Diamond processing method

Abstract

To form a modified layer at an arbitrary angle to a {001} plane of a main surface of single crystal diamond.SOLUTION: A diamond processing method comprises: arranging a laser light condensing part 119 which condenses laser light B opposite a {001} plane of a main surface 10a of a substrate 10 of single-crystal diamond; and condensing laser light into the substrate 10 by the laser light condensing part 119 to form a modified layer extending at an angle to the {001} plane toward the main surface 10a of the substrate 10, wherein the laser light B is condensed by the laser light condensing part 119 to form the modified layer graphitized by thermally decomposing the diamond and including a machining mark and cleavage of its peripheral [111] plane along a plane having an angle to a {001] plane toward the main surface 10a of the substrate 10.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a diamond processing method, and more particularly to a diamond processing method for processing a single crystal diamond by using a laser beam. [Background technology]

[0002] Conventionally, silicon carbide (SiC) and gallium nitride (GaN) have been used instead of silicon (Si) as semiconductor materials suitable for power devices, but diamond semiconductors have a higher dielectric breakdown field and power control index than these semiconductor materials, and also have the highest thermal conductivity, so they are attracting attention as a next-generation material, and research and development is underway toward practical use. In addition, nitrogen-vacancy centers (NV centers) in diamond are capable of highly sensitive magnetic detection at room temperature, so there are hopes for their application in magnetic sensors, and research into this is also being conducted (see Patent Document 1).

[0003] Single crystal diamond, which is expected to be applied to these semiconductors, is synthesized by the high pressure, high temperature (HPHT) method or homoepitaxial growth, but these synthesis methods are considered to be difficult to produce large-area bulk substrates of single crystal diamond for use in semiconductor processes. Therefore, the chemical vapor deposition (CVD) method, which grows single crystal diamond heteroepitaxially on single crystal magnesium oxide (MgO) as a base crystal, has been applied as it has an advantage in producing large-area substrates.

[0004] Also, a diamond substrate manufacturing method has been disclosed in which a diamond substrate is manufactured from a diamond ingot using laser light (see Patent Document 2). In this method, a laser light is focused and irradiated to a predetermined depth from the main surface of the diamond ingot, and a modified layer with a modified crystal structure is formed by scanning it two-dimensionally, and the diamond substrate is peeled off at this modified layer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2015-59069 A [Patent Document 2] JP 2020-50563 A Summary of the Invention [Problem to be solved by the invention]

[0006] Single crystal diamond has the property that cleavage easily proceeds along the {111} plane, and when a diamond ingot or block is scanned with a laser beam in two dimensions, a modified layer develops on the {111} plane, which is the cleavage plane, and cleavage easily occurs on the {111} plane. For this reason, it has been difficult to form a modified layer along a crystal plane other than the {111} plane.

[0007] The present invention has been proposed in view of the above-mentioned circumstances, and aims to provide a diamond processing method capable of forming a modified layer along any angle relative to the main surface {001} of a single crystal diamond. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the diamond processing method according to this application comprises the steps of: positioning a laser focusing unit that focuses laser light so that it faces the {001} plane of a main surface of a single crystal diamond substrate; and focusing the laser light inside the substrate with the laser focusing unit to form a modified layer that extends at an angle to the {001} plane toward the main surface of the substrate. The modified layer forming step focuses the laser light with the laser focusing unit to form a modified layer including processing marks created by pyrolyzing and graphitizing the diamond and the surrounding {111} cleavage planes along a plane that is angled with the {001} plane toward the main surface of the substrate.

[0009] The step of forming the modified layer may include forming the modified layer such that cleavage planes formed along the crystal planes constituting the {111} planes are connected to each other and extend along a plane having an angle with the {001} plane toward the main surface of the substrate. The step of forming the modified layer may include focusing the laser light with a laser focusing unit, forming a first scan line and a second scan line due to processing marks from the end of the wedge-shaped structure toward the tip on a first crystal plane and a second crystal plane that form a wedge-shaped structure inside the substrate and that has a tip that becomes thinner toward the main surface, among the crystal planes constituting the {111} planes, and the first scan line and the second scan line may join and be connected at the tip of the wedge-shaped structure.

[0010] The first and second scan lines may include adjacent first and second sides, and a ratio of the lengths of the first and second sides may be set with respect to an angle of the modified layer toward the main surface of the substrate. The step of forming the modified layer may further include forming the first and second scan lines spaced apart by a predetermined interval in a direction in which the tips of the wedge structures extend after forming the first and second scan lines.

[0011] The step of forming the modified layer may include focusing the laser light by a laser focusing unit, and forming first and second scan lines by processing marks in the direction in which the tip of the wedge-shaped structure extends on a first crystal plane and a second crystal plane that form a wedge-shaped structure with a tip that becomes thinner toward the main surface inside the substrate, among the crystal planes that constitute the {111} plane. The step of forming the modified layer may further include forming, after forming the first and second scan lines, a first scan line and a second scan line spaced apart by a predetermined distance toward the tip of the wedge-shaped structure.

[0012] The step of forming the modified layer may include forming a modified layer including a plurality of planes with different angles with respect to the {001} plane toward the main surface of the substrate, forming cleavage along the plurality of planes, and forming a modified layer with a three-dimensional structure in which the plurality of planes are connected. The step of forming the modified layer may include focusing laser light with a laser focusing unit, forming a first scan line and a second scan line due to processing marks from the end of the wedge-shaped structure toward the tip of the wedge-shaped structure on a first crystal plane and a second crystal plane that form a wedge-shaped structure with a tip that becomes thinner toward the main surface inside the substrate among the crystal planes that constitute the {111} plane, and the first scan line and the second scan line may be joined and connected at the tip of the wedge-shaped structure, and the first scan line and the second scan line may include adjacent first and second sides, and the wedge-shaped structure may have a different ratio of lengths between the adjacent first and second sides. The substrate may be separated by the modified layer. Effect of the Invention

[0013] According to the present invention, a modified layer can be formed along an arbitrary angle with respect to the {001} plane of the main surface of the single crystal diamond, and the modified layer enables the single crystal diamond to be separated along this angle. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2 is a perspective view showing a schematic configuration of a processing device. [Diagram 2] 2 is a plan view of a substrate to be processed by the processing apparatus; FIG. [Diagram 3] FIG. 2 is a schematic diagram showing the arrangement of {111} planes on a substrate. [Figure 4A] FIG. 2 illustrates the formation of a cleave in a substrate. [Figure 4B] FIG. 2 illustrates the formation of a cleave in a substrate. [Figure 5A] 1A to 1C are diagrams illustrating a processing method according to an embodiment of the present invention. [Figure 5B] 1A to 1C are diagrams illustrating a processing method according to an embodiment of the present invention. [Figure 6A] 1A to 1C are diagrams illustrating a laser light scanning method. [Figure 6B] 1A to 1C are diagrams illustrating a laser light scanning method. [Figure 7A] FIG. 2 is a diagram showing an embodiment of a modified layer. [Figure 7B] FIG. 2 is a diagram showing an embodiment of a modified layer. [Figure 7C] FIG. 2 is a diagram showing an embodiment of a modified layer. [Figure 8] FIG. 2 is a diagram showing a processing method in Experimental Example 1. [Figure 9A] 2 is a micrograph of a substrate processed by the processing method of Experimental Example 1. [Figure 9B] 2 is a micrograph of a substrate processed by the processing method of Experimental Example 1. [Figure 10A] 1 is a micrograph of a substrate processed by the processing method of Experimental Example 2. [Figure 10B] 1 is a micrograph of a substrate processed by the processing method of Experimental Example 2. [Figure 10C] 1 is a micrograph of a substrate processed by the processing method of Experimental Example 2. [Figure 11] FIG. 13 is a diagram showing a processing method in Experimental Example 3. [Figure 12A] 1 is a micrograph of a substrate processed by the processing method of Experimental Example 3. [Figure 12B] 1 is a micrograph of a substrate processed by the processing method of Experimental Example 3. [Figure 13A] FIG. 13 is a diagram showing a substrate separated by the processing method of Experimental Example 3. [Figure 13B] 13 is a photograph of a separated portion of a substrate separated by the processing method of Experimental Example 3. [Figure 13C] 13 is a graph showing the measurement results of the surface shape of the peeled surface of the substrate separated by the processing method of Experimental Example 3. [Figure 14] 11A to 11C are diagrams illustrating another example of the processing method according to the present embodiment. [Figure 15] 15 is a schematic perspective view showing a modified layer formed by the method shown in FIG. 14. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] 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 parts are given 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 thickness ratio of each layer, etc., differ from the actual ones. Therefore, the specific thickness and dimensions should be determined with reference to the following description. In addition, it goes without saying that the drawings include parts with different dimensional relationships and ratios.

[0016] The embodiments described below are merely examples of devices and methods for embodying the technical ideas of the present invention, and the materials, shapes, structures, arrangements, etc. of the components of the embodiments of the present invention are not limited to those described below. Various modifications can be made to the embodiments of the present invention within the scope of the claims.

[0017] 1 is a perspective view showing a schematic configuration of a processing apparatus 110 used in the diamond processing method of this embodiment. The processing apparatus 110 has a stage 111 on which a single crystal diamond substrate 10 is placed, a stage support 112 that supports the stage 111 so that it can move in the XY directions in a horizontal plane, and a fixture 113 that fixes the single crystal diamond substrate 10. The fixture 113 can be an adhesive layer, a mechanical chuck, an electrostatic chuck, a vacuum chuck, or the like.

[0018] A plate-like substrate 10 having a rectangular periphery obtained by cutting a single crystal diamond ingot to a predetermined length as the object to be processed is fixed on the stage 111 with its main surface, the {001} plane with an off angle of 0°, as the upper main surface 10a. The shape of the object to be processed is not limited to this, and so long as the main surface 10a is similarly a {001} plane, it may be, for example, a single crystal diamond ingot or a disk-shaped wafer, or a bulk crystal of single crystal diamond.

[0019] The processing apparatus 110 also has a laser light source 116 that generates pulsed laser light, and a laser focusing unit 119 that includes an objective lens 117 and an aberration adjustment unit 118, and irradiates laser light B emitted from the laser light source 116 toward the {001} plane of the main surface 10a of the single crystal diamond substrate 10 via the laser focusing unit 119.

[0020] 2 is a plan view showing a substrate 10 to be processed by a processing device 110. The substrate 10 has a rectangular {001} plane as a main surface 10a, and a direction indicated by an arrow. <110> The substrate 10 may have, for example, a (100) plane as the main surface 10a, and the direction indicated by the arrow as the

[0110] direction. In this case, an orientation flat may be provided by cutting out a corner of the rectangular substrate 10 in the [0-10] direction in order to indicate the crystal orientation of the substrate 10. Since there are restrictions on the characters that can be used in this specification, for the sake of convenience, the overscores added to the numbers in the Miller indices are replaced with a negative sign "-" before the numbers.

[0021] FIG. 3 is a schematic diagram showing the arrangement of the {111} planes in the substrate 10. The {111} planes are the cleavage planes of the substrate 10, which is a diamond single crystal. FIG. 3 is a plan view of the crystal structure of the substrate 10, whose main surface 10a is the (001) plane, as viewed from the main surface 10a. The orientation of

[0110] is also shown in the figure. The {111} planes constitute the (111), (-111), (-1-11), and (1-11) slopes of a square pyramid that protrudes from the (100) plane with the (001) plane as its base.

[0022] The carbon atoms in the diamond single crystal that constitutes the substrate 10 are covalently bonded to adjacent carbon elements by the arms of sp3 hybrid orbitals that extend in the direction of the four vertices of a regular tetrahedron centered on the carbon atom. The carbon atoms covalently bonded to the four adjacent carbon atoms form a body-centered cubic lattice called the diamond structure. In the diamond structure, the carbon atoms form covalent bonds with the four adjacent carbon atoms, and therefore single crystal diamond is known to be very hard. However, the carbon atoms <111> In the direction, it is covalently bonded to the adjacent carbon atom by only one arm of an sp3 hybrid orbital. <111> In the direction of the {111} plane perpendicular to the cleavage direction, it can be separated relatively easily by simply cutting the covalent bond of one of these arms, and therefore the {111} plane becomes the cleavage plane.

[0023] FIG. 4 is a diagram showing a method of forming a cleavage along a plane 101 at an arbitrary angle θ with respect to the {001} plane of the main surface 10a. FIG. 4A shows the case where θ≦55°, and FIG. 4B shows the case where θ≧55°. 55° is the angle that the {111} plane of the cleavage plane makes with the {001} plane of the main surface 10a. As described above, since the substrate 10 made of single crystal diamond has the {111} plane as the cleavage plane, the cleavage along the plane 101 can be formed by connecting the {111} planes of the cleavage plane. In detail, as shown in FIG. 4A and FIG. 4B, by setting the ratio of the side lengths along the first crystal plane 11 and the second crystal plane 12 constituting the {111} plane, the cleavage can be formed along the plane 101 at an arbitrary angle θ with respect to the {001} plane.

[0024] In FIG. 4, the length L1 of the first crystal plane and the length L2 of the second crystal plane for forming a processed layer along the 101 plane at an angle θ can be calculated by the formula (1) for the case of angle θ≦55° shown in FIG. 4A and the case of angle θ≧55° shown in FIG. 4B, where the length ratio L2 is set to L1=1.

number

[0025] Table 1 shows the results obtained using formula (1) for representative angles θ. [Table 1]

[0026] Fig. 5 is a diagram showing the processing method of this embodiment. Fig. 5A is a cross-sectional view showing the modified layer 16 formed by the processing method of this embodiment, and Fig. 5B is an enlarged cross-sectional view of an area VB in Fig. 5A. As shown in Fig. 5A, the substrate 10 is made of single crystal diamond having a predetermined thickness between the top surface 10a, which is a (001) plane among the {001} planes, and the bottom surface 10b, which is parallel to the top surface.

[0027] The processing method of this embodiment forms the modified layer 16 along the surface 101 set at θ=30° with respect to the main surface 10a. FIG. 5A shows a cross section of the substrate 10 cut by a plane perpendicular to the main surface 10a and the surface 101. Here, the modified layer 16 is shown formed along the surface 101 intersecting the main surface 10a and the bottom surface 10b at an angle of 30°. The modified layer 16 is composed of a processing mark made of graphite formed by focusing the laser beam B by the laser focusing unit 119 of the processing device 110, and a cleavage formed along the {111} plane around the processing mark. The laser beam B irradiated to the substrate 10 is controlled so that the modified layer 16 is formed along the surface 101, and the cleavage constituting the modified layer 16 is connected and extends along the surface 101.

[0028] 5B, in the modified layer 16 extending along the surface 101, among the crystal planes constituting the {111} plane, processing marks 25 are formed at a predetermined interval between the end 13b and the tip 13a of the wedge-shaped structure 13 on the (1-11) plane of the first crystal plane 11 and the (-111) plane of the second crystal plane 12, which form the wedge-shaped structure 13 whose tip becomes thinner toward the main surface 10a inside the substrate 10. The (1-11) plane of the first crystal plane 11 and the (-111) plane of the second crystal plane 12 have an angle of 55° with respect to the {001} plane, and the wedge-shaped structure 13 is formed when the (1-11) plane of the first crystal plane 11 and the (-111) plane of the second crystal plane 12 join toward the main surface 10a. Cleavage occurs along the {111} plane around the processing mark 25, and adjacent processing marks 25 are connected to each other by the cleavage, forming a cleavage extending along the modified layer 16. Since the modified layer 16 is formed along the face 101, the cleavage extends along the face 101. As described above, in a plane perpendicular to the main surface 10a and the face 101, the modified layer 16 is composed of a first side with a length of L1 formed along the first crystal face 11 and a second side with a length of L2 formed along the second crystal face 12, and can be set by the angle θ of the face 101.

[0029] In this embodiment, an example is shown in which the main surface 10a is a (001) plane among the {001} planes, and the first crystal plane 11 and the second crystal plane 12 are a (1-11) plane and a (-111) plane, respectively, but this embodiment is not limited to this example. The main surface 10a does not have to be a plane belonging to the {001} plane. The first crystal plane 11 and the second crystal plane 12 do not have to be a (1-11) plane and a (-111) plane as long as they are a pair of crystal planes among the {111} planes that can form a wedge-shaped structure 13 with a tapered tip facing the main surface 10a inside the substrate 10.

[0030] FIG. 6 is a diagram showing a scanning method of the laser light B. FIG. 6A is a diagram showing a scanning method of the processing method of this embodiment, and FIG. 6B is a diagram showing a scanning method of the processing method of the modified example. As shown in FIG. 6A, in the processing method of this embodiment, the processing marks 25 formed between the end 13b and the tip 13a of the wedge-shaped structure 13 are composed of a first scanning line 21 and a second scanning line 22 of the processing marks 25 formed from the end 13b of the wedge-shaped structure 13 to the tip 13a along the first crystal face 11 and the second crystal face 12, which are {111} faces. In detail, the first scanning line 21 is composed of the processing marks 25 formed at an interval of the dot pitch DP from the end 13b of the wedge-shaped structure 13 to the tip 13a along the first crystal face 11. The second scanning line 22 is composed of the processing marks 25 formed at an interval of the dot pitch DP from the end 13b of the wedge-shaped structure 13 to the tip 13a along the second crystal face 12. The first scan line 21 and the second scan line 22 are joined and connected at the tip 13a of the wedge-shaped structure 13. Note that the arrows in the first scan line 21 and the second scan line 22 in Fig. 6A indicate the scanning direction of the laser light B that forms the processing marks 25 at the dot pitch DP.

[0031] After the formation of the first scan line 21 and the second scan line 22 is completed, the first scan line 21 and the second scan line 22 are further formed at positions spaced apart by the line pitch LP in the direction in which the tip 13a of the wedge-shaped structure 13 extends. By repeating such an operation, the modified layer 16 can be formed in a predetermined region of the main surface 10a of the substrate 10. When the substrate 10 is peeled off by a plane 101 at an arbitrary angle θ to the (001) plane {001} of the main surface, the modified layer may be formed along a plane at an arbitrary angle θ by setting the length L1 of the first scan line 21, which is the first side, and the length of the second scan line 22, which is the second side, and sequentially moving the end 13b and the tip 13a of the wedge structure relative to that setting. By forming the modified layer 16 in this manner, the substrate 10 is separated by cleavage formed along the plane 101 at an arbitrary angle θ to the {001} plane of the main surface, so that peeling is possible.

[0032] The scanning method of the modified example shown in Figure 6B indicates the relationship between the dot pitch DP and line pitch LP at which the first scanning line 21 and the second scanning line 22 form processing marks 25 on the first crystal face 11 and the second crystal face 12, and differs from the scanning method of the form in Figure 6A in which the first scanning line 21 and the second scanning line 22 scan from the end 13b of the wedge-shaped structure 13 toward the tip 13a along the first crystal face 11 and the second crystal face 12, respectively.

[0033] Specifically, the first scan line 21 is composed of processing marks 25 formed at an interval of the dot pitch DP on the first crystal face 11 having a preset length L1. The second scan line 22 is composed of processing marks 25 formed at an interval of the dot pitch DP on the second crystal face 12 having a preset length L2. After the first scan line 21 and the second scan line 22 are formed, the focal position of the laser light B is sequentially moved along a direction 122 toward the tip 13a of the wedge-shaped structure 13 to further form the first scan line and the second scan line at a position spaced apart by the interval of the line pitch LP. The arrows of the first scan line 21 and the second scan line 22 in FIG. 6B indicate the scanning direction of the laser light B.

[0034] By repeating such an operation, a first scan line 21 and a second scan line 22 can be formed along the first crystal face 11 and the second crystal face 12 from the end 13b to the tip 13a of the wedge-shaped structure 13. The processing marks 25 formed on the first crystal face 11 and the second crystal face 12 by the first scan line 21 and the second scan line 22, respectively, merge and connect at the tip 13a of the wedge-shaped structure 13. A modified layer 16 is formed on the wedge-shaped structure 13 from the end 13b to the tip 13a.

[0035] In the scanning method of the modified example shown in Fig. 6B, each of the first scanning line 21 and the second scanning line 22 forms a processing mark 25 at a predetermined depth from the main surface 10a. Therefore, compared with the scanning method of the present embodiment in which the first scanning line 21 and the second scanning line 22 are formed from the end 13b toward the tip 13a of the wedge-shaped structure 13 shown in Fig. 6A, the first scanning line 21 and the second scanning line 22 can be scanned within the first crystal face 11 and the second crystal face 12 without moving the focusing position of the laser light B in the depth direction, and therefore the processing time can be shortened.

[0036] As described above, according to the processing method of the present embodiment, the modified layer 16 can be formed on the single crystal diamond substrate 10 along the face 101 that is angled with respect to the {001} plane toward the main surface 10a. This allows the modified layer 16 to be formed on the single crystal diamond substrate 10 along the face 101 that is angled with respect to the {001} plane of the main surface 10a. The modified layer 16 has a cleavage plane extending along the face 101. Therefore, the single crystal diamond substrate 10 can be separated along the face 101 by peeling at the cleavage plane.

[0037] According to the processing method of the present embodiment, the single crystal diamond substrate 10 can be separated along a plane at any angle θ with respect to the {001} plane of the main surface 10a, so there is no restriction on the cleavage direction due to the {111} plane, and the single crystal diamond substrate 10 can be effectively used. In addition, the separated single crystal diamond substrate 10 can be formed with a plane other than the {111} plane as the main surface 10a, which expands the range of options for using the single crystal diamond.

[0038] FIG. 7 is a diagram showing an embodiment of the modified layer 16 formed on the substrate 10 of single crystal diamond. As shown in FIG. 7A, in this embodiment, an example has been described in which the modified layer 16 is formed along a plane having an arbitrary angle θ with respect to the {001} plane of the main surface 10a, but this embodiment is not limited to this. For example, as shown in FIG. 7B, the modified layer 16 may be formed so that a plane formed along a first angle θ1 with respect to the main surface 10a and a plane formed along a second angle θ2 are connected. Also, as shown in FIG. 7C, the second angle θ2 may be a negative value.

[0039] The modified layer 16 can be formed not only on a flat surface such as a crystal surface, but also along a curved surface. In such a case, the modified layer 16 is formed such that the processed traces 25 are formed by two-dimensionally scanning the curved surface with the laser light B, and the cleavage formed around the processed traces 25 are connected to form a cleavage plane along the curved surface.

[0040] FIG. 14 is a diagram showing a method of forming a modified layer including a plurality of surfaces 101 having different angles θ with respect to the {001} surface facing the main surface 10a, forming cleavages along the plurality of surfaces 101 having different angles θ, and making the modified layer 16 have a three-dimensional structure. FIG. 14 shows a cross-section of the substrate 10 by a plane orthogonal to the surface 101 other than the {001} surface and the {111} surface of the main surface 10a. By separating the substrate with this modified layer 16, a diamond substrate having a surface with a three-dimensional structure can be obtained. As shown in FIG. 14, a first scanning line 21 and a second scanning line 22 are respectively formed on a first crystal surface 11 and a second crystal surface 12 having an angle of 55° with respect to the (001) plane parallel to the main surface 10a. At this time, as shown in FIG. 4, by making the ratio of the length L1 of the first crystal surface and the length L2 of the second crystal surface the same in all the wedge-shaped structures, a linear modified layer 16 is formed. In the method shown in FIG. 14, a modified layer 16 with a three-dimensional structure is formed by providing wedge-shaped structures with different ratios of the length L1 of the first crystal surface and the length L2 of the second crystal surface. In the method shown in FIG. 14, when L1>L2, a modified layer 16 extending along an arbitrary angle toward the main surface 10a rising to the upper right in the figure is formed. When L1<L2, a modified layer 16 extending along an arbitrary angle toward the main surface 10a rising to the upper left in the figure is formed. When L1 = L2, the modified layer 16 is formed along the (001) plane parallel to the main surface 10a. By continuously forming a plurality of modified layers 16 having different angles toward these main surfaces 10a, a modified layer 16 with a three-dimensional structure is formed. At least a part of the modified layer 16 with a three-dimensional structure may be formed so as to extend along an arbitrary angle toward the main surface 10a. As shown in FIG. 14, the modified layer 16 may not be formed up to the main surface 10a of the substrate, but may be formed inside the substrate penetrating both side surface portions of the substrate, and the substrate may be peeled into two sheets with the modified layer 16.

[0041] FIG. 15 is a perspective schematic diagram showing the modified layer 16 formed by the method shown in FIG. 14. By forming a modified layer 16 with a three-dimensional structure inside the substrate 10 and separating the substrate 10 with this modified layer 16, a diamond substrate having a surface with a three-dimensional structure can be obtained.

Example

[0042] (Experimental Example 1) Fig. 8 is a diagram showing a processing method of Experimental Example 1 to which the processing method of the present embodiment is applied. Fig. 8 shows a cross section of substrate 10 taken along a plane perpendicular to plane 101 other than the {001} and {111} planes of main surface 10a.

[0043] In Experimental Example 1, a wedge-shaped structure 13 with a thin tip is formed inside the substrate 10 facing the (001) plane of the main surface 10a by a first crystal face 11 of a (1-11) plane and a second crystal face 12 of a (-111) plane among {111} planes, so as to form a modified layer 16 along a plane 101 that forms an angle of 30° with respect to the (001) plane of the main surface 10a by using the scanning method of the laser light B shown in FIG. 6B. In the wedge-shaped structure 13, the first side and the second side are defined as the ends 13b to the ends 13a of the first crystal face 11 and the second crystal face 12, respectively, and the first side has a length L1=60 μm and the second side has a length L2=30 μm. In this case, the relationship between the length L1 of the first side and the length L2 of the second side is L1:L2=2:1. Furthermore, in the wedge-shaped structure 13, the height H1 of the tip 13a from the end 13b of the first crystal face 11 corresponding to the first side is 50 μm, and the height H2 of the tip 13a from the end 13b of the second crystal face 12 corresponding to the second side is 25 μm.

[0044] In Experimental Example 1, the first scanning line 21 and the second scanning line 22 were formed according to the conditions in Table 2 for Experimental Examples 1-1 and 1-2 along the first crystal plane 11 and the second crystal plane 12 constituting such a wedge-shaped structure 13, with the line pitch LP set to 1.1 μm for two conditions of dot pitch DP=15 μm and 25 μm. Then, modified layers 16 including processing marks 25 constituting the first scanning line 21 and the second scanning line 22 and cleavage occurring around the processing marks 25 were formed.

[0045] [Table 2]

[0046] FIG. 9 is a micrograph of the substrate 10 processed by the processing method of Experimental Example 1. The micrograph was taken by a differential interference microscope. FIG. 9A shows the results of Experimental Example 1-1, and FIG. 9B shows the results of Experimental Example 1-2. In FIG. 9A of Experimental Example 1-1, the dot pitch DP is 15 μm, and in FIG. 9B of Experimental Example 1-2, the dot pitch DP is 25 μm. In FIG. 9A, cleavage is formed around the processing mark 25, but in FIG. 9B, it is observed that graphitization and cleavage on the second crystal face 12 side are insufficient.

[0047] (Experimental Example 2) In Experimental Example 2, similarly to Experimental Example 1, the scanning method of laser light B shown in Fig. 6B was used to apply the processing method shown in Fig. 8. However, Experimental Example 2 differs from Experimental Example 1 in that processing was performed according to the conditions in Table 3. Table 3 shows the processing conditions of Experimental Examples 2-1, 2-2, and 2-3 in which the settings of the dot pitch DP and line pitch LP were changed. Other configurations of Experimental Example 2 are the same as those of Experimental Example 1.

[0048] Fig. 10 is a micrograph of a substrate 10 processed by the processing method of Experimental Example 2. Fig. 10A is Experimental Example 2-1, where the dot pitch DP is 25 μm, Fig. 10B is Experimental Example 2-2, where the dot pitch DP is 30 μm, and Fig. 10C is Experimental Example 2-3, where the dot pitch DP is 35 μm. In all of Figs. 10A, 10B, and 10C, it is observed that the graphite in the processing marks 25 and the cleavage around the processing marks 25 are sufficiently formed. It is observed that the cleavage is most connected in Fig. 10B, where the dot pitch DP is 30 μm.

[0049] [Table 3]

[0050] (Experimental Example 3) Fig. 11 is a diagram showing a processing method of Experimental Example 3 to which the processing method of the present embodiment is applied. Fig. 11 shows a cross section of substrate 10 taken along a plane perpendicular to the (001) plane of main surface 10a and plane 101 at an angle of 26° with respect to main surface 10a.

[0051] In Experimental Example 3, a wedge-shaped structure 13 having a thin tip is formed inside the substrate 10 facing the (001) plane of the main surface 10a by a first crystal face 11 formed by a (1-11) plane and a second crystal face 12 formed by a (-111) plane among the {111} planes, so as to form a modified layer 16 along the (001) plane of the main surface 10a and the face 101 that forms an angle of 26° with the bottom face 10b. In the wedge-shaped structure 13, if the ends 13b to the tips 13a of the first crystal face 11 and the second crystal face 12 are defined as the first side and the second side, respectively, there is a relationship of L1:L2=2:1 between the length L1 of the first side = 122 μm and the length L2 of the second side = 61 μm.

[0052] In Experimental Example 3, the first scan line 21 and the second scan line 22 were formed along the first crystal plane 11 and the second crystal plane 12 constituting such a wedge-shaped structure 13, using the scanning method of the laser light B shown in FIG. 6A, unlike Experimental Examples 1 and 2, according to the conditions in Table 4. As shown in Table 4, for the first scan line 21 and the second scan line 22, the dot pitch DP of the first scan line 21 corresponding to the first side was set to 2 μm, and the dot pitch DP of the second scan line 22 corresponding to the second side was set to 1 μm, so that the dot pitch DP of the second side was shorter than the dot pitch DP of the first side. Then, the modified layer 16 including the processing marks 25 constituting the first scan line 21 and the second scan line 22 and the cleavage generated around the processing marks 25 was formed.

[0053] Fig. 12 is a micrograph of the substrate 10 processed by the processing method of Experimental Example 3. Fig. 12A and Fig. 12B are views of the substrate 10 from different angles. It is observed that in the modified layer 16, cleavage is formed in both the dot pitch DP direction and the line pitch LP direction.

[0054] FIG. 13 is a diagram showing a substrate 10 separated by the processing method of Experimental Example 3. FIG. 13A is an overhead view of the separated substrate 10, and FIG. 13B is a photograph of the separated portion of the separated substrate 10. FIG. 13C is a graph showing the measurement results of the surface shape of the peeled surface formed by separation. As described above, a modified layer 16 was formed along the surface 101 of the substrate 10. Furthermore, laser light B was irradiated from the side wall to advance cleavage, and the modified layer 16 was peeled off by an external force, thereby separating the substrate 10.

[0055] As shown in Fig. 13A, a part of the substrate 10 is separated and removed by a peeled surface 17 formed along the modified layer 16 formed on the substrate 10. As shown in Fig. 13B, the peeled surface 17 is formed so as to be continuously connected to the modified layer 16, and it is observed that the peeled surface 17 is formed on the modified layer 16. Referring to Fig. 13C, in the portion surrounded by an oval, it is observed that the peeled surface 17 is somewhat displaced from the ideal line of the surface 101, but is formed along the ideal line near the processing mark 25.

[0056] [Table 4] [Explanation of symbols]

[0057] 10 Substrate 10a Main surface 10b Bottom 11 First crystal face 12 Second crystal face 13 Wedge-shaped structure 13a (tip of wedge-shaped structure) 13b (end of wedge-shaped structure) 16 Modification layer 21 1st scan line 22 2nd scan line 25 Machining marks 101 sides

Claims

1. a step of positioning a laser focusing unit for focusing a laser beam so as to face a {001} plane of a main surface of a single crystal diamond substrate; focusing a laser beam inside the substrate by the laser focusing unit to form a modified layer extending toward a main surface of the substrate at an angle to a {001} plane; Including, The step of forming the modified layer comprises focusing laser light with the laser focusing unit, and forming a modified layer including processing marks formed by thermally decomposing diamond and graphitizing it, as well as the surrounding cleavage of the {111} plane, along a plane angled with respect to the {001} plane toward the main surface of the substrate.

2. 2. A diamond processing method as described in claim 1, wherein the step of forming the modified layer comprises forming the modified layer such that cleavage planes formed along the crystal planes constituting the {111} plane are connected to each other and extend toward the main surface of the substrate along a plane having an angle with respect to the {001} plane.

3. The step of forming the modified layer comprises focusing laser light by the laser focusing unit, forming a first scanning line and a second scanning line by processing marks from the end of the wedge-shaped structure toward the tip on a first crystal face and a second crystal face that form a wedge-shaped structure inside the substrate and that becomes thinner toward the main surface within the crystal faces constituting the {111} plane, respectively, and the first scanning line and the second scanning line join and are connected at the tip of the wedge-shaped structure.

4. The diamond processing method according to claim 3, wherein the first scan line and the second scan line include adjacent first and second sides, and the ratio of the lengths of the first and second sides is set relative to the angle toward the main surface of the modified layer.

5. 4. The diamond processing method according to claim 3, wherein the step of forming the modified layer further comprises forming the first scan line and the second scan line, the first scan line and the second scan line being spaced apart by a predetermined distance in the direction in which the tip of the wedge structure extends, after forming the first scan line and the second scan line.

6. 3. The diamond processing method according to claim 1 or 2, wherein the step of forming the modified layer comprises focusing laser light by the laser focusing unit, and forming a first scan line and a second scan line due to processing marks in the direction in which the tip of the wedge-shaped structure extends on a first crystal face and a second crystal face that form a wedge-shaped structure whose tip becomes thinner toward the main surface inside the substrate, among the crystal faces that constitute the {111} plane.

7. 7. The diamond processing method according to claim 6, wherein the step of forming the modified layer further comprises forming the first and second scan lines, the first and second scan lines being spaced apart by a predetermined distance toward the tip of the wedge-shaped structure, after forming the first and second scan lines.

8. 3. The diamond processing method according to claim 1 or 2, wherein the step of forming the modified layer includes forming a modified layer including a plurality of planes having different angles with respect to the {001} plane toward the main surface of the substrate, forming cleavages along each of the plurality of planes, and forming a modified layer having a three-dimensional structure in which the plurality of planes are connected.

9. The step of forming the modified layer includes focusing a laser beam by the laser focusing unit, forming a first scanning line and a second scanning line by processing marks from the end of the wedge-shaped structure toward the tip on a first crystal face and a second crystal face that form a wedge-shaped structure inside the substrate and that is tapered toward the main surface within the {111} crystal face, respectively, the first scanning line and the second scanning line are joined and connected at the tip of the wedge-shaped structure, the first scanning line and the second scanning line include adjacent first and second sides, and the wedge-shaped structure has a different length ratio between the adjacent first and second sides.

10. 3. The method for processing diamond according to claim 1, wherein the substrate is separated by the modified layer.

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