Processing method

Abstract

To provide a processing method capable of suppressing the occurrence of burrs and the possibility of mounting defects while suppressing labor.SOLUTION: A processing method includes a preparatory protection step 1001 of preparing a wafer having a die attach layer formed on its back surface, a die attach layer cutting step 1003 of cutting the wafer by a cutting blade along a planned dividing line while cutting into the wafer from the die attach layer side of the back surface of the wafer to a depth that reaches the wafer, and forming a cutting groove obtained by cutting the die attach layer and an uncut portion of the wafer under the cutting groove, and a dividing step 1005 of dividing the uncut portion along the planned dividing line to form a plurality of chips after performing the die attach layer cutting step 1003, and the rotating direction of the cutting blade in the die attach layer cutting step 1003 is set in the direction in which the cutting blade is directed from the die attach layer side to the wafer side.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method for processing a wafer.

Background Art

[0002] A wafer may be divided into individual chips along a division line after a die attach material for fixing the divided chips is attached to the back surface (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For example, since a die attach material made of a synthetic resin such as an epoxy resin has ductility, when it is cut with a cutting blade, thread-like whisker burrs are generated.

[0005] When whisker burrs are generated on the die attach material, there is a risk that the generated whisker burrs may adhere to the device or cause mounting defects. Therefore, in the invention disclosed in Patent Document 1, a method for removing whisker burrs generated by cutting the die attach material with a cutting blade has been proposed.

[0006] However, since labor is required to remove whisker burrs, improvement has been eagerly desired.

[0007] An object of the present invention is to provide a processing method capable of suppressing the generation of whisker burrs while suppressing labor and suppressing the risk of mounting defects and the like.

Means for Solving the Problems

[0008] In order to solve the above-described problems and achieve the object, a processing method of the present invention is a processing method of a wafer, including: a preparation step of preparing a wafer having a plurality of division planned lines intersecting on a surface and a die attach layer formed on a back surface of the wafer in a region partitioned by the division planned lines, where devices are respectively formed; a die attach layer cutting step of cutting along the division planned line with a cutting blade while cutting the cutting blade into the wafer from the die attach layer side of the back surface of the wafer to a depth reaching the wafer, and forming a cutting groove for cutting the die attach layer and a remaining portion of the wafer under the cutting groove; and a division step of dividing the remaining portion along the division planned line after the die attach layer cutting step to form a plurality of chips. In the die attach layer cutting step, the surface of the wafer is imaged from below through the transparent plate of the holding table that holds the wafer on the holding surface with a lower imaging camera, alignment for aligning the wafer and the cutting blade is performed, and cutting is performed along the division planned line with the cutting blade, and In the die attach layer cutting step, the rotation direction of the cutting blade is set in a direction from the die attach layer side toward the wafer side. , in the dividing step, the surface of the wafer is imaged with an upper imaging camera, alignment for aligning the wafer and the cutting blade is performed, cutting is performed along the division planned line with the cutting blade from the surface of the wafer, and the remaining portion is divided It is characterized by this.

[0010] The present invention's Processing method is a method for processing a wafer, comprising: a preparation step of preparing a wafer having a die attach layer formed on the back surface thereof, on which a plurality of division planned lines intersecting the surface are set and devices are respectively formed in regions defined by the division planned lines; a die attach layer cutting step of cutting along the division planned line with the cutting blade while cutting the cutting blade into the wafer from the die attach layer side of the back surface of the wafer to a depth reaching the wafer, and forming a cutting groove for cutting the die attach layer and a remaining portion of the wafer under the cutting groove; and a dividing step of dividing the remaining portion along the division planned line to form a plurality of chips after the die attach layer cutting step is performed, wherein the rotation direction of the cutting blade in the die attach layer cutting step is set in a direction from the die attach layer side toward the wafer side, and the dividing step cuts along the division planned line with the cutting blade from the surface of the wafer, divides the remaining portion, and The die attach layer cutting step is performed by cutting into the wafer with a first cutting blade having a first blade thickness, and the division step is performed with a second cutting blade having a second blade thickness thinner than the first blade thickness, so that a stepped portion is formed in which the back surface side of the chip is formed smaller than the front surface side. The difference between the first blade thickness and the second blade thickness and the cutting amount of the first cutting blade into the wafer are set to values such that when the chip is mounted, the protrusion of the die attach layer on the back surface of the chip outside the chip is accommodated in the stepped portion. is characterized in that 。

[0011] In the above processing method, a surface protection step of disposing a surface protection member on the surface of the wafer and, after performing the surface protection step, a holding step of holding the wafer with a holding table via the surface protection member and exposing the back surface of the wafer may be performed before performing the die attach layer cutting step, and after performing the die attach layer cutting step and before performing the division step, a transfer step of attaching a tape to the upper surface of the die attach layer and removing the surface protection member may be further provided.

Advantages of the Invention

[0012] The present invention has the effect of suppressing the generation of beard burrs while suppressing labor and suppressing the risk of occurrence of mounting defects and the like.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

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Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Embodiments for Carrying Out the Invention

[0014] Embodiments (embodiment forms) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the content described in the following embodiments. Also, the constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. Also, various omissions, substitutions, or changes in the configuration can be made without departing from the gist of the present invention.

[0015] 〔Embodiment 1〕 A processing method according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a wafer to be processed in the processing method according to Embodiment 1. FIG. 2 is a flowchart showing the flow of the processing method according to Embodiment 1. The processing method according to Embodiment 1 is a processing method for the wafer 1 shown in FIG. 1. The wafer 1 to be processed in the processing method according to Embodiment 1 is a disk-shaped semiconductor wafer or an optical device wafer having a substrate 2 made of silicon, sapphire, gallium arsenide, or SiC (silicon carbide), etc. A plurality of division planned lines 4 intersecting the surface 3 of the substrate 2 are set on the wafer 1, and devices 5 are formed in regions partitioned in a grid pattern by the division planned lines 4.

[0016] The device 5 is, for example, an integrated circuit such as an IC (Integrated Circuit) or an LSI (Large Scale Integration), or an image sensor such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor). In Embodiment 1, after the die attach layer 10 is formed on the back surface 6 on the back side of the surface 3 of the substrate 2, the wafer 1 is divided into individual chips 11 along the division planned line 4. Note that the chip 11 includes a part of the substrate 2 and the device 5, and the die attach layer 10 is formed on the back surface 6. The die attach layer 10 is a layer laminated on the back surface 6 and is made of an adhesive having ductility for die bonding for fixing the chip 11 to another chip or a substrate or the like.

[0017] The processing method according to Embodiment 1 is a method of forming the die attach layer 10 on the wafer 1 and dividing the wafer 1 into individual chips 11. As shown in FIG. 2, the processing method includes a preparation protection step 1001, a holding step 1002, a die attach layer cutting step 1003, a transfer step 1004, and a division step 1005.

[0018] (Preparation Protection Step) FIG. 3 is a perspective view showing the preparation protection step of the processing method shown in FIG. 2. The preparation protection step 1001 is a preparation step of preparing the wafer 1 having the die attach layer 10 formed on the back surface 6, and is also a surface protection step of disposing the surface protection member 12 on the surface 3 of the wafer 1.

[0019] In Embodiment 1, in the preparation protection step 1001, a well-known mounter attaches a disk-shaped tape 13 having a diameter larger than that of the wafer 1 to the surface 3 of the wafer 1 as shown in FIG. 3, and attaches an annular frame 14 having an inner diameter larger than the outer diameter of the wafer 1 to the outer peripheral edge of the tape 13, thereby disposing a surface protection member 12 on the surface 3 of the wafer 1. Further, in Embodiment 1, in the preparation protection step 1001, a well-known mounter attaches a disk-shaped DAF 15 having the same diameter as the wafer 1 to the back surface 6 of the wafer 1. Note that in Embodiment 1, the surface protection member 12 includes a tape 13 and a frame 14. The DAF 15 forms a die attach layer 10.

[0020] Thus, in Embodiment 1, in the preparation protection step 1001, the wafer 1 having the die attach layer 10 formed on the back surface 6 thereof is prepared, and the surface protection member 12 is disposed on the surface 3 of the wafer 1. The wafer 1 is supported inside the frame 210 by the tape 13, with the die attach layer 10 formed on the back surface 205 facing upward.

[0021] Note that in Embodiment 1, as shown in FIG. 8 and the like, the tape 13 is a surface protection tape including a base material 13-1 made of a non-adhesive resin and an adhesive layer 13-2 laminated on the base material 13-1 and made of an adhesive resin. However, in the present invention, the tape 13 may be a sheet composed only of a base material made of an adherend resin such as polyolefin (Polyolefin). In the present invention, the surface protection member 12 may be composed only of the tape 13 attached to the surface 3 of the wafer 1 without including the frame 14.

[0022] (Cutting device) Next, a cutting device 100 that performs the holding step 1002, the die attach layer cutting step 1003, and the dividing step 1005 will be described. FIG. 4 is a perspective view showing a configuration example of a cutting device that performs the holding step, the die attach layer cutting step, and the dividing step of the processing method shown in FIG. 2. FIG. 5 is a perspective view showing the holding table and the lower imaging camera of the processing device shown in FIG. 4.

[0023] The cutting device 100 shown in Fig. 4 is a processing cutting device for cutting (equivalent to processing) the wafer 1. The cutting device 100 shown in Fig. 4 is a processing device that holds the wafer 1 on the holding table 115 and cuts it with the cutting blade 121 along the dividing line 4. As shown in Fig. 4, the cutting device 100 includes a holding unit 110, a cutting unit 120, a moving unit 130, an upper imaging camera 140, and a control unit 190.

[0024] As shown in Fig. 5, the holding unit 110 includes a housing 111 that is moved in the X-axis direction parallel to the horizontal direction by the X-axis moving unit 131 of the moving unit 130, and a holding table 115 that is rotatably provided about an axis parallel to the Z-axis direction along the vertical direction on the housing 111.

[0025] In Embodiment 1, the housing 111 includes a lower plate 112 that is moved in the X-axis direction by the X-axis moving unit 131 and is parallel to the horizontal direction, a side plate 113 erected from the outer edge of the lower plate 112, and an upper plate 114 whose outer edge is connected to the upper end of the side plate 113 and is parallel to the lower plate 112.

[0026] The holding table 115 is used in the cutting device 100, holds the wafer 1 on the holding surface 116, and is rotatably supported about an axis on the upper plate 114. The holding table 115 includes a transparent plate 117, an annular support member 118, and a frame holding portion 119.

[0027] The transparent plate 117 is formed in a disk shape with an outer diameter larger than the outer diameter of the wafer 1 and a uniform thickness. When the holding table 115 is installed on the upper plate 114 of the housing 111, the upper surface is parallel to the horizontal direction. The upper surface of the transparent plate 117 is the holding surface 116 for holding the wafer 1. That is, the transparent plate 117 includes the holding surface 116 for holding the wafer 1.

[0028] The transparent plate 117 is composed of a non-porous material that is transparent (has light transmittance) and airtight, such as quartz glass, borosilicate glass, sapphire, calcium fluoride, lithium fluoride, magnesium fluoride, etc. The transparent plate 117 holds the wafer 1 via the tape 13 on the holding surface 116, and holds the wafer 1 and the tape 13 on the outer periphery of the wafer 1.

[0029] Also, in Embodiment 1, as shown in FIG. 5, a suction groove 116-1 connected to a vacuum suction source (not shown) is formed on the holding surface 116 of the transparent plate 117. The suction groove 116-1 is formed as a concave groove from the holding surface 116, and includes an annular portion that is coaxial with the holding surface 116 and a plurality of linear portions whose both ends communicate with the annular portion and intersect each other at the center of the holding surface 116. The annular portion is formed in a ring shape whose inner and outer diameters are smaller than the outer diameter of the wafer 1. The linear portions extend linearly parallel to the radial direction of the holding surface 116, and in Embodiment 1, two linear portions are provided.

[0030] The annular support member 118 is made of a metal such as stainless steel and is formed in an annular shape with an opening at the center. The annular support member 118 is rotatably supported on the upper plate 114 of the housing 111 around an axis parallel to the Z-axis direction. The inner diameter of the annular support member 118 is smaller than the outer diameter of the transparent plate 117, and the outer diameter of the annular support member 118 is larger than the outer diameter of the transparent plate 117. The annular support member 118 supports the outer edge portion of the transparent plate 117 at its inner edge portion.

[0031] The frame holding portion 119 holds the frame 210, is fixed to the outer edge portion of the annular support member 118, and is disposed on the outer peripheral side of the transparent plate 117, that is, the holding surface 116. A plurality of frame holding portions 119 are arranged at intervals in the circumferential direction on the outer edge portion of the annular support member 118, and include a frame support portion 119-1 on which the frame 210 is placed on the upper surface, and a vacuum pad 119-2 that suction-holds the frame 210 placed on the upper surface of the frame support portion 119-1. The vacuum pad 119-2 is connected to a vacuum suction source (not shown).

[0032] The holding table 115 is sucked by a vacuum suction source to suck and hold the wafer 1 on the holding surface 116 to the holding surface 116 via the tape 13, and also suck and hold the frame 14 placed on the frame support portion 119-1 of the frame holding portion 119 to the vacuum pad 119-2.

[0033] Also, in Embodiment 1, the holding unit 110 is provided with a circular through hole (not shown) in the upper plate 114 of the housing 111. The through hole is disposed at a position coaxial with the transparent plate 117 and the annular support member 118 of the holding table 115.

[0034] The moving unit 130 relatively moves the holding table 115 and the cutting unit 120. The moving unit 130 includes an X-axis moving unit 131 which is a machining feed unit shown in FIG. 5, a Y-axis moving unit 132 which is an indexing feed unit shown in FIG. 4, a Z-axis moving unit 133 which is a plunge feed unit shown in FIG. 1, and a rotational moving unit 134 which rotates the holding table 115 shown in FIG. 5 around an axis parallel to the Z-axis direction.

[0035] The X-axis moving unit 131 relatively moves the holding table 115 and the cutting unit 120 in the X-axis direction by moving the lower plate 112 of the housing 111 of the holding unit 110 in the X-axis direction. The X-axis moving unit 131 moves the holding table 115 in the X-axis direction across the loading / unloading area where the wafer 1 is loaded / unloaded to / from the holding table 115 and the machining area where the wafer 1 held by the wafer 1 is cut.

[0036] The Y-axis moving unit 132 relatively moves the holding table 115 and the cutting unit 120 in the Y-axis direction by moving the cutting unit 120 in the Y-axis direction parallel to the horizontal direction and orthogonal to the X-axis direction. The Z-axis moving unit 133 relatively moves the holding table 115 and the cutting unit 120 in the Z-axis direction by moving the cutting unit 120 in the Z-axis direction parallel to the vertical direction orthogonal to both the X-axis direction and the Y-axis direction.

[0037] The X-axis moving unit 131, the Y-axis moving unit 132, and the Z-axis moving unit 133 include a well-known ball screw rotatably provided around an axis, a well-known motor for rotating the ball screw around the axis, and a well-known guide rail for movably supporting the holding table 115 or the cutting unit 120 in the X-axis direction, the Y-axis direction, or the Z-axis direction.

[0038] The rotational moving unit 134 rotates the holding table 115 around an axis parallel to the Z-axis direction. The rotational moving unit 134 rotates the holding table 115 around the axis within a range exceeding 180 degrees and less than 360 degrees. The rotational moving unit 134 includes a motor 141 fixed to the side plate 113 of the housing 111, a pulley 142 connected to the output shaft of the motor 141, and a belt 143 wound around the outer periphery of the annular support member 118 of the holding table 115 and rotated around the axis by the pulley 142. When the motor 141 rotates, the rotational moving unit 134 rotates the holding table 115 around the axis via the pulley 142 and the belt 143. Also, in Embodiment 1, the rotational moving unit 134 can rotate the holding table 115 by 220 degrees in both one direction around the axis and the other direction opposite to the one direction.

[0039] The cutting unit 120 is a processing means for performing cutting on the wafer 1 held by the transparent plate 117 of the holding table 115 with a cutting blade 121. The cutting unit 120 is movably provided in the Y-axis direction by the Y-axis moving unit 132 and movably provided in the Z-axis direction by the Z-axis moving unit 133 with respect to the wafer 1 held by the transparent plate 117 of the holding table 115. The cutting unit 120 is provided on a support frame 102 erected from the apparatus main body 101 via the Y-axis moving unit 132, the Z-axis moving unit 133, and the like.

[0040] The cutting unit 120 can position the cutting blade 121 at any position on the holding surface 116 of the holding table 115 by means of the Y-axis moving unit 132 and the Z-axis moving unit 133. The cutting unit 120 includes a cutting blade 121, a spindle housing 122 that is movably provided in the Y-axis direction and the Z-axis direction by the Y-axis moving unit 132 and the Z-axis moving unit 133, a spindle 123 that is rotatably provided around the axis of the spindle housing 122 and is rotated by a motor and has the cutting blade 121 mounted at its tip, and a cutting water nozzle 124 that is a machining fluid supply means.

[0041] The cutting blade 121 cuts the wafer 1 held by the holding table 115 and is an extremely thin cutting grindstone having a substantially ring shape. In Embodiment 1, the cutting blade 121 is a so-called hub blade including an annular circular base and an annular cutting edge disposed on the outer peripheral edge of the circular base for cutting the wafer 1. The cutting edge is made of abrasive grains such as diamond or CBN (Cubic Boron Nitride) and a bonding material (binding material) such as metal or resin and is formed to a predetermined thickness. In the present invention, the cutting blade 121 may also be a so-called washer blade composed only of the cutting edge.

[0042] The spindle 123 rotates around its axis by a motor to rotate the cutting blade 121 around its axis. Note that the axes of the cutting blade 121 and the spindle 123 of the cutting unit 120 are parallel to the Y-axis direction. The cutting water nozzle 124 is provided at the tip of the spindle housing 122 and supplies cutting water from a machining fluid supply source (not shown) to the wafer 1 and the cutting blade 121 during the cutting of the wafer 1 by the cutting blade 121. In Embodiment 1, the cutting water is pure water.

[0043] The upper imaging camera 140 is fixed to the cutting unit 120 so as to move integrally with the cutting unit 120. The upper imaging camera 140 includes a plurality of imaging elements that image the wafer 1 held on the holding table 115 from above. The imaging elements are, for example, CCD (Charge-Coupled Device) imaging elements or CMOS (Complementary MOS) imaging elements. The upper imaging camera 140 images the wafer 1 held on the transparent plate 117 of the holding table 115 and outputs the obtained image to the control unit 190.

[0044] Further, as shown in FIG. 5, the cutting device 100 includes a lower imaging camera 150 which is an imaging means disposed below the transparent plate 117 of the holding table 115 and images the wafer 1 held by the transparent plate 117 through the transparent plate 117. The lower imaging camera 150 images the surface 3 side of the wafer 1 held on the transparent plate 117 of the holding table 115 from below the wafer 1 through the transparent plate 117. For this purpose, the wafer 1 held by the transparent plate 117 is imaged by the lower imaging camera 150 through the transparent plate 117 through the opening of the annular support member 118.

[0045] FIG. 5 shows the lower imaging camera 150 adjacent to the holding unit 110 in the Y-axis direction. However, in the actual cutting device 100, the lower imaging camera 150 is disposed below the transparent plate 117 of the holding table 115. Further, the lower imaging camera 150 is disposed movably in the Y-axis direction by a second Y-axis moving unit 135 provided in the apparatus main body 101, and is disposed movably in the Z-axis direction by a second Z-axis moving unit 138 provided on an upright column 137 standing from a moving plate 136 that is moved in the Y-axis direction by the second Y-axis moving unit 135. In Embodiment 1, the lower imaging camera 150 is attached to the other end of a horizontally extending member 139, one end of which is attached to an elevating member that is movable in the Z-axis direction by the second Z-axis moving unit 138.

[0046] The second Y-axis moving unit 135 and the second Z-axis moving unit 138 include a well-known ball screw rotatably provided around an axis, a well-known motor that rotates the ball screw around the axis, and a well-known guide rail that movably supports a moving plate or the lower imaging camera 150 in the Y-axis direction or the Z-axis direction.

[0047] The lower imaging camera 150 includes an imaging element that images the wafer 1 held on the holding table 115 from below through the transparent plate 117. The imaging element is, for example, a CCD (Charge-Coupled Device) imaging element or a CMOS (Complementary MOS) imaging element. The lower imaging camera 150 images the wafer 1 held on the holding table 115 and outputs the obtained image to the control unit 190.

[0048] In addition, the cutting device 100 includes an X-axis direction position detection unit 151 (shown in FIG. 5) for detecting the position of the holding table 115 in the X-axis direction, a Y-axis direction position detection unit (not shown) for detecting the position of the cutting unit 120 in the Y-axis direction, and a Z-axis direction position detection unit for detecting the position of the cutting unit 120 in the Z-axis direction. The X-axis direction position detection unit 151 and the Y-axis direction position detection unit can be composed of a linear scale parallel to the X-axis direction or the Y-axis direction and a reading head. The Z-axis direction position detection unit detects the position of the cutting unit 120 in the Z-axis direction by the pulses of the motor. The X-axis direction position detection unit 151, the Y-axis direction position detection unit, and the Z-axis direction position detection unit output the positions of the holding table 115 in the X-axis direction, the cutting unit 120 in the Y-axis direction, or the Z-axis direction to the control unit 190.

[0049] Further, the cutting device 100 includes a second Y-axis direction position detection unit 155 (shown in FIG. 5) that detects the position of the lower imaging camera 150 in the Y-axis direction. The second Y-axis direction position detection unit 155 can be composed of a linear scale parallel to the Y-axis direction and a reading head. The second Y-axis direction position detection unit 155 outputs the position of the lower imaging camera 150 in the X-axis direction, the Y-axis direction, or the Z-axis direction of the cutting unit 120 to the control unit 190. Note that the positions of the holding table 115, the cutting unit 120, and the lower imaging camera in each axial direction detected by each position detection unit 151, 155 are determined based on a predetermined reference position of the cutting device 100. That is, in the cutting device 100 according to Embodiment 1, each position is determined based on a predetermined reference position.

[0050] The cutting device 100 further includes a cassette elevator 161 on which a cassette 160 for accommodating a plurality of wafers 1 before and after cutting is placed and that moves the cassette 160 in the Z-axis direction, a cleaning unit 162 for cleaning the wafer 1 after cutting, and a transfer unit (not shown) that takes in and out the wafer 1 from the cassette 160 and transfers the wafer 1.

[0051] The control unit 190 controls each of the above-described components of the cutting device 100 to cause the cutting device 100 to perform a processing operation on the wafer 1. Note that the control unit 190 is a computer having an arithmetic processing unit having a microprocessor such as a CPU (central processing unit), a storage device having a memory such as a ROM (read only memory) or a RAM (random access memory), and an input / output interface device. The arithmetic processing unit of the control unit 190 performs arithmetic processing according to a computer program stored in the storage device, and outputs a control signal for controlling the cutting device 100 to the above-described components of the cutting device 100 via the input / output interface device.

[0052] Further, the cutting device 100 is connected to a control unit 190 and is connected to a display unit (not shown) constituted by a liquid crystal display device or the like that displays the state and image of the machining operation, and an input unit that is connected to the control unit 190 and is used when an operator registers machining content information or the like. In Embodiment 1, the input unit is constituted by at least one of a touch panel provided on the display unit and an external input device such as a keyboard.

[0053] When the cutting blade 121 cuts the die attach layer 10 to which the cutting blade 121 is adhered to the wafer 1, since the die attach layer 10 has ductility, a part of the cut die attach layer 10 may extend in a thread shape to generate a so-called burr whisker in a thread shape.

[0054] (Holding Step) Next, the holding step 1002 will be described. FIG. 6 is a side view showing a part of the holding step of the processing method shown in FIG. 2 in a partial cross section. The holding step 1002 is a step of holding the wafer 1 on the holding table 115 through the surface protection member 12 and exposing the back surface 6 of the wafer 1 after performing the preparation protection step 1001 which is a surface protection step, and is a step performed before performing the die attach layer cutting step 1003.

[0055] In the holding step 1002, the control unit 190 of the cutting device 100 having the above-described configuration receives and registers the processing conditions of the die attach layer cutting step 1003 input by the operator, and a cassette 160 in which a plurality of wafers 1 with the back surface 6, that is, the die attach layer 10 facing upward, are accommodated after the preparation protection step 1001 is installed on the cassette elevator 161. In the holding step 1002, when the control unit 190 of the cutting device 100 receives an instruction to start the machining operation from the operator, the machining operation is started and the holding step 1002 is started.

[0056] In Embodiment 1, in the holding step 1002, the cutting device 100 controls the transfer unit to take out one wafer 1 from the cassette 160, positions the wafer 1 on the holding surface 116 of the holding table 115 located in the loading / unloading area, and places the frame 210 on the frame holding portion 119. As shown in FIG. 6, the cutting device 100 has the control unit 190 suck and hold the wafer 1 on the holding surface 116 of the holding table 115 and suck and hold the frame 210 on the frame holding portion 119.

[0057] (Die attach layer cutting step) FIG. 7 is a side view showing a partial cross-section of the die attach layer cutting step of the processing method shown in FIG. 2. FIG. 8 is a cross-sectional view of a main part of the wafer in the die attach layer cutting step of the processing method shown in FIG. 2. FIG. 9 is a cross-sectional view of another main part of the wafer in the die attach layer cutting step of the processing method shown in FIG. 2.

[0058] In the die attach layer cutting step 1003, while cutting the cutting blade 121 into the wafer 1 from the side of the die attach layer 10 on the back surface 6 of the wafer 1 to a cutting depth 127 (corresponding to the depth, shown in FIG. 8) reaching the wafer 1, the cutting is performed along the division planned line 4 with the cutting blade 121 to form a cutting groove 16 for cutting the die attach layer 10 and a remaining portion 17 of the wafer 1 under the cutting groove 16. In the die attach layer cutting step 1003, the cutting device 100 has the control unit 190 control the X-axis movement unit 131 and the second Y-axis movement unit 135 to position the lower imaging camera 150 below the wafer 1 held on the transparent plate 117 of the holding table 115. In the die attach layer cutting step 1003, the cutting device 100 has the control unit 190 image the wafer 1 from below through the transparent plate 117 with the lower imaging camera 150 and acquire an image for performing alignment to align the positions of the wafer 1 and the cutting blade 121.

[0059] In the die attach layer cutting step 1003, the cutting device 100 has the control unit 190 detect the division planned line 4 from the image acquired by imaging with the lower imaging camera 150 and perform alignment. In the die attach layer cutting step 1003, the control unit 190 controls the X-axis movement unit 131 to move the holding table 115 to the processing area. Then, according to the processing conditions, the control unit 190 controls the movement unit 130 and the cutting unit 120. As shown in FIG. 7, the cutting blade 121 of the cutting unit 120 and the holding table 115 are relatively moved along the division planned line 4, and while cutting water is supplied from the cutting water nozzle 124, the cutting blade 121 is cut into the center in the width direction of the division planned line 4 of the wafer 1 from the side of the die attach layer 10 along the division planned line 4.

[0060] In the die attach layer cutting step 1003, as shown in FIGS. 7, 8, and 9, the cutting device 100 has the control unit 190 control the movement unit 130 and the cutting unit 120 according to the processing conditions, and cut the cutting blade 121 into the cutting depth 127 that reaches the center of the thickness of the substrate 2 of the wafer 1 from the surface of the die attach layer 10. Note that the cutting depth 127 is the distance from the surface of the die attach layer 10 to the lower end of the cutting edge of the cutting blade 121 in the die attach layer cutting step 1003, and is a distance longer than the thickness of the die attach layer 10. In the present invention, the cutting depth 127 in the die attach layer cutting step 1003 is preferably the sum of about 30% to 50% of the thickness of the die attach layer 10 and the thickness of the substrate 2. When only the die attach layer 10 is cut with the cutting blade 121, clogging is likely to occur on the cutting blade 121. However, by cutting the substrate 2 made of silicon or the like together with the die attach layer 10, a dressing effect due to cutting the substrate 2 can be obtained, and clogging can be prevented. If the cutting depth 127 is too shallow, the dressing effect cannot be obtained sufficiently. On the other hand, if the cutting depth 127 is too deep (if the thickness of the remaining cut portion 17 is too thin), the remaining cut portion 17 will crack due to the impact of the cutting blade 121 during cutting.

[0061] Also, in Embodiment 1, in the die attach layer cutting step 1003, the cutting device 100 controls the moving unit 130 and the cutting unit 120 according to the processing conditions such that the rotation direction 125 of the cutting blade 121 (indicated by an arrow in FIG. 8) is set to the so-called down-cut direction in which the cutting edge of the cutting blade 121 faces from the die attach layer 10 side to the wafer 1 side at the machining point 128 where the cutting blade 121 cuts into the wafer 1. Thus, the rotation direction 125 of the cutting blade 121 in the die attach layer cutting step 1003 is set to the down-cut direction in which the cutting blade 121 faces from the die attach layer 10 side to the wafer 1 side.

[0062] Also, in the die attach layer cutting step 1003, the cutting device 100 cuts the cutting blade 121 into the center of the thickness of the substrate 2 of the wafer 1 and cuts the die attach layer 10 along each division planned line 4 to form a concave cutting groove 16 from the back surface 6 and a remaining portion 17 of the wafer 1 under the cutting groove 16. Also, in Embodiment 1, the die attach layer cutting step 1003 is performed by the cutting device 100 cutting into the center of the thickness of the substrate 2 of the wafer 1 with the first cutting blade 121-1 having a cutting edge with a first blade thickness 126-1.

[0063] In the die attach layer cutting step 1003, after the cutting device 100 cuts the first cutting blade 121-1 from the die attach layer 10 side along all the division planned lines 4 of the wafer 1 held by the holding table 115 to form the cutting groove 16 and the remaining portion 17, the control unit 190 controls the X-axis moving unit 131 to move the holding table 115 to the loading / unloading area and positions the holding table 115 in the loading / unloading area. In the die attach layer cutting step 1003, when the cutting device 100 positions the holding table 115 in the loading / unloading area, the control unit 190 stops sucking and holding the wafer 1 and the frame 14.

[0064] In the die attach layer cutting step 1003, the cutting device 100 controls the transfer unit by the control unit 190 to transfer the wafer 1 to the cleaning unit 162. After cleaning by the cleaning unit 162, it is accommodated in the cassette 160. The cutting device 100 finishes the processing operation when cutting grooves 16 and remaining portions 17 are formed in all the wafers 1 in the cassette 160.

[0065] (Transfer step) FIG. 10 is a perspective view of a wafer after the transfer step of the processing method shown in FIG. 2. The transfer step 1004 is a step of attaching a tape 23 to the upper surface of the die attach layer 10 and removing the surface protection member 12 after performing the die attach layer cutting step 1003 and before performing the dicing step 1005.

[0066] In Embodiment 1, in the transfer step 1004, a well-known mounter attaches a disk-shaped tape 23 having a diameter larger than that of the wafer 1 to the surface which is the upper surface of the die attach layer 10 attached to the back surface 6 as shown in FIG. 10, attaches an annular frame 24 having an inner diameter larger than the outer diameter of the wafer 1 to the outer peripheral edge of the tape 23, and peels the tape 13 from the surface 3 of the wafer 1. The wafer 1 is supported inside the frame 24 by the tape 23 with the surface 3 side facing upward.

[0067] Note that, in Embodiment 1, as shown in FIG. 13, the tape 23 is a tape including a base material 23-1 made of a non-adhesive resin and an adhesive layer 23-2 laminated on the base material 23-1 and made of an adhesive resin. However, in the present invention, the tape 23 may be a sheet composed only of a base material made of an adherend resin such as polyolefin (Polyolefin). Also, in the present invention, the outer diameter of the tape 23 may be made equal to the outer diameter of the wafer 1, and the frame 24 may not be attached to the outer peripheral edge of the tape 23.

[0068] (Dicing step) FIG. 11 is a side view showing in partial cross section the state of performing alignment in the splitting step of the processing method shown in FIG. 2. FIG. 12 is a side view showing in partial cross section the state of splitting the remaining portion with a cutting blade in the splitting step of the processing method shown in FIG. 2. FIG. 13 is a cross-sectional view of a main part of a wafer in the die attach layer cutting step of the processing method shown in FIG. 2. FIG. 14 is a cross-sectional view of a chip formed in the die attach layer cutting step of the processing method shown in FIG. 2. FIG. 15 is a cross-sectional view showing the state in which the die attach layer adhered to the chip shown in FIG. 14 is deformed.

[0069] The splitting step 1005 is a step of splitting the remaining portion 17 along the splitting planned line 4 after performing the die attach layer cutting step 1003 to form a plurality of chips 11. In the splitting step 1005, the control unit 190 of the cutting device 100 having the above-described configuration receives and registers the processing conditions of the splitting step 1005 input by the operator, and a cassette 160 containing a plurality of wafers 1 with the surface 3 facing upward after the die attach layer cutting step 1003 and the transfer step 1004 is installed on the cassette elevator 161. In the splitting step 1005, when the control unit 190 of the cutting device 100 receives an instruction to start the processing operation from the operator, the cutting device 100 starts the processing operation and starts the splitting step 1005.

[0070] In Embodiment 1, in the splitting step 1005, the cutting device 100 has the control unit 190 control the transfer unit to take out one wafer 1 from the cassette 160, place the wafer 1 on the holding surface 116 of the holding table 115 positioned in the loading / unloading area, and place the frame 210 on the frame holding portion 119. The cutting device 100 has the control unit 190 suck and hold the wafer 1 on the holding surface 116 of the holding table 115 and suck and hold the frame 210 on the frame holding portion 119.

[0071] In the dividing step 1005, the cutting device 100 positions the wafer 1 held on the transparent plate 117 of the holding table 115 under the upper imaging camera 140 as shown in FIG. 11 by the control unit 190 controlling the X-axis moving unit 131 and the Y-axis moving unit 132. In the holding step 1002, the cutting device 100 acquires an image for performing alignment in which the control unit 190 images the wafer 1 with the upper imaging camera 140 and aligns the wafer 1 and the cutting blade 121.

[0072] In the dividing step 1005, the cutting device 100 performs alignment by the control unit 190 detecting the division planned line 4 from the image captured by the upper imaging camera 140. In the die attach layer cutting step 1003, the control unit 190 controls the X-axis moving unit 131 to move the holding table 115 to the processing area, and according to the processing conditions, the control unit 190 controls the moving unit 130 and the cutting unit 120 to relatively move the holding table 115 and the cutting blade 121 of the cutting unit 120 along the division planned line 4 as shown in FIG. 12, and while supplying cutting water from the cutting water nozzle 124, the cutting blade 121 is cut into the center in the width direction of the division planned line 4 of the wafer 1 from the surface 3 side along the division planned line 4.

[0073] In the die attach layer cutting step 1003, as shown in FIG. 13, the cutting device 100 cuts the cutting blade 121 until it penetrates the remaining cut portions 17 formed in each division planned line 4 without cutting into the tape 23 by the control unit 190 controlling the moving unit 130 and the cutting unit 120 according to the processing conditions. Thus, in the dividing step 1005, the wafer 1 is cut along the division planned line 4 with the cutting blade 121 from the surface 3 of the wafer 1, the remaining cut portions 17 are divided, and the wafer 1 is divided into individual chips 11.

[0074] Also, in Embodiment 1, the dividing step 1005 is carried out with the second cutting blade 121-2 having a cutting edge with a second blade thickness 126-2 that is thinner than the first blade thickness 126-1 of the cutting device 100. For this purpose, as shown in FIG. 14, the individually divided chips 11 are formed with a stepped portion 18 in which the area on the back surface 6 side of the substrate 2 is formed to be smaller than the area on the front surface 3 side. Note that the cutting edge of the second cutting blade 121-2 is formed by bonding diamond, which is an abrasive grain with a finer particle size than that of the first cutting blade 121-1, with a bond.

[0075] Further, in the processing method according to Embodiment 1, the difference between the first blade thickness 126-1 and the second blade thickness 126-2, which are the processing conditions of the die attach layer cutting step 1003 and the dividing step 1005, and the cutting depth 127 (shown in FIG. 9), which is the amount of cutting of the first cutting blade 121-1 into the wafer 1, are set to values such that when the chip 11 is mounted and the thickness of the die attach layer 10 on the back surface 6 of the chip 11 is deformed to be thinner, the protrusion outside the chip 11 is accommodated in the stepped portion 18, as shown in FIG. 15.

[0076] In the dividing step 1005, when the cutting device 100 divides the remaining portion 17 along all the division planned lines 4 of the wafer 1 held by the holding table 115 with the second cutting blade 121-2, the control unit 190 controls the X-axis moving unit 131 to move the holding table 115 to the loading / unloading area and positions the holding table 115 in the loading / unloading area. In the dividing step 1005, when the cutting device 100 positions the holding table 115 in the loading / unloading area, the control unit 190 stops the suction holding of the wafer 1 and the frame 14.

[0077] In the dividing step 1005, when the cutting device 100, the control unit 190 controls the transfer unit to transfer the wafer 1 to the cleaning unit 162, after cleaning with the cleaning unit 162, it is accommodated in the cassette 160. When the cutting device 100 divides the remaining portion 17 of all the wafers 1 in the cassette 160, the processing operation ends. The individually divided chips 11 are picked up from the tape 23 by a well-known picker or the like.

[0078] In Embodiment 1, the die attach layer cutting step 1003 and the dividing step 1005 are performed by the same cutting device 100. However, in the present invention, the die attach layer cutting step 1003 and the dividing step 1005 may be performed by different cutting devices. Also, in Embodiment 1, the die attach layer cutting step 1003 and the dividing step 1005 are performed by different cutting blades 121-1 and 121-2. However, in the present invention, the die attach layer cutting step 1003 and the dividing step 1005 may be performed by the same cutting blade. Further, in the present invention, in the dividing step 1005, the second cutting blade 121-2 may be cut into the tape 23 to divide the remaining portion 17. Also, in the present invention, in the die attach layer cutting step 1003, imaging may be performed by an infrared imaging unit that acquires an infrared image from above the wafer 1 to detect the planned dividing line 4.

[0079] Normally, when dividing a wafer 1 having a die attach layer 10 formed on the back surface 6 into individual chips 11 by cutting, cutting is performed from the front surface 3 side of the wafer 1 with the die attach layer 10 on the back surface 6 side of the wafer 1 adhered to the tape 13. When the die attach layer 10 made of a synthetic resin and softer than the silicon constituting the substrate 2 is cut with the cutting blade 121 while supporting the substrate 2, cracks occur in the substrate on the interface side between the substrate and the die attach layer 10. Also, since the die attach layer 10 is supported by the adhesive layer of the soft tape 13, it is not cut by the cutting blade 121, and filamentous whisker burrs are generated.

[0080] However, in the processing method according to Embodiment 1 described above, the cutting blade 121 is cut into the die attach layer 10 from the die attach layer 10 side, and the die attach layer 10 is cut in the down-cut direction where the rotation direction 125 of the cutting blade 121 is from the die attach layer 10 side toward the wafer 1 side. Therefore, in the processing method according to Embodiment 11, since the die attach layer 10 is pressed against the substrate 2 of the hard wafer 1 by the cutting blade 121 and torn off, it is cut by the cutting blade 121. Therefore, the processing method according to Embodiment 1 can suppress the generation of whisker burrs without performing the step of removing the whisker burrs formed from the die attach layer 10, and can suppress the occurrence of mounting defects and the like.

[0081] As a result, the processing method according to Embodiment 1 has the effect of suppressing the generation of whisker burrs while suppressing labor and suppressing the possibility of occurrence of mounting defects and the like.

[0082] Note that the present invention is not limited to the above-described embodiments. That is, various modifications can be made and implemented without departing from the gist of the present invention. In the above-described embodiment, in the dividing step 1005, the remaining portion 17 is divided by the second cutting blade 121-2, but the present invention is not limited to this method. In the dividing step 1005 of the present invention, a laser beam having a wavelength that is transmissive to the substrate 2 is irradiated along the dividing planned line 4 with the focus point set inside the substrate 2 to form a modified layer inside the remaining portion 17, and the tape 13 is expanded or the wafer 1 is divided starting from the modified layer, and the wafer 1 may be divided into individual chips 11.

[0083] Further, in the dividing step 1005 of the present invention, a laser beam having a wavelength that is absorptive to the substrate 2 may be irradiated along the dividing planned line 4 to perform ablation processing on the remaining portion 17, and the wafer 1 may be divided into individual chips 11.

Explanation of Reference Numerals

[0084] 1 Wafer 3 Surface 4 Dividing Planned Line 5 Device 6 Back surface 10 Die attach layer 11 Chip 12 Surface protection member 16 Cutting groove 17 Remnant portion 18 Step portion 23 Tape 121 Cutting blade 121-1 First cutting blade 121-2 Second cutting blade 125 Rotation direction 126-1 First blade thickness 126-2 Second blade thickness 127 Cutting depth (depth, cutting amount) 1001 Preparation protection step (preparation step, surface protection step) 1002 Holding step 1003 Die attach layer cutting step 1004 Transfer step 1005 Division step

Claims

1. A method for processing a wafer, comprising: A preparation step of preparing a wafer having a dicing layer formed on the back surface thereof, wherein a plurality of planned dicing lines intersecting the surface are set, and devices are formed in regions partitioned by the planned dicing lines; A dicing layer cutting step of cutting along the planned dicing line with the cutting blade while cutting the cutting blade into the wafer to a depth reaching the wafer from the dicing layer side of the back surface of the wafer, thereby forming a cutting groove for cutting the dicing layer and a remaining portion of the wafer under the cutting groove; After performing the dicing layer cutting step, a dividing step of dividing the remaining portion along the planned dicing line to form a plurality of chips; In the dicing layer cutting step, the surface of the wafer is imaged from below through a transparent plate of a holding table that holds the wafer on the holding surface with a lower imaging camera, alignment for aligning the wafer and the cutting blade is performed, and the cutting blade cuts along the planned dicing line, and The rotation direction of the cutting blade in the dicing layer cutting step is set in a direction from the dicing layer side toward the wafer side; In the dividing step, the surface of the wafer is imaged with an upper imaging camera, alignment for aligning the wafer and the cutting blade is performed, and the cutting blade cuts along the planned dicing line from the surface of the wafer to divide the remaining portion.

2. A method for processing a wafer, comprising: A preparation step of preparing a wafer having a dicing layer formed on the back surface thereof, wherein a plurality of planned dicing lines intersecting the surface are set, and devices are formed in regions partitioned by the planned dicing lines; A dicing layer cutting step of cutting along the planned dicing line with the cutting blade while cutting the cutting blade into the wafer to a depth reaching the wafer from the dicing layer side of the back surface of the wafer, thereby forming a cutting groove for cutting the dicing layer and a remaining portion of the wafer under the cutting groove; After performing the die attach layer cutting step, a dividing step of dividing the remaining portion along the planned dividing line to form a plurality of chips, In the die attach layer cutting step, the rotation direction of the cutting blade is set to the direction in which the cutting blade goes from the die attach layer side toward the wafer side, The dividing step cuts along the planned dividing line with a cutting blade from the surface of the wafer, divides the remaining portion, The die attach layer cutting step is performed by cutting into the wafer with a first cutting blade having a first blade thickness, and the dividing step is performed with a second cutting blade having a second blade thickness thinner than the first blade thickness, so that a stepped portion is formed in which the back surface side of the chip is formed smaller than the front surface side, A processing method in which the difference between the first blade thickness and the second blade thickness and the cutting amount of the first cutting blade into the wafer are set to values such that when the chip is mounted, the protrusion of the die attach layer on the back surface of the chip outside the chip is accommodated in the stepped portion.

3. A surface protection step of disposing a surface protection member on the surface of the wafer, After performing the surface protection step, a holding step of holding the wafer with a holding table through the surface protection member to expose the back surface of the wafer is performed before performing the die attach layer cutting step, After performing the die attach layer cutting step and before performing the dividing step, a transfer step of attaching a tape to the upper surface of the die attach layer and removing the surface protection member is further provided, and the processing method according to claim 1 or claim 2.

Images