Workpiece processing preparation method, and processing method
The method addresses the challenge of achieving uniform thickness and high flatness in thinning plate-shaped workpieces by using multiple resin layers and laminates, ensuring parallel alignment and resulting in high-quality, uniformly thinned products.
Patent Information
- Application Number
- JP2023183165
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-10-25
- Publication Date
- 2025-05-12
AI Technical Summary
Existing methods for thinning plate-shaped workpieces, such as wafers, face challenges in achieving uniform thickness and high flatness due to limitations in resin layer accuracy and device mounting errors, leading to potential cracking, chipping, and reduced thinning capabilities.
A method involving multiple resin layers and laminates is employed, where a first resin layer is formed on a sheet, a second resin layer is applied between a workpiece and a support plate, and the layers are solidified using external stimulation. This process ensures parallel alignment of the workpiece and support surfaces, enabling uniform thinning.
The method achieves uniformly thinned workpieces with minimal thickness variations, improving the quality of the final product by preventing cracking and ensuring the workpiece can be thinned to the desired thickness.
Smart Images
Figure 2025072811000001_ABST
Abstract
Description
[Technical field]
[0001] The present invention relates to a method for machining a plate-shaped workpiece, and more particularly to a preparation method for machining a workpiece by grinding it to reduce its thickness to a predetermined thickness, and also to a method for machining a prepared workpiece. [Background technology]
[0002] Conventionally, when a wafer, which is a plate-shaped workpiece, is thinned, the rigidity of the wafer decreases significantly as the wafer is thinned, causing cracks, warping, etc. during transportation and processing. To prevent this problem, a grinding method is known in which the wafer is bonded to a rigid support substrate and then ground.
[0003] Regarding such a grinding method, for example, as disclosed in Patent Document 2, it is known that the wafer is fixed to the surface of a support member via a liquid resin that serves as a fixing agent, and then ground to a predetermined thickness. [Prior art documents] [Patent documents]
[0004] [Patent Document 1] JP 2004-207606 A [Patent Document 2] JP2011-119578A Summary of the Invention [Problem to be solved by the invention]
[0005] When performing processing such as that disclosed in Patent Document 2, it is necessary to realize a small variation in thickness after bonding the wafer, the fixing agent, and the support member, that is, a high degree of flatness. If the flatness (variation in thickness) is low, it may cause cracks or chipping during grinding. Furthermore, the limit of thinning also depends on this flatness, that is, there may be cases where the desired thinning cannot be achieved due to low flatness.
[0006] In the apparatus configuration disclosed in Patent Document 2, for example, the post-bonding accuracy (resin thickness variation) depends heavily on the parallelism caused by the component accuracy and installation error of each component of the apparatus. Specifically, although the parallelism between the stage (upper base, holding pad) that holds the wafer, which is the workpiece, and the stage (platen) that lays the support member and liquid resin can be improved by adjustment, the desired accuracy cannot be achieved due to component tolerances and installation errors, and the thickness variation of the bonded resin determines the limit of thinning when the composite wafer is ground. This causes a problem that the wafer may not reach the desired thickness, or even if it does reach the desired thickness, the wafer thickness variation is large, resulting in poor quality after processing.
[0007] In view of the above problems, the present invention proposes a new technique for a processing method in which a workpiece is fixed to a support member via resin and thinned, a method for preparing the workpiece before thinning, and a method for processing the workpiece prepared thereby. [Means for solving the problem]
[0008] The problem to be solved by the present invention has been described above, and the means for solving this problem will now be described.
[0009] According to one aspect of the present invention, there are provided a first resin supplying step of laying resin on a sheet, a first laminate forming step of pressing a first plate-like object held by a holding means against the resin laid on the upper surface of the sheet to form a first laminate, and solidifying the resin sandwiched between the first plate-like object and the sheet by an external stimulus to form a first laminate, a resin layer forming step of peeling the first plate-like object from the first laminate to form a first resin layer, and a second plate-like object being placed on the upper surface of the first resin layer after the resin layer forming step. The method for preparing a workpiece for processing includes a plate-shaped object setting step, a second resin supplying step of laying resin on the second plate-shaped object, a second laminate forming step of pressing the plate-shaped workpiece held by the holding means against the resin laid on the upper surface of the second plate-shaped object to form a second laminate by solidifying the resin sandwiched between the second plate-shaped object and the workpiece by an external stimulus, and a third laminate forming step of removing the first resin layer and the sheet from the second laminate to form a third laminate.
[0010] According to one embodiment of the present invention, the first plate-like object has a larger diameter than the second plate-like object and the workpiece.
[0011] According to one aspect of the present invention, the resin is a liquid resin that is cured by an external stimulus.
[0012] Furthermore, according to one aspect of the present invention, the processing method includes a holding step for holding the second plate-like object of the third laminate on a holding surface of a chuck table of a grinding device, and a grinding step for grinding the upper surface of the workpiece with a grinding means of the grinding device to thin it to a desired thickness. Effect of the Invention
[0013] The present invention provides the following advantages. That is, according to one aspect of the present invention, even if high parallelism cannot be ensured due to component tolerances or installation errors in the components of the device for forming the resin layer, the lower surface of the second plate-like object and the processed surface of the workpiece can be made parallel in the third laminate. As a result, the workpiece is uniformly thinned during grinding, and a thinned workpiece with no thickness variation can be obtained. Eliminating thickness variation can improve the quality of the chips that are finally manufactured. [Brief description of the drawings]
[0014] [Figure 1] FIG. 2 is a diagram showing an outline of the configuration of a bonding device. [Diagram 2] 1A is a diagram illustrating a first resin supplying step, and FIG. 1B is a diagram illustrating a first laminate forming step. [Diagram 3] 1A is a diagram showing a resin layer forming step, and FIG. 1B is a diagram showing a state in which a first resin layer has been formed on a sheet. [Figure 4] 1A is a diagram showing a plate-shaped object placement step, and FIG. 1B is a diagram showing a state in which a second plate-shaped object is placed on a first resin layer. [Diagram 5] 1A is a diagram illustrating a second resin supplying step, and FIG. 1B is a diagram illustrating a second laminate forming step. [Figure 6] 1A is a diagram showing a third laminate formation step, and FIG. 1B is a diagram showing the third laminate. [Figure 7] (A) is a diagram showing the holding step, and (B) is a diagram showing the grinding step. [Figure 8] 1A is a diagram for explaining how thickness variations do not occur in an embodiment of the present invention, and FIG. 1B is a diagram for explaining how thickness variations occur in a comparative example that is not based on an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015] 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 bonding device used for preparing a workpiece for processing. Fig. 1 shows a state in which a wafer W, which is a workpiece, is faced to a resin 25 laid on the upper surface of a second plate-like object 20 in the bonding device 1.
[0016] The bonding device 1 comprises a base 2, a holding pad 4, a lifting means 6, an ultraviolet light irradiation means 5, a resin supplying means 3, and a control device 7 for controlling various operating parts.
[0017] The surface plate 2 has a horizontal upper surface 2a and is configured to transmit ultraviolet rays, and is made of a transparent material such as glass. A suction groove that leads to a suction source (not shown) is formed in the horizontal upper surface 2a, and by generating negative pressure on the horizontal upper surface 2a, the horizontal upper surface 2a is configured as a suction holding surface.
[0018] The holding pad 4 is disposed above the horizontal upper surface 2a of the surface plate 2, and a suction groove that is connected to a suction source (not shown) is formed in the horizontal lower surface 4a, and the horizontal lower surface 4a is configured as a suction holding surface by generating negative pressure on the horizontal lower surface 4a. One side (upper surface) of the wafer W, which is the workpiece, is suction-held by the horizontal lower surface 4a, and the other side (lower surface) is exposed.
[0019] The holding pad 4 is fixed to the lower surface side of a lifting base 61 of the lifting movement means 6, and moves up and down together with the lifting base 61. The lifting movement means 6 has an actuator (not shown), and moves the lifting base 61 up and down by operating the actuator.
[0020] The ultraviolet light irradiation means 5 is disposed below the base 2, and has a light source 5a for emitting ultraviolet light. As will be described in detail later, the ultraviolet light passes through the base 2 and the sheet S, and solidifies the resin 25.
[0021] The resin supplying means 3 has a supply nozzle 3a for supplying liquid resin 25 onto the upper surface of the second plate-like object 20 held by the surface plate 2. The supply nozzle 3a is driven by an actuator (not shown). The supply nozzle 3a is configured to be movable, and can be positioned at a supply position where the supply nozzle 3a is positioned at the center of the base plate 2, and at a retracted position where the supply nozzle 3a is away from the base plate 2. The supply nozzle 3a is connected to a resin supply source (not shown), and can supply a predetermined amount of resin 25 to the upper surface of the second plate-like object 20, etc.
[0022] Next, a preparation method for processing using the bonding device configured as above will be described. <First resin supply step> As shown in FIG. 2(A), this is a step of laying a resin 25 on a sheet S. The sheet S is placed on the horizontal upper surface 2a of the base plate 2 and forms a flat surface on the upper surface thereof, and is made of, for example, a film made of a transparent PET (polyethylene terephthalate) material that transmits ultraviolet rays.
[0023] A supply nozzle 3a is positioned above the sheet S placed on the base 2, and a predetermined amount of resin 25 is supplied onto the upper surface of the sheet S by dripping resin 25 from the supply nozzle 3a onto the upper surface of the sheet S. The resin 25 is, for example, an ultraviolet-curable resin, and for example, "Regilock" (registered trademark) manufactured by Disco Corporation is used. The resin 25 transmits ultraviolet light after it has solidified.
[0024] <First Laminate Forming Step> As shown in Figures 2(A) and (B), this is the step in which the first plate-like object 10 held by the holding pad 4 serving as the holding means is pressed against the resin 25 laid on the upper surface of the sheet S to form one piece, and the resin 25 sandwiched between the first plate-like object 10 and the sheet S is solidified by an external stimulus to form a first laminate 41.
[0025] Specifically, first, the supply nozzle 3a is retracted away from a position below the holding pad 4. Then, the upper surface 10a of the first plate-like object 10 is suction-held by the horizontal lower surface 4a of the holding pad 4, and the first plate-like object 10 is lowered by the lifting means 6 (FIG. 1). When the lower surface 10b of the first plate-like object 10 reaches the resin 25, the resin 25 is spread between the first plate-like object 10 and the sheet S with no gaps.
[0026] The first plate-like object 10 has a larger diameter than the wafer and the second plate-like object described later. For example, in the case where the wafer described later is 12 inches, a silicon wafer having a diameter of 306 mm is used, which is larger than the wafer. This allows the diameter of the first resin layer 31 described later to be larger than the diameter of the second plate-like object 20, as shown in FIG. 4(B). In addition, it is preferable that the first plate-like object 10 has a good TTV (Total Thickness Variation). The first plate-like object 10 may be a silicon wafer, or may be, for example, a plate made of a glass material.
[0027] 2(B), the first plate-like object 10 is lowered to a predetermined height relative to the platen 2 to press the resin 25, and ultraviolet light UV is irradiated from below by the ultraviolet light irradiation means 5 (FIG. 1) to irradiate the resin 25 with ultraviolet light through the platen 2 and the sheet S to solidify the resin 25. This causes the resin 25 to solidify to a predetermined thickness.
[0028] Thus, in this embodiment, the means of the external stimulus for solidifying the resin 25 is the irradiation of ultraviolet rays. Other external stimuli include, for example, heat, and in this case, it is conceivable to use a thermosetting resin as the resin.
[0029] <Resin layer formation step> This is a step in which the first plate-like object 10 is peeled off from the first laminate 41 shown in FIG. 2(B) to form a first resin layer 31 as shown in FIG. 3(A).
[0030] As shown in Fig. 3(A), the first resin layer 31 remains on the sheet S, and the inclination of the first plate-like object 10 is transferred to the upper surface 31a of the first resin layer 31. In the example of Fig. 3(A), the upper surface 31a of the first resin layer 31 is inclined at an angle θ so that the right side is lower, and this angle θ is the same as the angle of inclination of the first plate-like object 10 (holding pad 4) as shown in Fig. 2(A). Note that in Fig. 2(A), the inclination of the first plate-like object 10 is also the inclination of the holding pad 4, and the plate-like object held by the holding pad 4 is held at an angle θ.
[0031] Fig. 3(B) is a plan view of Fig. 3(A), showing a state in which the first plate-like object 10 (Fig. 2(A)) is peeled off to form a first resin layer 31 on the sheet S. The first resin layer 31 transmits ultraviolet light.
[0032] In addition, peeling between the first resin layer 31 and the first plate-like object 10 (Figure 2 (A)) can be easily performed because the resin 25 is solidified by ultraviolet light to become the first resin layer 31 and the adhesive strength in the direction of peeling them off is weak.
[0033] <Plate installation step> As shown in FIG. 4(A), this is a step of placing a second plate-like object 20 on the upper surface of the first resin layer 31 after the resin layer forming step. The second plate-like object 20 is, for example, a plate made of a transparent glass material that transmits ultraviolet light and has high rigidity. The purpose of using the second plate-like object 20 is to function as a support member for the wafer to be thinned later by bonding and integrating it with the wafer, thereby suppressing cracking and warping of the wafer. In addition, it is preferable that the second plate-like object 20 has a good TTV (Total Thickness Variation).
[0034] 4(B) is a plan view of FIG. 4(A) and shows a state in which the second plate-like object 20 is placed on the first resin layer 31. The diameter of the first resin layer 31 is larger than the diameter of the second plate-like object 20, and the second plate-like object 20 is placed so as to be contained within the range of the first resin layer 31.
[0035] As shown in FIG. 4(A), the second plate-like object 20 is placed on the upper surface 31a of the first resin layer 31 which is inclined at an angle θ, and the upper surface 20a of the second plate-like object 20 is also inclined at the angle θ.
[0036] <Second resin supply step> As shown in FIG. 5(A), this is a step of laying a resin 25 on a second plate-like object 20. Specifically, the supply nozzle 3a is positioned above the second plate-like object 20, and the resin 25 is dripped from the supply nozzle 3a onto the upper surface 20a of the second plate-like object 20, thereby supplying a predetermined amount of the resin 25 onto the upper surface of the second plate-like object 20. This resin 25 may be the same as or different from the resin used in the above-mentioned first laminate formation step.
[0037] <Second laminate formation step> As shown in Figures 5(A) and (B), this is the step in which the plate-shaped wafer W held by the holding pad 4 is pressed against the resin 25 laid on the upper surface of the second plate-shaped object 20 to form one piece, and the resin 25 sandwiched between the second plate-shaped object 20 and the wafer W is solidified by an external stimulus to form a second laminate 42.
[0038] Specifically, first, the supply nozzle 3a is retracted away from a position below the holding pad 4. Then, the back surface Wb of the wafer W is suction-held by the horizontal lower surface 4a of the holding pad 4, and the wafer W is lowered by the elevating means 6 (FIG. 1). When the wafer W reaches the resin 25, the resin 25 is spread between the wafer W and the second plate-like object 20 with no gaps.
[0039] The wafer W is, for example, a silicon wafer, which is to be thinned later by grinding the back surface Wb. The workpiece may be an oxide wafer, a compound wafer, a device wafer, a mold wafer, or the like, in addition to a silicon wafer. The upper surface of the wafer W, i.e., the surface held by the holding pad 4, is supported by the holding pad 4, so that the wafer W does not bend when the resin 25 is pressed.
[0040] Then, as shown in FIG. 5(B), while the resin 25 is pressed by the wafer W, ultraviolet light UV is irradiated from below by the ultraviolet light irradiation means 5 (FIG. 1), and the ultraviolet light UV is irradiated onto the resin 25 through the base plate 2, the sheet S, the first resin layer 31, and the second plate-like object 20, thereby solidifying the resin 25.
[0041] Thus, in this embodiment, the means of the external stimulus for solidifying the resin 25 is the irradiation of ultraviolet rays. Other external stimuli include, for example, heat, and in this case, it is conceivable to use a thermosetting resin as the resin.
[0042] In this manner, the second resin layer 32 is formed between the wafer W and the second plate-like object 20. The second resin layer 32 transmits ultraviolet light.
[0043] <Third laminate formation step> 6(A) and 6(B), this is a step of removing the first resin layer 31 and the sheet S from the second laminate 42 to form a third laminate 43. In other words, this is a step of peeling the second plate-like object 20 from the first resin layer 31 to form the third laminate 43. The third laminate 43 is configured to include the second plate-like object 20, the second resin layer 32, and the wafer W.
[0044] Peeling between the first resin layer 31 and the second plate-like object 20 can be easily performed because the resin 25 has been solidified by ultraviolet light to become the first resin layer 31 and the adhesive strength in the direction of peeling them off is weak.
[0045] As described above, the upper surface of the second plate-like object 20 is inclined at the angle θ, and the wafer W is also held by the holding pad 4 at an angle θ, so that the lower surface 20a of the second plate-like object 20 and the exposed surface of the wafer W, that is, the back surface Wb of the wafer W, are parallel to each other. Therefore, as shown in Fig. 6(B), when the lower surface 20a of the second plate-like object 20 is placed on a horizontal plane H, the back surface Wb of the wafer W also becomes horizontal, and the wafer W can be thinned to a uniform thickness in the subsequent thinning process.
[0046] The method for forming the third laminate 43 as described above is a preparation method for processing the workpiece, that is, the wafer W. The third laminate 43 thus prepared is then processed as follows.
[0047] <Retention step> 7(A), this is a step of holding the lower surface 20a of the second plate-like object 20 of the third stack 43 on a holding surface 71a of a chuck table 71 of a grinding device 70. By holding the lower surface 20a of the second plate-like object 20 on the chuck table 71, the back surface Wb of the wafer W, which is the workpiece, is exposed.
[0048] The grinding device 70 is mainly composed of a chuck table 71 and a grinding unit 72, and grinds the back surface Wb of the wafer W, which is a workpiece, to thin the wafer W. A suction groove (not shown) is formed on a holding surface 71a of the chuck table 71, and the third laminate 43 is sucked and held on the holding surface 71a by generating a negative pressure in the suction groove. The chuck table 71 is configured to rotate by a rotation mechanism (not shown).
[0049] The grinding unit 72 has a grinding wheel 74 in which a plurality of grinding stones 74a are arranged at intervals in an annular shape. The grinding wheel 74 is rotated at a predetermined speed by a rotation mechanism (not shown) and is fed for grinding at a predetermined speed by a grinding feed mechanism (not shown).
[0050] <Grinding step> As shown in FIG. 7(B), this is a step in which the back surface Wb, which is the upper surface of the wafer W, is ground by a grinding unit 72, which is a grinding means of a grinding device, to thin the wafer W to a desired thickness.
[0051] Specifically, the chuck table 71 is rotated to rotate the third stack 43, and the grinding wheel 74 is rotated and fed downward for grinding, thereby grinding the back surface Wb of the wafer W and thinning the wafer W to a predetermined thickness. Since the wafer W is fixed to the rigid second plate-like object 20, grinding can be performed while suppressing the occurrence of cracks, warping, and the like.
[0052] In addition, between the second resin layer 32 and the second plate-like object 20, and between the second resin layer 32 and the wafer W, mechanical adhesion (anchor effect) is achieved by solidifying the liquid resin in a state where it has filled the gaps. Therefore, no misalignment occurs between the layers constituting the third laminate 43 during the grinding process, and processing can be performed stably.
[0053] According to the above-described embodiments, even if, for example, as shown in FIG. 2(A), the horizontal lower surface 4a of the holding pad 4, which is a component of the bonding device 1, is inclined and not parallel to the horizontal upper surface 2a of the base plate 2, in other words, high parallelism cannot be ensured due to component tolerance or installation error, in the third laminate 43 shown in FIG. 6(B), the lower surface 20a of the second plate-like object 20 and the processing surface (rear surface Wb) of the wafer W, which is the workpiece, can be made parallel.
[0054] As a result, as shown in Fig. 8(A), the wafer W is uniformly thinned during grinding, and a thinned wafer W without thickness variations can be obtained. By eliminating the thickness variations, the quality of the chips that are finally manufactured can be improved.
[0055] 8(B) shows a comparative example not according to this embodiment, in which the workpiece, the wafer W, is integrated with the second plate-like object 120 via the resin layer 132. Since the back surface Wb of the wafer W is inclined, the wafer W is not uniformly thinned during grinding, resulting in thickness variations. There is a concern that the quality of the chips finally manufactured will be poor due to the existence of such thickness variations. [Explanation of symbols]
[0056] 1 Pasting device 2. Surface Plate 2a Horizontal top surface 3. Resin supply means 3a Supply nozzle 4 Retaining Pad 5 Ultraviolet light irradiation means 6 Lifting means 7 Control Device 10 First plate 20 Second plate 20a Bottom side 25 Resin 31 First resin layer 31a Top surface 32 Second resin layer 41 First laminate 42 Second laminate 43 Third Stack 61 Lifting Base 70 Grinding Equipment 71 Chuck Table 71a Holding surface 72 Grinding unit 74 Grinding Wheel 74a Grinding wheel S Seat W wafer Wb back side θ angle
Claims
1. a first resin supply step of laying resin on a sheet; and a first laminate formation step of pressing a first plate-like object held by a holding means against the resin laid on the upper surface of the sheet to form a first laminate by applying an external stimulus to solidify the resin sandwiched between the first plate-like object and the sheet; a resin layer forming step of peeling the first plate-like object from the first laminate to form a first resin layer; a plate-shaped object setting step of setting a second plate-shaped object on an upper surface of the first resin layer after the resin layer forming step; a second resin supply step of laying a resin on the second plate-like object; a second laminate formation step in which the plate-shaped workpiece held by the holding means is pressed against resin laid on the upper surface of the second plate-shaped workpiece to form a single body, and the resin sandwiched between the second plate-shaped workpiece and the workpiece is solidified by an external stimulus to form a second laminate; a third laminate formation step of forming a third laminate by removing the first resin layer and the sheet from the second laminate; A method for preparing a workpiece for processing, comprising:
2. The first plate-like object has a larger diameter than the second plate-like object and the workpiece; 2. The method for preparing a workpiece for processing according to claim 1.
3. The resin is a liquid resin that hardens when exposed to an external stimulus.
3. The method for preparing a workpiece for processing according to claim 1 or 2.
4. The third laminate prepared by the method for preparing a workpiece for processing according to claim 1 or 2, a holding step of holding the second plate-like object of the third stack on a holding surface of a chuck table of a grinding device; a grinding step of grinding the upper surface of the workpiece by a grinding means of the grinding device to thin the workpiece to a desired thickness; A processing method in which the following is performed.
5. The resin is a liquid resin that hardens when exposed to an external stimulus. The processing method according to claim 4 .
Citation Information
Patent Citations
Wafer support plate
JP2004207606A
Sticking apparatus
JP2011119578A
Cited By
Game machine
JP2025013511A
Game machine
JP2025026503A
Game machine
JP2025026504A
Game machine
JP2025085725A
Game machine
JP2025089363A