JP2020074468A - Substrate processing method - Google Patents

Abstract

To solve the problem that, when a processed layer is formed on a substrate such as SiC or sapphire by laser and peeled off, cracks easily occur along the crystal orientation and processing is difficult.SOLUTION: There are provided a laser condensing step of condensing the laser light by irradiating the laser light from a laser light source 150 of pulse irradiation to the surface of a substrate 10 by a laser condensing unit 160, and a positioning step of positioning the laser condensing unit 160 with respect to the substrate 10. The laser condensing step includes a laser light adjusting step in which a diffractive optical element 170 that branches the laser light from the laser light source 150 is used so that the intensities of the adjacent branched laser lights are different for the plurality of branched laser lights. In the branched laser light, the substrate 10 is processed by extending a processing layer 14 so that the processing marks are connected by the branched laser light having a relatively high intensity. At the same time, in the branched laser light, the extension of the processing layer 14 is suppressed by the branched laser light having a relatively low intensity.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for processing a substrate such as silicon carbide, sapphire, gallium nitride, etc., and more specifically to a method for processing a substrate by laser processing.

  Conventionally, when manufacturing a semiconductor wafer typified 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, and The peripheral portion is ground to have a target diameter, and then the blocked ingot is sliced into a wafer shape with 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 manner is subjected to various treatments such as circuit pattern formation in a pre-process and then subjected to a post-process. In the post-process, the back surface is back-ground to be thinned. ..

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

  On the other hand, after combining a high numerical aperture condenser lens with an aberration enhancing material consisting of a glass plate and irradiating the inside of the wafer with a pulsed laser to form a processing layer, this is attached to a rigid substrate and peeled off at the processing layer. A technique for obtaining a thin release substrate by doing so is disclosed (see Patent Document 1 below).

JP, 2014-19120, A

  However, when a crystal material such as a SiC, sapphire, or gallium nitride wafer is processed by a laser to form a separation substrate and a processed layer is formed inside, a crack is easily generated along the crystal orientation due to the processing. However, it was difficult to form a stable processed layer.

  The present invention is provided in view of the above circumstances, and an object of the present invention is to provide a substrate processing method capable of suppressing the occurrence of cracks in a crystalline material and stably forming a processing layer. And

  In order to solve the above-mentioned problems, a substrate processing method according to the present application is a substrate processing method of processing a substrate so as to form a processing layer inside a crystal substrate, in which laser light from a pulsed laser light source is used. A laser focusing step of irradiating the surface of the substrate with the laser focusing means to focus the laser light to a predetermined depth from the surface of the substrate; and moving the laser focusing means relatively to the substrate. And a positioning step of performing positioning, wherein the laser focusing step uses a diffractive optical element for branching the laser light from the laser light source into a plurality of branched laser lights, and the intensity of the branched laser lights is different. Laser beam adjusting step is performed to expand the processing layer by the branched laser beam having a relatively high intensity in the branched laser beam to process the substrate, 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 the result of relative comparison with another branched laser light among a plurality of branched laser lights.

  In the laser beam adjusting step, it is preferable that the intensity of the branched laser beam be varied at a magnification within a 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 one row or a plurality of rows or in a pattern inside the substrate.

  The laser beam adjusting step branches the laser beam into a plurality of branched laser beams, and at least one branched laser beam arranged at an end of the one or a plurality of columns or a plurality of branched laser beams arranged in a pattern. It is preferable that the strength is relatively low. In the laser light adjusting step, it is preferable that the relative intensities of the plurality of branched laser lights arranged in the line are in a range of 1.1 to 5.0.

  The laser beam adjusting step is to dispose the laser beam into a plurality of branched laser beams, and to relatively disperse the intensity of the laser beam, and the laser beam adjusting step is the one row or a plurality of rows, Alternatively, it is preferable that the relative intensities of the plurality of branched laser lights arranged in a pattern are in the range of 1.1 to 5.0.

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

  The positioning step includes an operation of moving the laser focusing means in the scanning direction at a predetermined speed on the surface of the substrate and an operation of shifting the laser focusing means in a direction orthogonal to the scanning direction over a predetermined distance. It is preferable to repeat by sandwiching.

  A peeled substrate manufacturing method according to the present application includes a substrate processing step of forming a processing layer on the substrate by the substrate processing method, and peeling and peeling the substrate on which a processing layer is formed by the substrate processing step at the processing layer. And a substrate peeling step of forming a substrate.

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

It is a perspective view of a substrate processing apparatus. It is a top view of a stage on which a substrate is placed. It is sectional drawing of the stage which mounted the board | substrate. It is a figure explaining formation of a processing layer in a substrate. It is a figure which shows the three branched laser beams with which the board | substrate was irradiated. It is a figure explaining adjustment of the space | interval of the adjacent processing marks. It is a microscope picture which shows the processing mark formed in the inside of a substrate by laser light. 3 is a photograph showing Example 1. 7 is a measurement result of surface roughness on the peeled surface of Example 1. 5 is a photograph showing Example 2. 5 is a result of measuring surface roughness on a peeled surface of Example 2. 5 is a photograph showing Example 3. 9 is a result of measuring surface roughness on a peeled surface of Example 3. 5 is a photograph showing Example 4. 9 is a result of measuring surface roughness on a peeled surface of Example 4. 5 is a photograph showing Example 5. 8 is a measurement result of surface roughness on a peeled surface of Example 5. It is a graph which shows the example of distribution of the intensity | strength of a some branched laser beam. It is a figure which shows the some branch laser beam arrange | positioned at multiple rows or pattern form.

  Next, an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar reference numerals are given to the same or similar parts. However, it should be noted that the drawings are schematic and the relationship between the thickness and the plane dimension, 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. Further, it is needless to say that the drawings include portions having different dimensional relationships and ratios.

  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 below. The embodiment of the present invention can be modified in various ways 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 unit 120 that supports the stage 110 so as to be movable in the XY directions, and a substrate fixture 130 that is disposed on the stage 110 and that fixes the substrate 10. There is. 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 it toward the substrate 10. The laser condensing unit 160 has a diffractive optical element (DOE) 170 and an objective lens 180.

  The diffractive optical element 170 splits the incident laser beam 190 into a predetermined number of split laser beams. The branched laser light is condensed by the objective lens 180 and arranged in a line at the focal position of the laser condensing unit 160. Although the diffractive optical element 170 generates three branched laser beams in the figure, the present invention is not limited to this. The branched laser light may be two or more branched laser lights.

  The diffractive optical element 170 adjusts the intensities of the plurality of branched laser lights so that they are different from each other. Here, the different intensities of the plurality of branched laser beams mean that at least one of the plurality of branched laser beams has an intensity different from that of the other branched laser beams. For example, the intensities of the adjacent branched laser lights may be different from each other.

  In the present embodiment, the relative intensities of the plurality of branched laser lights can be varied at magnifications 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 even more preferably in the range of 1.8 to 2.2.

  In the present embodiment, by adjusting the intensities of the plurality of branched laser beams branched by the diffractive optical element 170 to be different, it is possible to control cracks that occur when forming a processing mark inside the substrate 10. ing.

  In the present embodiment, a relatively high-intensity beam of a plurality of branch lasers forms a peelable processing state in which cracks propagate at right angles to the laser irradiation direction. In addition, by forming a processed layer in which cracks do not propagate due to a beam having a relatively low intensity, the crack formed by a beam having a high intensity acts as a stopper that does not propagate unintentionally along the crystal orientation. There is.

  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 a substrate fixture 130. The board fixing tool 130 fixes the board 10 by a fixing table 125 provided thereon. A general adhesive layer, a mechanical chuck, an electrostatic chuck, or the like can be applied to the fixed table 125.

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

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

  FIG. 4 is a diagram illustrating 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 via the diffractive optical element 170 of the laser condensing unit 160 and the objective lens 180, and the branched beams are collected at the condensing points P inside the substrate 10. It is irradiated with light and a processing mark 12 is formed at the condensing point P.

  The laser condensing unit 160 condenses the branched laser light so as to substantially reduce the diameter of the branched laser light in the range t of the predetermined depth of the substrate 10, and the energy required for forming the processing layer 14 to which the processing traces 12 are connected. I try to secure the density. In the figure, the processing layer 14 formed in the range t of a predetermined depth including the condensing point P by the branched laser light incident from the front surface side of the substrate 10 is shown.

  The processing layer 14 is formed by connecting processing marks having different crystal structures, which are formed by the impact of each branched laser beam with which the substrate 10 is irradiated. The processing layer 14 thus formed has a predetermined periodic structure because the adjacent branched laser beams have a predetermined interval.

  FIG. 5 is a diagram showing the three branched laser beams applied to the substrate 10. 5A is a top view of the substrate 10, and FIG. 5B is a sectional view of the substrate 10. The three branched laser lights L1, L2, L3 irradiated toward the surface of the substrate 10 form three beam spots R1, R2, R3 arranged in a line on the surface of the substrate 10 and are incident on the substrate 10. Then, three converging points F1, F2, F3 are formed inside the substrate 10. The processing marks 12 are formed by these focal points F1, F2, and F3.

  Since the substrate 10 is a crystal substrate such as SiC, it has a property that cracks are likely to occur along the crystal orientation when forming the processing traces F1, F2, and F3. In the present embodiment, the generation of cracks is controlled by adjusting the intensities of adjacent branched laser beams so that they are different.

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

  For example, by setting the intensity of the central branched laser beam L2 to be higher than the intensity of the branched laser beams L1 and L3 on both sides, a crack generated when the machining mark 12 is formed by the central focusing point F2 is focused on both sides. Even when the cracks propagate in the directions of the points F1 and F3, the cracks can be stopped from progressing by the processing marks 12 formed by the condensing points F1 and F3 on both sides.

  The intensities of the three branched beams are 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 in the range of 1.1 to 5.0. You can This magnification is preferably in the range of 1.2 to 3, more preferably in the range of 1.5 to 2.5, and even 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 R1, R2, R3 arranged in a line are formed by the three branched laser beams L1, L2, L3 supplied from the light condensing unit 16. The three branched laser lights are condensed at the condensing points F1, F2, F3 inside the substrate 10 via these beam spots R1, R2, R3, and the processing marks at the condensing points F1, F2, F3, respectively. Is formed.

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

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

  FIG. 6A shows a case in which the direction of the row in which the three beam spots R1, R2, R3 are arranged is set to be orthogonal to the scanning direction. At this time, the adjoining distance of the three beam spots R1, R2, and R3 becomes the maximum in the direction orthogonal to the scanning direction, and thus the interval of the processing marks 12 formed via the three beam spots R1, R2, and R3. Will also be the maximum.

  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 form an angle of θ = 45 °. The angle θ is not limited to 45 °, and the larger the angle θ, the shorter the adjacent distance between the beam spots R1, R2, and R3 in the direction orthogonal to the scanning direction, and therefore, the beam spots R1, R2, and R3. The intervals between the processing marks 12 formed by the above are also shortened.

  In the present embodiment, the substrate 10 on which the processing layer 14 is formed as described above is cut by the processing layer 14 and the substrate 10 is separated by the processing layer 14, whereby a peeled substrate can be formed. Since the processing marks are connected in the processing layer 14, the substrate 10 can be easily cut and peeled along the processing layer 14.

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

  As the diffractive optical element 170, used is one manufactured by Furukawa Kikai Kogyo Kogyo Co., Ltd., which splits three branched laser beams having an intensity of 1: 2: 1 from the laser beam 190. LCPLN 100 × IR was used for the objective lens 180.

  As the substrate 10, a polycrystalline SiC substrate having a crystal structure 4H with a mirror-finished surface was used. Then, the substrate 10 was processed under the conditions as shown in Table 2 in order to clarify the properties of the processing marks 12. In Table 2, the angle of the diffractive optical element is an angle formed by the direction orthogonal to the scanning direction and the directions of the three laser spots R1, R2, R3 arranged in a line. The depth of focus is the depth from the surface of the substrate 10 of the focus corresponding to the condensing point P.

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

  In FIG. 7B, the processing marks 12 formed on the substrate 10 are observed in a cross section substantially perpendicular to the extending direction of the processing marks 12, and three processing marks 12 are shown. Here, a crack propagates laterally from each machining mark 12, and a crack that propagates from the central machining mark 12 propagates to the machining marks 12 on both sides, but is stopped at the machining marks 12 on both sides. Was seen. Therefore, it was revealed that these three processing marks 12 are connected by the cracks and further progress of the cracks is controlled.

  Next, after forming the processing layer 14 by the processing marks 12 formed on the entire surface of the substrate 10, the substrate 10 is cut by the processing layer 14 to be peeled off to form a release substrate. 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 above example were used. For example, a polycrystalline SiC substrate having a crystal structure 4H was used as the substrate 10, and a diffractive optical element 170 used was one that splits into three branched laser beams.

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

  From FIGS. 8C and 8D, it can be seen that the processing layer 14 in which the processing marks 12 are connected is formed in the direction parallel to the surface of the substrate 10 and in the horizontal direction in the drawing. FIG. 8D is a photograph showing the peeled surface of the peeled substrate cut by the processing layer 14 using the tensile tester. In Example 1, the peeled surface was formed in 90% of the entire surface of the peeled substrate.

  Then, the surface roughness of the peeled surface of the peeled 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) has a shape as shown in FIG. 9B, and the results shown in Table 4 are obtained. was gotten. In Table 4, three-point surface roughness measurement values and their average values are shown. The same applies below.

  The scanning direction means the roughness in the scanning direction of the laser beam, and the offset direction means the roughness formed between the branched beams in the direction of 90 ° with respect to the scanning direction.

  In addition, the lower surface on the side mounted on the stage 110 has a shape as shown in FIG. 9C for Ra (μm) and as shown in FIG. 9D for Rz (μm). 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 conditions were the same as in Example 1 except for the conditions shown in Table 3. In Example 2, the peeled surface was formed on 50% of the surface of the peeled substrate.

  Regarding the surface roughness of the peeling surface of the peeling substrate, the shape on the upper surface on the laser irradiation side is as shown in FIG. 11A for Ra (μm) and as shown in FIG. 11B for Rz (μm), and is shown in Table 6. The result is as follows. Further, the lower surface on the stage side had a shape as shown in FIG. 11C for Ra (μm) and as shown in FIG. 11D for Rz (μm), 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 conditions were the same as in Example 1 except for the conditions shown in Table 3. In Example 3, the peeled surface was formed on 30% of the surface of the peeled substrate.

  Regarding the surface roughness of the peeling surface of the peeling 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), and is shown in Table 8. The result is as follows. Further, the lower surface on the stage side had a shape as shown in FIG. 13C for Ra (μm) and as shown in FIG. 13D for Rz (μm), 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 conditions were the same as in Example 1 except for the conditions shown in Table 3. In Example 4, the peeled surface was formed on 98% of the surface of the peeled substrate.

  Regarding the surface roughness of the peeling surface of the peeling substrate, the shape on 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), and is shown in Table 10. The result is as follows. Further, the lower surface on the stage side had a shape as shown in FIG. 15C for Ra (μm) and as shown in FIG. 15D for Rz (μm), and the results as 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 conditions were the same as in Example 1 except for the conditions shown in Table 3. In Example 5, the peeled surface was formed on 10% of the surface of the peeled substrate.

  Regarding the surface roughness of the peeling surface of the peeling 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 is as follows. Further, the lower surface on the stage side had a shape as shown in FIG. 17C for Ra (μm) and as shown in FIG. 17D for Rz (μm), and the results shown in Table 13 were obtained.

  According to the above Examples 1 to 5, the processing layer 14 is formed on the substrate 10 made of SiC having the crystal structure 4H by using the diffractive optical element 170 that divides the laser beam into three branched laser beams, and the processing layer 14 is cut. It was revealed that the peeling substrate can be easily prepared by peeling. In addition, it was confirmed from the measurement of the surface roughness that the peeled substrate had a smooth peeled surface.

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

  Although the polycrystalline SiC substrate 10 having the crystal structure 4H was used in Examples 1 to 5, 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. Can be similarly applied to. Further, the present invention is not limited to the SiC substrate, but can be similarly applied to a sapphire substrate or the like.

  Further, in each of Examples 1 to 5, only one processing layer 14 was formed in parallel with the surface of the substrate 10. However, by setting the depth of the focusing point P by the laser focusing section 160 as appropriate, It is also possible to form more than one processed layer 14 and cut the substrate 10 in these processed layers 14 to separate them.

  In the present embodiment, three branched laser lights are illustrated as an example of the plurality of branched laser lights, but the present invention is not limited to this. The plurality of branched laser lights are two or more branched laser lights and may have different intensities. For example, as shown in FIG. 18, nine branched laser lights may be used. The plurality of branched laser lights are arranged in a line. In FIG. 18A, the intensity of the branched laser lights at both ends is low, and the intensity of the central branched laser light is higher than the intensities of the branched laser lights at both ends. In FIG. 18B, the intensity of the branched laser light at both ends and the center is small. It is preferable that the plurality of branched laser lights include the branched laser light of the same intensity in order to stabilize the processed layer because it affects peeling.

  Further, in the present embodiment, as an example of the plurality of branched laser lights, ones arranged in a line are illustrated, but the present invention is not limited to this. The plurality of branched laser lights may be arranged in a plurality of columns or may be arranged in a pattern.

  FIG. 19 is a top view showing a state in which the beam spots of the branched laser light with which the substrate 10 is irradiated are arranged in a plurality of rows or patterns. The branched laser light is composed of four beam spots R11, R12, R13, R14 in the first row and four beam spots R21, R22, R23 in the second row in the direction orthogonal to the scanning direction shown by the alternate long and short dash line in the figure. , 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, that is, a total of four rows from the first row to the fourth row. In addition, a pattern is formed by 16 beam spots of 4 × 4 in total, four rows in the scanning direction and four rows in the direction orthogonal to the scanning direction. Of these beam spots, the central four beam spots R22, R23, R32, and R33 surround the other beam spots R11, R12, R13, R14, R21, R24, R31, R34, R41, R42, and R43. , R44 has a relative strength larger than that of R44, and may be in a range of, for example, 1.1 to 5.0.

  The plurality of rows formed by the beam spots may be two or more rows, and the beam spot pattern 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. If so, it can be applied to SiC-based power devices and the like, and can be applied to a wide range of fields such as transparent electronics fields, lighting fields, and hybrid / electric vehicle fields.

10 Substrate 14 Processing Layer 100 Substrate Processing Device 150 Laser Light Source 160 Laser Condensing Unit 170 Diffractive Optical Element 180 Objective Lens

Claims (4)

A substrate processing method for processing a substrate to form a processing layer inside a crystal substrate, comprising:
A laser condensing step of irradiating a 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.
The laser condensing step includes a laser light adjusting step of using a diffractive optical element that branches the laser light from the laser light source into a plurality of branched laser lights, and making the intensities of the branched laser lights different,
The substrate is processed by extending the processing layer so that the processing marks are connected by the branched laser light having relatively high intensity in the branched laser light, and the substrate is processed by the branched laser light having relatively low intensity in the branched laser light. A substrate processing method, characterized in that the expansion of a processing layer is suppressed.   In the positioning step, an operation of moving the laser condensing means in a predetermined scanning direction at a predetermined speed on the surface of the substrate, and shifting the laser condensing means in a direction orthogonal to the scanning direction over a predetermined distance. The substrate processing method according to claim 1, wherein the operation is repeated with the operation interposed. Further comprising a substrate peeling step of peeling the substrate at the processing layer to create a peeled substrate,
The peeled substrate created in the substrate peeling step has a substrate surface roughness Ra in the scanning direction in the range of 0.032 to 2.534 μm, and a substrate surface roughness Ra in the direction orthogonal to the scanning direction. Is in the range of 1.478 to 3.514 μm. 3. The substrate processing method according to claim 2, wherein Further comprising a substrate peeling step of peeling the substrate at the processing layer to create a peeled substrate,
The peeled substrate created by the substrate peeling step has a substrate surface roughness Rz in the scanning direction in the range of 0.202 to 12.713 μm, and the substrate surface roughness Rz in the direction orthogonal to the scanning direction. Is in the range of 9.819 to 18.892 μm. 3. The substrate processing method according to claim 2, wherein