Processing method

Abstract

To provide a processing method that can easily hollow out a desired region of a workpiece.SOLUTION: A processing method is for hollowing out a part of a workpiece from a first surface of the workpiece having a first surface and a second surface that is a rear surface of the first surface. The processing method comprises a contour groove forming step 101 of forming, along a contour of a part on the first surface, a contour groove that opens to the first surface, a separation starting point forming step 102 of, after performing the contour groove forming step 101, irradiating a region surrounded by the contour groove with a laser beam while a focal point of the laser beam having a wavelength transmissive to the workpiece is positioned inside the workpiece to form a separation starting point composed of a modified region and a crack extending from the modified region, and a separation step 103 of, after performing the separation starting point forming step 102, separating the part defined by the contour groove and the separation starting point from the workpiece.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a processing method for hollowing out a part of a workpiece. [Background technology]

[0002] BACKGROUND ART A workpiece may be processed by hollowing out a part thereof, and conventionally, this has been done by etching or the like (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2023-523896 [Patent Document 2] Patent Publication No. 2021-124646 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the processes shown in Patent Documents 1 and 2 make it difficult to control the hollowed-out area, and improvements have been eagerly desired.

[0005] An object of the present invention is to provide a processing method that can easily hollow out a desired area of ​​a workpiece. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the processing method of the present invention is a processing method for carving out a portion of a workpiece having a first surface and a second surface behind the first surface, the portion being opened on the first surface, and is characterized by comprising: a contour groove forming step for forming a contour groove that opens on the first surface along the contour of the portion on the first surface; after performing the contour groove forming step, a delamination origin forming step for irradiating a laser beam of a wavelength that is transparent to the workpiece with the focal point positioned inside the workpiece, and forming a delamination origin consisting of a modified region and a crack extending from the modified region; and a delamination step for peeling the portion defined by the contour groove and the delamination origin from the workpiece after performing the delamination origin forming step.

[0007] In the above processing method, in the peeling start point forming step, the laser beam may be irradiated with the focusing point positioned closer to the first surface than the groove bottom of the contour groove.

[0008] In the processing method, the contour groove forming step may involve irradiating a laser beam having a wavelength that is absorbed by the workpiece along the contour toward the first surface multiple times to form the contour groove.

[0009] In the above processing method, the contour may include a curved line. [Effects of the Invention]

[0010] The present invention has the advantage that a desired area of ​​a workpiece can be easily hollowed out. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a perspective view schematically showing a workpiece to be processed by the processing method according to the first embodiment. [Figure 2] FIG. 2 is an enlarged plan view showing a part of the first surface of the workpiece shown in FIG. [Figure 3] FIG. 3 is a flowchart showing the flow of the processing method according to the first embodiment. [Figure 4] FIG. 4 is a side view, partly in section, schematically showing the contour groove forming step of the processing method shown in FIG. [Figure 5] FIG. 5 is a side view, partially in section, schematically showing the peeling start point forming step of the processing method shown in FIG. [Figure 6] FIG. 6 is a cross-sectional view of a main part of a workpiece, which diagrammatically shows a peeling layer and the like formed in the peeling start point forming step of the processing method shown in FIG. [Figure 7] FIG. 7 is a cross-sectional view schematically showing the peeling step of the processing method shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] Modes (embodiments) 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 embodiments. Furthermore, the components described below include those that can be easily imagined by a person skilled in the art and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the configuration can be made within the scope of the gist of the present invention.

[0013] [Embodiment 1] A 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 schematically showing a workpiece to be processed by the processing method according to the first embodiment. Fig. 2 is a plan view showing an enlarged view of a part of a first surface of the workpiece shown in Fig. 1. Fig. 3 is a flowchart showing the flow of the processing method according to the first embodiment.

[0014] (workpiece) The processing method according to the first embodiment is a method for processing a workpiece 1 shown in Fig. 1. In the first embodiment, the workpiece 1 is a wafer having a substrate made of silicon, sapphire, gallium, glass, ceramics, lithium tantalate, lithium niobate, or the like, and having a circular first surface 2 and a circular second surface 3 that is parallel to and behind the first surface 2. In the first embodiment, the workpiece 1 is a disk-shaped silicon wafer having a substrate made of silicon, but the material and shape of the substrate are not limited to this in the present invention.

[0015] In embodiment 1, a portion 4 (shown in FIG. 2) is cut out of the workpiece 1 from the first surface 2 side. In embodiment 1, the portion 4 cut out of the workpiece 1 is set at a predetermined position on the first surface 2 of the workpiece 1, and in embodiment 1, multiple portions are cut out of the workpiece 1. In embodiment 1, the portion 4 cut out of the workpiece 1 integrally comprises a pair of circular portions 5 and a bent portion 6 that connects the circular portions 5 and is bent at the center, as shown in FIG. 2, and has a contour 7 that includes a curve. Note that in the present invention, the shape of the portion 4 cut out of the workpiece 1 is not limited to that shown in FIG. 2.

[0016] (Processing method) The processing method according to the first embodiment is a method of hollowing out a part 4 of a workpiece 1 having a first surface 2 and a second surface 3 behind the first surface 2, the part 4 having an opening in the first surface 2. As shown in Fig. 3, the processing method according to the first embodiment includes a contour groove forming step 101, a peeling start point forming step 102, and a peeling step 103.

[0017] (Contour groove forming step) Fig. 4 is a side view, partially in cross section, schematically showing the contour groove forming step of the processing method shown in Fig. 3. The contour groove forming step 101 is a step of forming a contour groove 11 that opens onto the first surface 2 along the contour 7 of the portion 4 on the first surface 2.

[0018] In the first embodiment, in the contour groove forming step 101, a disk-shaped protective tape 10 having the same diameter as the workpiece 1 is adhered to the second surface 3 of the workpiece 1, and the laser processing device 20 shown in Fig. 4 suction-holds the second surface 3 of the workpiece 1 to the holding surface 22 of the holding table 21 via the protective tape 10. In the first embodiment, in the contour groove forming step 101, the laser processing device 20 images the workpiece 1 with an imaging camera and performs alignment to align the workpiece 1 with the focusing lens 24, which is a collector of the laser beam irradiation unit 23.

[0019] In embodiment 1, in the contour groove forming step 101, as shown in Figure 4, the laser processing device 20 moves the holding table 21 and the laser beam irradiation unit 23 relatively along the contour 7 of a predetermined portion 4, sets the focal point of a pulsed laser beam 27, which is oscillated by an oscillator 25 and attenuated by an attenuator 26 and has a wavelength that is absorbable by the workpiece 1, on the first surface 2 of the workpiece 1, and irradiates the laser beam toward the first surface 2 of the workpiece 1, thereby forming a contour groove 11 that opens on the first surface 2 of the workpiece 1 along the contour 7 by ablation processing.

[0020] In the first embodiment, in the contour groove forming step 101, a laser beam 27 having a wavelength absorbable by the workpiece 1 is irradiated multiple times toward the first surface 2 along the contour 7, thereby forming a contour groove 11 having a depth 13 from the first surface 2 to the groove bottom 12 that is deeper than the thickness of the portion 4 to be hollowed out. In the first embodiment, when the holding table 21 and the laser beam irradiation unit 23 are moved relative to each other, they are moved relatively along X-axis and Y-axis directions (not shown) that are parallel to the holding surface 22 and perpendicular to each other, and the holding table 21 is rotated around an axis perpendicular to the holding surface 22. In the present invention, in the contour groove forming step 101, the contour groove 11 may be formed in the workpiece 1 by etching without irradiating the workpiece with the laser beam 27.

[0021] (peeling start point formation step) Fig. 5 is a side view, partially in cross section, schematically showing the delamination start point forming step of the processing method shown in Fig. 3. Fig. 6 is a cross-sectional view of a main part of a workpiece, schematically showing the delamination layer and the like formed in the delamination start point forming step of the processing method shown in Fig. 3. In the delamination start point forming step 102, after the contour groove forming step 101 is performed, the laser beam 36 is irradiated onto the region 14 surrounded by the contour groove 11 with the laser beam 36 having a wavelength that is transparent to the workpiece 1, with the focal point 37 of the laser beam 36 positioned inside the workpiece 1, to form a delamination layer 17 (corresponding to a delamination start point) consisting of a modified region 15 and a crack 16 extending from the modified region 15.

[0022] In the first embodiment, in the peel start point forming step 102, the laser processing device 30 shown in Fig. 5 suction-holds the second surface 3 of the workpiece 1 on the holding surface of the holding table via the protective tape 10 (omitted in Fig. 5). In the first embodiment, in the peel start point forming step 102, the laser processing device 30 images the workpiece 1 with an imaging camera and performs alignment to align the workpiece 1 with the condenser lens 32, which is a condenser of the laser beam irradiation unit 31.

[0023] In the first embodiment, in the peel start point forming step 102, the laser processing device 30, while moving the holding table and the laser beam application unit 31 relatively as shown in Fig. 5, sets a focal point 37 of a pulsed laser beam 36 having a wavelength that is transparent to the workpiece 1, the pulsed laser beam 36 being oscillated by an oscillator 33, attenuated by an attenuator 34, and branched into a plurality of beams (six in the first embodiment) by a branching unit 35 in a direction parallel to the holding surface, inside the region 14 of the workpiece 1, and irradiates the laser beam 36 toward the first surface 2 of the workpiece 1. In the first embodiment, in the peel start point forming step 102, the laser processing device 30 irradiates the laser beam 36 by positioning the focal point 37 closer to the first surface 2 than the groove bottom 12 of the contour groove 11.

[0024] 6, a plurality of modified regions 15 with a disordered crystal structure are formed side by side on the first surface 2 of the workpiece 1, with the center being a focal point 37 inside the substrate of the workpiece, and cracks 16 extend from the modified regions 15 along the first surface 2 along a predetermined crystal plane of the workpiece 1. Therefore, in the delamination start point forming step 102 in the first embodiment, cracks 16 connect the modified regions 15 to each other, and the cracks 16 extend from the outermost modified region 15 along the first surface 2. In the first embodiment, in the delamination start point forming step 102, the laser processing apparatus 30 positions the focal point 37 at the aforementioned position inside each region 14 and irradiates the laser beam 36 at predetermined intervals.

[0025] In embodiment 1, in the peel starting point formation step 102, the crack 16 extending from the modified region 15 closest to the contour groove 11 reaches the inner surface of the contour groove 11, as shown in Figure 6, and the cracks 16 extending from adjacent modified regions 15 connect to each other, forming a peel layer 17 consisting of multiple modified regions 15 and cracks 16 inside each region 14, and the portion 4 to be cut out from the workpiece 1 is defined by the contour groove 11 and the peel layer 17.

[0026] (peeling step) Fig. 7 is a cross-sectional view schematically showing the peeling step of the processing method shown in Fig. 3. In the peeling step 103, after the peeling start point forming step 102 is performed, the part 4 defined by the contour groove 11 and the peeling layer 17 is peeled from the workpiece 1.

[0027] In the first embodiment, in the peeling step 103, tape 18 is adhered to first surface 2 of workpiece 1, and then tape 18 is peeled off from first surface 2 of workpiece 1. Then, because a release layer 17 is formed inside region 14 surrounded by contour groove 11, as shown in FIG. 7 , the release layer 17 is torn as a starting point, and part 4 is separated from workpiece 1 while remaining adhered to tape 18.

[0028] The processing method according to the first embodiment described above forms a contour groove 11 along the contour 7 of the portion 4 to be cut out of the workpiece 1 in the contour groove forming step 101, and forms a peel layer 17 inside the aforementioned region 14 of the workpiece 1 in the peel start point forming step 102, so that the portion 4 to be cut out of the workpiece 1 can be defined by the contour groove 11 and the peel layer 17.

[0029] As a result, the processing method of embodiment 1 has the advantage that the aforementioned portion 4 can be easily peeled off from the workpiece 1 in the peeling step 103, and the desired area of ​​the workpiece 1 can be easily carved out.

[0030] The present invention is not limited to the above-described embodiment, and can be implemented in various modifications without departing from the gist of the present invention. [Explanation of symbols]

[0031] 1 Workpiece 2 Front page 3 Side 2 4 part 7. Contour 11 Contour groove 12 Groove bottom 14 areas 15 Modification Area 16 Crack 17 Peeling layer (peeling starting point) 27 Laser Beam 36 Laser Beam 37 Focus point 101 Contour groove forming step 102 Peeling origin formation step 103 Peeling step

Claims

1. A processing method for hollowing out a part of a workpiece having a first surface and a second surface behind the first surface, the second surface having an opening in the first surface, the method comprising: a contour groove forming step of forming a contour groove that opens onto the first surface along the contour of the portion on the first surface; a peeling initiation forming step in which, after the contour groove forming step, a laser beam having a wavelength that is transparent to the workpiece is irradiated onto the region surrounded by the contour groove with the laser beam positioned at a focal point inside the workpiece, thereby forming a peeling initiation point consisting of a modified region and a crack extending from the modified region; a peeling step of peeling the portion defined by the contour groove and the peeling starting point from the workpiece after the peeling starting point forming step is performed.

2. 2. The processing method according to claim 1, wherein in the separation start point forming step, the laser beam is irradiated with the focusing point positioned closer to the first surface than the groove bottom of the contour groove.

3. The processing method according to claim 1 or claim 2, wherein the contour groove forming step forms the contour groove by irradiating a laser beam having a wavelength that is absorbed by the workpiece toward the first surface along the contour multiple times.

4. The method of claim 3 , wherein the contour includes a curve.

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