Diamond processing method

Abstract

The present application can form a modification layer at an arbitrary angle with respect to the {001} plane of the main surface of a single-crystal diamond. In a diamond processing method, a laser condensing section (119) that condenses laser light (B) is disposed so as to face the {001} plane of a single-crystal diamond substrate (10) as a main surface (10a), laser light is condensed inside the substrate (10) by the laser condensing section (119), and a modification layer that extends at an angle with respect to the {001} plane toward the main surface (10a) of the substrate (10) is formed; and for the modification layer, laser light (B) is condensed by the laser condensing section (119), and a modification layer is formed on a plane that extends at an angle with respect to the {001} plane toward the main surface (10a) of the substrate (10), and the modification layer includes a processing mark that graphitizes by thermal decomposition of the diamond and cleavage of the {111} plane around the processing mark.

Description

Technical Field

[0001] This invention relates to diamond processing methods, 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) have been used as semiconductor materials suitable for power devices to replace silicon (Si). However, compared with these semiconductor materials, diamond semiconductors have higher dielectric breakdown electric field and power control index, as well as the highest thermal conductivity. Therefore, they have attracted attention as a next-generation material, and research and development for practical application are underway. In addition, nitrogen vacancy centers (NV centers) in diamond can perform high-sensitivity magnetic detection at room temperature, so their application in magnetic sensors is anticipated, and research on this is also ongoing (see Patent Document 1).

[0003] Single-crystal diamond for semiconductor applications is expected to be synthesized via high-temperature, high-pressure (HPHT) methods and homoepitaxial growth. However, these methods make it difficult to achieve large-area production of bulk substrates for single-crystal diamond used in semiconductor processes. In contrast, vapor-phase (CVD) synthesis, which uses single-crystal magnesium oxide (MgO) as the substrate crystal for heteroepitaxial growth of single-crystal diamond, has advantages in large-area production and has remained applicable.

[0004] 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 to a predetermined depth from the main surface of the diamond ingot, and scanned in two dimensions to form a modified layer with a modified crystal structure. This modified layer is then used to peel off the diamond substrate.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2015-59069

[0008] Patent Document 2: Japanese Patent Application Publication No. 2020-50563 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] Single-crystal diamond readily undergoes cleavage along the {111} plane. When a diamond ingot or block is scanned with a two-dimensional laser, the modified layer extends along the {111} plane, which serves as a cleavage plane, where cleavage is easily achieved. Therefore, it is difficult to form a modified layer along crystal planes other than the {111} plane.

[0011] 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 form a modified layer at any angle relative to the main surface {001} of single crystal diamond.

[0012] Methods for solving problems

[0013] To address the aforementioned issues, the diamond processing method disclosed in this application includes: a step of arranging a laser focusing section for focusing a laser beam in a manner facing the {001} plane of the main surface of a single-crystal diamond substrate; and a step of focusing the laser beam into the interior of the substrate by the laser focusing section to form a modified layer extending toward the main surface of the substrate at an angle relative to the {001} plane. In the step of forming the modified layer, the laser beam is focused by the laser focusing section, and the modified layer is formed along the plane extending toward the main surface of the substrate at an angle relative to the {001} plane. The modified layer includes processing marks that cause the diamond to thermally decompose and graphitize, and cleavage of the {111} plane around them.

[0014] In the process of forming the modified layer, the modified layer may be formed by connecting the cleavage planes formed along the crystal plane constituting the {111} plane to each other and extending along a plane facing the main surface of the substrate and having an angle relative to the {001} plane. In the process of forming the modified layer, a laser may be focused by a laser focusing section, and a first scan line and a second scan line formed by a processing mark may be formed from the end of the wedge structure toward the tip of the wedge structure in the first crystal plane and the second crystal plane constituting the {111} plane, which form a wedge structure that thins towards the main surface inside the substrate. The first scan line and the second scan line converge and connect at the tip of the wedge structure.

[0015] The first scan line and the second scan line may include adjacent first and second sides, and the length ratio of the first side and the second side is set with respect to the angle of the modified layer toward the main surface of the substrate. In the process of forming the modified layer, after the first scan line and the second scan line are formed, the first scan line and the second scan line, which are spaced apart by a predetermined interval in the direction extending from the top of the wedge structure, may be further formed.

[0016] In the process of forming the modified layer, a laser can be focused using a laser focusing section. On the first and second crystal planes constituting the {111} plane, which form a wedge-shaped structure with its tip thinning towards the main surface inside the substrate, a first scan line and a second scan line formed by machining marks are formed in the direction extending from the tip of the wedge-shaped structure, respectively. In the process of forming the modified layer, after forming the first and second scan lines, a first scan line and a second scan line spaced at a predetermined interval towards the tip of the wedge-shaped structure can be further formed.

[0017] In the process of forming the modified layer, a modified layer comprising multiple faces facing the main surface of the substrate and having different angles relative to the {001} plane may be formed. This modified layer is a three-dimensional structure formed by forming cleavage along the multiple faces and connecting the multiple faces. In the process of forming the modified layer, a laser may be focused using a laser focusing section. In the first and second crystal planes constituting the {111} plane, a wedge-shaped structure with a thinning tip towards the main surface is formed inside the substrate. A first scan line and a second scan line formed by processing marks are formed from the end of the wedge-shaped structure towards the tip, respectively. The first scan line and the second scan line converge and connect at the tip of the wedge-shaped structure. The first scan line and the second scan line include adjacent first and second sides and have a wedge-shaped structure with different length ratios of adjacent first and second sides. The substrate can be separated by the modified layer.

[0018] Invention Effects

[0019] According to the present invention, a modified layer can be formed at any angle relative to the {001} plane of the main surface of the single crystal diamond, and the single crystal diamond can be separated along the modified layer at that angle. Attached Figure Description

[0020] Figure 1 It is a three-dimensional diagram showing the general structure of the processing equipment.

[0021] Figure 2 This is a top view of a substrate processed by a processing device.

[0022] Figure 3 This is a schematic diagram showing the arrangement of the {111} plane in the substrate.

[0023] Figure 4A This is a diagram illustrating the formation of cleavage in a substrate.

[0024] Figure 4B This is a diagram illustrating the formation of cleavage in a substrate.

[0025] Figure 5A This is a diagram illustrating the processing method of this embodiment.

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

[0027] Figure 6A This is a diagram illustrating laser scanning methods.

[0028] Figure 6B This is a diagram illustrating laser scanning methods.

[0029] Figure 7A It is a diagram showing the morphology of the modified layer.

[0030] Figure 7BIt is a diagram showing the morphology of the modified layer.

[0031] Figure 7C It is a diagram showing the morphology of the modified layer.

[0032] Figure 8 This is a diagram illustrating the processing method of Experiment Example 1.

[0033] Figure 9A Microscopic photographs of a substrate processed by the method in Experimental Example 1.

[0034] Figure 9B Microscopic photographs of a substrate processed by the method in Experimental Example 1.

[0035] Figure 10A These are microscope images of a substrate processed using the method described in Example 2.

[0036] Figure 10B Microscopic photographs of a substrate processed using the method described in Experimental Example 2.

[0037] Figure 10C These are microscope images of a substrate processed using the method described in Example 2.

[0038] Figure 11 This is a diagram illustrating the processing method of Experiment Example 3.

[0039] Figure 12A These are microscope images of a substrate processed using the method described in Example 3.

[0040] Figure 12B These are microscope images of a substrate processed using the method described in Example 3.

[0041] Figure 13A This is a diagram showing the substrate separated by the processing method in Experimental Example 3.

[0042] Figure 13B This is a photograph of the separated portion of the substrate separated by the processing method in Experiment Example 3.

[0043] Figure 13C This 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.

[0044] Figure 14 This is a diagram illustrating another example of the processing method of this embodiment.

[0045] Figure 15 It means through Figure 14 A three-dimensional schematic diagram of the modified layer formed by the method shown. Detailed Implementation

[0046] 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 thicknesses of each layer, etc., differ from reality. Therefore, specific thicknesses and dimensions should be determined by referring to the following description. Furthermore, the drawings also include parts with different dimensional relationships and ratios.

[0047] 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 configurations of the constituent components to the following. Various modifications can be made to the embodiments of the present invention within the scope of the claims.

[0048] Figure 1 This is a perspective view showing the schematic configuration of the processing apparatus 110 used in the diamond processing method of this embodiment. The processing apparatus 110 includes a stage 111 for placing a single-crystal diamond substrate 10, a stage support 112 that supports the stage 111 in a manner that allows it to move in the XY direction within a horizontal plane, and a fixing member 113 for fixing the single-crystal diamond substrate 10. For the fixing member 113, adhesive layers, mechanical chucks, electrostatic chucks, vacuum chucks, etc., can be used.

[0049] A plate-shaped substrate 10, which is a single-crystal diamond ingot cut to a predetermined length and has a rectangular outer perimeter, is fixed on the stage 111. The substrate has a main surface 10a with an offset angle of 0° at the {001} surface, which is the main surface. The shape of the object being processed is not limited to this. As long as the main surface 10a is the {001} surface, it can be a single-crystal diamond ingot, a disk-shaped wafer, or a bulk single-crystal diamond crystal.

[0050] Furthermore, the processing apparatus 110 includes a laser light source 116 that generates pulsed laser light and a laser focusing section 119 that includes an objective lens 117 and an aberration adjustment section 118, and irradiates the {001} surface of the single crystal diamond substrate 10, which is the main surface 10a, with laser light B emitted from the laser light source 116 via the laser focusing section 119.

[0051] Figure 2This is a top view showing the substrate 10 processed by the processing apparatus 110. 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 the (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 can be cut off to form an orientation plane. It should be noted that, due to the limitations of the text that can be used in this specification, for convenience, the overline marked on the number in the Miller index is replaced with a minus sign "-" before the number.

[0052] 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 with the (001) plane as the base and protruding from the (100) plane.

[0053] In the diamond single crystal constituting substrate 10, carbon atoms form covalent bonds with adjacent carbon elements at the arms of sp3 hybrid orbitals extending along the four vertices of a tetrahedron centered on the carbon atom. These carbon atoms, covalently bonded to their four neighboring carbon atoms, form a body-centered cubic lattice known as the diamond structure. In the diamond structure, carbon atoms form covalent bonds with their four neighboring carbon atoms, hence single-crystal diamond is known to be very hard. However, carbon atoms in… <111> In this direction, it forms a covalent bond 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, the covalent bonds of only one arm can be easily broken, so the {111} plane becomes a cleavage plane.

[0054] Figure 4A and Figure 4B This is a diagram showing the method of forming a cleavage along a plane 101 at an arbitrary angle θ relative to the {001} plane of the main surface 10a. Figure 4A This is the case where θ ≤ 55°. Figure 4B This refers to the case where θ ≥ 55°. 55° is the angle formed by the {111} facet of the cleavage plane and the {001} facet of the main surface 10a. As described above, the substrate 10, made of single-crystal diamond, uses the {111} facet as its cleavage plane; therefore, by connecting the {111} facets, which serve as cleavage planes, cleavage along facet 101 can be formed. More specifically, as... Figure 4A and Figure 4BAs shown, by setting the length ratio of the edges along the first crystal plane 11 and the second crystal plane 12 constituting the {111} plane, cleavage can be formed along the plane 101 which is at an arbitrary angle θ relative to the {001} plane.

[0055] Regarding Figure 4A and Figure 4B The lengths L1 and L2 of the first crystal plane used to form the processing layer along the 101 plane at angle θ are [not specified]. Figure 4A The angle shown is θ≤55°. Figure 4B When the angle θ ≥ 55°, it can be calculated by equation (1) in the form of the length ratio L2 when L1 = 1.

[0056] [Number 1]

[0057]

[0058] Regarding the representative angle θ, the result obtained by equation (1) is shown in Table 1.

[0059] [Table 1]

[0060]

[0061] Figure 5A and Figure 5B This is a diagram illustrating the processing method of this embodiment. Figure 5A This is a cross-sectional view showing the modified layer 16 formed by the processing method of this embodiment. Figure 5B It is Figure 5A The magnified cross-sectional view of region VB in the image. Figure 5A As shown, the substrate 10 is made of single-crystal diamond, which has a top surface with a (001) facet in the {001} plane as the main surface 10a, and has a predetermined thickness between it and the bottom surface 10b parallel to the top surface.

[0062] In the processing method of this embodiment, a modified layer 16 is formed along a surface 101 with θ=30° relative to the main surface 10a. Figure 5A This represents the cross-section of the substrate 10 cut by a plane orthogonal to the main surface 10a and the surface 101. Here, it represents the modified layer 16 formed along the surface 101, which intersects the main surface 10a and the bottom surface 10b at an angle of 30°. The modified layer 16 is composed of a graphite processing mark formed by focusing laser B through the laser focusing section 119 of the processing apparatus 110 and cleavage formed along the {111} surface around the processing mark. The laser B irradiated onto the substrate 10 is controlled such that the modified layer 16 is formed along the surface 101, and the cleavage connection constituting the modified layer 16 extends along the surface 101.

[0063] like Figure 5BAs shown, in the modified layer 16 extending along surface 101, within the crystal plane constituting the {111} plane, in the interior of the substrate 10, a wedge-shaped structure 13 is formed with its tip facing the main surface 10a. In the (1-11) plane of the first crystal plane 11 and the (-111) plane of the second crystal plane 12, which are thinner towards the main surface 10a, processing marks 25 are formed at predetermined intervals between the end 13b and the tip 13a of the wedge-shaped structure 13. 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° relative to the {001} plane. The wedge-shaped structure 13 is formed by the convergence of the (1-11) plane of the first crystal plane 11 and the (-111) plane of the second crystal plane 12 towards the main surface 10a. Around the processing marks 25, cleavage occurs along the {111} plane, and adjacent processing marks 25 are connected to each other through cleavage, thereby forming cleavage extending along the modified layer 16. Since the modified layer 16 is formed along the surface 101, the cleavage extends along the surface 101. As described above, in a plane orthogonal to the main surface 10a and the surface 101, the modified layer 16 is composed of a first side of length L1 formed along the first crystal surface 11 and a second side of length L2 formed along the second crystal surface 12, which can be set according to the angle θ of the surface 101.

[0064] It should be noted that, in this embodiment, an example is shown in which the main surface 10a is a (001) plane within the {001} plane, and the first crystal plane 11 and the second crystal plane 12 are (1-11) planes and (-111) planes, respectively. However, this embodiment is not limited to this example. The main surface 10a may not be a plane belonging to the {001} plane. The first crystal plane 11 and the second crystal plane 12 may not be (1-11) planes and (-111) planes, as long as they are a pair of crystal planes that can form a wedge-shaped structure 13 facing the main surface 10a and thinning at the tip within the {111} plane.

[0065] Figure 6A and Figure 6B This is a diagram illustrating the scanning method of laser B. Figure 6A This is a diagram illustrating the scanning method of the processing method in this embodiment. Figure 6B This is a diagram illustrating the scanning method for a modified processing method. For example... Figure 6AAs shown, in the processing method of this embodiment, the processing mark 25 formed between the end 13b and the top 13a of the wedge-shaped structure 13 is composed of a first scan line 21 and a second scan line 22 formed along the first crystal plane 11 and the second crystal plane 12, which are {111} planes, respectively, from the end 13b of the wedge-shaped structure 13 toward the top 13a. Specifically, the first scan line 21 is composed of a processing mark 25 formed along the first crystal plane 11 from the end 13b of the wedge-shaped structure 13 toward the top 13a at a point distance DP. The second scan line 22 is composed of a processing mark 25 formed along the second crystal plane 12 from the end 13b of the wedge-shaped structure 13 toward the top 13a at a point distance DP. The first scan line 21 and the second scan line 22 converge and connect at the top 13a of the wedge-shaped structure 13. It should be noted that... Figure 6A The arrows in the first scan line 21 and the second scan line 22 indicate the scanning direction of the laser B that forms the machining mark 25 with a point spacing DP.

[0066] Once the formation of the first scan line 21 and the second scan line 22 is complete, the first scan line 21 and the second scan line 22 are further formed at a distance LP from the line spacing in the direction extending from the tip 13a of the wedge structure 13. By repeatedly performing this operation, a modified layer 16 can be formed in a predetermined area of ​​the main surface 10a of the substrate 10. When peeling the substrate 10 by means of a surface 101 at an arbitrary angle θ relative to the (001) surface {001} of the main surface, a modified layer along the surface at an arbitrary angle θ can also be formed by setting the length L1 of the first scan line 21 as the first side and the length of the second scan line 22 as the second side, and by sequentially moving the end 13b and the tip 13a of the wedge structure corresponding to the setting. By forming the modified layer 16 in this way, the substrate 10 can be separated by cleavage along the surface 101 at an arbitrary angle θ relative to the (001) surface of the main surface, and thus can be peeled off.

[0067] Figure 6B The scanning method of the modified example shown represents the relationship between the dot pitch DP and line pitch LP of the processing marks 25 formed by the first scan line 21 and the second scan line 22 in the first crystal plane 11 and the second crystal plane 12, and the scanning method of the first scan line 21 and the second scan line 22 scanning along the first crystal plane 11 and the second crystal plane 12 from the end 13b of the wedge structure 13 toward the top 13a, respectively. Figure 6A The scanning methods for their shapes are different.

[0068] In detail, the first scan line 21 is formed by machining marks 25 spaced at intervals of dot pitch DP in a first crystal plane 11 of a predetermined length L1. The second scan line 22 is formed by machining marks 25 spaced at intervals of dot pitch DP in a second crystal plane 12 of a predetermined length L2. After forming the first scan line 21 and the second scan line 22, the focal position of the laser B is moved sequentially along the direction 122 toward the tip 13a of the wedge structure 13, and the first scan line and the second scan line are further formed at positions separated by intervals of dot pitch LP. Figure 6B The arrows on the first scan line 21 and the second scan line 22 indicate the scanning direction of laser B.

[0069] By repeatedly performing this operation, a first scan line 21 and a second scan line 22 can be formed along the first crystal plane 11 and the second crystal plane 12 from the end 13b to the top 13a of the wedge structure 13. The processing marks 25 formed by the first scan line 21 and the second scan line 22 on the first crystal plane 11 and the second crystal plane 12 respectively converge and connect at the top 13a of the wedge structure 13. In the wedge structure 13, a modified layer 16 is formed from the end 13b to the top 13a.

[0070] exist Figure 6B In the scanning method of the modified example shown, each scan line of the first scan line 21 and the second scan line 22 forms a machining mark 25 at a predetermined depth from the main surface 10a. Therefore, with Figure 6A Compared to the scanning method of this embodiment, which forms the first scan line 21 and the second scan line 22 from the end 13b of the wedge structure 13 toward the top 13a, the first scan line 21 and the second scan line 22 can be scanned without moving the focusing position of the laser B in the depth direction within the first crystal plane 11 and the second crystal plane 12, thus shortening the processing time.

[0071] As described above, according to the processing method of this embodiment, a modification layer 16 can be formed on a single-crystal diamond substrate 10 along a surface 101 that has an angle relative to the {001} surface toward the main surface 10a. Therefore, the modification layer 16 can be formed on the single-crystal diamond substrate 10 along a surface 101 that has an arbitrary angle relative to the {001} surface of the main surface 10a. In the modification layer 16, cleavage surfaces extending along the surface 101 are provided. Therefore, by peeling off the cleavage surfaces, the single-crystal diamond substrate 10 can be separated along the surface 101.

[0072] According to the processing method of this embodiment, the single-crystal diamond substrate 10 can be separated along a plane at an arbitrary angle θ relative to the {001} plane of the main surface 10a. Therefore, it is not restricted by the cleavage direction of the {111} plane, and the single-crystal diamond substrate 10 can be utilized effectively. In addition, the separated single-crystal diamond substrate 10 can be formed with the area other than the {111} plane as the main surface 10a, thus expanding the range of single-crystal diamonds that can be used.

[0073] Figure 7A , Figure 7B and Figure 7C This diagram shows the morphology of the modified layer 16 formed on the single-crystal diamond substrate 10. (See diagram for example.) Figure 7A As shown in this embodiment, an example is illustrated where the modified layer 16 is formed along a surface at an arbitrary angle θ relative to the {001} surface of the main surface 10a; however, this embodiment is not limited to this. For example, as... Figure 7B As shown, the modified layer 16 can also be formed by connecting a surface formed along a first angle θ1 relative to the main surface 10a with a surface formed along a second angle θ2. Additionally, as... Figure 7C As shown, the second angle θ2 can also be negative.

[0074] Not limited to a plane like a crystal face, the modified layer 16 can also be formed along a curved surface. In this case, the modified layer 16 is formed by performing a two-dimensional scan along the curved surface using a laser B to form a processing mark 25, and forming cleavage connections around the processing mark 25, thereby forming a cleavage surface along the curved surface.

[0075] Figure 14 This diagram illustrates a method for setting up a modified layer containing multiple surfaces 101 facing the main surface 10a at different angles θ relative to the {001} surface, forming cleavage along the multiple surfaces 101 at different angles θ, thereby making the modified layer 16 a three-dimensional structure. Figure 14 This represents a cross-section of the substrate 10 on a plane orthogonal to the surfaces 101 other than the {001} and {111} surfaces, which serve as the main surface 10a. By separating the substrate using this modified layer 16, a diamond substrate with a three-dimensional surface structure can be obtained. For example... Figure 14 As shown, a first scan line 21 and a second scan line 22 are formed on a first crystal plane 11 and a second crystal plane 12, respectively, at an angle of 55° to the (001) plane parallel to the main surface 10a. At this time, as... Figure 14 As shown, by making the ratio of the length L1 of the first crystal plane to the length L2 of the second crystal plane the same in all wedge-shaped structures, a linear modified layer 16 can be formed. Figure 14 In the method shown, a three-dimensional modified layer 16 can be formed by using a wedge-shaped structure having a different ratio of the length L1 of the first crystal plane to the length L2 of the second crystal plane. Figure 14In the method shown, when L1 > L2, a modified layer 16 is formed extending at an arbitrary angle towards the main surface 10a and slanting upwards to the upper right in the figure. When L1 < L2, a modified layer 16 is formed extending at an arbitrary angle towards the main surface 10a and slanting upwards to the upper left in the figure. When L1 = L2, the modified layer 16 is formed along the (001) plane parallel to the main surface 10a. By continuously forming these multiple modified layers 16 with different angles towards the main surface 10a, a three-dimensional structure of the modified layer 16 can be formed. In the three-dimensional structure of the modified layer 16, at least a part thereof may be formed so as to extend at an arbitrary angle towards the main surface 10a. As Figure 14 shown, the modified layer 16 may not be formed up to the main surface 10a of the substrate but may be formed inside the substrate by penetrating both side faces of the substrate, and the substrate may be peeled into two pieces using the modified layer 16.

[0076] Figure 15 It shows Figure 14 a three-dimensional schematic view of the modified layer 16 formed by the method shown. By forming a three-dimensional structure of the modified layer 16 inside the substrate 10, the substrate 10 can be separated using the modified layer 16, and thus a diamond substrate having a surface with a three-dimensional structure can be obtained.

[0077] Example

[0078] (Experimental Example 1)

[0079] Figure 8 It is a diagram showing the processing method of Experimental Example 1 to which the processing method of the present embodiment is applied. Figure 8 It shows a cross-section of the substrate 10 in a plane orthogonal to the surface 101 other than the {001} plane and the {111} plane which is the main surface 10a.

[0080] In Experimental Example 1, by using Figure 6BThe scanning method of laser B shown forms a modified layer 16 along a surface 101 at a 30° angle to the (001) surface, which is the main surface 10a. This is achieved by forming a wedge-shaped structure 13 inside the substrate 10, facing the (001) surface of the main surface 10a and thinning at its tip, using a first crystal plane 11 formed by the (1-11) plane and a second crystal plane 12 formed by the (-111) plane within the {111} plane. In the wedge-shaped structure 13, if the ends 13b of the first crystal plane 11 and the second crystal plane 12 are respectively designated as the first side and the second side, then the length of the first side L1 = 60 μm and the length of the second side L2 = 30 μm. In this case, there is a ratio of L1:L2 = 2:1 between the lengths of the first side L1 and the second side L2. In addition, in the wedge structure 13, the height H1 from the end 13b to the top 13a of the first crystal plane 11 corresponding to the first side is 50 μm, and the height H2 from the end 13b to the top 13a of the second crystal plane 12 corresponding to the second side is 25 μm.

[0081] In Experimental Example 1, along the first crystal plane 11 and the second crystal plane 12 constituting the wedge-shaped structure 13, according to the conditions in Table 2 for Experimental Examples 1-1 and 1-2, the first scan line 21 and the second scan line 22 were formed with a line spacing LP of 1.1 μm, under the conditions of a dot pitch DP of 15 μm and 25 μm. Then, a modified layer 16 containing a processing mark 25 constituting the first scan line 21 and the second scan line 22 and a cleavage generated around the processing mark 25 was formed.

[0082] [Table 2]

[0083]

[0084] Figure 9A and Figure 9B These are microscope images of the substrate 10 processed using the method described in Example 1. The microscope images were obtained using a differential interference microscope. Figure 9A This represents the result of Experiment 1-1. Figure 9B This represents the results of Experiment 1-2. Experiment 1-1's... Figure 9A For a point spacing DP = 15 μm, in Experiment 1-2 Figure 9B The point spacing DP = 25 μm. In Figure 9A Cleavage forms around machining mark 25, but... Figure 9B Insufficient graphitization and cleavage were observed on the 12th side of the second crystal plane.

[0085] (Experimental Example 2)

[0086] Experiment 2 also uses the same method as Experiment 1. Figure 6B The scanning method for laser B is shown, and the application is as follows: Figure 8The processing method is shown. However, in Experiment 2, the processing is performed according to the conditions in Table 3, which differs from Experiment 1, where the processing is performed according to the conditions in Table 2. Table 3 shows the processing conditions for Experiments 2-1, 2-2, and 2-3, with the point distance DP and line distance LP settings changed. The other components of Experiment 2 are the same as those of Experiment 1.

[0087] Figure 10A , Figure 10B and Figure 10C The image shows a microscope photograph of the substrate 10 processed using the processing method in Example 2. Figure 10A In Experiment 2-1, the point distance DP = 25 μm. Figure 10B In Experiment 2-2, the point distance DP = 30 μm. Figure 10C In Experiment 2-3, the point spacing DP = 35 μm. Figure 10A , Figure 10B and Figure 10C In both cases, graphite at machining mark 25 and cleavage around machining mark 25 were observed to be well formed. At a point distance DP = 30 μm... Figure 10B The most important connection is found in the cleavage theorem.

[0088] [Table 3]

[0089]

[0090] (Experimental Example 3)

[0091] Figure 11 This is a diagram illustrating the processing method of Experimental Example 3, which applies the processing method of this embodiment. Figure 11 This indicates the cross section of the substrate 10 on a plane orthogonal to the (001) plane, which is the main surface 10a, and the plane 101, which is at an angle of 26° relative to the main surface 10a.

[0092] In Experimental Example 3, a modified layer 16 was formed along a surface 101 at an angle of 26° to the (001) surface (which is the main surface 10a) and the bottom surface 10b. A wedge-shaped structure 13, thinning at its tip and facing the (001) surface (which is the main surface 10a), was formed inside the substrate 10 by a first crystal plane 11 formed from the (1-11) surface and a second crystal plane 12 formed from the (-111) surface in the {111} surface. In the wedge-shaped structure 13, if the ends 13b of the first crystal plane 11 and the second crystal plane 12 are respectively designated as the first side and the second side, then the length L1 = 122 μm of the first side and the length L2 = 61 μm of the second side have a ratio of L1:L2 = 2:1.

[0093] In Experiment 3, along the first crystal plane 11 and the second crystal plane 12 constituting such a wedge-shaped structure 13, unlike in Experiment 1 and Experiment 2, the following was used: Figure 6AThe scanning method of laser B shown is used to form a first scan line 21 and a second scan line 22 according to the conditions in Table 4. As shown in Table 4, regarding the first scan line 21 and the second scan line 22, the point pitch DP of the first scan line 21 corresponding to the first side is set to 2 μm, and the point pitch DP of the second scan line 22 corresponding to the second side is set to 1 μm, such that the point pitch DP of the second side is shorter than the point pitch DP of the first side. Then, a modified layer 16 is formed, including the machining marks 25 constituting the first scan line 21 and the second scan line 22 and the cleavage generated around the machining marks 25.

[0094] Figure 12A and Figure 12B The image shows a microscope photograph of the substrate 10 processed using the processing method described in Example 3. Figure 12A and Figure 12B These are images showing the substrate 10 viewed from different angles. In the modified layer 16, cleavage is observed to be formed by connections in both the point-to-pitch (DP) and line-to-pitch (LP) directions.

[0095] Figure 13A , Figure 13B and Figure 13C This is a diagram showing the substrate 10 separated by the processing method of Experimental Example 3. Figure 13A This is a top view of the separated substrate 10. Figure 13B This is a photograph of the separated portion of the separated substrate 10. Figure 13C This is a graph showing the measurement results of the surface shape of the peel surface formed by separation. As described above, a modified layer 16 is formed on the substrate 10 along the surface 101. Then, laser B is irradiated from the sidewall to cause cleavage expansion, and the modified layer 16 is peeled off by external force, thereby separating the substrate 10.

[0096] like Figure 13A As shown, a portion of the substrate 10 is separated and removed via a peeling surface 17 formed along the modified layer 16 formed on the substrate 10. Figure 13B As shown, it is observed that the peeling surface 17 is continuously connected to the modified layer 16, and the peeling surface 17 is formed in the modified layer 16. (Refer to...) Figure 13C It was observed that in the portion surrounded by the elongated circle, the peeling surface 17, although slightly displaced from the ideal line of surface 101, is formed along the ideal line near the machining mark 25.

[0097] [Table 4]

[0098]

[0099] The embodiments and experimental examples have been described above. However, these embodiments and experimental examples are merely illustrative of the technical concept of the present invention and are not intended to limit the scope of the invention. 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.

[0100] This application claims priority based on Japanese Patent Application No. 2023-191748, filed on November 9, 2023, and Japanese Patent Application No. 2024-113206, filed on July 16, 2024, the entire contents of which are incorporated herein by reference.

[0101] Explanation of reference numerals in the attached figures

[0102] 10: Substrate, 10a: Main surface, 10b: Bottom surface, 11: First crystal plane, 12: Second crystal plane, 13: Wedge structure, 13a: (Wedge structure) Top end, 13b: (Wedge structure) End end, 16: Modified layer, 21: First scan line, 22: Second scan line, 25: Processing mark, 101: Surface.

Claims

1. A method for processing diamond, comprising: A process of arranging a laser focusing section to focus laser light in a manner that faces the {001} plane of the main surface of a single-crystal diamond substrate; as well as The process of focusing laser light into the interior of the substrate using the laser focusing section to form a modified layer that extends at an angle relative to the {001} plane and faces the main surface of the substrate. In the process of forming the modified layer, the laser is focused by the laser focusing part, and the modified layer is formed along a surface facing the main surface of the substrate and having an angle relative to the {001} surface. The modified layer includes processing marks that cause the diamond to be thermally decomposed and graphitized, and cleavage of the {111} surface around them.

2. The diamond processing method according to claim 1, wherein, In the process of forming the modified layer, the modified layer is formed by connecting the cleavage planes formed along the crystal plane constituting the {111} plane to each other and extending along a plane that faces the main surface of the substrate and has an angle relative to the {001} plane.

3. The diamond processing method according to claim 1 or 2, wherein, In the process of forming the modified layer, the laser is focused by the laser focusing part. In the first and second crystal planes that form the {111} plane and form a wedge-shaped structure with the tip thinning towards the main surface inside the substrate, a first scan line and a second scan line formed by processing marks are formed from the end of the wedge-shaped structure towards the tip. The first scan line and the second scan line converge and connect 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 sides and second sides, and the ratio of the lengths of the first side and the second side is set with respect to the angle of the modified layer toward the main surface.

5. The diamond processing method according to claim 3, wherein, In the process of forming the modified layer, after the first scan line and the second scan line are formed, the first scan line and the second scan line are further formed at a predetermined interval in the direction extending from the top of the wedge structure.

6. The diamond processing method according to claim 1 or 2, wherein, In the process of forming the modified layer, the laser is focused by the laser focusing part, and in the first crystal plane and the second crystal plane that form the {111} plane and form a wedge-shaped structure with the tip thinning towards the main surface inside the substrate, a first scan line and a second scan line formed by processing marks are formed in the direction extending from the tip of the wedge-shaped structure, respectively.

7. The diamond processing method according to claim 6, wherein, In the process of forming the modified layer, after forming the first scan line and the second scan line, the first scan line and the second scan line are further formed at a predetermined interval toward the tip of the wedge structure.

8. The diamond processing method according to claim 1 or 2, wherein, In the process of forming the modified layer, a modified layer is formed comprising a plurality of surfaces facing the main surface of the substrate and having different angles relative to the {001} surface. The modified layer is a three-dimensional modified layer in which cleavage is formed along the plurality of surfaces and the plurality of surfaces are connected.

9. The diamond processing method according to claim 8, wherein, In the process of forming the modified layer, the laser is focused by the laser focusing part. In the first and second crystal planes that form the {111} plane and form a wedge-shaped structure with the tip thinning towards the main surface inside the substrate, a first scan line and a second scan line formed by processing marks are formed from the end of the wedge-shaped structure towards the tip. The first scan line and the second scan line converge and connect at the tip of the wedge-shaped structure. The first scan line and the second scan line include adjacent first sides and second sides, and have a wedge-shaped structure with different length ratios of the adjacent first sides and second sides.

10. The diamond processing method according to claim 1 or 2, wherein, The substrate is separated by the modified layer.

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