Diamond processing method

Abstract

In the diamond substrate processing method, a laser light collecting part (190) is arranged opposite to a main surface (10a) of a {001} surface of a substrate (10), and laser light (B) is irradiated to positions respectively set on a first crystal surface (111) and a second crystal surface (112) which form a wedge-shaped structure with a top end thinning towards the main surface (10a) in a crystal surface forming a {111} surface. A first starting point (221) and a second starting point (222) formed by the machining mark (21) are formed, a starting point is formed on the machining mark (21) formed by irradiating the first starting point (221) and the second starting point (222) with laser light (B) in an overlapping manner, and cleavage generated from the first starting point (221) and the second starting point (222) irradiated with the laser light (B) in the overlapping manner extends along the first crystal face (111) and the second crystal face (112) and is connected at the top end of the wedge-shaped structure. A processing mark is formed by irradiating laser between the first starting point (221) and the second starting point (222).

Description

Technical Field

[0001] This invention relates to a diamond processing method, and more specifically, to a diamond processing method using a laser to process single-crystal diamond. Background Technology

[0002] Previously, silicon carbide (SiC) and gallium nitride (GaN) were offered as semiconductor materials suitable for power devices to replace silicon (Si). However, compared with these semiconductor materials, diamond semiconductors have higher insulation breakdown electric field and power control index, as well as the highest thermal conductivity. Therefore, it has attracted attention as a next-generation material, and research and development are being carried out with the aim of practical application. In addition, the nitrogen-hole centers (NV centers) in diamond can perform high-sensitivity magnetic detection at room temperature, so it is expected to be used in magnetic sensors, and research has also been carried out in this area (see Patent Document 1).

[0003] Single-crystal diamond for use in these semiconductors is expected to be synthesized via high-temperature, high-pressure (HPHT) methods and homoepitaxial growth. However, in these methods, it is difficult to scale up the bulk substrates used for single-crystal diamond in semiconductor processes. Therefore, vapor-phase (CVD) synthesis, which uses single-crystal magnesium oxide (MgO) as the substrate crystal for heteroepitaxial growth of single-crystal diamond, is being applied due to its advantages in scaling up the substrate.

[0004] Diamond substrates are manufactured by using a wire saw with diamond abrasive grains to cut diamond single crystal ingots or further cut ingots into blocks of a certain length and slices of a certain thickness. Since the metal wire of the wire saw has a diameter of, for example, at least tens of μm, a portion of a certain width along the cut surface is lost as a cutting allowance during the grinding process when the diamond single crystal ingot or block is sliced ​​into diamond substrates.

[0005] In addition, a method for manufacturing a diamond substrate using a laser to produce a diamond substrate from a diamond ingot is disclosed (see Patent Document 2). In this method, a laser is focused and irradiated from the main surface of the diamond ingot to a predetermined depth, and scanned in a two-dimensional manner to form a modified layer whose crystal structure is modified. The diamond substrate is then peeled off using this modified layer.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2015-59069

[0009] Patent Document 2: Japanese Patent Application Publication No. 2020-50563 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] Diamond single crystals have the property of easily cleaving along the {111} plane. If a diamond ingot or block with the {001} plane as the main surface is scanned with a two-dimensional laser, the modified layer will advance along the {111} plane, which is the cleavage plane. Cleavage is more likely to occur on the {111} plane than on the {001} plane. Therefore, it is difficult to manufacture diamond substrates with the desired {001} plane as the main surface.

[0012] The present invention is proposed in view of the above-mentioned actual situation, and its purpose is to provide a diamond processing method that can manufacture a diamond substrate with a main surface of {001} from single crystal diamond with a main surface of {001}.

[0013] Methods for solving problems

[0014] To address the aforementioned issues, the substrate processing method of the present invention includes: a step of arranging a laser focusing section for focusing a laser beam in a manner opposite to the main surface of the {001} face of a single-crystal diamond substrate; a step of focusing the laser beam by the laser focusing section and irradiating a first crystal facet and a second crystal facet, respectively set at positions where a wedge-shaped structure with a tip thinning towards the main surface is formed within the {111} facet of the substrate, thereby forming a first starting point and a second starting point constituted by a processing mark; a step of focusing the laser beam by the laser focusing section and irradiating the first starting point and the second starting point in overlapping manner, thereby forming a starting point on the formed processing mark; and a step of focusing the laser beam by the laser focusing section and irradiating the area between the first starting point and the second starting point with a laser beam formed by irradiating the area between the first starting point and the second starting point in a manner in which cleavage extends from the starting point along the first crystal facet and the second crystal facet, respectively, and connects at the tip of the wedge-shaped structure, thereby forming a processing mark.

[0015] In the process of forming a machining mark, a modified layer comprising a machining mark formed by thermally decomposing diamond into graphitization and a cleavage layer formed along the {111} plane around it can be formed. The first starting point and the second starting point can be set to the same depth from the main surface of the substrate. In the process of forming a machining mark by irradiating a laser between the first starting point and the second starting point, the laser can also be focused to the same depth as the first starting point and the second starting point to form the machining mark.

[0016] In the process of forming a machining mark by irradiating a laser between the first and second starting points, machining marks can also be formed from the first and second starting points toward the opposite second and first starting points along the first and second crystal planes respectively, until they converge at the top of the wedge-shaped structure.

[0017] The process of forming a processing mark by irradiating a laser between the first starting point and the second starting point may also include a process of forming a processing mark from one of the first starting point and the second starting point toward the other along the first crystal plane or the second crystal plane until the top of the wedge structure; and a process of forming a processing mark from the other of the first starting point and the second starting point toward one along the first crystal plane or the second crystal plane until the top of the wedge structure.

[0018] In the process of forming a machining mark by irradiating a laser between the first and second starting points, a modified layer containing the machining mark of thermally decomposing diamond into graphitization and cleavage along the {111} plane around it can be formed.

[0019] The process of forming a machining mark by irradiating a laser between a first starting point and a second starting point may include forming a machining mark by forming a cleavage along a first crystal plane starting from the first starting point until the tip of the wedge-shaped structure; and forming a machining mark by forming a cleavage along a second crystal plane starting from the second starting point until the tip of the wedge-shaped structure.

[0020] Invention Effects

[0021] According to the present invention, a diamond substrate with a main surface of {001} can be manufactured from single-crystal diamond with a main surface of {001}. Attached Figure Description

[0022] Figure 1 It is a perspective view showing the general structure of the processing device.

[0023] Figure 2 This is a top view of a substrate processed by a processing device.

[0024] Figure 3 This is a schematic diagram showing the arrangement of the {111} facets of the substrate.

[0025] Figure 4 This is a cross-sectional view showing the processing method of this embodiment.

[0026] Figure 5A This is a diagram illustrating the principle of the processing method in this embodiment.

[0027] Figure 5B This is a diagram illustrating the principle of the processing method in this embodiment.

[0028] Figure 6A This is a diagram illustrating the processing method of this embodiment.

[0029] Figure 6B This is a diagram illustrating the processing method of this embodiment.

[0030] Figure 7A This is a diagram illustrating the processing method of this embodiment.

[0031] Figure 7B This is a diagram illustrating the processing method of this embodiment.

[0032] Figure 8A This is a diagram illustrating the processing method of this embodiment.

[0033] Figure 8B This is a diagram illustrating the processing method of this embodiment.

[0034] Figure 9A This is a microscope photograph of Experiment Example 1.

[0035] Figure 9B This is a microscope photograph of Experiment Example 1.

[0036] Figure 10A This is a microscope photograph of Experiment Example 2.

[0037] Figure 10B This is a microscope photograph of Experiment Example 2.

[0038] Figure 10C This is a microscope photograph of Experiment Example 2.

[0039] Figure 11A This is a microscope photograph of Experiment Example 3.

[0040] Figure 11B This is a microscope photograph of Experiment Example 3.

[0041] Figure 11C This is a microscope photograph of Experiment Example 3.

[0042] Figure 12A This is a microscope photograph of Experiment Example 4.

[0043] Figure 12B This is a microscope photograph of Experiment Example 4.

[0044] Figure 13A This is a microscope photograph of Experiment Example 5.

[0045] Figure 13B This is a microscope photograph of Experiment Example 5.

[0046] Figure 14A This is a microscope photograph of Experiment Example 5.

[0047] Figure 14B This is a microscope photograph of Experiment Example 5.

[0048] Figure 15A This is a diagram illustrating the processing method for a modified example.

[0049] Figure 15BThis is a diagram illustrating the processing method for a modified example.

[0050] Figure 15C This is a diagram illustrating the processing method for a modified example.

[0051] Figure 16A This is a diagram illustrating the processing method for a modified example.

[0052] Figure 16B This is a diagram illustrating the processing method for a modified example. Detailed Implementation

[0053] Next, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description of the drawings, the same or similar parts will be labeled with the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between thickness and planar dimensions, the ratio of thickness of each layer, etc., differs from reality. Therefore, specific thicknesses and dimensions should be determined by referring to the following description. Furthermore, the drawings also include parts where the dimensional relationships and ratios differ from each other.

[0054] Furthermore, the embodiments shown below illustrate apparatus and methods for embodying the technical concept of the present invention. The embodiments of the present invention do not limit the materials, shapes, structures, and arrangements of the constituent components to the following descriptions. Various modifications can be made to the embodiments of the present invention within the scope of the claims.

[0055] Figure 1 This is a perspective view showing the schematic structure of the processing apparatus 100 used in the diamond processing method of this embodiment. The processing apparatus 100 includes a stage 110 for placing a single-crystal diamond substrate 10, a stage support 120 for supporting the stage 110 in a manner that allows it to move in the XY direction within a horizontal plane, and a fixing member 130 for fixing the single-crystal diamond substrate 10. The fixing member 130 can be an adhesive layer, a mechanical chuck, an electrostatic chuck, a vacuum chuck, etc.

[0056] A plate-shaped substrate 10, which has a rectangular outer perimeter and is cut from a single-crystal diamond ingot to a predetermined length, is fixed on the stage 110, such that the {001} surface, which has an offset angle of 0° as the main surface, becomes the main surface 10a of the upper surface. The shape of the object being processed is not limited to this; it can be any shape that makes the main surface 10a the {001} surface. For example, it can be a single-crystal diamond ingot, a disk-shaped wafer, or a bulk single-crystal diamond crystal.

[0057] Furthermore, the processing apparatus 100 includes a laser light source 160 that generates pulsed laser light and a laser focusing section 190 that includes an objective lens 170 and an aberration adjustment section 180, and irradiates the laser B emitted from the laser light source 160 toward the {001} surface of the main surface 10a of the single crystal diamond substrate 10 via the laser focusing section 190.

[0058] Figure 2 This is a top view showing the substrate 10 processed by the processing apparatus 100. The substrate 10 has a rectangular {001} surface as its main surface 10a, and the direction indicated by the arrow is... <110> Orientation. For example, the substrate 10 may have (100) surface as the main surface 10a and the direction indicated by the arrow as the

[110] direction. In this case, in order to indicate the crystal orientation of the substrate 10, the corners of the rectangular substrate 10 in the [0-10] direction may be cut off to form an orientation flat. It should be noted that there are limitations on the text that can be used in this specification, so for convenience, when displaying the Miller index, the upper line marked on the number is replaced by a minus sign "-" before the number.

[0059] Figure 3 This is a schematic diagram showing the arrangement of the {111} planes in the substrate 10. The {111} planes are the cleavage planes of the diamond single-crystal substrate 10. Figure 3 This is a top view of the crystal structure of the substrate 10 with the (001) plane as the main surface 10a. The orientation of

[110] is also shown in the figure. The {111} plane forms the inclined planes (111), (-111), (-1-11), and (1-11) in a quadrangular pyramid protruding from the (100) plane with the (001) plane as the base.

[0060] In the diamond single crystal constituting substrate 10, carbon atoms are covalently bonded to adjacent carbon atoms at the arms of sp3 hybrid orbitals extending along the four vertices of a tetrahedron centered on the carbon atom. These covalently bonded carbon atoms form a body-centered cubic lattice known as the diamond structure. In the diamond structure, carbon atoms form covalent bonds with adjacent tetragonal carbon atoms, hence single-crystal diamond is known to be very hard. However, carbon atoms in… <111> In this direction, it covalently bonds with an adjacent carbon atom only through one arm of its sp3 hybrid orbital. Therefore, in relation to... <111> In the direction of the orthogonal {111} plane, it is relatively easy to cut off the covalent bond of only one arm, so the {111} plane becomes the cleavage plane.

[0061] Figure 4This diagram illustrates the principle of the processing method according to this embodiment. In the processing method of this embodiment, for the first crystal plane 111 and the second crystal plane 112 intersecting in the {111} planes that form a wedge-shaped structure with the tip facing the main surface 10a, a depth D and a starting point distance BP are set from the main surface 10a, and laser B is focused from the laser focusing section 190 to form a first starting point 221 and a second starting point 222 formed by processing marks. Then, laser B is irradiated in an overlapping manner at the first starting point 221 and the second starting point 222 (i.e., the position set by the depth D and the starting point distance BP), forming a starting point at the position, and graphitized processing marks are formed on the first crystal plane 111 and the second crystal plane 112 from the first starting point 221 and the second starting point 222 toward the tip of the wedge-shaped structure. As a result, cleavage extending outwards from the first starting point 221 and the second starting point 222 respectively is formed along the {111} plane containing the first crystal plane 111 and the second crystal plane 112. It should be noted that the depth D is set as the focal depth of the laser B of the laser focusing section 190, and is therefore sometimes referred to as the focal depth D.

[0062] Next, laser B is scanned from the laser focusing section 190 at a depth D, starting from the first starting point 221 and the second starting point 222 respectively, and directed toward the opposing second starting point 222 and the first starting point 221. At this time, laser B is set to overlap with the graphitized processing marks formed on the first crystal plane 111 and the second crystal plane 112 starting from the first starting point 221 and the second starting point 222. As a result, laser B is absorbed by the aforementioned graphitized processing marks. Processing marks 21 are formed in the wedge-shaped structure formed by the first crystal plane 111 and the second crystal plane 112, while no processing marks are formed at the focal depth D. Furthermore, the spacing of the line spacing LP at this time reflects the spacing LP' between the first starting point 221 and the second starting point 222 and the processing mark 21. The direction of movement of the focusing point of laser B is shown as the line spacing direction 102 in the figure.

[0063] More specifically, around the first starting point 221 and the second starting point 222, graphitized processing marks and cleavage are formed along the {111} plane containing the first crystal plane 111 and the second crystal plane 112. When laser B is focused and irradiated at a position extending at a depth D of the line spacing LP along the line spacing direction 102 starting from the first starting point 221 and the second starting point 222, the light is absorbed by the graphitized processing marks extending along the {111} plane starting from the first starting point 221 and the second starting point 222 and reflected by the cleavage, forming graphitized processing marks 21 respectively. Then, by forming processing marks 21 on the first crystal plane 111 and the second crystal plane 112, cleavage progresses along the first crystal plane 111 and the second crystal plane 112. Then, laser B, which further irradiates a position on the line spacing direction 102 that has progressed beyond the line spacing LP, is absorbed by the graphitized processing marks along the first crystal plane 111 and the second crystal plane 112 and reflected by cleavage, forming subsequent processing marks 21 on the first crystal plane 111 and the second crystal plane 112, respectively. Cleavage also progresses along the first crystal plane 111 and the second crystal plane 112. When this cleavage is continuously formed along the first crystal plane 111 and the second crystal plane 112, the diamond substrate 10 can be in a state where the first crystal plane 111 and the second crystal plane 112 are peeled off. It should be noted that, as described above, the spacing of the line spacing LP reflects the spacing LP' between the processing marks 21, which can be optimized by appropriately setting the laser processing conditions, as illustrated in the experimental examples described later.

[0064] The processing marks 21 converge at the apex of the wedge-shaped structure where the first crystal plane 111 and the second crystal plane 112 intersect, forming a vertex 23. The processing marks 21 formed along the first crystal plane 111 and the second crystal plane 112 also form a wedge-shaped structure; therefore, the processing marks 21 formed along the first crystal plane 111 and the second crystal plane 112 are sometimes referred to as wedge-shaped processing marks 21 below. The height of vertex 23 from the first starting point 221 and the second starting point 222 is H. On the first crystal plane 111 and the second crystal plane 112, cleavage is formed along with the processing marks 21 that begin to form from the first starting point 221 and the second starting point 222 and converge at vertex 23, forming a modified layer extending from the cleavage on adjacent processing marks. In the modified layer, the cleavages formed along the first crystal plane 111 and the second crystal plane 112 are interconnected and extend parallel to the main surface 10a, ending at vertex 23. The thickness of the modified layer is approximately equivalent to the height H from the first starting point 221 and the second starting point 222 at depth D to the vertex 23. The starting point spacing BP between the first starting point 221 and the second starting point 222 can be set according to the height H, which is equivalent to the desired thickness of the modified layer.

[0065] Figures 5 to 8 are diagrams illustrating the processing method of this embodiment. Figure 4The diagram illustrates the principle of the processing method of this embodiment, which connects the cleavage between the first starting point 221 and the second starting point 222 formed on the substrate 10. However, Figures 5 to 8 explain the application... Figure 4 The method shown is to form a cleavage along the main surface 10a of the substrate 10 using the principle illustrated. It should be noted that, for convenience, the following will... Figure 4 The starting points that form the first crystal plane 111 and the second crystal plane 112 by irradiating a pair of crystal planes 11, the first starting point 221 and the second starting point 222 with a second laser B are called a pair of starting points 22.

[0066] Figure 5 shows the processing mark 21 formed by the first irradiation of laser B at the location of the starting point 22 in order to form the starting point 22 on the substrate 10. Figure 5A This is a top view of substrate 10. Figure 5B Based on Figure 5A A cross-sectional view of substrate 10 with cut line VB-VB in the figure.

[0067] Inside the substrate 10, on a plane formed by a pair of crystal planes 11 of {111} planes intersecting in a manner that forms a wedge-shaped structure with its tip facing the main surface 10a, at depth D, a machining mark 21 is formed at a starting point spacing BP in the starting point spacing direction 103. The starting point spacing direction is... Figure 4 The line spacing direction 102 is shown as one direction. A pair of adjacent processing marks 21 in the starting point spacing direction 103 are located on a pair of crystal planes forming a wedge-shaped structure, separated only by the starting point spacing BP. Such processing marks 21 are formed with a dot pitch DP in the dot pitch direction 101. The dot pitch direction 101 is one direction orthogonal to the starting point spacing direction 103 in a plane parallel to the main surface 10a. The processing marks 21 are formed by repeatedly performing the following operation: a laser B is scanned in the dot pitch direction 101 with a dot pitch DP to form a series of processing marks 21; when the formation of this series of processing marks 21 is completed, the laser B is moved in the starting point spacing direction 103 to similarly scan an adjacent series of processing marks. The laser B is focused at a depth D of the substrate 10 for irradiation.

[0068] Figure 6 shows the starting point 22 formed by irradiating the processing mark 21 formed on the substrate 10 by the first laser B irradiation. Figure 6A This is a top view of substrate 10. Figure 6B Based on Figure 6AThe image shows a cross-sectional view of the substrate 10 with cut lines VIB-VIB. The starting point 22 is formed by scanning a row of machining marks 21 a second time along the dot pitch direction 101, thereby forming the starting point 22. Then, the laser beam B is moved along the starting point pitch direction 103 to similarly irradiate an adjacent row of machining marks 21 a second time. The laser B is focused at a depth D of the substrate 10 for irradiation.

[0069] Figure 7 shows a machining mark 21 formed from the starting point 22 formed by focusing the laser again at the first starting point 221 and the second starting point 222, plus the starting points 22 that are opposite each other along the starting point spacing direction 103. Figure 7A This is a top view of substrate 10. Figure 7B Based on Figure 7A A cross-sectional view of substrate 10 with cut lines VIIB-VIIB. Processing marks 21 are formed at a spacing LP along the line spacing direction 102, starting from the starting point 22 and moving towards the opposite starting point 22. Regarding the processing marks 21, after forming a series of processing marks 21 by scanning laser B along the point spacing direction 101, the laser beam B is moved along the starting point spacing direction 103 to similarly irradiate the series of processing marks 21, thereby forming the processing marks 21. Laser B is focused at depth D of substrate 10, similar to the starting point 22. As described above, laser B is focused at depth D of substrate 10, but the processing marks 21 are formed at a spacing LP' on a set of crystal planes 11 forming a wedge shape.

[0070] Figure 8 shows a machining mark 21 formed from the starting point 22 formed by focusing the laser again at the first starting point 221 and the second starting point 222, and converging at the apex 23 along the starting point spacing direction 103. Figure 8A This is a top view of substrate 10. Figure 8B Based on Figure 8A A cross-sectional view of substrate 10 with cut lines VIIIB-VIIIB. Starting from point 22 and moving towards the opposite point 22, processing marks 21 formed at a line spacing LP along the line spacing direction 102 are formed at the apex of a wedge-shaped structure formed by a set of crystal planes 11, becoming vertex 23. The vertex 23 processing marks 21 are formed by repeatedly moving the laser beam B along the point spacing direction 103 to form an adjacent row of vertex processing marks 21 after forming a row of vertex processing marks 21 by scanning the laser beam B along the point spacing direction 101. The laser beam B is focused at depth D of substrate 10 and irradiates it, just like the point 22. As described above, the laser beam B is focused at depth D of substrate and irradiates it, but the vertex 23 processing marks 21 are formed at the apex of the wedge-shaped structure formed by a set of crystal planes 11. The height of the vertex 23 processing mark 21 from the point 22 at depth D is H.

[0071] It should be noted that, preferably, when the machining mark 21 is connected at the vertex 23, specifically, when the modified layer containing the cleavage is connected, the progress of the modified layer ends at the vertex 21, and the cleavage and the modified layer do not extend significantly from the vertex 21 toward the main surface.

[0072] Thus, through a series of processes shown in Figures 5 to 8, processing marks 21 are formed along the main surface 10a of the substrate 10. Cleavages extending between adjacent processing marks 21 in the starting point spacing direction 103 or the line spacing direction 102 are interconnected, and cleavages extending between adjacent processing marks 21 in the dot pitch direction 101 are also interconnected, thereby forming a modified layer extending parallel to the main surface 10a. The thickness of the modified layer is approximately equivalent to the height H from the starting point 22 to the apex 23.

[0073] (Experimental Example 1)

[0074] Figure 9 is a microscope photograph showing the results of Experiment Example 1. Figure 9A This shows a microscope image of the substrate 10 that underwent the processing described in Experiment Example 1. Figure 9B Microscopic images of substrate 10 in a comparative example where no starting point was formed. In Experimental Example 1, substrate 10 was processed according to the processing method of this embodiment under the processing conditions shown in Table 1 below. The starting point spacing BP was set to 80 μm, and the height H was set to 9.42 μm. Figure 9A In the substrate 10 of Experimental Example 1, it was observed that a processing mark 21 was formed on the line spacing direction 102 with a dot pitch DP, and that graphitization occurred around the processing mark 21 and cleavage also occurred around it. Furthermore, it was observed that the cleavage was connected in the direction of the dot pitch DP. Figure 9A In, it is shown as follows Figure 4 The schematic diagram of the machining mark 21 formed along the line spacing direction 102 of a pair of crystal planes 11 forming a wedge structure starting from the starting point 22 clarifies the correspondence between the microscope photograph and the wedge structure of the machining mark 21.

[0075] [Table 1]

[0076]

[0077] exist Figure 9B In the comparative example, except that the starting point 22 was not formed and was replaced by a processing mark 21, the substrate 10 was processed under the same processing conditions as in Experimental Example 1. As described above, the starting point 22 is formed by irradiating the processing mark 21 with a second laser B after the processing mark 21 is formed by irradiating it with the first laser B. Therefore, irradiating the position where the starting point 22 was formed by irradiating it with the laser B twice in Experimental Example 1 with the laser B once is sufficient to form the processing mark 21 instead of the starting point 22. Refer to Figure 9B , compared with Experimental Example 1 Figure 9A Similarly, machining marks were formed on the line spacing direction 102, but compared with Experimental Example 1, it was observed that not much cleavage extended around the machining mark 21.

[0078] (Experimental Example 2)

[0079] Figure 10 is a microscope photograph showing the results of Experiment Example 2. Figure 10A This is a microscope image of substrate 10, which was fabricated with a dot pitch (DP) of 10 μm. Figure 10B This is a microscope image of substrate 10 fabricated with a dot pitch (DP) of 12 μm. Figure 10C Microscopic images of substrate 10 processed with a dot pitch DP of 15 μm are shown. As shown in Table 2 below, the processing conditions in Experimental Example 2 differ from those in Experimental Example 1 in that the height H, the starting point spacing BP, and the value of the dot pitch DP are increased; other processing conditions are the same as in Experimental Example 1. At a dot pitch DP of 10 μm... Figure 10A 12μm pixel pitch (DP) Figure 10B 15μm dot pitch Figure 10C In all cases, the results were consistent with those of Experimental Example 1. Figure 9A Similarly, processing marks 21 were observed to form on the line spacing direction 102, along with graphitization of the processing marks 21 and cleavage extending around them. Additionally, cleavage was observed to connect in the direction of the point spacing DP.

[0080] [Table 2]

[0081]

[0082] (Experimental Example 3)

[0083] Figure 11 is a microscope photograph showing the results of Experiment Example 3. Figure 11A This is a microscope image of substrate 10, which was fabricated with a dot pitch (DP) of 10 μm. Figure 11B This is a microscope image of substrate 10 fabricated with a dot pitch (DP) of 12 μm. Figure 11C Microscopic images of substrate 10 processed with a dot pitch DP of 15 μm are shown. As shown in Table 3 below, the processing conditions in Experimental Example 3 differ from those in Experimental Example 1 in that the values ​​of height H and starting point spacing BP are changed, and the interval of the dot pitch DP is altered; other processing conditions are the same as in Experimental Example 1. At a dot pitch DP of 10 μm... Figure 11A 12μm pixel pitch (DP) Figure 11B 15μm dot pitch Figure 11C In all cases, the results were consistent with those of Experimental Example 1. Figure 9ASimilarly, processing marks 21 were observed to form on the line spacing direction 102, along with graphitization of the processing marks 21 and cleavage extending around them. Additionally, cleavage was observed to connect in the direction of the point spacing DP.

[0084] In this experimental example, the height H was set to 3.14 μm, thus having the advantage of a smaller thickness of the modified layer formed inside the diamond substrate 10.

[0085] [Table 3]

[0086]

[0087] (Experimental Example 4)

[0088] Figure 12 is a microscope photograph showing the results of Experiment Example 4. Figure 12A This is a microscope image of substrate 10, which was fabricated with a dot pitch (DP) of 15 μm. Figure 12B Microscopic images of substrate 10 processed with a dot pitch DP of 20 μm are shown. Experimental Example 4 increased the number of processing lines compared to Experimental Examples 1 to 3. As shown in Table 4 below, the processing conditions of Experimental Example 4 differ from those of Experimental Example 1 in that the height H, the starting point spacing LP, the number of wedge-shaped structures processed, and the value of the dot pitch DP are all increased; other processing conditions are the same as in Experimental Example 1. At a dot pitch DP of 15 μm... Figure 12A In the process, machining marks 21 were observed to form along the line spacing direction 102, and cleavage extended around the machining marks 21. Furthermore, cleavage was observed to connect along the point spacing DP. On the other hand, in a point spacing DP of 20 μm... Figure 12B In the process, processing marks 21 were observed to form in the line spacing direction 102. Graphitization and cleavage of processing marks 21 extended around them, but insufficient cleavage was observed in the direction of the point spacing DP. When the point spacing DP was 20 μm, sufficient cleavage was observed. Therefore, regarding the point spacing DP direction, a point spacing DP of 15 μm is considered to be the upper limit.

[0089] [Table 4]

[0090]

[0091] (Experimental Example 5)

[0092] Figures 13 and 14 are microscope photographs showing the results of Experiment Example 5. Figure 13A 13B is a microscope image of the lower surface of the substrate 10 after peeling, and 13B is a microscope image of the upper surface. Figure 14A and Figure 14B It is Figure 13A and Figure 13BMicroscopic images of the samples are magnified. Example 5 is an example where, after forming cleavage along the main surface 10a of the substrate 10 using the processing method of this embodiment, the substrate 10 is divided into upper and lower individual pieces by the cleavage. As shown in Table 5 below, the processing conditions of Example 4 differ from those of Example 1 in that the values ​​of height H and the number of starting point spacing LP are changed, and the value of the point spacing DP is increased; other processing conditions are the same as in Example 1. In Example 5, numerous wedge-shaped processing marks 21 are formed to cover the main surface 10a; therefore, the number of wedge-shaped processing marks is not specified in Table 5.

[0093] Reference Figure 13A and Figure 13B It was observed that the cleavage of the connection forms over approximately the entire surface of the main surface 10a of the substrate 10, and the substrate 10 is cut along the cleavage of the connection. (Refer to...) Figure 13A and Figure 13B as well as Figure 14A and Figure 14B It was observed that regular patterns were formed on the peeling surfaces of both the lower and upper surfaces. Figure 3 The square pyramid formed by the {111} face, as shown, undergoes cleavage along the connection formed by the {111} face. In the cleavage of the connection, the {001} face is formed parallel to the main surface 10a by the arrangement of the square pyramids formed by the {111} face.

[0094] As illustrated in this experimental example, in order to peel off the substrate 10, it is necessary to graphitize and connect the processing marks formed on the {111} surface constituting the wedge-shaped structure to advance cleavage. Therefore, the spacing LP' between the processing marks is preferably 3 μm or less. If the spacing LP' between the processing marks exceeds 3 μm, the processing marks become dot-like and cannot be connected. In order to make the spacing between the processing marks 3 μm or less, the laser scanning spacing LP needs to be 1.7 μm or less.

[0095] In this experimental example, the line spacing LP is 1.1 μm and the machining mark spacing LP' is 1.917≈2 μm.

[0096] [Table 5]

[0097]

[0098] As described above, according to this embodiment, a diamond substrate with a main surface of {001} can be manufactured by peeling off a single-crystal diamond substrate 10 with a main surface of {001}. In this embodiment, the cleavage generated from the machining mark is connected in a manner extending along the {111} plane; therefore, the width of the modified layer including the machining mark and the cleavage remains relatively small around the machining mark. Since the portion of the modified layer that becomes the cutting allowance when cutting the substrate 10 is relatively small, the single-crystal diamond substrate 10 can be utilized effectively.

[0099] (Modified Example)

[0100] Figure 15 is a diagram showing the first step of the processing method of the modified example. Figure 15A This is a top view of substrate 10. Figure 15B Therefore Figure 15A The cross-sectional view showing the cutting line XVB-XVB cutting the substrate 10. Figure 15C yes Figure 15B Microscopic photographs of the cross-section. In the processing method of this embodiment shown in Figures 5 to 8, processing marks 21 are sequentially formed from a pair of opposing starting points 22 toward the vertex 23. In contrast, the variation differs in that processing is performed by a first step of forming processing marks 21 from one of the opposing starting points 22 along the starting point spacing direction 103 to the vertex 23, and then a second step of forming processing marks 21 from the other starting point 22 in the opposite direction to the starting point spacing direction 103 to the vertex 23. Other structures of the variation, such as the formation of the starting points 22, are the same as the processing method of the embodiment. Figure 15 shows the processing marks 21 formed in the first step of these steps.

[0101] like Figure 15A and Figure 15B As shown, inside the substrate 10, along one of the pair of crystal planes 11 forming a wedge-shaped structure, a processing mark 21 is formed at a line spacing LP in the starting point spacing direction 103, starting from the starting point 22 and continuing until the apex 23 is reached. For the processing mark 21, a row of processing marks 21 is formed by scanning a laser B in the point spacing direction 101. After forming this row of processing marks 21, a second laser B irradiation is performed to form the starting point. Then, this process is repeated by moving the laser B in the starting point spacing direction 103 and similarly scanning an adjacent row of processing marks. The laser B is focused at the depth D of the substrate 10 for irradiation. In the line spacing direction 103, the processing width L1 for forming the processing mark 21 in the first process and the moving width L2 for moving without forming the processing mark 21 are both set to 40 μm.

[0102] exist Figure 15C The microscopic photograph shows a machining mark 21 formed from a starting point 22 along one of a pair of crystal planes 11 in the starting point spacing direction 103 to a vertex 23. The starting point 22 is formed at a depth D of the substrate 10, and the vertex 23 is formed at a height H from the depth D. It is observed that the machining mark 21 is formed along one of the pair of crystal planes 11 from the starting point 22 to the vertex 23 at a height H.

[0103] Figure 16 is a diagram showing the second step of the processing method of the modified example. Figure 16A This is a top view of substrate 10. Figure 16B Therefore Figure 16AA cross-sectional view of the XVIB-XVIB cut-off substrate 10. Figure 15 shows the machining mark 21 formed in the first process of these processes.

[0104] like Figure 16A As shown in 16B, inside the substrate 10, along the other side of the pair of crystal planes 11 forming the wedge-shaped structure, starting from the starting point 22, a processing mark 21 is formed in a direction opposite to the starting point spacing direction 103 with a line spacing LP until the vertex 23. For the processing mark 21, after forming a row of processing marks 21 by scanning the laser B in the point spacing direction 101, a second laser B irradiation is performed to form the starting point. Then, the processing is formed by repeatedly scanning an adjacent row by moving the laser B in the direction opposite to the starting point spacing direction 103. The laser B is focused at the depth D of the substrate 10 for irradiation. In the line spacing direction 102, the processing width L2 for forming the processing mark 21 in the second process and the moving width L1 for moving without forming the processing mark 21 are both set to 40 μm.

[0105] Thus, after the process of forming the starting point 22, by performing the first process shown in FIG. 15 and the second process shown in FIG. 16, a processing mark 21 is formed along the main surface 10a of the substrate 10. Cleavages extending between adjacent processing marks 21 in the starting point spacing direction 103 are interconnected, and cleavages extending between adjacent processing marks 21 in the dot spacing direction 101 are also interconnected, thereby forming a modified layer extending parallel to the main surface 10a. The thickness of the modified layer is approximately equivalent to the height H from the starting point 22 to the vertex 23.

[0106] According to a modified example, a processing mark 21 is formed along one crystal plane 11 where the wedge-shaped structure is formed in the first process, and a processing mark is formed along the other crystal plane 11 where the wedge-shaped structure is formed in the second process. Since processing marks 21 are continuously formed on one and the other crystal planes 11, the moving distance of the laser focusing section 190, which is focused by the laser B forming the processing mark 21, is shortened. Therefore, according to the modified example, the time for forming the wedge-shaped structure with processing marks 21 can be shortened, thereby increasing the processing speed of the substrate 10.

[0107] The embodiments and experimental examples have been described above, but these embodiments and experimental examples are merely illustrative of the technical concept of the present invention, and the scope of the invention is not limited thereto. These embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention.

[0108] This application claims priority based on Japanese Patent Application No. 2023-140527, filed on August 30, 2023, the entire contents of which are incorporated herein by reference.

[0109] Explanation of reference numerals in the attached figures

[0110] 10: Substrate, 10a: Main surface, 11: Crystal plane, 21: Processing mark, 22: Starting point, 23: Vertex, 101: Dot pitch direction, 102: Line pitch direction, 103: Starting point pitch direction, 190: Laser focusing section.

Claims

1. A substrate processing method comprising: a step of disposing a laser condensing section that condenses laser light in opposition to a main surface of a {001} surface of a single-crystal diamond substrate; a step of condensing laser light by the laser condensing section, irradiating laser light at positions respectively set for a first crystal surface and a second crystal surface that form a wedge-shaped structure inside the substrate that tapers toward the main surface at a tip, in a crystal surface constituting a {111} surface, to form a first starting point and a second starting point constituted by processed marks; a step of condensing laser light by the laser condensing section, overlapping and irradiating laser light at the first starting point and the second starting point to form processed marks at the starting points; a step of condensing laser light by the laser condensing section, irradiating laser light between the first starting point and the second starting point to form processed marks, in a manner that cleavage extends from the starting points along the first crystal surface and the second crystal surface respectively and joins at the tip of the wedge-shaped structure.

2. The substrate processing method according to claim 1, wherein In the step of forming the processed marks, a modified layer is formed that includes processed marks that graphitize by thermal decomposition of diamond and cleavage formed along {111} surfaces around the processed marks.

3. The substrate processing method according to claim 1, wherein The first starting point and the second starting point are set to the same depth from the main surface of the substrate.

4. The substrate processing method according to claim 3, wherein In the step of irradiating laser light between the first starting point and the second starting point to form processed marks, laser light is condensed to the same depth as the first starting point and the second starting point to form processed marks.

5. The substrate processing method according to claim 4, wherein In the step of irradiating laser light between the first starting point and the second starting point to form processed marks, processed marks are formed from the first starting point and the second starting point toward the second starting point and the first starting point in opposition along the first crystal surface and the second crystal surface respectively until they meet at the tip of the wedge-shaped structure.

6. The substrate processing method according to claim 4, wherein The step of irradiating laser light between the first starting point and the second starting point to form processed marks includes: a step of forming processed marks from one of the first starting point and the second starting point toward the other along the first crystal surface or the second crystal surface until the tip of the wedge-shaped structure; and a step of forming processed marks from the other of the first starting point and the second starting point toward one along the first crystal surface or the second crystal surface until the tip of the wedge-shaped structure.

7. The method for processing a substrate according to claim 1, wherein In the step of irradiating laser light between the first starting point and the second starting point to form processed marks, a modified layer is formed that includes processed marks that graphitize by thermal decomposition of diamond and cleavage formed along {111} surfaces around the processed marks.

8. The method for processing a substrate according to claim 1, wherein, The step of irradiating laser light between the first starting point and the second starting point to form processed marks includes: a step of forming processed marks in a manner that cleavage is formed from the first starting point along the first crystal surface until the tip of the wedge-shaped structure; and a step of forming processed marks in a manner that cleavage is formed from the second starting point along the second crystal surface until the tip of the wedge-shaped structure.

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