Processing methods

Abstract

To provide a method for performing cutting processing with a cutting blade without turning over a multilayer substrate with different kind of intermediate layers arranged between same kind of substrates.SOLUTION: A processing method for dividing a multilayer substrate W in which a first substrate 10 and a second substrate 20 having the same kind of a material as the first substrate are layered through an intermediate layer 30 including metal, along a scheduled division line L, comprises: preparing a cutting blade 51a for substrate and a cutting blade for metal having a blade thickness larger than a blade thickness 51w of the cutting blade for substrate; exposing and holding the first substrate of the multilayer substrate; cutting the multilayer substrate with the cutting blade for substrate along the scheduled division line; forming a first cutting groove M1 wider than the blade thickness of the cutting blade for metal in the first substrate; cutting and dividing the intermediate layer along the first cutting groove with the cutting blade for metal; forming a second cutting groove M2; and dividing the multilayer substrate by cutting it along the second cutting groove with the cutting blade for substrate to divide the second substrate.SELECTED DRAWING: Figure 8

Description

Technical Field

[0006] , ,

[0005] ,

[0001] The present invention relates to a processing method for dividing a laminated substrate in which a first substrate and a second substrate made of the same material as the first substrate are laminated via an intermediate layer containing metal, along a plurality of division planned lines that intersect the laminated substrate.

Background Art

[0002] Conventionally, in the cutting of a laminated substrate (laminated wafer) as disclosed in, for example, Patent Document 1, it is known to use two types of cutting blades, a first cutting blade for a silicon substrate and a second cutting blade for a glass substrate, and an optimal cutting blade is selected for each material of the workpiece.

[0003] In particular, in a laminated substrate in which substrates of different materials are laminated, if an attempt is made to cut with one type of cutting blade, there is a concern that chipping, which is a large notch occurring at the edge of the cutting groove, will occur significantly. For this reason, a method of stepwise cutting each substrate with a cutting blade suitable for each laminated substrate has been adopted.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] There are laminated substrates having a three-layer structure in which, for example, like a three-dimensional laminated device wafer, by bonding the surfaces of silicon wafers on which devices are formed on the surface, an intermediate layer of a different material is sandwiched between substrates of the same type.

[0006] To process such a multilayer substrate, one possible method is to first cut the outer layers of the substrate from both the front and back sides using a substrate cutting blade, and then cut the intermediate layers with an intermediate layer blade; or to cut the substrate from one side using a substrate cutting blade, then cut the intermediate layers with an intermediate layer blade, and finally cut the substrate from the opposite side using a substrate cutting blade.

[0007] However, in either case, the laminated substrate, once the cutting grooves have been formed, must be inverted for further processing, and there is a risk of wafer damage during the inversion process.

[0008] In view of the above problems, the present invention proposes a novel processing method for cutting a laminated substrate in which different types of intermediate layers are arranged between substrates of the same type using a cutting blade. [Means for solving the problem]

[0009] The problems that this invention aims to solve are as described above, and the means for solving these problems will now be explained.

[0010] According to one aspect of the present invention, a processing method for dividing a laminated substrate, in which a first substrate and a second substrate made of the same material as the first substrate are laminated with an intermediate layer containing metal in between, along a plurality of intersecting dividing lines, comprising: a blade preparation step of preparing a substrate cutting blade and a metal cutting blade having a blade thickness greater than the blade thickness of the substrate cutting blade; a support member placement step of arranging a support member on the second substrate side of the laminated substrate; a holding step of holding the laminated substrate with a holding table via the support member and exposing the first substrate; and cutting the laminated substrate held on the holding table along the dividing lines with the substrate cutting blade to create a first cutting groove wider than the blade thickness of the metal cutting blade in the first substrate. The processing method comprises: a first cutting step of forming a groove; a second cutting step of cutting a planned division line multiple times by moving the substrate cutting blade relative to the planned division line multiple times in the index direction in the first cutting step, and after performing the first cutting step, cutting the laminated substrate held in the holding table along the first cutting groove with the metal cutting blade to divide the intermediate layer and form a second cutting groove having a width corresponding to the blade thickness of the metal cutting blade; and a third cutting step of dividing the laminated substrate by cutting the laminated substrate held in the holding table along the second cutting groove with the substrate cutting blade after performing the second cutting step.

[0011] Furthermore, according to one aspect of the present invention, the metal cutting blade is set to be thicker than the blade thickness of the substrate cutting blade and thinner than twice the blade thickness of the substrate cutting blade, and in the first cutting step, the laminated substrate is cut twice with the substrate cutting blade along the planned division line to form a first cutting groove having a width equivalent to twice the blade thickness of the substrate cutting blade.

[0012] Furthermore, according to one aspect of the present invention, in the first cutting step, the laminated substrate is cut twice along the planned division line with the substrate cutting blade to form two cutting grooves, and a first cutting groove is formed between the two cutting grooves, with a remaining portion narrower than the blade thickness of the metal cutting blade and along the planned division line. In the second cutting step, the intermediate layer is cut together with the remaining portion using the metal cutting blade. [Effects of the Invention]

[0013] The present invention provides the following effects: In other words, according to one aspect of the present invention, the laminated substrate can be cut with a cutting blade suitable for cutting each substrate and intermediate layer without inverting the laminated substrate, thereby preventing chipping, which occurs at the edges of the cutting grooves. Furthermore, since the first to third cutting steps can be performed while the laminated substrate is held on the holding table without inverting the laminated substrate, damage to the laminated substrate caused by inverting the laminated substrate or attaching and detaching the laminated substrate from the holding table can be prevented. Moreover, since inverting and detaching the laminated substrate is unnecessary, processing time can be reduced.

[0014] Furthermore, according to one aspect of the present invention, it is possible to remove the portion of the first substrate (e.g., silicon) that overlaps with the area to be cut by the metal cutting blade with the fewest number of cuts, thereby preventing deterioration of processing quality caused by cutting the first substrate with the metal cutting blade. [Brief explanation of the drawing]

[0015] [Figure 1] A figure illustrating one embodiment of a wafer processed by the processing method according to the present invention. [Figure 2] A magnified view of a section of the cross-section of a multilayer substrate. [Figure 3] A diagram illustrating one embodiment of a cutting device. [Figure 4] A flowchart illustrating the procedure of one embodiment of the processing method. [Figure 5](A) is a diagram for explaining the step of disposing the support member. (B) is a diagram for explaining the holding step. (C) is a diagram for explaining the first cutting step. [Figure 6] A diagram for explaining the first cutting step. [Figure 7] A diagram for explaining the second cutting step. [Figure 8] A diagram for explaining the third cutting step. [Figure 9] A diagram for explaining another embodiment of the first cutting step. [Figure 10] A diagram for explaining another embodiment of the second cutting step. [Figure 11] A diagram for explaining another embodiment of the third cutting step.

Mode for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIGS. 1 and 2 are diagrams showing an embodiment of a laminated substrate W processed by the processing method according to the present invention.

[0017] As shown in FIGS. 1 and 2, the laminated substrate W includes a first substrate 10, a second substrate 20 made of the same material as the first substrate 10, and an intermediate layer 30 containing metal between both substrates. The first substrate 10 and the second substrate 20 are laminated via the intermediate layer 30 to form the laminated substrate W.

[0018] The first substrate 10 and the second substrate 20 are, for example, silicon wafers. Devices 11 and 21 are formed on the surfaces 10a and 20a of each substrate, and the substrates are joined to each other so that the positions of the devices 11 and 21 on each substrate coincide, and the laminated substrate W is formed as a whole. Streets 13 and 23 including metal wiring, an interlayer insulating film, TEG, etc. are formed between the devices 11 and 21 of each substrate.

[0019] When the first substrate 10 and the second substrate 20 are bonded together, the areas other than where devices 11 and 21 are formed become an intermediate layer 30 containing metal. The areas of streets 13 and 23 constitute part of the intermediate layer 30 containing metal.

[0020] Street 13 of the first substrate 10 and Street 23 of the second substrate 20 extend in mutually orthogonal first direction F1 and second direction F2, respectively, and are arranged in a grid pattern. Division lines are set along these streets 13 and 23, and the chip is divided along these division lines into chips containing devices 11 and 21.

[0021] Furthermore, the materials for the first substrate 10 and the second substrate 20 are not limited to silicon; other materials such as glass, sapphire, SiC, and GaN are also possible.

[0022] Figure 3 shows an example of a cutting device used for cutting a multilayer substrate W. The cutting device 50 has two cutting units 51 and 52 and is configured as a dual dicer, making it possible to sequentially perform cutting on one planned division line using the two cutting units 51 and 52.

[0023] A holding table 60 is mounted on the base 55 of the cutting device 50. The holding table 60 is configured to reciprocate in the X-axis direction, which is the machining feed direction, by a moving mechanism (not shown). It is also configured to rotate in the horizontal plane by a rotating mechanism (not shown).

[0024] Work units U, each with a laminated substrate W attached to a tape T, are sequentially supplied to the holding table 60, and the laminated substrate W is held in place by suction via the tape T on the holding surface 60a of the holding table 60.

[0025] An imaging device 53 for imaging the laminated substrate W is provided near the cutting unit 51. The controller 100 sets the planned division lines of the laminated substrate W based on the captured images and performs alignment (processing position detection) by rotating the holding table 60. Depending on the type of laminated substrate W, the imaging device 53 uses either a visible light camera or an IR camera to detect patterns within the laminated substrate W, enabling the controller 100 to set the planned division lines and perform alignment.

[0026] A gate-shaped column 56 is erected on the base 55, and the column 56 is provided with moving mechanisms 57 and 58 that support the first cutting unit 51 and the second cutting unit 52 so that they can move in the Y-axis direction and the Z-axis direction, respectively. The first cutting unit 51 is provided with a substrate cutting blade 51a which is rotationally driven by a motor (not shown). The second cutting unit 52 is provided with a metal cutting blade 52a which has a blade thickness greater than that of the substrate cutting blade 51a and is rotationally driven by a motor (not shown).

[0027] Multiple clamps 62 are arranged around the holding table 60 to grip the frame F of the work unit U.

[0028] A cleaning device 59 is provided on the base 55 of the cutting device 50, and the laminated substrate W is cleaned after cutting.

[0029] Next, an example of the wafer processing method according to the present invention will be described. Figure 4 is a flowchart showing the procedure of one embodiment of the processing method according to the present invention. Each step will be described in order below.

[0030] <Blade preparation steps> As shown in Figure 3, the cutting device 50 is equipped with a cutting blade 51a for substrates and a cutting blade 52a for metals, the cutting blade having a thickness greater than that of the cutting blade 51a.

[0031] The substrate cutting blade 51a is a blade suitable for cutting the first substrate 10 and the second substrate 20 shown in Figure 2, and is, for example, an electroformed blade with a thickness of 40 μm and a mesh size of #3000 (particle size 2-4 μm).

[0032] The metal cutting blade 52a is a suitable blade for cutting the intermediate layer 30 shown in Figure 2, and is, for example, a resin blade with a thickness of 50 μm and a mesh size of #800 (particle size 10-20 μm).

[0033] Furthermore, the metal cutting blade 52a is made of a blade that wears down more easily than the substrate cutting blade 51a, and it is possible to use a blade with a lower concentration or a softer bonding material than the substrate cutting blade 51a.

[0034] Furthermore, the metal cutting blade 52a can be, for example, one that is thicker than the cutting blade thickness of the substrate cutting blade 51a but thinner than twice the cutting blade thickness of the substrate cutting blade.

[0035] <Support member placement step> As shown in Figure 5(A), the step involves placing the tape T as a support member on the second substrate 20 side of the laminated substrate W. The tape T may have an adhesive layer or it may not have an adhesive layer.

[0036] In this embodiment, as shown in Figures 2 and 5(B), a second substrate 20, which is thicker than the first substrate 10, is attached to the tape T. This allows for a so-called half-cut, in which the thin first substrate 10 is cut (first cutting step) while the intermediate layer 30 and the second substrate 20 remain on the underside, as will be described in more detail later. This prevents the thin first substrate 10, which is prone to cracking during cutting, from cracking. In particular, since the likelihood of cracking increases when the substrate thickness is 40 μm or less, it is preferable to perform a half-cut, in which only the thin substrate of 40 μm or less is cut first, without cutting into the intermediate layer or the thicker substrate.

[0037] Furthermore, as shown in Figure 5(A), an annular frame F is fixed to the tape T so as to surround the laminated substrate W, and a work unit U is formed in which the laminated substrate W and the frame F are integrated.

[0038] <Holding step> As shown in Figure 5(B), this step involves holding the laminated substrate W with the holding table 60 via the support member tape T, while simultaneously exposing the first substrate 10.

[0039] The holding surface 60a of the holding table 60 is connected to a suction source (not shown), and the laminated substrate W is held in place by suction to the holding surface 60a via a support member, which is tape T. The frame F is also held in place by a clamp 62.

[0040] <First cutting step> As shown in Figure 5(C), the laminated substrate W held by the holding table 60 is cut along the planned division line with a substrate cutting blade 51a, forming a first cutting groove in the first substrate 10 that is wider than the blade thickness of the metal cutting blade 52a.

[0041] Specifically, first, the laminated substrate W is imaged using the imaging device 53 shown in Figure 1 to perform alignment and set the planned division lines within the street. Next, as shown in Figure 5(C), the substrate cutting blade 51a is positioned at the cutting height and rotated at high speed, and the holding table 60 is fed in the processing feed direction (X-axis direction), thereby forming the first cutting groove M1 along the planned division line L within the street 13 of the first substrate 10, as shown in Figures 6(A) and (B).

[0042] Here, since the cutting thickness 51w of the substrate cutting blade 51a (Figure 6(A)) is narrower than the cutting thickness 52w of the metal cutting blade 52a (Figure 7(A)), by performing groove machining multiple times with the substrate cutting blade 51a, the width W1 (Figure 6(D)) of the first cutting groove M1 is made wider than the cutting thickness 52w of the metal cutting blade 52a (Figure 7(A)).

[0043] Specifically, as shown in Figures 6(A) to (F), the cutting blade 51a for the substrate is moved relative to the planned division line L multiple times in the index direction (Y-axis direction), thereby cutting the planned division line L multiple times.

[0044] More specifically, as shown in Figures 6(A) and 6(B), first, for the first substrate 10, the substrate cutting blade 51a is positioned so that the center position of the blade is shifted to one side from the position of the division line L, and the first groove is machined along the division line L. Next, as shown in Figures 6(C) and 6(D), the substrate cutting blade 51a is positioned so that the center position of the blade is shifted to the other side from the position of the division line L, and the second groove is machined along the division line L. This machines the first cutting groove M1 with a width W1 that is wider than the blade thickness 52w of the metal cutting blade 52a (Figure 7(A)). As shown in Figures 6(E) and 6(F), the same machining is performed on the adjacent division line L.

[0045] In the examples shown in Figures 6(A) to (F), the first cutting groove M1 is formed within the width 13w of the street 13 (Figure 6(B)) by two groove machining passes. However, the number of groove machining passes may be changed to, for example, three passes, depending on the blade thickness 52w of the metal cutting blade 52a (Figure 7(A)). In this first cutting step, the intermediate layer 30 and the second substrate 20 are not cut, and the entire laminated substrate W is half-cut.

[0046] <Second cutting step> As shown in Figures 7(A) to 7(D), after performing the first cutting step, the laminated substrate W held by the holding table 60 (Figure 5(C)) is cut along the first cutting groove M1 with the metal cutting blade 52a of the second cutting unit 52 (Figure 3), thereby dividing the intermediate layer 30 and forming a second cutting groove M2 having a width corresponding to the blade thickness 52w of the metal cutting blade 52a.

[0047] As shown in Figures 7(A) and 7(B), a first cutting groove M1 is formed in the first substrate 10 at locations corresponding to streets 13 and 23 of the intermediate layer 30. The intermediate layer 30 containing metal is grooved by cutting along this first cutting groove M1 into streets 13 and 23 with a metal cutting blade 52a.

[0048] As a result, as shown in Figures 7(C) and 7(D), a second cutting groove M2 is formed at the bottom of the first cutting groove M1.

[0049] <Third cutting step> As shown in Figures 8(A) to (D), after performing the second cutting step, the laminated substrate W held in the holding table 60 (Figure 5(C)) is cut along the second cutting groove M2 with the substrate cutting blade 51a, thereby dividing the laminated substrate W into two parts.

[0050] As shown in Figures 8(A) and 8(B), a second cutting groove M2 is formed in the intermediate layer 30 at locations corresponding to streets 13 and 23, and the second substrate 20 is cut along this second cutting groove M2 using a substrate cutting blade 51a to machine the groove.

[0051] As a result, a third cutting groove M3 is formed at the bottom of the second cutting groove M2, as shown in Figures 8(C) and 8(D). The third cutting groove M3 reaches the tape T, which is a support member, and completely separates the second substrate 20.

[0052] In the above embodiment, for one planned division line L (Figure 6(A)), a first cutting groove M1 (Figure 6(E)) is formed in the first cutting step by two groove cuts with the substrate cutting blade 51a of the first cutting unit 51 (Figure 1). Then, a second cutting groove M2 (Figure 7(C)) is formed in the second cutting step by groove cuts with the metal cutting blade 52a of the second cutting unit 52 (Figure 2). Then, a third cutting groove M3 (Figure 8(C)) is formed in the second cutting step by groove cuts with the substrate cutting blade 51a of the first cutting unit 51 (Figure 1). By performing such so-called step cuts for all streets 13, 23 (Figure 1), the laminated substrate W can be divided into chips.

[0053] In the processing method described above, the laminated substrate W can be cut with cutting blades suitable for each substrate and intermediate layer without inverting the substrate, thus preventing chipping, which occurs at the edges of the cutting grooves. Furthermore, since the first to third cutting steps can be performed while the laminated substrate W is held in place by the holding table 60 without inverting the substrate W, damage to the laminated substrate W caused by inversion or attachment / detachment of the laminated substrate W to the holding table 60 can be prevented. In addition, since inversion and attachment / detachment of the laminated substrate W are unnecessary, processing time can be reduced.

[0054] Furthermore, in the embodiment described with reference to Figures 6 to 8, the metal cutting blade 52a is set to have a thickness 52w that is thicker than the blade thickness 51w of the substrate cutting blade 51a and thinner than twice the blade thickness of the substrate cutting blade 51a. In the first cutting step, the laminated substrate W is cut twice along one planned division line L with the substrate cutting blade 51a to form a first cutting groove M1 having a width equivalent to twice the blade thickness of the substrate cutting blade 51a.

[0055] In this example, in the first cutting step, by cutting twice along the planned division line L, a first cutting groove M1 wider than the cutting edge thickness 52w of the metal cutting blade 52a can be formed. In this way, the number of cuts along the planned division line L in the first cutting step can be designed based on the relationship between the cutting edge thicknesses of the two blades 51a and 52a. Furthermore, according to this example, it is possible to form the first cutting groove M1 in the minimum number of cuts (2), thereby reducing the processing time.

[0056] Figures 9 to 11 illustrate another embodiment of the first and second cutting steps. In this embodiment, the laminated substrate W is cut twice along one planned division line L with a substrate cutting blade 51a to form two cutting grooves Ma, and a first cutting groove MA is formed between the two cutting grooves Ma, with a remaining portion K that is narrower than the blade thickness 52w of the metal cutting blade 52a along the planned division line L. In the second cutting step, the intermediate layer 30 is cut together with the remaining portion K using the metal cutting blade 52a.

[0057] Specifically, as shown in Figure 9(A), the cutting blade 51a for the substrate is positioned on the first substrate 10 such that the center position of the blade is shifted to one side from the position of the division line L, and the first groove is machined along the division line L to form a cutting groove Ma. Next, as shown in Figure 9(C), the cutting blade 51a for the substrate is positioned such that the center position of the blade is shifted to the other side from the position of the division line L, and the second groove is machined along the division line L to form a cutting groove Ma. At this time, the center position of the cutting blade 51a for the substrate is set to a position shifted from the division line L so that a remaining portion K is formed between the first and second grooves.

[0058] In this way, as shown in Figures 9(C) to (F), a first cutting groove M1 is formed having two cutting grooves Ma and a remaining portion K between them. The width WA of this first cutting groove M1 is narrower than the width of streets 13 and 23, and wider than the blade thickness 52w of the metal cutting blade 52a used in the subsequent second cutting step. The width of the remaining portion K is also narrower than the blade thickness 52w of the metal cutting blade 52a and is set to the width that will be removed by the metal cutting blade 52a in the subsequent second cutting step.

[0059] Next, as shown in Figures 10(A) to (D), in the second cutting step, the metal cutting blade 52a is used to cut into the remaining portion K, removing the remaining portion K, while simultaneously cutting into the intermediate layer 30 to form the second cutting groove M2.

[0060] Here, as shown in Figures 10(A) and (B), the remaining portion K is cut by the metal cutting blade 52a. However, since cutting grooves Ma are formed on both sides of the remaining portion K, a gap S can be secured between the first substrate 10 and the metal cutting blade 52a, preventing chipping of the first substrate 10. In other words, deterioration of processing quality caused by cutting the first substrate 10 with the metal cutting blade 52a can be prevented.

[0061] Next, as shown in Figures 11(A) to (D), a cutting blade 51a for the substrate is used to cut into the second substrate 20 along the second cutting groove M2 formed in the intermediate layer 30 at locations corresponding to streets 13 and 23, thereby forming a third cutting groove M3 at the bottom of the second cutting groove M2.

[0062] In the above embodiment, a portion K is left uncut in the first cutting step, and the remaining portion K is removed in the second step. This embodiment is particularly effective in shortening processing time when the cutting blade thickness 52w of the metal cutting blade 52a is wide and it is desired to secure a wide width WA of the first cutting groove MA. In other words, for example, if it is necessary to cut three times along the planned division line L without leaving any remaining portion K, it is possible to complete the process in two cuts, thus shortening processing time. In other words, the portion of the first substrate 10 (e.g., silicon) that overlaps with the area cut by the metal cutting blade 52a can be removed with the minimum number of cuts. [Explanation of Symbols]

[0063] 10. First board 13th Street 20 Second board 23rd Street 30 Middle Class 50 Cutting equipment 51 Cutting Unit 51a Cutting blade for substrates 52 cutting units 52a Metal cutting blade 52w blade thickness 53 Imaging device 60 holding tables 60a Retaining surface 62 Clamps 100 controllers F Frame K Uncut portion L division planned line M1 cutting groove M2 cutting groove M3 cutting groove MA cutting groove Ma cutting groove S Gap T Tape U Work Unit W multilayer substrate

Claims

1. A processing method for dividing a laminated substrate, in which a first substrate and a second substrate made of the same material as the first substrate are laminated with an intermediate layer containing metal in between, along a plurality of intersecting planned division lines, A blade preparation step involves preparing a cutting blade for substrates and a cutting blade for metal having a blade thickness greater than that of the cutting blade for substrates. A support member placement step involves arranging a support member on the second substrate side of the laminated substrate, A holding step in which the laminated substrate is held by a holding table via the support member and the first substrate is exposed, A first cutting step involves cutting the laminated substrate held in the holding table along the planned division line with a cutting blade for the substrate, thereby forming a first cutting groove in the first substrate that is wider than the cutting thickness of the metal cutting blade. In the first cutting step, the cutting blade for the substrate is moved relative to the planned division line multiple times in the index direction, thereby cutting the planned division line multiple times. After performing the first cutting step, a second cutting step is performed in which the laminated substrate held in the holding table is cut along the first cutting groove with the metal cutting blade to divide the intermediate layer and form a second cutting groove having a width corresponding to the blade thickness of the metal cutting blade, A processing method comprising: a third cutting step, after performing the second cutting step, cutting the laminated substrate held in the holding table along the second cutting groove with a cutting blade for the substrate, thereby dividing the laminated substrate.

2. The metal cutting blade is set to be thicker than the cutting blade for the substrate, and thinner than twice the cutting blade thickness of the substrate cutting blade. The processing method according to claim 1, characterized in that in the first cutting step, the laminated substrate is cut twice along the planned division line with the substrate cutting blade to form a first cutting groove having a width equivalent to twice the blade thickness of the substrate cutting blade.

3. In the first cutting step, the laminated substrate is cut twice along the planned division line with the substrate cutting blade to form two cutting grooves, and a first cutting groove is formed between the two cutting grooves, the remaining portion being cut along the planned division line having a width narrower than the blade thickness of the metal cutting blade. The machining method according to claim 1, characterized in that in the second cutting step, the intermediate layer is cut together with the remaining portion using the metal cutting blade.

Images