JP2017070961A - Substrate processing method and peeling substrate manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that it is difficult to process when a processing layer is formed by laser on a substrate of such as Sic, and sapphire and is peeled because a crack is liable to be generated along crystal orientation.SOLUTION: A substrate processing method includes: a laser light condensing step of irradiating a surface of a substrate 10 with a laser light from a laser light source 150 of pulse irradiation by a laser light condensing part 160 and condensing the laser light to a predetermined depth from the surface; and a positioning step of relatively moving the laser light condensing part 160 to the substrate 10 and positioning. The laser light condensing step includes a laser light adjusting step of using a diffraction optical element 170 for branching the laser light from the laser light source 150 into a plurality of branched laser lights and making intensity of the adjacent branched laser lights different.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a substrate processing method and a release substrate manufacturing method of silicon carbide, sapphire, gallium nitride, etc., and more specifically to a substrate processing method and a release substrate manufacturing method by laser processing.

  Conventionally, when manufacturing a semiconductor wafer represented by a silicon (Si) wafer, a cylindrical ingot solidified from a silicon melt melted in a quartz crucible is cut into blocks of an appropriate length, A peripheral edge is ground to a target diameter, and then a block ingot is sliced into a wafer shape by a wire saw to manufacture a semiconductor wafer. In this specification, a wafer is appropriately referred to as a substrate unless otherwise specified.

  The semiconductor wafer manufactured in this way is subjected to various processes such as circuit pattern formation in the previous process in order and used in the subsequent process. In this subsequent process, the back surface is back-grinded and thinned. .

  In recent years, silicon carbide (SiC), which has high hardness and high thermal conductivity, has attracted attention. However, because of its higher hardness than crystalline silicon, the ingot cannot be easily sliced with a wire saw, and the back It is not easy to thin the substrate by grinding. Furthermore, sapphire substrates and gallium nitride substrates are also difficult to process, and processing techniques are required.

  On the other hand, an aberration-enhancing material consisting of a glass plate is combined with a high numerical aperture condensing lens, and a processed layer is formed by irradiating the inside of the wafer with a pulsed laser. Thus, a technique for obtaining a thin release substrate is disclosed (see Patent Document 1 below).

JP 2014-19120 A

  However, if a crystal material such as a SiC, sapphire, or gallium nitride wafer is processed with a laser to form a release layer in order to form a release substrate, cracks are likely to occur along the crystal orientation due to processing. It was difficult to form a stable processed layer.

  The present invention is provided in view of the above circumstances, and a substrate processing method capable of suppressing the generation of cracks in a crystalline material and stably forming a processed layer, and such a substrate processing. An object of the present invention is to provide a method for producing a release substrate to which the method is applied.

  In order to solve the above-mentioned problems, a substrate processing method according to the present application is a substrate processing method for processing a substrate so as to form a processing layer inside a crystal substrate, and a laser beam from a laser light source for pulse irradiation is used. A laser condensing step of irradiating the surface of the substrate with a laser condensing means and condensing the laser light to a predetermined depth from the surface of the substrate, and moving the laser condensing means relative to the substrate A positioning step of positioning the laser beam, wherein the laser focusing step uses a diffractive optical element that splits the laser beam from the laser light source into a plurality of branch laser beams so that the intensities of the branch laser beams are different. A step of adjusting the laser beam to process the substrate by extending the processing layer with the branch laser beam having a relatively high intensity in the branch laser beam, and It is intended to suppress the extension of the working layer by a relatively low strength branched laser light in light. Here, “relative” means a result of relative comparison with other branched laser beams among the plurality of branched laser beams.

  In the laser beam adjusting step, it is preferable that the intensity of the branched laser beam is varied at a magnification in the range of 1.1 to 5.0. In the laser beam adjusting step, it is preferable that the plurality of branched laser beams are arranged in a single row, a plurality of rows, or a pattern inside the substrate.

  In the laser beam adjusting step, the laser beam is branched into a plurality of branched laser beams, and at least one branched laser beam arranged at an end of the plurality of branched laser beams arranged in one row, a plurality of rows, or a pattern. It is preferable to make the strength relatively low. In the laser beam adjusting step, it is preferable that the relative intensity of the plurality of branched laser beams arranged in a row is in a range of a magnification of 1.1 to 5.0.

  The laser beam adjusting step is an arrangement in which the laser beam is branched into a plurality of branched laser beams, and the intensity of the laser beam is relatively provided. The laser beam adjusting step includes the one or more columns, Or it is preferable to make it the relative intensity | strength of the some branched laser beam arrange | positioned at pattern form in the range of the magnification of 1.1-5.0.

  In the positioning step, it is preferable that the laser condensing means is moved at a predetermined speed in a scanning direction that forms a predetermined angle in the direction of one row, a plurality of rows, or a pattern on the surface of the substrate. The scanning direction preferably includes a direction orthogonal to the one or more rows or the pattern direction.

  In the positioning step, on the surface of the substrate, an operation of moving the laser condensing unit at a predetermined speed in the scanning direction, and an operation of shifting the laser condensing unit over a predetermined distance in a direction orthogonal to the scanning direction. It is preferable to repeat the process between them.

  According to another aspect of the present invention, there is provided a peeled substrate manufacturing method comprising: a k substrate processing step for forming a processed layer on the substrate by the substrate processing method; and peeling the substrate on which the processed layer has been formed by the substrate processing step. And a substrate peeling step for producing a peeling substrate.

  According to the present invention, it is possible to suppress the occurrence of cracks in a crystalline material, to form a stable processed layer, and to provide a substrate on which such a stable processed layer is formed. Furthermore, the peeling substrate can be easily manufactured by peeling the substrate with the processed layer.

It is a perspective view of a substrate processing apparatus. It is a top view of the stage which mounted the board | substrate. It is sectional drawing of the stage which mounted the board | substrate. It is a figure explaining formation of the process layer in a board | substrate. It is a figure which shows three branch laser beams irradiated to the board | substrate. It is a figure explaining the adjustment of the space | interval of an adjacent process mark. It is a microscope picture which shows the processing trace formed in the board | substrate inside with the laser beam. 2 is a photograph showing Example 1; 2 is a measurement result of surface roughness on a release surface of Example 1. FIG. 6 is a photograph showing Example 2. It is a measurement result of the surface roughness in the peeling surface of Example 2. FIG. 6 is a photograph showing Example 3. It is a measurement result of the surface roughness in the peeling surface of Example 3. 6 is a photograph showing Example 4. It is a measurement result of the surface roughness in the peeling surface of Example 4. 6 is a photograph showing Example 5. It is a measurement result of the surface roughness in the peeling surface of Example 5. It is a graph which shows the example of distribution of the intensity | strength of several branch laser beam. It is a figure which shows the some branched laser beam arrange | positioned at multiple rows or a pattern form.

  Next, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the thickness of each layer, and the like are different from the actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  Further, the embodiments described below exemplify a method and a substrate for embodying the technical idea of the present invention, and the embodiments of the present invention include the material, shape, structure, The layout is not specified as follows. Various modifications can be made to the embodiment of the present invention within the scope of the claims.

  FIG. 1 is a perspective view showing the configuration of the substrate processing apparatus 100. The substrate processing apparatus 100 includes a stage 110, a stage support 120 that supports the stage 110 so that the stage 110 can move in the XY directions, and a substrate fixture 130 that is disposed on the stage 110 and fixes the substrate 10. Yes. As the substrate 10, a silicon carbide (SiC) wafer obtained by cutting an ingot can be used.

  The substrate processing apparatus 100 also includes a laser light source 150 and a laser condensing unit 160 that condenses the laser light 190 emitted from the laser light source 150 and irradiates the laser light 190 toward the substrate 10. The laser condensing unit 160 includes a diffractive optical element (DOE) 170 and an objective lens 180.

  The diffractive optical element 170 branches the incident laser beam 190 into a predetermined number of branched laser beams. The branched laser beams are condensed by the objective lens 180 and arranged so as to be aligned in a line at the focal position of the laser condensing unit 160. In the figure, the diffractive optical element 170 generates three branched laser beams, but is not limited to this. The branched laser beam may be two or more plural branched laser beams.

  The diffractive optical element 170 is adjusted so that the intensities of the plurality of branched laser beams are different. Here, that the intensity | strength of several branched laser beams differs means that at least 1 intensity | strength of several branched laser beams differs from the intensity | strength of other branched laser beams. For example, the intensity of adjacent branched laser beams may be different from each other.

  In the present embodiment, the relative intensities of the plurality of branched laser beams can be made different at a magnification in the range of 1.1 to 5.0. This magnification is preferably in the range of 1.2 to 3, more preferably in the range of 1.5 to 2.5, and still more preferably in the range of 1.8 to 2.2.

  In the present embodiment, by adjusting the intensity of the plurality of branched laser beams branched by the diffractive optical element 170 to be different from each other, cracks generated when forming a processing mark in the substrate 10 are controlled. ing.

  In the present embodiment, a peelable processing state in which a crack progresses at right angles to the laser irradiation direction is formed by a relatively high intensity beam among a plurality of branch lasers. In addition, a processed layer in which cracks do not progress with a relatively low intensity beam is formed, and the crack formed by a high intensity beam acts as a stopper so that it does not unintentionally propagate along the crystal orientation. Yes.

  FIG. 2 is a top view showing the substrate 10 placed on the stage 110. FIG. 3 is a cross-sectional view showing the substrate 10 placed on the stage 110.

  The substrate 10 is held on the stage 110 by the substrate fixture 130. The substrate fixture 130 fixes the substrate 10 by a fixing table 125 provided thereon. A normal adhesive layer, mechanical chuck, electrostatic chuck or the like can be applied to the fixed table 125.

  A condensing point P of the laser beam 190 that is condensed and irradiated on the substrate 10 forms a processing mark 12 having a predetermined shape in a region having a predetermined depth from the surface inside the substrate 10. The processing mark 12 is formed in the substrate 10 according to a predetermined pattern by positioning the laser condensing unit 160 relative to the substrate 10 held on the stage 110.

  For example, a linear process is performed by repeating an operation of moving the condensing point P at a predetermined speed in a predetermined scanning direction with an operation of shifting the condensing point P over a predetermined distance in a direction orthogonal to the scanning direction. A processed layer 14 in which the marks 12 are two-dimensionally arranged can be formed.

  FIG. 4 is a diagram illustrating the formation of the processed layer 14 on the substrate 10. In the substrate processing apparatus 100, the laser light 190 is irradiated toward the substrate 10 through the diffractive optical element 170 and the objective lens 180 of the laser condensing unit 160, and the branched beams are collected at the condensing point P inside the substrate 10. The processing mark 12 is formed at the condensing point P.

  The laser condensing unit 160 condenses light so that the diameter of the branched laser light is substantially reduced in a predetermined depth range t of the substrate 10, and energy necessary for forming the processing layer 14 to which the processing marks 12 are connected. The density is ensured. In the drawing, the processed layer 14 formed in a range t of a predetermined depth including the condensing point P by the branched laser light incident from the surface side of the substrate 10 is shown.

  The processed layer 14 is formed by connecting processing marks having different crystal structures formed by impacts of the branched laser beams irradiated on the substrate 10. The processed layer 14 formed in this manner has a predetermined periodic structure because adjacent branched laser beams are at a predetermined interval.

  FIG. 5 is a diagram showing three branched laser beams irradiated on the substrate 10. FIG. 5A is a top view of the substrate 10, and FIG. 5B is a cross-sectional view of the substrate 10. The three branched laser beams L1, L2, and L3 irradiated toward the surface of the substrate 10 form three beam spots R1, R2, and R3 arranged in a line on the surface of the substrate 10 and enter the substrate 10. Then, three condensing points F1, F2, and F3 are formed inside the substrate 10. The machining marks 12 are formed by these condensing points F1, F2, and F3, respectively.

  Since the substrate 10 is a crystal substrate such as SiC, there is a property that cracks are likely to occur along the crystal orientation when forming the processing marks F1, F2, and F3. In the present embodiment, the occurrence of cracks is controlled by adjusting the intensity of adjacent branch laser beams to be different.

  At this time, the intensities of the branched laser beams L1 and L3 are set to the minimum intensity at which the processing traces do not progress in the crystal orientation from the condensing points F1 and F3, and the processing traces necessary for peeling the substrate can be obtained. It is necessary.

  For example, by making the intensity of the central branched laser beam L2 greater than the intensity of the branched laser beams L1 and L3 on both sides, the cracks generated when the processing mark 12 is formed by the central focal point F2 are collected on both sides. Even if progressing in the direction of the points F1 and F3, the progress of the cracks can be stopped by the processing marks 12 formed by the condensing points F1 and F3 on both sides.

  The intensity of the three branched beams is set so that the magnification of the intensity of the central branched laser beam L2 with respect to the intensity of the branched laser beams L1 and L3 on both sides is different at a magnification in the range of 1.1 to 5.0. Can do. This magnification is preferably in the range of 1.2 to 3, more preferably in the range of 1.5 to 2.5, and still more preferably in the range of 1.8 to 2.2.

  FIG. 6 is a diagram for explaining the adjustment of the interval between the adjacent processing marks 12 formed on the substrate 10. On the surface of the substrate 10, three beam spots R 1, R 2, R 3 arranged in a row are formed by the three branched laser beams L 1, L 2, L 3 supplied from the light converging unit 16. The three branched laser lights are condensed at the condensing points F1, F2, and F3 inside the substrate 10 through these beam spots R1, R2, and R3, and processing traces are respectively obtained at the condensing points F1, F2, and F3. Is formed.

  The three beam spots R1, R2, and R3 are scanned at a predetermined speed in a predetermined scanning direction. Pulse laser light is supplied from the laser light source 150, and the beam spots R1, R2, and R3 are formed at predetermined intervals in the scanning direction. The interval in the scanning direction can be arbitrarily set.

  Further, by adjusting the direction of the row in which the three beam spots R1, R2, and R3 are arranged, it is possible to adjust the interval between the three processing marks 12 formed through the beam spots R1, R2, and R3. It is.

  FIG. 6A shows a case where the direction of the row in which the three beam spots R1, R2, and R3 are arranged is set to be orthogonal to the scanning direction. At this time, the adjacent distance between the three beam spots R1, R2, and R3 is maximized in the direction orthogonal to the scanning direction, and therefore the distance between the processing marks 12 formed through the three beam spots R1, R2, and R3. Is also maximized.

  FIG. 6B shows a case where the direction in which the three beam spots R1, R2 and R3 are arranged and the direction orthogonal to the scanning direction are set to form an angle of θ = 45 °. The angle θ is not limited to 45 °, and the larger the angle θ, the shorter the adjacent distances of the beam spots R1, R2, and R3 in the direction orthogonal to the scanning direction, and thus the beam spots R1, R2, and R3 are passed through. The interval between the processing marks 12 formed in this way is also shortened.

  In the present embodiment, the substrate 10 on which the processed layer 14 is formed as described above is cleaved by the processed layer 14, and the substrate 10 is peeled off by the processed layer 14, whereby a release substrate can be created. Since the processing traces are connected in the processing layer 14, the substrate 10 can be easily cleaved and peeled along the processing layer 14.

  Hereinafter, examples to which the present embodiment is applied will be described. In this embodiment, a HALO GN 35k-100 laser oscillator manufactured by Innolight was used as the laser light source 150 of the substrate processing apparatus 100. The laser light source 150 can supply laser light 190 as shown in Table 1.

  As the diffractive optical element 170, one manufactured by Furukawa Machine Metal Industries, which branches three branched laser beams having an intensity of 1: 2: 1 from the laser beam 190 was used. LCPLN 100 × IR was used for the objective lens 180.

  The substrate 10 was a polycrystalline SiC substrate having a crystal structure 4H with a mirror-finished surface. And in order to clarify the property of the processing mark 12, the board | substrate 10 was processed on the conditions as Table 2. FIG. In Table 2, the angle of the diffractive optical element is an angle formed by the direction perpendicular to the scanning direction and the directions of three laser spots R1, R2, and R3 arranged in a line. The depth of focus is the depth from the surface of the substrate 10 at the focus corresponding to the condensing point P.

  FIG. 7 is a photomicrograph showing the processing marks 12 formed on the substrate 10 by such processing. FIG. 7A is an observation from the upper surface of a transparent SiC substrate 10 and shows three processing marks 12 formed through three laser spots R1, R2, and R3. Here, since the diffractive optical element 170 generates three branched laser beams L1, L2, and L3 having an intensity of 1: 2: 1, the central processing mark 12 is slightly thick and the processing marks 12 on both sides are slightly thin. ing.

  In FIG. 7B, the processing trace 12 formed on the substrate 10 is observed in a cross section substantially perpendicular to the extending direction of the processing trace 12, and three processing traces 12 are shown. Here, a crack progresses in the lateral direction from each processing mark 12, and the crack that has progressed from the central processing mark 12 extends to the processing marks 12 on both sides, but is stopped by the processing marks 12 on both sides. Was seen. Therefore, it became clear that these three processing marks 12 are connected by cracks, and further progress of cracks is controlled.

  Next, after forming the processing layer 14 with the processing marks 12 formed over the entire surface of the substrate 10, the substrate 10 is cleaved by the processing layer 14 to create a separation substrate, and the properties of the separation surface of the separation substrate are determined. Examined. In Example 1, the processed layer 14 was formed under the conditions shown in the column of Example 1 in Table 3. Except for the conditions shown in Table 3, the same conditions as in the previous example were used. For example, a polycrystalline SiC substrate having a crystal structure 4H is used as the substrate 10, and a diffractive optical element 170 that is branched into three branched laser beams is used.

  FIG. 8 is a photograph showing Example 1. FIGS. 8A and 8B are photomicrographs showing the processing marks before and after scribing formed on the substrate 10. FIG. 8C is a photomicrograph of a cross section of the substrate 10 using a laser microscope, and FIG. 8D is an enlarged photomicrograph in which the inside of the frame of FIG. 8C is enlarged.

  8 (c) and 8 (d), it can be seen that a processed layer 14 is formed in which the processing marks 12 are connected in the horizontal direction in the direction parallel to the surface of the substrate 10. FIG. 8D is a photograph showing the peeled surface of the peeled substrate cleaved by the processed layer 14 using a tensile tester. In Example 1, the peeling surface was formed in 90% of the entire surface of the peeling substrate.

  Subsequently, the surface roughness of the release surface of the release substrate was measured. On the upper surface on the laser irradiation side toward the laser condensing unit 160, Ra (μm) has a shape as shown in FIG. 9A and Rz (μm) as shown in FIG. 9B, and the results shown in Table 4 are obtained. was gotten. In Table 4, three-point measured values of surface roughness and average values thereof are shown. The same applies to the following.

  Note that the scanning direction indicates roughness in the scanning direction of the laser beam, and the offset direction indicates roughness formed between the branched beams in a direction of 90 ° with respect to the scanning direction.

  Further, on the lower surface on the side where it is placed on the stage 110, the shape shown in FIG. 9C for Ra (μm) and the shape shown in FIG. 9D for Rz (μm) are obtained, and the results shown in Table 5 are obtained. was gotten.

  In Example 2, the processed layer 14 was formed under the conditions shown in the column of Example 2 in Table 3. The test was performed under the same conditions as in Example 1 except for the conditions shown in Table 3. In Example 2, a release surface was formed on 50% of the surface of the release substrate.

  As for the surface roughness of the release surface of the release substrate, the upper surface on the laser irradiation side has a shape as shown in FIG. 11 (a) for Ra (μm) and FIG. 11 (b) for Rz (μm). The result was obtained. Further, on the lower surface on the stage side, the shape as shown in FIG. 11C for Ra (μm) and the shape as shown in FIG. 11D for Rz (μm) were obtained, and the results shown in Table 7 were obtained.

  In Example 3, the processed layer 14 was formed under the conditions shown in the column of Example 3 in Table 3. The test was performed under the same conditions as in Example 1 except for the conditions shown in Table 3. In Example 3, a release surface was formed on 30% of the surface of the release substrate.

  Regarding the surface roughness of the release surface of the release substrate, the upper surface on the laser irradiation side has a shape as shown in FIG. 13A for Ra (μm) and FIG. 13B for Rz (μm), as shown in Table 8. The result was obtained. Further, on the lower surface on the stage side, the shape as shown in FIG. 13C for Ra (μm) and the shape as shown in FIG. 13D for Rz (μm) were obtained, and the results shown in Table 9 were obtained.

  In Example 4, the processed layer 14 was formed under the conditions shown in the column of Example 4 in Table 3. The test was performed under the same conditions as in Example 1 except for the conditions shown in Table 3. In Example 4, a release surface was formed on 98% of the surface of the release substrate.

  Regarding the surface roughness of the release surface of the release substrate, the upper surface on the laser irradiation side has a shape as shown in FIG. 15A for Ra (μm) and FIG. 15B for Rz (μm). The result was obtained. Further, on the lower surface on the stage side, the shape as shown in FIG. 15C for Ra (μm) and the shape as shown in FIG. 15D for Rz (μm) were obtained, and the results shown in Table 11 were obtained.

  In Example 5, the processed layer 14 was formed under the conditions shown in the column of Example 5 in Table 3. The test was performed under the same conditions as in Example 1 except for the conditions shown in Table 3. In Example 5, a release surface was formed on 10% of the surface of the release substrate.

  Regarding the surface roughness of the release surface of the release substrate, the upper surface on the laser irradiation side has a shape as shown in FIG. 17A for Ra (μm) and FIG. 17B for Rz (μm), and is shown in Table 12. The result was obtained. Further, on the lower surface on the stage side, the shape as shown in FIG. 17C for Ra (μm) and the shape as shown in FIG. 17D for Rz (μm) were obtained, and the results shown in Table 13 were obtained.

  By forming the processed layer 14 on the substrate 10 made of SiC having the crystal structure 4H using the diffractive optical element 170 that is divided into three branched laser beams according to Examples 1 to 5, the processed layer 14 is cleaved. It became clear that a peeling substrate can be easily prepared by peeling. Moreover, it was recognized by the measurement of surface roughness that the smooth peeling surface was formed in the peeling board | substrate.

  In Examples 1 to 5, no clear dependency on the processing speed and the intensity of the laser beam was observed. This is considered to be because the SiC substrate 10 used for processing has a polycrystalline structure.

  In Examples 1 to 5, the polycrystalline SiC substrate 10 having the crystal structure 4H is used. However, the present invention is not limited to this, and the SiC substrate having the crystal structure 6H or the single crystal SiC substrate is used. It can be similarly applied to. Further, the present invention is not limited to a SiC substrate, and can be similarly applied to a sapphire substrate.

  In Examples 1 to 5, only one processed layer 14 is formed parallel to the surface of the substrate 10, but by setting the depth of the condensing point P appropriately by the laser condensing unit 160, 2 It is also possible to form a processed layer 14 that is equal to or greater than one layer, and to cleave and peel off the substrate 10 in these processed layers 14.

  In the present embodiment, three branched laser beams are exemplified as an example of a plurality of branched laser beams. However, the present invention is not limited to this. The plurality of branch laser beams may be two or more branch laser beams and have different intensities. For example, as shown in FIG. 18, nine branched laser beams may be used. The plurality of branched laser beams are arranged in a line. In FIG. 18A, the intensity of the branched laser beams at both ends is small, and the intensity of the central branched laser beam is larger than the intensity of the branched laser beams at both ends. In FIG. 18B, the intensity of the branched laser light at both ends and the center is small. In addition, since it affects peeling, it is preferable that the branched laser beams having the same intensity are included in the plurality of branched laser beams in order to stabilize the processed layer.

  Moreover, in this Embodiment, what was arrange | positioned in a line was illustrated as an example of a some branching laser beam, However, This invention is not limited to this. The plurality of branched laser beams may be arranged in a plurality of rows or in a pattern.

  FIG. 19 is a top view showing a state in which the beam spots of the branched laser light irradiated on the substrate 10 are arranged in a plurality of rows or patterns. The branched laser light is divided into four beam spots R11, R12, R13, R14 in the first row and four beam spots R21, R22, R23 in the second row in a direction orthogonal to the scanning direction indicated by the one-dot chain line in the drawing. , R24, four beam spots R31, R32, R33, R34 in the third row, and four beam spots R41, R42, R43, R44 in the fourth row.

  These beam spots form an arrangement of a plurality of rows composed of a total of four rows from the first row to the fourth row. In addition, a pattern of 16 beam spots of a total of 4 × 4, 4 rows in the scanning direction and 4 rows in the direction orthogonal to the scanning direction is also formed. Among these beam spots, the central four beam spots R22, R23, R32, R33 are the other beam spots R11, R12, R13, R14, R21, R24, R31, R34, R41, R42, R43 surrounding them. , R44 is stronger than R44, and may be in a range of magnification of 1.1 to 5.0, for example.

  The plurality of rows formed by the beam spots may be two or more, and the pattern of the beam spots may be a specific pattern formed by three or more beam spots.

  Since the release substrate can be efficiently and thinly formed by the substrate processing method of the present invention, the release substrate can be applied to a light emitting diode, a laser diode, or the like as long as it is a sapphire substrate such as a GaN-based semiconductor device. Can be applied to SiC power devices and the like, and can be applied in a wide range of fields such as transparent electronics, lighting, and hybrid / electric vehicles.

DESCRIPTION OF SYMBOLS 10 Substrate 14 Processed layer 100 Substrate processing apparatus 150 Laser light source 160 Laser condensing part 170 Diffractive optical element 180 Objective lens

Claims (9)

A substrate processing method for processing a substrate so as to form a processing layer inside a crystal substrate,
A laser condensing step of irradiating laser light from a laser light source of pulse irradiation toward the surface of the substrate by a laser condensing means, and condensing the laser light to a predetermined depth from the surface of the substrate;
A positioning step of moving the laser focusing means relative to the substrate for positioning, and
The laser condensing step includes a laser light adjustment step using a diffractive optical element that branches the laser light from the laser light source into a plurality of branched laser lights, so that the intensities of the branched laser lights are different.
The substrate is processed by extending the processing layer with the branch laser light having a relatively high intensity in the branch laser light, and the extension of the processing layer is suppressed by the branch laser light having a relatively low intensity in the branch laser light. A substrate processing method characterized by the above.   2. The substrate processing method according to claim 1, wherein in the laser beam adjusting step, the intensity of the branched laser beam is varied at a magnification in a range of 1.1 to 5.0. 3.   3. The substrate processing method according to claim 1, wherein in the laser beam adjustment step, the plurality of branched laser beams are arranged in a single row, a plurality of rows, or a pattern in the substrate.   The laser beam adjusting step branches the laser beam into a plurality of branched laser beams, and among the plurality of branched laser beams arranged in a single row, a plurality of rows or a pattern, at least one branched laser arranged at an end. 4. The substrate processing method according to claim 3, wherein the light intensity is relatively lowered.   The laser light adjusting step is characterized in that intensities of the plurality of branched laser beams arranged in one row, a plurality of rows, or a pattern are made different at a magnification in a range of 1.1 to 5.0. Item 5. A substrate processing method according to Item 4.   6. The positioning step according to claim 3, wherein, in the positioning step, the laser condensing unit is moved at a predetermined speed in a scanning direction that forms a predetermined angle in the direction of one row, a plurality of rows, or a pattern on the surface of the substrate. Substrate processing method.   The substrate processing method according to claim 6, wherein the scanning direction includes a direction orthogonal to the one or more rows or a pattern direction.   In the positioning step, on the surface of the substrate, an operation of moving the laser condensing unit at a predetermined speed in the scanning direction, and an operation of shifting the laser condensing unit over a predetermined distance in a direction orthogonal to the scanning direction. The substrate processing method according to claim 6, wherein the substrate processing method is repeated while sandwiching. A substrate processing step of forming a processed layer on the substrate by the substrate processing method according to claim 1;
And a substrate peeling step for creating a release substrate by peeling the substrate on which the processed layer is formed by the substrate processing step with the processed layer.