Processing method of wafer

Abstract

To provide a processing method of a wafer, capable of suppressing the generation of a particle.SOLUTION: A processing method of a wafer comprises: a protection member distribution step 101 of distributing a protection member to a front surface that is a back surface of the wafer or an opposite side of a back surface; a separation groove formation step 102 of forming a separation groove along a peripheral direction of the wafer to an outer edge of a circular concave part of a boundary between the circular concave part and an annular shaped convex part in order to separate the circular concave part and the annular shaped convex part; a groove formation step 103 of forming a groove along a radial direction of the wafer to the annular shaped convex part; and a removal step 104 of removing the annular shaped convex part from the back surface of the wafer by dropping the annular shaped convex part while holding the wafer via the protection member by the holding unit after the separation groove formation step 102 and the groove formation step 103.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a wafer processing method for separating a wafer having a recess and an annular protrusion surrounding the recess formed on one surface thereof from the recess and the protrusion. [Background technology]

[0002] There is a processing method called TAIKO (registered trademark) grinding, in which a recess and a protrusion surrounding the recess are formed on one side of the wafer by grinding the center of the wafer so as to leave the outer peripheral edge of one side of the wafer. According to this processing method, the protrusion remaining on one side of the wafer serves as a reinforcing part of the wafer, making the thinned wafer relatively easy to handle.

[0003] In order to separate the TAIKO-ground wafer into individual device chips, a method has been proposed in which a reinforcing member such as a dicing tape is first placed on one side of the wafer, and then the convex portions are cut off and removed (see, for example, Patent Document 1).

[0004] The method described in Patent Document 1 involves attaching tape to a ring-shaped frame with an opening for accommodating a wafer, and attaching one side of a TAIKO-ground wafer to the tape of the tape-attached frame. After that, a laser beam is irradiated to the boundary between the recessed and protruding parts to cut them, and then ultraviolet light is irradiated onto the tape, and the protruding parts are pressed downward with a pressure roller to drop them, thereby removing the protruding parts. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2022-127872 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the method described in Patent Document 1, when the convex portion is dropped, the convex portion separates due to the impact of landing, and may fly off into pieces. The scattered powder turns into fine particles that float inside the device and adhere to the wafer. If the wafer is pressed with the particles pinched in between, the stress concentration can lead to wafer breakage.

[0007] Therefore, when separating a recess and a ring-shaped protrusion surrounding the recess from a protrusion formed on one side of a wafer, there is a problem that the protrusion should be removed using a method that suppresses the generation of particles.

[0008] An object of the present invention is to provide a wafer processing method capable of suppressing generation of particles. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems and achieve the object, the wafer processing method of the present invention is a wafer processing method for separating a recess and a ring-shaped protrusion surrounding the recess formed on one side of a wafer, the method comprising: a protective member disposing step of disposing a protective member on the one side of the wafer or the other side opposite to the one side; a separation groove forming step of forming a separation groove along the circumferential direction of the wafer in the recess at the boundary between the recess and the protrusion of the wafer in order to separate the recess and the protrusion; a groove forming step of forming a groove along the radial direction of the wafer in the protrusion; and a removal step of removing the protrusion from the one side of the wafer after the separation groove forming step and the groove forming step by dropping the protrusion while the wafer is held by a holding unit via the protective member.

[0010] In the wafer processing method, the separation groove forming step may involve irradiating the wafer with a laser beam having a wavelength that is absorbent, thereby forming the separation grooves that either completely cut the wafer or do not completely cut the wafer.

[0011] In the wafer processing method, the groove forming step may form the groove by irradiating the wafer with a laser beam having a wavelength that is absorbent.

[0012] In the wafer processing method, the groove forming step may form the groove in a direction along a crystal orientation in a direction of the one surface of the wafer. Effect of the Invention

[0013] The present invention has an effect of suppressing the generation of particles. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a perspective view that illustrates a wafer to be processed by the wafer processing method according to the first embodiment. [Diagram 2] FIG. 2 is a perspective view of the wafer shown in FIG. 1 as seen from the backside. [Diagram 3] FIG. 3 is a flowchart showing the flow of the wafer processing method according to the first embodiment. [Figure 4] FIG. 4 is a cross-sectional view that illustrates the protective member providing step illustrated in FIG. [Diagram 5] FIG. 5 is a perspective view showing the wafer after the protective member providing step shown in FIG. [Figure 6] FIG. 6 is a cross-sectional view that illustrates the separation groove forming step illustrated in FIG. [Figure 7] FIG. 7 is a perspective view showing the wafer after the isolation groove forming step shown in FIG. [Figure 8] FIG. 8 is a cross-sectional view that illustrates the groove forming step illustrated in FIG. [Figure 9] FIG. 9 is a perspective view of the wafer after the groove formation step shown in FIG. [Figure 10] FIG. 10 is a cross-sectional view that typically illustrates a state in which the wafer is suction-held by the holding unit in the removing step illustrated in FIG. [Figure 11]FIG. 11 is a cross-sectional view that typically illustrates a state in which the annular convex portion has been dropped in the removing step illustrated in FIG. [Figure 12] FIG. 12 is a cross-sectional view illustrating a schematic view of a main part of a wafer after a separation groove forming step in a wafer processing method according to a modified example of the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The form (embodiment) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiment. Furthermore, the components described below include those that a person skilled in the art can easily imagine and those that are substantially the same. Furthermore, the configurations described below can be appropriately combined. Furthermore, various omissions, substitutions, or modifications of the configurations can be made without departing from the gist of the present invention.

[0016] [Embodiment 1] A wafer processing method according to a first embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a perspective view showing a wafer to be processed by the wafer processing method according to the first embodiment. Fig. 2 is a perspective view of the wafer shown in Fig. 1, seen from the back side.

[0017] (Wafer) The wafer processing method according to the first embodiment is a processing method for processing a wafer 1 shown in Figures 1 and 2. The wafer 1 shown in Figures 1 and 2, which is the processing target of the wafer processing method according to the first embodiment, is a wafer such as a disk-shaped semiconductor wafer or an optical device wafer, with silicon, sapphire, gallium, or the like as a substrate 2. As shown in Figure 1, the wafer 1 has a device region 4 on a surface 3 of the substrate 2, and a peripheral excess region 5 surrounding the device region 4.

[0018] The device region 4 has dividing lines 6 set in a grid pattern on the surface 3 of the substrate 2, and devices 7 formed in each region partitioned by the dividing lines 6.

[0019] The device 7 is, for example, an integrated circuit such as an IC (Integrated Circuit) or an LSI (Large Scale Integration), an image sensor such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor), a MEMS (Micro Electro Mechanical Systems), or a semiconductor memory (semiconductor storage device). The peripheral excess region 5 is a region surrounding the entire device region 4 and on the front surface 3 of the substrate 2 where no device 7 is formed.

[0020] In addition, in embodiment 1, the wafer 1 is a so-called TAIKO (registered trademark) wafer in which the back surface 8 (corresponding to one surface) of the device region 4 is ground by a well-known grinding device to form a circular recess 10 (corresponding to a recess) on the back surface 8 of the device region 4 as shown in FIG. 2, and the peripheral excess region 5 is formed into an annular convex portion 11 (corresponding to a convex portion) that is thicker than the device region 4 and surrounds the circular recess 10.

[0021] The circular recess 10 is formed in a region overlapping in the thickness direction with the device region 4 of the back surface 8, and the annular protrusion 11 is formed in a region overlapping in the thickness direction with the peripheral surplus region 5 of the back surface 8. In this specification, the region overlapping in the thickness direction with the device region 4 of the back surface 8 is referred to as the device region 4 of the back surface 8, and the region overlapping in the thickness direction with the peripheral surplus region 5 of the back surface 8 is referred to as the peripheral surplus region 5 of the back surface 8.

[0022] In this manner, the back surface 8 of the wafer 1 has a circular recess 10 formed in the center and an annular protrusion 11 surrounding the circular recess 10, forming a step between the device region 4 and the peripheral surplus region 5. In addition, the front surface 3 of the wafer 1 is formed to be flush with the device region 4 and the peripheral surplus region 5.

[0023] Moreover, in the wafer 1, the crystal orientation of the rear surface 8 of the substrate 2 is parallel to the longitudinal direction of each of the division lines 6.

[0024] (Wafer processing method) Next, a wafer processing method according to the first embodiment will be described. Fig. 3 is a flow chart showing the flow of the wafer processing method according to the first embodiment. The wafer processing method according to the first embodiment is a method for separating the circular recess 10 and the annular protrusion 11 of a wafer 1 having a circular recess 10 and an annular protrusion 11 surrounding the circular recess 10 formed on the rear surface 8 from each other. As shown in Fig. 3, the wafer processing method according to the first embodiment includes a protective member providing step 101, a separation groove forming step 102, a groove forming step 103, and a removal step 104.

[0025] (Protective member disposing step) Fig. 4 is a cross-sectional view that typically shows the protective member providing step shown in Fig. 3. Fig. 5 is a perspective view that shows the wafer after the protective member providing step shown in Fig. 3. The protective member providing step 101 is a step of providing a protective member 21 on the back surface 8 of the wafer 1 or on the front surface 3 that is the other surface opposite to the back surface 8.

[0026] In the first embodiment, in the protective member disposing step 101, as shown in Fig. 4, a central portion of a protective member 21, which is a disk-shaped member having a diameter larger than the outer diameter of the wafer 1 and has an annular frame 20 attached to its outer edge, is attached to the rear surface 8 of the wafer 1, and the wafer 1 is supported within the opening of the annular frame 20 as shown in Fig. 5. In the first embodiment, the protective member 21 is an adhesive tape that includes a base material made of a non-adhesive and flexible resin and a glue layer laminated on the base material and made of an adhesive and flexible resin, and the glue layer is attached to the annular frame 20 and the wafer 1.

[0027] In embodiment 1, in protective member placement step 101, as shown in FIG. 4, a placement device 30 suction-holds the front surface 3 of the wafer 1 onto the holding surface 32 of the holding table 31, and uses a roller 33 to press the adhesive layer of the protective member 21 onto the back surface 8 of the wafer 1 while adhering it, thereby tightly adhering the protective member 21 to the bottom surface 12 of the circular recess 10, the inner surface 13 of the annular protrusion 11, and the annular protrusion 11.

[0028] (Separation Groove Formation Step) Fig. 6 is a cross-sectional view showing the separation groove forming step shown in Fig. 3. Fig. 7 is a perspective view showing the wafer after the separation groove forming step shown in Fig. 3. The separation groove forming step 102 is a step of forming a separation groove 14 along the circumferential direction of the wafer 1 on the outer edge of the circular recess 10 at the boundary between the circular recess 10 and the annular protrusion 11 of the wafer 1 in order to separate the circular recess 10 and the annular protrusion 11.

[0029] 6, in the separation groove forming step 102, a removal device 40 sucks and holds the bottom surface 12 of the circular recess 10 of the wafer 1 via a protective member 21 on a flat holding surface 42 along the horizontal direction of a disk-shaped conveyance table 41 having a diameter smaller than the inner diameter of the circular recess 10. In the embodiment 1, in the separation groove forming step 102, the removal device 40 sets a focusing point 44 of a laser beam 43 having a wavelength absorbed by the wafer 1 on the outer peripheral surface 3 of the device region 4, rotates the conveyance table 41 around its axis, and irradiates the laser beam 43 from a laser beam application unit 45 onto the outer peripheral surface 3 of the device region 4 over the entire circumference of the wafer 1.

[0030] 7, in the separation groove forming step 102, the removal device 40 forms a separation groove 14 penetrating the entire circumference of the wafer 1 from the surface 3 of the outer edge of the device region 4 along the outer edge of the bottom surface 12 of the circular recess 10. Thus, in the embodiment 1, the separation groove forming step 102 forms the separation groove 14 that completely cuts the wafer 1 by irradiating the wafer 1 with a laser beam 43 having an absorbent wavelength.

[0031] In the first embodiment, in the separation groove forming step 102, for example, when the thickness of the device region 4 is 100 μm, the laser beam 43 has an infrared (IR) wavelength and an average output of 30 W, and the conveyor table 41 holding the wafer 1 is rotated at a processing feed speed of 120 rpm or the like to process in the circumferential direction, and a separation groove 14 that completely cuts the wafer 1 is formed in about 30 seconds.

[0032] (Groove formation step) Fig. 8 is a cross-sectional view that shows a schematic diagram of the groove forming step shown in Fig. 3. Fig. 9 is a perspective view that shows the wafer after the groove forming step shown in Fig. 3. The groove forming step 103 is a step of forming a groove 15 in the annular protrusion 11 along the radial direction of the wafer 1.

[0033] In the first embodiment, in the groove forming step 103, the removing device 40 sets a focal point 44 of a laser beam 43 having a wavelength absorbent for the wafer 1 on the outer peripheral surface 3 of the outer circumferential surplus region 5. In the first embodiment, in the groove forming step 103, as shown in Fig. 8, the removing device 40 moves the conveying table 41 parallel to the horizontal direction and along the radial direction of the wafer 1 so that the laser beam application unit 45 approaches the device region 4 relatively, and irradiates the laser beam 43 from the laser beam application unit 45 onto the surface 3 of the outer circumferential surplus region 5 along the radial direction of the wafer 1.

[0034] In the first embodiment, in the groove forming step 103, the removal device 40 stops the irradiation of the laser beam 43 at the outer circumferential surplus region 5, i.e., the inner edge of the annular convex portion 11. Thus, in the first embodiment, in the groove forming step 103, the removal device 40 forms a concave groove 15 from the surface 3 of the outer circumferential surplus region 5. In the first embodiment, in the groove forming step 103, as shown in FIG. 8, after forming one groove 15, the removal device 40 rotates the conveying table 41 around the axis by a predetermined angle, stops the rotation of the conveying table 41, and again moves the conveying table 41 parallel to the horizontal direction and along the radial direction of the wafer 1, and irradiates the laser beam 43 from the laser beam application unit 45 to the surface 3 of the outer circumferential surplus region 5 along the radial direction of the wafer 1, thereby forming the concave groove 15 from the surface 3 of the outer circumferential surplus region 5. Note that in the first embodiment, the groove 15 does not communicate with the separation groove 14.

[0035] In the first embodiment, in the groove forming step 103, as shown in Fig. 9, the removing device 40 forms a plurality of grooves 15 along the radial direction in the outer peripheral excess region 5. In the first embodiment, in the groove forming step 103, the removing device 40 forms grooves 15 parallel to the planned dividing lines 6 of the wafer 1, and forms four grooves 15 in a direction along the crystal orientation of the back surface 8 of the wafer. Thus, in the first embodiment, the groove forming step 103 forms the grooves 15 by irradiating the wafer 1 with a laser beam 43 having an absorbent wavelength.

[0036] In the first embodiment, in the groove forming step 103, for example, when the thickness of the annular convex portion 11 is about 700 μm and the radial width of the annular convex portion 11 is about 3 mm, a groove 15 with a depth of about 200 μm is formed by processing for about 1 to 2 seconds per location. Also, in the first embodiment, in the groove forming step 103, the conveyor table 41 holding the wafer 1 moves in the radial direction of the wafer 1 to form the groove 15 in the radial direction in the annular convex portion 11. In the first embodiment, four grooves 15 are formed, and the annular convex portion 11 is divided into four in the removal step 104 described later. The number of grooves 15 is optimal without reducing productivity, but it is considered that about four is optimal in order for the annular convex portion 11 to be neatly broken along the grooves 15 by the impact of the drop, but more than four may be used.

[0037] (Removal step) Fig. 10 is a cross-sectional view showing a state in which the wafer is suction-held by the holding unit in the removal step shown in Fig. 3. Fig. 11 is a cross-sectional view showing a state in which the annular convex portion is dropped in the removal step shown in Fig. 3. The removal step 104 is a step in which, after the separation groove forming step 102 and the groove forming step 103, the annular convex portion 11 is dropped while the wafer 1 is held by the holding unit 46 via the protective member 21, thereby removing the annular convex portion 11 from the back surface 8 of the wafer 1.

[0038] 10 , in the removing step 104, the removing device 40 suction-holds the bottom surface 12 of the circular recess 10 of the wafer 1 via the protective member 21 on a flat holding surface 47 along the horizontal direction of a disk-shaped holding unit 46 having a diameter smaller than the inner diameter of the circular recess 10. In the removing step 104 in the embodiment 1, the removing device 40 clamps both surfaces of the annular frame 20 with clamping rollers 48, and brings the pressing roller 49 into contact with the back surface 8 of the annular protrusion 11.

[0039] 11, in the removing step 104, the removing device 40 rotates the holding unit 46 around its axis while pressing the back surface 8 of the annular protrusion 11 with the pressing roller 49, causing the annular protrusion 11 to drop into a collection box 50. At this time, the grooves 15 become the starting points for fracture of the annular protrusion 11, causing the annular protrusion 11 to break regularly, and the annular protrusion 11 to be divided into a plurality of pieces. Thus, in the removing step 104 in the embodiment 1, the removing device 40 removes the annular protrusion 11 from the back surface 8 of the wafer 1.

[0040] As described above, the processing method of the wafer according to the first embodiment includes a separation groove forming step 102 in which a separation groove 14 is formed along the circumferential direction of the wafer 1 on the outer edge of the circular recess 10 at the boundary between the circular recess 10 and the annular protrusion 11 of the wafer 1, a groove forming step 103 in which a groove 15 is formed in the annular protrusion 11 along the radial direction of the wafer 1 with respect to the annular protrusion 11, and a removal step 104 in which the annular protrusion 11 is dropped while the wafer 1 is held by the holding unit 46 via the protective member 21 after the separation groove forming step 102 and the groove forming step 103 to remove the annular protrusion 11. Therefore, in the processing method of the wafer according to the first embodiment, when the annular protrusion 11 is removed from the rear surface 8 of the wafer 1 and dropped, the groove 15 becomes the starting point of the fracture of the annular protrusion 11 and the annular protrusion 11 is regularly broken, so that it is possible to prevent the annular protrusion 11 from being shattered and scattered.

[0041] As a result, the wafer processing method according to the first embodiment has the effect of suppressing the generation of particles when the circular recess 10 and the annular protrusion 11 of the wafer 1 are separated.

[0042] Furthermore, in the wafer processing method according to embodiment 1, since grooves 15 are aligned along the crystal orientation toward back surface 8, annular protrusion 11 can be divided along grooves 15 in removal step 104, and the annular protrusion 11 can be prevented from shattering and scattering.

[0043] The present invention is not limited to the above embodiment. That is, various modifications can be made without departing from the gist of the present invention. For example, in the separation groove forming step 102, the removal device 40 may set a focal point 44 as in the first embodiment and irradiate the surface 3 of the outer edge of the device region 4 with a laser beam 43 over the entire circumference of the wafer 1, as shown in FIG. 12, to form a separation groove 14 that does not completely cut the wafer 1 from the surface 3 of the outer edge of the device region 4 along the outer edge of the bottom surface 12 of the circular recess 10 over the entire circumference of the wafer 1.

[0044] In this case, the thickness 17 of the remaining portion 16 connecting the circular recess 10 and the annular protrusion 11 at the bottom of the separation groove 14 is desirably a thickness 17 that allows the circular recess 10 and the annular protrusion 11 to be separated in the removal step 104, and is desirably greater than 0 μm and less than 100 μm. Note that Fig. 12 is a cross-sectional view that shows a schematic view of the main part of the wafer after the separation groove forming step in the wafer processing method according to the modified example of the first embodiment. In Fig. 12, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0045] In the present invention, in the protective member providing step 101 , a protective member 21 may be provided on the front surface 3 of the wafer 1 .

[0046] In the present invention, the groove forming step 103 may be performed before or after the separation groove forming step 102, or the groove 15 may be formed while the separation groove 14 is being formed.

[0047] In the present invention, it is preferable that the groove forming step 103 forms the groove 15 that does not completely cut the annular projection 11 in the thickness direction, but it is also possible to form the groove 15 that cuts it completely.

[0048] In addition, in embodiment 1, removal step 104 is a method in which the annular convex portion 11 is pressed from above and dropped downward, but in the present invention, a method in which a thin blade-like jig is inserted between the wafer 1 and the protective member 21 to drop the annular convex portion 11 may also be used. [Explanation of symbols]

[0049] 1 wafer 3 Surface (other side) 8 Back side (one side) 10 Circular recess (recess) 11 Annular protrusion 14 Separation groove 15 groove 21 Protective materials 43 Laser Beam 101 Protective member installation step 102 Separation groove formation step 103 Groove formation step 104 Removal Step

Claims

1. A wafer processing method for separating a wafer having a recess on one surface and a ring-shaped protrusion surrounding the recess from the protrusion, the method comprising the steps of: a protective member providing step of providing a protective member on the one surface of the wafer or on the other surface opposite to the one surface; a separation groove forming step of forming a separation groove along a circumferential direction of the wafer in the recess at the boundary between the recess and the protrusion of the wafer in order to separate the recess and the protrusion; a groove forming step of forming a groove in the protrusion along a radial direction of the wafer; a separation groove forming step and, after the groove forming step, a removal step of removing the convex portion from the one side of the wafer by dropping the convex portion while the wafer is held by a holding unit via the protective member.

2. 2. The wafer processing method according to claim 1, wherein the separation groove forming step comprises irradiating a laser beam having a wavelength absorbed by the wafer to form the separation grooves which either completely cut the wafer or do not completely cut the wafer.

3. 3. The wafer processing method according to claim 1, wherein the groove forming step forms the groove by irradiating the wafer with a laser beam having a wavelength which is absorbed by the wafer.

4. 2. The wafer processing method according to claim 1, wherein the groove forming step forms the groove in a direction along a crystal orientation of the one surface of the wafer.

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