparent material such as glass, and is bonded to the wafer W to prevent cracking or warping of the wafer W, which will be thinned later. The shape of the support substrate 31 may be a circular plate or a rectangular shape.

[0033] Then, the supply nozzle 3a is positioned above the approximate center of the support substrate 31, and a predetermined amount of the resin 25 is supplied to the upper surface 2a by dripping the resin 25 from the supply nozzle 3a. The resin 25 is, for example, an ultraviolet curable resin, and for example, "Regilock" (registered trademark) manufactured by Disco Corporation is used.

[0034] Furthermore, the adhesive material preferably contains abrasive grains having an average particle size of, for example, 0.1 μm to 20 μm, in addition to the resin 25 alone. By including abrasive grains in the resin 25, the resin 25 can be ground with a grinding wheel, as will be described in detail later, thereby achieving the effect of so-called dressing.

[0035] The abrasive grains may be, for example, white alundum (WA) or green carbon (GC), but are not limited thereto. The average grain size is defined, for example, as the grain size at which the cumulative height reaches 50% in a sedimentation test (i.e., the median size or 50% diameter). The average grain size may also be defined as the most frequently occurring grain size in an electrical resistance test (i.e., the most frequent grain size or mode diameter).

[0036] <Face-to-face steps> As shown in FIG. 4(A), this is a facing step in which a wafer W, which is a plate-shaped workpiece having a peripheral groove G formed in the outer peripheral edge of its surface Wa, is faced to a resin 25, which is an adhesive material.

[0037] Specifically, the back surface Wb of the wafer W is held by suction with the holding means 4 so that the front surface Wa of the wafer W is exposed downward.

[0038] <Pressing step> As shown in Figure 4(B), this is a step in which resin 25, which is an adhesive material, is pressed against the surface Wa of the wafer W, which is the workpiece, and the resin 25 is spread between the wafer W and the support substrate 31 to fill the outer circumferential groove G with the resin 25.

[0039] Specifically, first, the supply nozzle 3a is retracted away from a position below the holding means 4. Then, the back surface Wb of the wafer W is held by suction on the lower surface 4a of the holding means 4, and the wafer W is lowered to a predetermined height by the elevating means 6 (FIG. 1). When the front surface Wa of the wafer W reaches the resin 25, the resin 25 is spread between the wafer W and the table 2 without leaving any gaps.

[0040] The area of ​​the support substrate 31 used is larger than the surface Wa of the wafer W. This allows the resin 25 to infiltrate and wrap around the peripheral groove G, thereby filling the peripheral groove G with the resin 25, as shown in the enlarged portion of FIG.

[0041] Here, in the adhesive material laying step, a sufficient amount of resin 25 is supplied so that the outer circumferential groove G is reliably filled with the resin 25. For example, as shown in Fig. 4(B), in addition to filling the space in the outer circumferential groove G so that no gap is formed between the outer circumferential edge portion Wg and the support substrate 31, a large amount of resin 25 may be supplied so that it overflows from the space in the outer circumferential groove G.

[0042] <Laminate formation step> As shown in FIG. 5(A), this is a step in which the resin 25, which is an adhesive material, is solidified by an external stimulus to form a laminate 40 shown in FIG. 5(B).

[0043] Specifically, the height of the wafer W is maintained at a predetermined height so as to maintain the state in which the outer circumferential groove G is filled with the resin 25 by the pressing step, and ultraviolet light UV is irradiated from below by the ultraviolet light irradiation means 5 (FIG. 1), and the resin 25 is irradiated with ultraviolet light through the table 2 and the support substrate 31 to solidify the resin 25. At this time, the resin 25 filling the outer circumferential groove G is also solidified.

[0044] In this embodiment, the external stimulus for solidifying the resin 25 is irradiation with ultraviolet light. Other external stimuli include heat, in which case a thermosetting resin may be used. As the resin 25 solidifies, the device D (FIG. 2A) formed on the front surface Wa of the wafer W is protected by the resin 25.

[0045] After the resin 25 has solidified, the wafer W is released from the holding means 4 (Figure 5(A)), thereby forming a laminate 40 (bonded wafer (composite wafer)) in which the wafer W, the support substrate 31, and the resin 25 are integrated, as shown in Figure 5(B).

[0046] Next, a method for thinning the laminate 40 formed as described above will be described. <Holding step> As shown in FIG. 6(A), this is a step in which the support substrate 31 side of the laminate 40 is held by a holding table 51, and the back surface Wb of the wafer W, which is the workpiece, is exposed.

[0047] 6(A), the support substrate 31 of the stack 40 is suction-held by a holding surface 51a of a holding table 51 of the grinding device 45, thereby exposing the back surface Wb of the wafer W. The holding table 51 is controlled to rotate by a motor (not shown).

[0048] 6(A), the grinding device 45 has a spindle 52 controlled to rotate by a motor (not shown), and a grinding wheel 54 fixed to the tip of the spindle 52. A plurality of grinding stones 54a are arranged on the grinding wheel 54 in the circumferential direction.

[0049] <Grinding step> As shown in FIG. 6(B), this is a step in which the back surface Wb of the wafer W, which is the workpiece, is ground with a grinding wheel 54a to thin the wafer W to a predetermined thickness.

[0050] Specifically, the holding table 51 is rotated, and the grinding wheel 54 is rotated while the grinding wheel 54 is moved downward by a lifting mechanism (not shown), thereby pressing the grinding stone 54a against the back surface Wb of the wafer W to perform grinding.

[0051] During grinding, grinding water is supplied to the processing point by the grinding wheel, but as shown in Fig. 6(B), since the peripheral groove G is filled with resin 25, it is possible to prevent the grinding water from penetrating between the wafer W and the resin 25, thereby suppressing the occurrence of peeling between the wafer W and the resin 25. Similarly, it is possible to suppress the occurrence of peeling between the support member 31 and the resin 25.

[0052] 7(A), when the wafer W is ground and gradually thinned to a predetermined finished thickness, the outer peripheral edge Wg that formed the outer peripheral groove G is completely removed, exposing the surface 25a of the resin 25. Then, as shown in FIG. 7(B), a stack 40 is formed in which the wafer W is buried in the resin 25.

[0053] 7(A) and (B), in the grinding step, the outer peripheral edge Wg that formed the outer peripheral groove G in the wafer W is completely removed, and the wafer W is further thinned until the resin 25 is ground away, so that the diameter Wr of the wafer W after thinning becomes smaller than the diameter 25r of the resin layer 25s formed by the resin 25. Alternatively, the outer peripheral edge Wg (FIG. 7(A)) may be left.

[0054] The present invention can be implemented as described above. According to the present invention, as shown in Fig. 7(A), the outer circumferential groove G is filled with resin 25, which is an adhesive material, to eliminate gaps, thereby reinforcing the outer circumferential edge portion Wg so that it is supported by resin 25. This prevents the outer circumferential edge portion Wg from breaking into large scraps and scattering.

[0055] In addition, it is possible to prevent grinding water from penetrating between the workpiece (wafer W) and the adhesive material (resin 25), and between the support substrate 31 and the adhesive material (resin 25), thereby suppressing peeling between different materials.

[0056] In addition, as shown in Figures 7(A) and (B), by grinding the surface 25a of the adhesive material (resin 25) that is exposed after the workpiece (wafer W) is thinned, even if the grinding wheel 54a is prone to being dulled, it is possible to dress (sharpen) the grinding wheel 54a using the abrasive grains contained in the adhesive material (resin 25).

[0057] 8 is a diagram for explaining a defect that occurs when the present invention is not used, and shows that the presence of a gap in the outer circumferential groove G between the outer circumferential edge Wg and the support member 35 causes cracks 36 to form in the outer circumferential edge Wg during thinning, resulting in waste material Wh. In the present invention, this outer circumferential groove G is filled and reinforced with resin 25 (FIG. 7(A)), so the occurrence of such a defect can be effectively suppressed. [Explanation of symbols]

[0058] 1. Pressure shaping device 2 tables 2a Top side 3. Resin supply means 3a Supply nozzle 4 Holding means 4a Bottom side 5 Ultraviolet light irradiation means 5a light source 6 Lifting means 7 Control Device 21 Support substrate 25 Resin 25a surface 25r diameter 25s resin layer 31 Support substrate 36 Crack 40 laminate 45 Cutting Blade 50 Grinding equipment 51 Holding table 51a Holding surface 52 Spindle 54 Grinding Wheel 54a Grinding wheel 61 Lifting Platform W wafer Wa surface Wb back side G Outer groove Wg outer edge Wh Scraps Wr diameter

Claims

1. an adhesive material laying step of laying an adhesive material on a surface of a support substrate; a facing step of bringing a plate-shaped workpiece having an outer peripheral groove formed on an outer peripheral edge portion of its surface into contact with the adhesive material; a pressing step of pressing the adhesive material against the surface of the workpiece to spread the adhesive material between the workpiece and the support substrate and fill the outer circumferential groove with the adhesive material; a laminate formation step of solidifying the adhesive material by an external stimulus to form a laminate; A method for preparing a workpiece for processing, comprising:

2. a trimming step of removing a part of an edge of the outer peripheral portion of the workpiece to form the outer peripheral groove in the outer peripheral portion of the surface of the workpiece, 2. The method for preparing a workpiece for processing according to claim 1.

3. The adhesive material includes abrasive grains.

3. The method for preparing a workpiece for processing according to claim 1 or 2.

4. an adhesive material laying step of laying an adhesive material on a surface of a support substrate; a facing step of bringing a plate-shaped workpiece having an outer peripheral groove formed on an outer peripheral edge portion of its surface into contact with the adhesive material; a pressing step of pressing the adhesive material against the surface of the workpiece to spread the adhesive material between the workpiece and the support substrate and fill the outer circumferential groove with the adhesive material; a laminate formation step of solidifying the adhesive material by an external stimulus to form a laminate; a holding step of holding the support substrate side of the laminate on a holding table and exposing the back surface of the workpiece; a grinding step of grinding the back surface of the workpiece with a grinding wheel to thin the workpiece to a predetermined thickness; A processing method having the above structure.

5. a trimming step of removing a part of an edge of the outer peripheral portion of the workpiece to form the outer peripheral groove in the outer peripheral portion of the surface of the workpiece, The processing method according to claim 4 .

6. The adhesive material includes abrasive grains.

6. The processing method according to claim 4 or claim 5.

7. In the grinding step, the workpiece is thinned until the adhesive material is ground away. The processing method according to claim 6 .

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