WORKPIECE PROCESSING PREPARATION METHOD AND PROCESSING METHOD

Abstract

A processing method of thinning a sheet-shaped workpiece having an outer peripheral groove formed in an outer peripheral edge portion of a top surface thereof. The method includes the steps of: laying an adhesive material on a top surface of a supporting substrate; causing the sheet-shaped workpiece to face the adhesive material; pressing the adhesive material with the top surface of the workpiece to press-spread the adhesive material between the workpiece and the supporting substrate, and to fill the outer peripheral groove with the adhesive material; hardening the adhesive material with an external stimulus to form a laminated body; holding the supporting substrate side of the laminated body on a holding table to expose a back surface of the workpiece; and grinding the back surface of the workpiece with a grinding stone to thin the workpiece to a predetermined thickness.

Claims

1. A workpiece processing preparation method comprising: an adhesive material laying step of laying an adhesive material on a top surface of a supporting substrate; a facing step of causing a sheet-shaped workpiece having an outer peripheral groove formed in an outer peripheral edge portion of a top surface thereof to face the adhesive material; a pressing step of pressing the adhesive material with the top surface of the workpiece to press-spread the adhesive material between the workpiece and the supporting substrate, and fill the outer peripheral groove with the adhesive material; and a laminated body forming step of hardening the adhesive material with an external stimulus to form a laminated body.

2. The workpiece processing preparation method of claim 1, further comprising: a trimming step of removing, to form the outer peripheral groove in the outer peripheral edge portion of the top surface of the workpiece, a portion of an edge of the outer peripheral edge portion of the workpiece to form the outer peripheral groove.

3. The workpiece processing preparation method of claim 1, wherein the adhesive material contains an abrasive grain.

4. A processing method comprising: an adhesive material laying step of laying an adhesive material on a top surface of a supporting substrate; a facing step of causing a sheet-shaped workpiece having an outer peripheral groove formed in an outer peripheral edge portion of a top surface thereof to face the adhesive material; a pressing step of pressing the adhesive material with the top surface of the workpiece to press-spread the adhesive material between the workpiece and the supporting substrate, and fill the outer peripheral groove with the adhesive material; a laminated body forming step of hardening the adhesive material with an external stimulus to form a laminated body; a holding step of holding the supporting substrate side of the laminated body on a holding table to expose a back surface of the workpiece; and a grinding step of grinding the back surface of the workpiece with a grinding stone to thin the workpiece to a predetermined thickness.

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

6. The processing method of claim 4, wherein the adhesive material contains an abrasive grain.

7. The processing method of claim 6, wherein, in the grinding step, the workpiece is thinned until the adhesive material is ground.

8. The processing method of claim 5, wherein the adhesive material contains an abrasive grain.

9. The workpiece processing preparation method of claim 2, wherein the adhesive material contains an abrasive grain.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG. 1 is an overview diagram of a press-shaping device to be used for workpiece processing preparation;

[0016] FIG. 2A is a diagram illustrating an overview of a wafer as an example of a workpiece;

[0017] FIG. 2B is a diagram illustrating edge trimming;

[0018] FIG. 3 is a flow chart of a processing preparation method according to the present invention;

[0019] FIG. 4A is a diagram illustrating an adhesive material laying step;

[0020] FIG. 4B is a diagram illustrating a pressing step;

[0021] FIG. 5A is a diagram illustrating a laminated body forming step;

[0022] FIG. 5B is a diagram illustrating a laminated body;

[0023] FIG. 6A is a diagram illustrating a holding step;

[0024] FIG. 6B is a diagram illustrating a grinding step;

[0025] FIG. 7A is a diagram illustrating thinning of a workpiece;

[0026] FIG. 7B is a diagram illustrating the laminated body after the grinding step; and

[0027] FIG. 8 is a diagram illustrating a problem when not according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Referring to the drawings, a description will be given hereinbelow of an embodiment of the present invention.

[0029] FIG. 1 is a diagram illustrating an overview of a configuration of a press-shaping device to be used for workpiece processing preparation. In FIG. 1, in a press-shaping device 1, a wafer W as a workpiece is caused to face an adhesive material (resin 25) laid on an upper surface of a supporting substrate 31.

[0030] The press-shaping device 1 is configured to have a table 2, a holding means 4 (holding pad), a lifting means 6, an ultraviolet light applying means 5, a resin supply means 3, and a control device 7 for controlling various operation units.

[0031] A table 2 is configured to have a horizontal upper surface 2a and transmit ultraviolet light, and is formed of a transparent member made of, e.g., glass or the like. In the horizontal upper surface 2a, a suction groove is formed to lead to a suction source not shown and, by generating a negative pressure on the upper surface 2a, the upper surface 2a is configured as a suction-holding surface.

[0032] The holding means 4 is disposed above the horizontal upper surface 2a of the table 2, while a suction groove is formed in a horizontal lower surface 4a thereof to lead to a suction source not shown and, by generating a negative pressure on the lower surface 4a, the lower surface 4a is configured as the suction-holding surface. By the lower surface 4a, a back surface (upper surface) of the wafer W as the workpiece is suction-held to expose a top surface (lower surface) thereof.

[0033] The holding means 4 is fixed to a lower surface of a lifting base 61 of the lifting means 6 to rise and fall with the lifting base 61. The lifting means 6 has an actuator not shown and operates the actuator to raise and lower the lifting base 61.

[0034] The ultraviolet light applying means 5 has a light source 5a disposed below the table 2 to emit ultraviolet light. Specifically, as will be described later, the ultraviolet light penetrates the table 2 and the supporting substrate 31 to harden the resin 25.

[0035] The resin supply means 3 has a supply nozzle 3a for supplying the liquid resin 25 to an upper surface of the supporting substrate 31 or the like laid on the table 2. The supply nozzle 3a is configured to be movable by the actuator not shown, and is located at a supply position that locates the supply nozzle 3a at a center position of the table 2 and at a retracted position away from the table 2. The supply nozzle 3a is connected to a resin supply source not shown to be able to supply a predetermined amount of the resin 25 to the upper surface of the supporting substrate 31 or the like.

[0036] As illustrated in FIG. 2A, the wafer W as the workpiece has a disc shape and a chamfered portion Wm formed at an edge portion thereof serving as an outer peripheral edge portion Wg. A top surface Wa of the wafer W is configured as a device surface where, in each of regions defined by, e.g., division lines perpendicular to each other, a device is to be formed.

[0037] When a back surface Wb of the wafer W is thinned, an R-shape of the chamfered portion Wm of the edge portion becomes a knife-edge shape, and consequently edge chipping is likely to occur. Accordingly, as illustrated in FIG. 2B, by, e.g., a processing device 52 including a cutting blade 50, edge trimming for trimming a portion of an outer peripheral edge of the top surface Wa of the wafer W is performed to form an outer peripheral groove G in the outer peripheral edge portion of the top surface Wa.

[0038] Specifically, the back surface Wb of the wafer W is suction-held by a holding table 54, while the outer peripheral edge portion Wg of the top surface Wa of the wafer W is cut with the cutting blade 50, and the holding table 54 is rotated by 360 degrees to form the circumferentially continuous stepped outer peripheral groove G.

[0039] The edge trimming of the workpiece described above can be incorporated as a trimming step into preliminary preparation for the workpiece processing preparation method according to the present invention.

[0040] Note that the outer peripheral groove G illustrated in FIG. 2B is not particularly limited except that the outer peripheral groove G is formed by the edge trimming method using the cutting blade 50, and may also be formed by, e.g., laser abrasion processing or the like.

[0041] In addition, the wafer W as the workpiece may be not only a silicon wafer, but also, e.g., a plate made of a glass material or a composite wafer obtained by combining a plurality of wafers and the like together. The workpiece may have not only a disc shape, but also a rectangular shape.

[0042] Next, a description will be given of a processing preparation method including each of steps of a flow chart shown in FIG. 3.

<Adhesive Material Laying Step>

[0043] As illustrated in FIG. 4A, an adhesive material laying step is a step of laying the resin 25 as the adhesive material on the surface of the supporting substrate 31.

[0044] Specifically, on the horizontal upper surface 2a of the table 2, the sheet-shaped supporting substrate 31 is placed. The supporting substrate 31 is made of a transparent member made of, e.g., glass or the like and laminated on the wafer W so as to prevent cracking, warping, or the like of the wafer W, which will be extremely thinned later. The supporting substrate 31 may have not only a disc shape, but also a rectangular shape.

[0045] Then, above a substantially center portion of the supporting substrate 31, the supply nozzle 3a is located, and the resin 25 is dropped from the supply nozzle 3a so that a predetermined amount of the resin 25 is supplied to the upper surface 2a. For example, the resin 25 is an ultraviolet-curing resin and, e.g., Resilock (registered trademark) manufactured by DISCO Corporation is used.

[0046] The adhesive material may be the resin 25 alone, but preferably contains abrasive grains having an average gain size of, e.g., not less than 0.1 m and not more than 20 m. By causing the resin 25 to contain the abrasive grains, it is possible to grind the resin 25 with grinding stones and thereby achieve an effect of setting by so-called dressing, as will be described later in detail.

[0047] Note that the abrasive grains are, e.g., fused white alundum (WA), green carbon (GC), or the like, but is not particularly limited. The average grain size is defined as, e.g., a grain size when an accumulated height is 50% in a precipitation test method (i.e., a median size or 50% size). Note that the average grain size may also be defined as a most frequent grain size in an electrical resistance test method (i.e., a most frequent grain size or mode size).

<Facing Step>

[0048] As illustrated in FIG. 4A, a facing step causes the wafer W as the sheet-shaped workpiece having the outer peripheral groove G formed in the outer peripheral edge portion of the top surface Wa to face the resin 25 as the adhesive material.

[0049] Specifically, the wafer W is brought into a state where the back surface Wb is suction-held by the holding means 4 such that the top surface Wa of the wafer W is exposed to face downward.

<Pressing Step>

[0050] As illustrated in FIG. 4B, the resin 25 as the adhesive material is pressed with the top surface Wa of the wafer W as the workpiece so that the resin 25 is press-spread between the wafer W and the supporting substrate 31 and fills the outer peripheral groove G.

[0051] Specifically, first, the supply nozzle 3a is retracted so as to move away from the position below the holding means 4. Then, the back surface Wb of the wafer W is suction-held by the lower surface 4a of the holding means 4, while the wafer W is lowered to a predetermined height by the lifting means 6 (see FIG. 1). When the top surface Wa of the wafer W reaches the resin 25, the resin 25 is spread with no gap between the wafer W and the table 2.

[0052] The supporting substrate 31 having an area larger than that of the top surface Wa of the wafer W is used. Thus, as illustrated in an enlarged portion of FIG. 4B, it is possible to cause the resin 25 to flow around and enter the outer peripheral groove G and fill the outer peripheral groove G.

[0053] It is to be noted herein that, to reliably fill the outer peripheral groove G with the resin 25, in the adhesive material laying step, the resin 25 is supplied in a sufficient amount. For example, as illustrated in FIG. 4B, the resin 25 may also be supplied in such a large amount as to fill a space of the outer peripheral groove G and thereby prevent a gap from being formed between the outer peripheral edge portion Wg and the supporting substrate 31, while flowing out of the space of the outer peripheral groove G. Note that the resin 25 is not necessarily required to fill the outer peripheral groove G entirely (100%) but may fill only 30% or more of the outer peripheral groove G.

<Laminated Body Forming Step>

[0054] As illustrated in FIG. 5A, a laminated body forming step is a step of hardening the resin 25 as the adhesive material with an external stimulus to form a laminated body 40 illustrated in FIG. 5B.

[0055] Specifically, a height of the wafer W is maintained at a predetermined height so as to maintain a state where the outer peripheral groove G is filled with the resin 25 by the pressing step, while ultraviolet light UV is applied from below by the ultraviolet light applying means 5 (FIG. 1) to the resin 25 via the table 2 and the supporting substrate 31 to harden the resin 25. At this time, the resin 25 filling the outer peripheral groove G is also hardened.

[0056] In the present embodiment, a means for the external stimulus for hardening the resin 25 is the application of the ultraviolet light. Another example of the external stimulus is heat and, in this case, it can be considered to use a thermosetting resin as the resin. As a result of the hardening of the resin 25, a device D (FIG. 2A) formed on the top surface Wa of the wafer W is protected by the resin 25.

[0057] After the hardening of the resin 25, the wafer W held by the holding means 4 (FIG. 5A) is released therefrom to form the laminated body 40 (laminated wafer (composite wafer)) in which the wafer W, the supporting substrate 31, and the resin 25 are integrated, as illustrated in FIG. 5B.

[0058] Next, a description will be given of a method of performing thinning processing on the laminated body 40 formed as described above.

<Holding Step>

[0059] As illustrated in FIG. 6A, a holding step is a step of holding the supporting substrate 31 of the laminated body 40 on a holding table 51 to expose the back surface Wb of the wafer W as the workpiece.

[0060] Specifically, as illustrated in FIG. 6A, the supporting substrate 31 of the laminated body 40 is suction-held on a holding surface 51a of the holding table 51 of a grinding device 45 to expose the back surface Wb of the wafer W. The holding table 51 is controlled to be rotated by a motor not shown.

[0061] As illustrated in FIG. 6A, the grinding device 45 includes a spindle 52 controlled to be rotated by the motor not shown and a grinding wheel 54 to be fixed to a leading end of the spindle 52. On the grinding wheel 54, a plurality of grinding stones 54a are arranged in a circumferential direction.

<Grinding Step>

[0062] As illustrated in FIG. 6B, a grinding step is a step of grinding the back surface Wb of the wafer W as the workpiece with the grinding stones 54a to thin the wafer W to a predetermined thickness.

[0063] Specifically, by rotating the holding table 51 and simultaneously feeding the grinding wheel 54 downward with a lifting mechanism not shown, while rotating the grinding wheel 54, grinding is performed in such a manner as to press the grinding stones 54a against the back surface Wb of the wafer W.

[0064] At the time of grinding, grinding water is supplied to points of processing by the grinding stones but, as illustrated in FIG. 6B, the outer peripheral groove G is filled with the resin 25, and therefore it is possible to prevent the grinding water from entering a gap between the wafer W and the resin 25, and thereby suppress occurrence of delamination between the wafer W and the resin 25. Likewise, it is also possible to suppress occurrence of delamination between the supporting member 31 and the resin 25.

[0065] As illustrated in FIG. 7A, when the wafer W is ground and gradually thinned so as to have a predetermined finishing thickness, the outer peripheral edge portion Wg forming the outer peripheral groove G is completely removed to expose a surface 25a of the resin 25. Then, as illustrated in FIG. 7B, the laminated body 40 in a state where the wafer W is filled with the resin 25 is formed.

[0066] In an example in FIGS. 7A and 7B, in the grinding step, the outer peripheral edge portion Wg forming the outer peripheral groove G in the wafer W is completely removed, the wafer W is further thinned until the resin 25 is ground, and a diameter Wr of the thinned wafer W becomes smaller than a diameter 25r of a resin layer 25s formed of the resin 25. Note that, alternatively, the outer peripheral edge portion Wg (FIG. 7A) may also be left.

[0067] The present invention can be implemented as described above. According to the present invention, as illustrated in FIG. 7A, by filling the outer peripheral groove G with the resin 25 as the adhesive material and thereby eliminating a gap, it is possible to reinforce the outer peripheral edge portion Wg such that the resin 25 supports the outer peripheral edge portion Wg. This can prevent a situation in which the outer peripheral edge portion Wg is scattered as large scraps.

[0068] It is also possible to prevent the grinding water from entering a gap between the workpiece (wafer W) and the adhesive material (resin 25), and a gap between the supporting substrate 31 and the adhesive material (resin 25), and suppress occurrence of delamination between different materials.

[0069] In addition, as illustrated in FIGS. 7A and 7B, even when the grinding stones 54a are susceptible to loading as a result of grinding the surface 25a of the adhesive material (resin 25) exposed after the thinning of the workpiece (wafer W), it is possible to perform dressing (setting) of the grinding stones 54a with abrasive grains contained in the adhesive material (resin 25).

[0070] Note that FIG. 8 is a diagram illustrating a problem when not according to the present invention, which shows that the presence of a gap of the outer peripheral groove G between the outer peripheral edge portion Wg and the supporting member 35 causes a problem in that a crack 36 occurs in the outer peripheral edge portion Wg during the thinning to cause a scrap Ws. In the present embodiment, the portion of the outer peripheral groove G is filled with and reinforced by the resin 25 (FIG. 7A), and therefore it is possible to effectively suppress such a problem.

REFERENCE SIGNS LIST

[0071] 1 Press-shaping device [0072] 2 Table [0073] 2a Upper surface [0074] 3 Resin supply means [0075] 3a Supply nozzle [0076] 4 Holding means [0077] 4a Lower surface [0078] 5 Ultraviolet light applying means [0079] 5a Light source [0080] 6 Lifting means [0081] 7 Control device [0082] 21 Supporting substrate [0083] 25 Resin [0084] 25a Surface [0085] 25r Diameter [0086] 25s Resin layer [0087] 31 Supporting substrate [0088] 36 Crack [0089] 40 Laminated body [0090] 45 Cutting blade [0091] 50 Grinding device [0092] 51 Holding table [0093] 51a Holding surface [0094] 52 Spindle [0095] 54 Grinding wheel [0096] 54a Grinding stone [0097] 61 Lifting base [0098] W Wafer [0099] Na Top surface [0100] Wb Back surface [0101] G Outer peripheral groove [0102] Wg Outer peripheral edge portion [0103] Ws Scrap [0104] Nr Diameter