Substrate substrates, single-crystal diamond laminated substrates, and methods for manufacturing the same.

Abstract

The present invention is a base substrate for a single crystal diamond multilayer substrate, said base substrate having an initial substrate that is one of a single crystal Si{111} substrate, a single crystal α-Al2O3{0001} substrate, and the like, and an intermediate layer on the initial substrate, wherein the frontmost surface of the initial substrate has an off angle in the crystal axis <-1-12> direction with respect to the cubic crystal plane orientation {111}, or has an off angle in a crystal axis <10-10> or <11-20> direction with respect to the hexagonal crystal plane orientation {0001}, for example. In this way, a base substrate is provided that can be used to produce a high-purity, low-stress, and high-quality single crystal diamond layer that can be used in electronic or magnetic devices, has a large surface area (large diameter), is highly crystalline, and has few dislocation defects, hillocks, abnormal growth particles such as crystal twinning, or the like.

Description

[Technical Field]

[0001] This invention relates to a base substrate, a single-crystal diamond laminated substrate, and methods for manufacturing the same. [Background technology]

[0002] Diamond has a wide bandgap of 5.47 eV at room temperature and is known as a wide-bandgap semiconductor.

[0003] Among semiconductors, diamond has an extremely high dielectric breakdown field strength of 10 MV / cm, enabling high-voltage operation. Furthermore, it possesses the highest thermal conductivity of any known material, resulting in excellent heat dissipation. In addition, its very high carrier mobility and saturation drift rate make it suitable for high-speed devices.

[0004] Therefore, diamond exhibits the highest Johnson figure of merit, which indicates performance as a high-frequency, high-power device, compared to semiconductors such as silicon carbide and gallium nitride, and is considered the ultimate semiconductor. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] H.Yamada,Appl.Phys.Lett.104,102110(2014). [Overview of the project] [Problems that the invention aims to solve]

[0006] As mentioned above, diamond is expected to be put into practical use as a semiconductor material and a material for electronic and magnetic devices, and there is a demand for the supply of large-area, high-quality diamond substrates.

[0007] Currently, most single-crystal diamonds used for diamond semiconductor fabrication are of type Ib, synthesized by the high-temperature, high-pressure (HPHT) method. This type Ib diamond contains many nitrogen impurities and can only be obtained in sizes up to about 8 mm square, making it impractical. A mosaic method has also been proposed (Non-Patent Literature 1) in which many HPHT substrates (diamond substrates synthesized by the HPHT method) are arranged and joined together, but the problem of incomplete seams remains.

[0008] In contrast, while chemical vapor deposition (CVD) can produce high-purity, large-area diamonds of about 6 inches (150 mm) in diameter for polycrystalline diamonds, single crystallization, which is usually suitable for electronic devices, has been difficult. This is because a suitable combination of materials with small differences in lattice constants and coefficients of thermal expansion between the diamond and the substrate has not been realized as a substrate for forming diamond. For example, the difference in lattice constants between diamond and single-crystal silicon is as large as 34.3%, making it extremely difficult to heteroepitaxially grow diamond on the surface of the substrate.

[0009] The present invention was made to solve the above problems and aims to provide a substrate and a method for manufacturing the same that can be used to fabricate a high-quality single-crystal diamond layer with a large area (large diameter), high crystallinity, few hillocks, abnormally grown particles, dislocation defects, high purity, and low stress, which is applicable to electronic and magnetic devices. It also aims to provide a method for manufacturing a single-crystal diamond laminated substrate and a single-crystal diamond self-supporting structure substrate having such a single-crystal diamond layer. [Means for solving the problem]

[0010] To solve the above objective, the present invention provides a base substrate for a single-crystal diamond laminated substrate, comprising an initial substrate which is one of the following: a single-crystal Si{111} substrate, a single-crystal Si{001} substrate, a single-crystal α-Al2O3{0001} substrate, a single-crystal α-Al2O3{11-20} substrate, a single-crystal Fe{111} substrate, a single-crystal Fe{001} substrate, a single-crystal Ni{111} substrate, a single-crystal Ni{001} substrate, a single-crystal Cu{111} substrate, and a single-crystal Cu{001} substrate, and a single crystal The initial substrate has an intermediate layer consisting of a single layer or multilayer film containing at least one of the following: an Ir film, a single crystal MgO film, a single crystal yttria-stabilized zirconia film, a single crystal SrTiO3 film, and a single crystal Ru film, wherein the outermost surface of the initial substrate has an off-angle in the direction of the crystal axis <-1-12> with respect to the cubic crystal plane orientation {111}, or an off-angle in the direction of the crystal axis <10-10> or <11-20> with respect to the hexagonal crystal plane orientation {0001}, or the crystal axis <110> Those having an off-angle in the direction, or with respect to the hexagonal crystal plane orientation {11-20}, the crystal axis <10-10> or <0001> The present invention provides a substrate characterized by having an off-angle in the direction.

[0011] With such a substrate, the initial substrate, its off-angle, and the intermediate layer can be appropriately combined, resulting in a substrate suitable for electronic and magnetic devices. It is capable of forming a high-quality single-crystal diamond layer with a large diameter, high crystallinity, few hillocks, abnormally grown particles, and dislocation defects, and possessing high purity and low stress.

[0012] In this case, the off-angle of the outermost surface of the initial substrate can be in the range of +8.0 to +24.0° or -8.0 to -24.0°. Furthermore, the off-angle of the outermost surface of the initial substrate can be in the range of greater than +15.0° and less than or equal to +24.0°, or greater than -15.0° and less than or equal to -24.0°.

[0013] By setting the range in this way, the effect of improving quality through the off-angle can be maximized.

[0014] Also, the outermost surface of the intermediate layer may have an off-angle with respect to the cubic crystal plane orientation {111} in the direction of the crystal axis <-1 -1 2>, or may have an off-angle with respect to the hexagonal crystal plane orientation {0001} in the direction of the crystal axis <1 0 -1 0> or <1 1 -2 0>, or may have an off-angle with respect to the cubic crystal plane orientation {001} in the direction of the crystal axis <1 1 0>, or may have an off-angle with respect to the hexagonal crystal plane orientation {1 1 -2 0} in the direction of the crystal axis <1 0 -1 0> or <0 0 0 1>.

[0015] By providing such an off-angle, it is possible to obtain a high-quality single-crystal diamond layer with high crystallinity, few abnormal growths such as hillocks and twins, and few dislocation defects, which can be used as a high-quality underlying substrate more effectively.

[0016] In this case, the off-angle of the outermost surface of the intermediate layer can be in the range of +8.0 to +24.0° or -8.0 to -24.0°. Furthermore, the off-angle of the outermost surface of the intermediate layer can be in the range of greater than +15.0 and less than or equal to +24.0°, or greater than -15.0 and less than or equal to -24.0°.

[0017] By setting it within such a range, the effect of improving quality due to the off-angle can be maximized.

[0018] The present invention also provides a single-crystal diamond laminated substrate, which has a single-crystal diamond layer on the intermediate layer of any of the above-mentioned underlying substrates.

[0019] Such a single-crystal diamond laminated substrate can be a single-crystal diamond laminated substrate having a large-diameter, high-crystallinity, high-quality single-crystal diamond layer with few hillocks, abnormal growth particles, dislocation defects, etc., high purity, and low stress, which is suitable for electronic and magnetic devices.

[0020] At this time, in the single-crystal diamond laminated substrate of the present invention, it is preferable that the single-crystal diamond layer is a {111} crystal or a {001} crystal.

[0021] In the single crystal diamond laminated substrate of the present invention, a single crystal diamond layer having these plane orientations can be provided on the above-mentioned base substrate.

[0022] Further, the present invention includes a step of preparing an initial substrate which is any one of a single crystal Si{111} substrate, a single crystal Si{001} substrate, a single crystal α-Al2O3{0001} substrate, a single crystal α-Al2O3{11-20} substrate, a single crystal Fe{111} substrate, a single crystal Fe{001} substrate, a single crystal Ni{111} substrate, a single crystal Ni{001} substrate, a single crystal Cu{111} substrate, and a single crystal Cu{001} substrate, and a step of forming an intermediate layer made of a single layer or a laminated film including at least any one of a single crystal Ir film, a single crystal MgO film, a single crystal yttria-stabilized zirconia film, a single crystal SrTiO3 film, and a single crystal Ru film on the initial substrate. A method for manufacturing a base substrate for a single crystal diamond laminated substrate, wherein as the initial substrate, the outermost surface of the initial substrate has an off-angle in the crystal axis <-1-12> direction with respect to the cubic crystal plane orientation {111}, or has an off-angle in the crystal axis <10-10> or <11-20> direction with respect to the hexagonal crystal plane orientation {0001}, or has an off-angle in the crystal axis <110> direction with respect to the cubic crystal plane orientation {001}, or has an off-angle in the crystal axis <10-10> or <0001> direction with respect to the hexagonal crystal plane orientation {11-20}. A method for manufacturing a base substrate is provided, characterized by using any one of them.

[0023] With such a method for manufacturing a base substrate, by appropriately combining the initial substrate, its off-angle, and the intermediate layer, it is possible to manufacture a base substrate suitable for electronic and magnetic devices, which is large-diameter, highly crystalline, has few hillocks, abnormal growth particles, dislocation defects, etc., and can form a high-quality single crystal diamond layer with high purity and low stress.

[0024] In this case, the off-angle of the outermost surface of the initial substrate can be in the range of +8.0 to +24.0° or -8.0 to -24.0°. Furthermore, the off-angle of the outermost surface of the initial substrate can be in the range of greater than +15.0° and less than or equal to +24.0°, or greater than -15.0° and less than or equal to -24.0°.

[0025] By using an initial substrate with an off-angle within this range, the quality improvement effect due to the off-angle can be maximized.

[0026] Furthermore, the outermost surface of the intermediate layer may have an off-angle in the direction of the crystal axis <-1-12> with respect to the cubic crystal plane orientation {111}, or an off-angle in the direction of the crystal axis <10-10> or <11-20> with respect to the hexagonal crystal plane orientation {0001}, or a crystal axis <110> Those having an off-angle in the direction, or with respect to the hexagonal crystal plane orientation {11-20}, the crystal axis <10-10> or <0001> It can have an off-angle in the direction.

[0027] By applying this off-angle, it becomes possible to manufacture a substrate that more effectively produces a high-quality single-crystal diamond layer with high crystallinity and fewer hillocks, abnormal growth, and dislocation defects.

[0028] In this case, the intermediate layer can be formed with an off-angle of the outermost surface of the intermediate layer in the range of +8.0 to +24.0° or -8.0 to -24.0°. Furthermore, the off-angle of the outermost surface of the intermediate layer can be in the range of greater than +15.0° and less than or equal to +24.0°, or greater than -15.0° and less than or equal to -24.0°.

[0029] By setting the range in this way, the effect of improving quality through the off-angle can be maximized.

[0030] Furthermore, the present invention provides a method for manufacturing a single-crystal diamond laminated substrate, comprising the steps of: preparing a base substrate manufactured by any of the above-described methods for manufacturing a base substrate; performing a bias treatment on the surface of the intermediate layer of the base substrate for diamond nucleation; and growing the diamond nuclei formed on the intermediate layer to perform epitaxial growth and form a single-crystal diamond layer.

[0031] The single-crystal diamond laminated substrate manufactured in this manner can be a high-quality single-crystal diamond substrate suitable for electronic and magnetic devices, possessing a large diameter, high crystallinity, few hillocks, abnormally grown particles, dislocation defects, high purity, and low stress single-crystal diamond layers.

[0032] In this case, in the single-crystal diamond laminated substrate of the present invention, it is preferable that the single-crystal diamond layer be a {111} crystal or a {001} crystal.

[0033] The single-crystal diamond laminated substrate of the present invention can be manufactured having a single-crystal diamond layer having these plane orientations on the above-mentioned base substrate.

[0034] Furthermore, the present invention provides a method for manufacturing a single-crystal diamond self-supporting substrate, characterized by extracting only the single-crystal diamond layer from a single-crystal diamond laminated substrate manufactured by any of the above-described methods for manufacturing a single-crystal diamond laminated substrate, thereby manufacturing a single-crystal diamond self-supporting substrate.

[0035] In this way, a single-crystal diamond self-supporting substrate consisting solely of a single-crystal diamond layer can be manufactured.

[0036] Furthermore, an additional single-crystal diamond layer can be formed on the single-crystal diamond self-supporting substrate obtained by the above-described method for manufacturing a single-crystal diamond self-supporting substrate.

[0037] In this way, it is also possible to further increase the thickness of the film by depositing an additional film on a substrate consisting only of the diamond layer. [Effects of the Invention]

[0038] According to the substrate and manufacturing method of the present invention, by appropriately combining the initial substrate, its off-angle, and the intermediate layer, a diamond layer can be formed, resulting in a laminated substrate having a high-quality single-crystal diamond layer with a large diameter, high crystallinity, few hillocks, abnormally grown particles, dislocation defects, high purity, and low stress, suitable for electronic and magnetic devices. Furthermore, according to the present invention, it is also possible to manufacture a single-crystal diamond self-supporting structure substrate by separating only the single-crystal diamond layer from such a single-crystal diamond laminated substrate, or to manufacture a single-crystal diamond self-supporting structure substrate by depositing an additional single-crystal diamond layer on a single-crystal diamond self-supporting structure substrate. [Brief explanation of the drawing]

[0039] [Figure 1] This is a schematic diagram showing an example of a substrate for the present invention. [Figure 2] This is a schematic diagram showing an example of a single-crystal diamond laminated substrate of the present invention. [Figure 3] This is a schematic diagram showing an example of a self-supporting single-crystal diamond substrate according to the present invention. [Figure 4] This is a schematic diagram showing another example of a single-crystal diamond self-supporting substrate according to the present invention. [Figure 5] This is a flowchart showing an example of a method for manufacturing a substrate according to the present invention. [Figure 6] This flowchart shows an example of the process for manufacturing a single-crystal diamond laminated substrate and a single-crystal self-supporting structure substrate according to the present invention. [Figure 7] This shows the pole method results of the X-ray diffraction measurement in Example 1. [Figure 8] This shows the results of the out-of-plane method for X-ray diffraction measurement in Example 1. [Figure 9] This shows the results of the pole method for X-ray diffraction measurements in the comparative example. [Figure 10] This shows the results of the out-of-plane method for X-ray diffraction measurements in the comparative example. [Modes for carrying out the invention]

[0040] The present invention will be described in detail below, but the present invention is not limited to these descriptions.

[0041] As mentioned above, there has been a conventional need for large-diameter, low-cost, and high-quality single-crystal diamond laminated substrates. Therefore, the inventors diligently conducted research to solve these problems. As a result, they discovered the optimal materials for the initial substrate and the intermediate layer in single-crystal diamond laminated substrates and the base substrates for manufacturing them, as well as methods for forming them, thus completing the present invention.

[0042] The present invention will be described in more detail below with reference to the drawings. Similar components will be denoted by the same reference numerals below.

[0043] First, the substrate and single-crystal diamond laminated substrate of the present invention will be described with reference to Figures 1 and 2.

[0044] As shown in Figure 1, the base substrate 20 for the single-crystal diamond laminated substrate of the present invention has an initial substrate 11 and an intermediate layer 21 on the initial substrate 11. In the present invention, the initial substrate 11 is one of the following: single-crystal Si{111} substrate, single-crystal Si{001} substrate, single-crystal α-Al2O3{0001} substrate, single-crystal α-Al2O3{11-20} substrate, single-crystal Fe{111} substrate, single-crystal Fe{001} substrate, single-crystal Ni{111} substrate, single-crystal Ni{001} substrate, single-crystal Cu{111} substrate, and single-crystal Cu{001} substrate. Furthermore, the intermediate layer 21 on the initial substrate 11 has a layer consisting of a single layer or a laminated film containing at least one of the following: a single-crystal Ir film, a single-crystal MgO film, a single-crystal yttria-stabilized zirconia film, a single-crystal SrTiO3 film, and a single-crystal Ru film. In the base substrate 20 of the present invention, the outermost surface of the initial substrate 11 has an off-angle in the direction of the crystal axis <-1-12> with respect to the cubic crystal plane orientation {111}, or has an off-angle in the direction of the crystal axis <10-10> or <11-20> with respect to the hexagonal crystal plane orientation {0001}, or the crystal axis <110> Those having an off-angle in the direction, or with respect to the hexagonal crystal plane orientation {11-20}, the crystal axis <10-10> or <0001> It has an off-angle in the direction.

[0045] Furthermore, as shown in Figure 2, the single-crystal diamond laminated substrate 30 of the present invention has a single-crystal diamond layer 31 on an intermediate layer 21 of the base substrate 20 shown in Figure 1. The intermediate layer 21 plays a role in buffering the lattice mismatch between the initial substrate 11 and the single-crystal diamond layer 31.

[0046] As described above, the initial substrate 11 can be any of the following: single crystal Si{111} substrate, single crystal Si{001} substrate, single crystal α-Al2O3{0001} substrate, single crystal α-Al2O3{11-20} substrate, single crystal Fe{111} substrate, single crystal Fe{001} substrate, single crystal Ni{111} substrate, single crystal Ni{001} substrate, single crystal Cu{111} substrate, or single crystal Cu{001} substrate. Because these initial substrates 11 (bulk substrates) have small lattice mismatch with the material of the intermediate layer 21, epitaxial growth of the intermediate layer 21 is easily possible when forming the intermediate layer 21. Furthermore, large diameters exceeding 6 inches (150 mm) can be obtained, and the price can be kept relatively low.

[0047] At this time, if you want to obtain {111} crystals and {001} crystals as the single-crystal diamond layer 31 to be fabricated, select the appropriate initial substrate 11.

[0048] Furthermore, the off-angle of the outermost surface of the initial substrate 11 shall be as specified above. That is, the outermost surface of the initial substrate 11 may have an off-angle in the direction of the crystal axis <-1-12> with respect to the cubic crystal plane orientation {111} of a single crystal Si{111} substrate, etc., and may have an off-angle in the direction of the crystal axis <10-10> or <11-20> with respect to the hexagonal crystal plane orientation {0001} of a single crystal α-Al2O3{0001} substrate, etc. Also, the outermost surface of the initial substrate 11 may have an off-angle in the direction of the crystal axis with respect to the cubic crystal plane orientation {001} of a single crystal Si{001} substrate, etc. <110> It can have an off-angle in the direction, and with respect to the hexagonal crystal plane orientation {11-20} of a single crystal α-Al2O3{11-20} substrate, the crystal axis <10-10> or <0001> It can also have an off-angle in the direction.

[0049] By defining the off-angle in this way, it becomes possible to obtain a high-quality intermediate layer formed on the outermost surface of the initial substrate 11, which is highly crystalline and has few hillocks, abnormal growth, dislocation defects, etc.

[0050] When applying an off-angle to the outermost surface of the initial substrate 11 at this time, it is preferable that the off-angle be in the range of +8.0 to +24.0° or -8.0 to -24.0°. If this off-angle is +8.0° or higher and -8.0° or higher, the effect of applying the off-angle can be sufficiently obtained, and if it is +24.0° or lower and -24.0° or lower, the effect of improving quality can be sufficiently obtained.

[0051] Furthermore, it is more preferable that the off-angle when applying the off-angle to the outermost surface of the initial substrate 11 be in the range of greater than +15.0° and less than or equal to +24.0°, or greater than -15.0° and less than or equal to -24.0°. Within this range of off-angles, the effect of applying the off-angle can be obtained more stably and sufficiently, and the effect of improving quality can be fully obtained.

[0052] It is preferable to polish the surface of the initial substrate 11 on the side where the intermediate layer will be formed to achieve a Ra ≤ 0.5 nm. This allows for the formation of a smooth intermediate layer with fewer defects.

[0053] The intermediate layer 21 consists of a single layer or a multilayer film containing at least one of the following: a single crystal Ir film, a single crystal MgO film, a single crystal yttria-stabilized zirconia film, a single crystal SrTiO3 film, and a single crystal Ru film, as described above.

[0054] In the substrate 20 of the present invention, the intermediate layer 21 can be made not only a single layer of the material as described above, but also a laminated structure, and good quality can be achieved in this case as well. Such a laminated film can be designed to more appropriately buffer the lattice mismatch between the initial substrate 11 and the single-crystal diamond layer 31. For example, the layers can be arranged in the order from the surface side → Ir film / MgO film → initial substrate 11 side, and similarly, by creating a laminated structure with an Ir film / YSZ film, an Ir film / SrTiO3 film, etc., the buffering role for lattice mismatch can be made more effective.

[0055] The thickness of the intermediate layer 21 is preferably between 5 nm and 50 μm. If the thickness of the intermediate layer 21 is 5 nm or more, it will not be removed during the subsequent diamond formation process. Also, if the thickness of the intermediate layer 21 is 50 μm or less, it is sufficient. Furthermore, with a thickness of 50 μm or less, the film formation time will not be long and the surface roughness will remain low. Therefore, polishing is not always necessary, and film formation can be done at a low cost.

[0056] The outermost surface of the intermediate layer 21 may have an off-angle. The outermost surface of the intermediate layer 21 may have an off-angle in the direction of the crystal axis <-1-12> with respect to the cubic crystal plane orientation {111}, and may have an off-angle in the direction of the crystal axis <10-10> or <11-20> with respect to the hexagonal crystal plane orientation {0001}. Furthermore, the outermost surface of the intermediate layer 21 may have an off-angle in the direction of the crystal axis with respect to the cubic crystal plane orientation {001}. <110> Those having an off-angle in the direction, or with respect to the hexagonal crystal plane orientation {11-20}, the crystal axis <10-10> or <0001> The layer may also have an off-angle in the direction. By defining the off-angle of the outermost surface of the intermediate layer 21 in this way, it becomes possible to obtain a high-quality single-crystal diamond layer formed on the surface that is highly crystalline and has few hillocks, abnormal growths, dislocation defects, etc.

[0057] It is preferable that the off-angle of the outermost surface of the intermediate layer 21 at this time be in the range of +8.0 to +24.0° or -8.0 to -24.0°. If this off-angle is +8.0 and -8.0° or higher, the effect of creating an off-angle can be sufficiently obtained, and if it is +24.0 and -24.0° or lower, the effect of improving quality can be sufficiently obtained. Furthermore, within these ranges, the deviation from the crystal plane of the outermost surface is not too large, so it is easy to use according to the purpose.

[0058] Furthermore, it is more preferable that the off-angle of the outermost surface of the intermediate layer 21 be in the range of greater than +15.0° and less than or equal to +24.0°, or greater than -15.0° and less than or equal to -24.0°. Within this range of off-angles, the effect of creating an off-angle can be obtained more stably and sufficiently, and the effect of improving quality can be fully obtained.

[0059] The following describes the manufacturing methods for the substrate and the single-crystal diamond laminate shown in Figures 1 and 2. The manufacturing method for the substrate of the present invention will be described with reference to Figure 5, and the manufacturing method for the single-crystal diamond laminate of the present invention will be described with reference to Figure 6.

[0060] Furthermore, the present invention can manufacture a single-crystal diamond self-supporting substrate 35 consisting of a single-crystal diamond layer 31, as shown in Figure 3, and a single-crystal diamond self-supporting substrate 40 consisting of a single-crystal diamond layer 31 and an additional single-crystal diamond layer 41, as shown in Figure 4. This manufacturing method will also be explained with reference to Figure 6.

[0061] (Preparation process: Step S11 in Figure 5) First, the initial substrate 11 is prepared (step S11). The initial substrate 11 is one of the following substrates (bulk substrates): single crystal Si{111} substrate, single crystal Si{001} substrate, single crystal α-Al2O3{0001} substrate, single crystal α-Al2O3{11-20} substrate, single crystal Fe{111} substrate, single crystal Fe{001} substrate, single crystal Ni{111} substrate, single crystal Ni{001} substrate, single crystal Cu{111} substrate, and single crystal Cu{001} substrate. The materials of these listed initial substrates 11 have small lattice mismatches with the material of the intermediate layer 21, making it easy to grow the intermediate layer 21 epitaxially. In addition, large diameters exceeding 6 inches (150 mm) can be obtained, and the price is relatively low.

[0062] Furthermore, as the initial substrate 11, the outermost surface of the initial substrate has an off-angle in the direction of the crystal axis <-1-12> with respect to the cubic crystal plane orientation {111}, or has an off-angle in the direction of the crystal axis <10-10> or <11-20> with respect to the hexagonal crystal plane orientation {0001}, or the crystal axis <110> Those having an off-angle in the direction, or with respect to the hexagonal crystal plane orientation {11-20}, the crystal axis <10-10> or <0001> One of the initial substrates having an off-angle in the direction is used. By using such an initial substrate 11, it becomes possible to more effectively obtain a high-quality intermediate layer 21 formed on the surface, which is highly crystalline and has fewer hillocks, abnormal growth, dislocation defects, etc.

[0063] If a {111} crystal plane orientation is desired for the single-crystal diamond layer 31, the outermost surface of the initial substrate 11 can be given an off-angle in the direction of the crystal axis <-1-12> relative to the cubic crystal plane orientation {111}, or an off-angle in the direction of the crystal axis <10-10> or <11-20> relative to the hexagonal crystal plane orientation {0001}. On the other hand, if a {001} crystal plane orientation is desired for the single-crystal diamond layer, the outermost surface of the initial substrate 11 can be given an off-angle in the direction of the crystal axis <-1-10> or <11-20> relative to the cubic crystal plane orientation {001}. <110> To give an off-angle to the direction, or to the hexagonal crystal plane orientation {11-20}, <10-10> or <0001> It can be made by adding an off-angle to the direction.

[0064] It is preferable to polish the surface of the initial substrate 11 on which the intermediate layer 21 will be formed so that Ra ≤ 0.5 nm. This allows for the formation of a smooth intermediate layer 21 with few defects.

[0065] It is preferable that the off-angle of the outermost surface of the initial substrate 11 at this time be in the range of +8.0 to +24.0° or -8.0 to -24.0°. If this off-angle is +8.0° or higher and -8.0° or higher, the effect of adding an off-angle can be sufficiently obtained, and if it is +24.0° or lower and -24.0° or lower, the effect of improving quality can be sufficiently obtained. Furthermore, within these ranges, the deviation from the crystal plane of the outermost surface is not too large, so it is easy to use in a way that suits the purpose.

[0066] Furthermore, it is more preferable to set the off-angle of the outermost surface of the initial substrate 11 to a range greater than +15.0° and less than or equal to +24.0°, or greater than -15.0° and less than or equal to -24.0°. Within such an off-angle range, the effect of creating an off-angle can be obtained more stably and sufficiently, and the effect of improving quality can be fully obtained.

[0067] (Intermediate layer formation process: Step S12 in Figure 5) After preparing the initial substrate 11 in step S11, an intermediate layer 21 is then formed on the initial substrate 11. The intermediate layer 21 consists of a single layer or a multilayer film containing at least one of the following: a single crystal Ir film, a single crystal MgO film, a single crystal yttria-stabilized zirconia film, a single crystal SrTiO3 film, and a single crystal Ru film (step S12).

[0068] Here, the outermost surface of the intermediate layer 21 may have an off-angle. The outermost surface of the intermediate layer 21 may have an off-angle in the direction of the crystal axis <-1-12> with respect to the cubic crystal plane orientation {111}, and may have an off-angle in the direction of the crystal axis <10-10> or <11-20> with respect to the hexagonal crystal plane orientation {0001}. Furthermore, the outermost surface of the intermediate layer 21 may have an off-angle in the direction of the crystal axis with respect to the cubic crystal plane orientation {001}. <110> Those having an off-angle in the direction, or with respect to the hexagonal crystal plane orientation {11-20}, the crystal axis <10-10> or <0001> The layer may also have an off-angle in the direction. By defining the off-angle of the outermost surface of the intermediate layer 21 in this way, it becomes possible to obtain a high-quality single-crystal diamond layer formed on the surface that is highly crystalline and has few hillocks, abnormal growths, dislocation defects, etc.

[0069] If you want to obtain a {111} crystal orientation for the single-crystal diamond layer 31, at least the outermost surface of the intermediate layer 21 should also have a {111} crystal orientation if it is cubic, and a {0001} crystal orientation if it is hexagonal. On the other hand, if you want to obtain a {001} crystal orientation for the single-crystal diamond layer 31, at least the outermost surface of the intermediate layer 21 should also have a {001} crystal orientation if it is cubic, and a {11-20} crystal orientation if it is hexagonal.

[0070] It is preferable that the off-angle of the outermost surface of the intermediate layer 21 at this time be in the range of +8.0 to +24.0° or -8.0 to -24.0°. If this off-angle is +8.0 and -8.0° or higher, the effect of creating an off-angle can be sufficiently obtained, and if it is +24.0 and -24.0° or lower, the effect of improving quality can be sufficiently obtained. Furthermore, within these ranges, the deviation from the crystal plane of the outermost surface is not too large, so it is easy to use according to the purpose.

[0071] Furthermore, it is more preferable that the off-angle of the outermost surface of the intermediate layer 21 be in the range of greater than +15.0° and less than or equal to +24.0°, or greater than -15.0° and less than or equal to -24.0°. Within this range of off-angles, the effect of creating an off-angle can be obtained more stably and sufficiently, and the effect of improving quality can be fully obtained.

[0072] The intermediate layer 21 can be formed using sputtering, electron beam deposition, atomic layer deposition, molecular beam epitaxy, pulsed laser deposition, and other methods. Furthermore, the single-crystal Ir film, single-crystal MgO film, single-crystal yttria-stabilized zirconia (YSZ) film, single-crystal SrTiO3 film, and single-crystal Ru film, which are metals and metal oxides used in this invention, can be formed using mist CVD, which allows for large-diameter and low-cost formation.

[0073] A film-forming apparatus using the mist CVD method consists of a misting unit that generates mist by atomizing a raw material solution containing atoms of the material to be formed into a film using ultrasonic vibrations, a carrier gas supply unit that supplies a carrier gas to transport the mist, a chamber where a substrate is set and film formation is performed, and an exhaust system that discharges the unwanted raw materials.

[0074] Within the chamber, the substrate is heated on a heater stage and rotated as needed to enable the formation of a highly crystalline and uniform film. The flow of the raw material gas is also controlled to ensure the formation of a highly crystalline and uniform film.

[0075] Alternatively, a substrate can be placed on a heater stage installed in an open system, and mist can be supplied to the surface of the substrate from a mist discharge nozzle to form a film through a thermal reaction.

[0076] The raw material solution is not particularly limited in its composition, as long as it contains at least the metal atoms to be formed into a film and can be atomized; it may be an inorganic or organic material.

[0077] The raw material solution is not particularly limited as long as it can atomize the above-mentioned metal atoms, but it is preferable to use a raw material solution in which the metal is dissolved or dispersed in an organic solvent or water in the form of a complex or salt. Examples of complexes include acetylacetonate complexes, carbonyl complexes, ammine complexes, and hydride complexes. Examples of salts include metal chloride salts, metal bromide salts, and metal iodide salts. Furthermore, solutions in which the above-mentioned metal is dissolved in hydrobromic acid, hydrochloric acid, hydrogen iodide, etc., can also be used as aqueous solutions of salts.

[0078] Furthermore, additives such as hydrohalic acids and oxidizing agents may be mixed into the raw material solution. Examples of hydrohalic acids include hydrobromic acid, hydrochloric acid, and hydroiodic acid, with hydrobromic acid or hydroiodic acid being preferred. Examples of oxidizing agents include peroxides such as hydrogen peroxide, sodium peroxide, barium peroxide, and benzoyl peroxide, as well as hypochlorous acid, perchloric acid, nitric acid, ozonated water, peracetic acid, and nitrobenzene.

[0079] For MgO formation, an aqueous solution of magnesium chloride can also be used as the raw material solution.

[0080] To obtain oxides of multi-element metals, one can either mix multiple raw material solutions and atomize them, or atomize each element separately using its own raw material solution.

[0081] It is preferable to heat the substrate temperature in the range of 200 to 1000°C to form the film.

[0082] As described above, the intermediate layer 21 can achieve good quality not only as a single layer of the material but also in a laminated structure. For example, the layers can be arranged in the following order from the surface side: →Ir film / MgO film →initial substrate 11 side. Similarly, by creating a laminated structure with Ir film / YSZ film, Ir film / SrTiO3 film, etc., the buffering role for lattice mismatch can be made more effective.

[0083] The thickness of the intermediate layer 21 is preferably between 5 nm and 50 μm. If the thickness of the intermediate layer 21 is 5 nm or more, it will not be removed during the subsequent diamond formation process. Also, if the thickness of the intermediate layer 21 is 50 μm or less, it is sufficient. Furthermore, with a thickness of 50 μm or less, the film formation time will not be long and the surface roughness will remain low. Therefore, polishing is not always necessary, and film formation can be done at a low cost.

[0084] The outermost surface of the intermediate layer 21 can be set with an off-angle in the direction of the crystal axis <-1-12> relative to the cubic crystal plane orientation {111}, or with an off-angle in the direction of the crystal axis <10-10> or <11-20> relative to the hexagonal crystal plane orientation {0001}. This makes it possible to more effectively obtain a high-quality single-crystal diamond {111} layer with high crystallinity and fewer hillocks, abnormal growths, and dislocation defects as the single-crystal diamond layer 31 formed on the surface.

[0085] In this case, the off-angle of the outermost surface of the intermediate layer 21 is preferably in the range of +8.0 to +24.0° or -8.0 to -24.0°. If this off-angle is +8.0° or higher and -8.0° or higher, the effect of creating an off-angle can be sufficiently obtained, and if it is +24.0° or lower and -24.0° or lower, the effect of improving quality can be sufficiently obtained. Furthermore, within these ranges, the deviation from the {111} crystal plane of the outermost surface is not too large, making it easy to use for the intended purpose.

[0086] Furthermore, it is more preferable that the off-angle of the outermost surface of the intermediate layer 21 be in the range of greater than +15.0° and less than or equal to +24.0°, or greater than -15.0° and less than or equal to -24.0°. Within this range of off-angles, the effect of creating an off-angle can be obtained more stably and sufficiently, and the effect of improving quality can be fully obtained.

[0087] As described above, the outermost surface of the intermediate layer 21 has a crystal axis in the cubic crystal orientation {001}. <110> To add an off-angle to the direction, and for the hexagonal crystal plane orientation {11-20}, <10-10> or <0001> By applying an off-angle in the direction, it becomes possible to obtain a high-quality single-crystal diamond {001} layer on the surface that is highly crystalline and has few hillocks, abnormal growths, dislocation defects, etc.

[0088] In this case, the off-angle of the outermost surface of the intermediate layer 21 is preferably in the range of +8.0 to +24.0° or -8.0 to -24.0°. If this off-angle is +8.0° or higher and -8.0° or higher, the effect of creating an off-angle can be sufficiently obtained, and if it is +24.0° or lower and -24.0° or lower, the effect of improving quality can be sufficiently obtained. Furthermore, within these ranges, the deviation from the {001} crystal plane of the outermost surface is not too large, making it easy to use for a specific purpose.

[0089] Furthermore, it is more preferable that the off-angle of the outermost surface of the intermediate layer 21 be in the range of greater than +15.0° and less than or equal to +24.0°, or greater than -15.0° and less than or equal to -24.0°. Within this range of off-angles, the effect of creating an off-angle can be obtained more stably and sufficiently, and the effect of improving quality can be fully obtained.

[0090] The base substrate 20 of the present invention (see Figure 1) can be manufactured by following steps S11 and S12 shown in Figure 5 above.

[0091] The present invention further provides a method for manufacturing a single-crystal diamond laminated substrate 30, characterized by comprising the steps of: preparing a base substrate 20 manufactured by the method for manufacturing the base substrate 20 as described above; performing a bias treatment on the surface of the intermediate layer 21 of the base substrate 20 for diamond nucleation; and growing the diamond nuclei formed on the intermediate layer 21 to perform epitaxial growth and form a single-crystal diamond layer 31. A more detailed description follows below.

[0092] Steps S11 and S12 in Figure 6 are the same as steps S11 and S12 in Figure 5. Steps S11 and S12 produce the base substrate 20. Furthermore, by performing the subsequent steps S13 and S14 shown in Figure 6, the single-crystal diamond laminated substrate 30 is produced.

[0093] (Bias processing step: S13 in Figure 6) A bias treatment is performed on the surface of the intermediate layer 21 of the base substrate 20 to form diamond nuclei (step S13). The base substrate 20 with the intermediate layer 21 formed is placed in a reduced pressure chamber, and after reducing the pressure with a vacuum pump, diamond nuclei are formed by DC discharge with the crystal orientation aligned with the outermost surface of the intermediate layer 21. The discharge gas is preferably hydrogen-diluted methane.

[0094] (Single-crystal diamond layering process: S14 in Figure 6) Next, the diamond nuclei formed on the intermediate layer 21 are grown epitaxially to form a single-crystal diamond layer 31 (step S14). In other words, a single-crystal layer is formed on the bias-treated substrate 20. This step can be carried out by vapor-phase synthesis (CVD) methods such as microwave plasma CVD, DC plasma CVD, thermal filament CVD, or arc discharge CVD.

[0095] The single-crystal diamond layer 31 can consist of individual undoped or doped diamond layers, or a stacked structure of undoped and doped diamonds.

[0096] The single-crystal diamond laminated substrate 30 (see Figure 2) of the present invention can be manufactured by steps S13 and S14 following steps S11 and S12 described above.

[0097] Furthermore, in the method for manufacturing the single-crystal diamond laminated substrate described above, single-crystal diamond {111} can be obtained by setting the crystal orientation of either the initial substrate 11, the intermediate layer 21, or both to {111} in the case of a cubic crystal, or {0001} in the case of a hexagonal crystal. For example, single-crystal diamond {111} can be formed using either a single-crystal Si {111} substrate or a single-crystal α-Al2O3 {0001} substrate as the initial substrate 11.

[0098] On the other hand, in the method for manufacturing the single-crystal diamond laminated substrate described above, single-crystal diamond {001} can be obtained by setting the crystal orientation of either the initial substrate 11, the intermediate layer 21, or both to {001} in the case of a cubic crystal, or to {11-20} in the case of a hexagonal crystal. For example, single-crystal diamond {001} can be formed using either a single-crystal Si {001} substrate or a single-crystal α-Al2O3 {11-20} substrate as the initial substrate 11.

[0099] The present invention also provides a method for manufacturing a single-crystal diamond self-supporting substrate 35 (see Figure 3) by extracting only the single-crystal diamond layer 31 from the single-crystal diamond laminated substrate 30 manufactured through steps S11 to S14 by the method described above. A more detailed explanation follows below.

[0100] (Single-crystal diamond extraction process: S15 in Figure 6) In this process, after the single-crystal diamond layer 31 formation process (step S14), only the single-crystal diamond layer 31 is removed to form a single-crystal diamond self-supporting substrate 35 (step S15). This self-supporting substrate can be created using chemical etching, laser irradiation, polishing, or other methods.

[0101] By achieving self-sufficiency, the process becomes easier to adapt to subsequent additional film deposition and device fabrication.

[0102] Furthermore, when using diamond as an electronic and magnetic device, a single-crystal diamond self-supporting substrate composed solely of single-crystal diamond layers can be advantageous because it is unaffected by the intermediate layers and below.

[0103] (Single-crystal diamond additional film deposition process: S16 in Figure 6) Furthermore, in this invention, a single-crystal diamond self-supporting substrate 40 (see Figure 4) can be manufactured by forming an additional single-crystal diamond layer 41 on the single-crystal diamond self-supporting substrate 35 obtained up to step S15 (step S16). In other words, an additional film can be formed on the single-crystal diamond self-supporting substrate 35, which consists only of the single-crystal diamond layer 31 shown in Figure 3. Since the film is formed on a single material, there is no damage, and it is effective in reducing stress. This process is also advantageous for increasing the thickness of the diamond film.

[0104] The additional single-crystal diamond layer 41 formed in this process may be undoped, doped, or a combination of both.

[0105] If the surface of the underlying single-crystal diamond self-supporting structure substrate 35 is polished before the additional single-crystal diamond layer 41 is deposited, a smooth crystal with few defects can be obtained.

[0106] The manufacturing methods for the base substrate, single-crystal diamond laminated substrate, and single-crystal diamond self-supporting structure substrate of the present invention, as described above, make it possible to provide a low-cost method for manufacturing laminated substrates having a high-quality single-crystal diamond layer with a large diameter, high crystallinity, few hillocks, abnormally grown particles, dislocation defects, high purity, and low stress, which are suitable for electronic and magnetic devices. [Examples]

[0107] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0108] (Example 1) A single-crystal α-Al2O3 wafer with a diameter of 150 mm, a thickness of 1000 μm, a crystal plane orientation of {0001}, and an off-angle of 16° in the <11-20> direction, polished on both sides, was prepared as the initial substrate 11 (see initial substrate 11 in Figure 1) (step S11 in Figures 5 and 6).

[0109] Next, an Ir film was heteroepitaxially grown on the surface of the initial substrate 11 to form an intermediate layer 21 of the Ir film {111} (step S12 in Figures 5 and 6).

[0110] For the deposition of the Ir film, which is the intermediate layer 21, an RF (13.56 MHz) magnetron sputtering method was used, targeting an Ir target with a diameter of 8 inches (200 mm), a thickness of 5 mm, and a purity of 99.9% or higher. The substrate was heated to 850°C, evacuated with a vacuum pump, and the base pressure was approximately 8.0 × 10⁻⁶. -5 After confirming that the pressure was below Pa, Ar gas was introduced. The opening of the valve leading to the exhaust system was adjusted to 14 Pa, and then RF 1500W was applied for 30 minutes to deposit the film. The resulting film thickness was approximately 1 μm.

[0111] Crystallinity was measured from the outermost surface of the film using the pole method and the out-of-plane method with an X-ray diffraction (XRD) instrument (RIGAKU SmartLab). As a result, the pole method detected the (111) plane diffraction peak when the (111) plane was oriented in the direction normal to the main surface of the substrate, while the (111) plane diffraction peak was not detected when the (001) plane was oriented in the direction normal to the main surface of the substrate. The results of the pole method are shown in Figure 7. The spot arrangement of the (111) diffraction peak was as if there were no twins constituting {111}.

[0112] Furthermore, the out-of-plane method revealed only the main diffraction intensity peak and its multiple reflection peaks at 2θ = 40.7°, which are attributed to Ir(111), confirming that the intermediate layer is an epitaxially grown single-crystal Ir(111) crystal. The results of the out-of-plane method are shown in Figure 8. The full width at half maximum of the rocking curve of the Ir(111) peak was 0.13°.

[0113] As described above, the base substrate 20 of the present invention was manufactured (see Figure 1).

[0114] Next, the base substrate 20 was subjected to a pretreatment (bias treatment) for diamond nucleation (step S13 in Figure 6). Here, the base substrate 20 on which the intermediate layer 21 was formed was set on a flat electrode, and the base pressure was approximately 1.3 × 10⁻⁶. -4 After confirming that the pressure was below Pa, hydrogen-diluted methane (CH4 / (CH4+H2)=5.0 vol.%) was introduced into the treatment chamber at a flow rate of 500 sccm. The opening of the valve leading to the exhaust system was adjusted to set the pressure to 1.3 × 10⁻⁶. 4 After setting the temperature to Pa, a negative voltage was applied to the substrate-side electrode and the substrate was exposed to the plasma for 90 seconds to bias-treat the surface of the intermediate layer 21 (i.e., the surface of the single-crystal Ir(111) film).

[0115] Next, a single-crystal diamond layer 31 (undoped diamond film) was heteroepitaxially grown by microwave CVD (step S14 in Figure 6). Here, the bias-treated substrate 20 was set in the chamber of the microwave CVD apparatus, and the base pressure was increased to approximately 1.3 × 10⁻⁶ using a vacuum pump. -4 After exhausting the gas until it was below Pa, hydrogen-diluted methane (CH4 / (CH4+H2)=4.0 vol.%), the raw material gas, was introduced into the treatment chamber at a flow rate of 1000 sccm. The opening of the valve leading to the exhaust system was adjusted to set the pressure to 1.5 × 10⁻⁶. 4 After setting the temperature to Pa, a DC current was applied and film deposition was carried out for 150 hours. The substrate temperature during film deposition was measured with a pyrometer and was found to be 980°C.

[0116] The obtained single-crystal diamond layer 31 was a perfectly continuous film with no delamination across its entire 150 mm diameter. A schematic cross-sectional view of the single-crystal diamond laminated substrate 30 manufactured in this manner is shown in Figure 2.

[0117] Next, the initial substrate 11, an α-Al2O3 wafer, was etched with thermal phosphoric acid. Furthermore, the intermediate layer 21, an Ir film, was removed by dry etching. This resulted in the acquisition of a single-crystal diamond {111} self-supporting substrate 35 (step S15 in Figure 6).

[0118] Finally, a single-crystal diamond layer (additional single-crystal diamond layer 41) was heteroepitaxially grown again by microwave CVD (step S16 in Figure 6). This additional single-crystal diamond layer 41 was formed under the same conditions as when the undoped diamond film was formed as described above.

[0119] The obtained single-crystal diamond layer was also a perfectly continuous film with no delamination across the entire 150 mm diameter. A schematic cross-sectional view of the single-crystal diamond self-supporting substrate 40, consisting of the single-crystal diamond layer 31 and the additional single-crystal diamond layer 41, is shown in Figure 4.

[0120] A 2mm square section was cut from this single-crystal diamond self-supporting substrate 40 and used as an evaluation sample. Film thickness and crystallinity were then evaluated.

[0121] Regarding the film thickness, a scanning secondary electron microscope (SEM) observation of the sample cross-section revealed that the total thickness of the diamond layer was approximately 400 μm.

[0122] The crystallinity of the film surface was measured using an X-ray diffraction (XRD) instrument (RIGAKU SmartLab). As a result, only a diffraction intensity peak attributed to diamond (111) at 2θ = 43.9° was observed, confirming that the diamond layer was an epitaxially grown single-crystal diamond {111} crystal. No twinning components were found.

[0123] Applying the single-crystal diamond {111} laminated substrate and self-supporting substrate to electronic and magnetic devices can yield high-performance devices. For example, high-performance power devices can be obtained.

[0124] Moreover, since it can be obtained on large-diameter substrates, it is possible to keep manufacturing costs low.

[0125] (Example 2) A double-sided polished single-crystal α-Al2O3 wafer with a diameter of 150 mm, a thickness of 1000 μm, a crystal plane orientation of {0001}, and an off-angle of 8° in the <11-20> direction was prepared as the initial substrate 11 (see initial substrate 11 in Figure 1) (step S11 in Figures 5 and 6).

[0126] Next, an Ir film was heteroepitaxially grown on the surface of the initial substrate 11 to form an intermediate layer 21 of the Ir film {111} (step S12 in Figures 5 and 6).

[0127] For the deposition of the Ir film, which is the intermediate layer 21, an RF (13.56 MHz) magnetron sputtering method was used, targeting an Ir target with a diameter of 8 inches (200 mm), a thickness of 5 mm, and a purity of 99.9% or higher. The substrate was heated to 850°C, evacuated with a vacuum pump, and the base pressure was approximately 8.0 × 10⁻⁶. -5After confirming that the pressure was below Pa, Ar gas was introduced. After adjusting the opening degree of the valve leading to the exhaust system to 14 Pa, R.F. 1500 W was input and film formation was carried out for 30 minutes. The obtained film thickness was about 1 μm.

[0128] Using an X-ray diffraction (XRD) apparatus (RIGAKU SmartLab), the crystallinity was measured from the outermost surface of the film by the pole figure method and the out-of-plane method. As a result, no twin components constituting Ir{111} were found, and only the diffraction intensity main peak attributed to Ir(111) at 2θ = 40.7° and its multiple reflection peaks were observed, confirming that the intermediate layer was an epitaxially grown single crystal Ir(111) crystal. The rocking curve half-value width of the Ir(111) peak was 0.12°.

[0129] In this way, the underlayer substrate 20 of the present invention was manufactured (see FIG. 1).

[0130] Next, a pretreatment (bias treatment) for diamond nucleation was performed on the underlayer substrate 20 (step S13 in FIG. 6). Here, the underlayer substrate 20 on which the intermediate layer 21 was formed was set on a flat electrode, and after confirming that the base pressure was about 1.3×10 -4 Pa or less, hydrogen-diluted methane (CH4 / (CH4+H2) = 5.0 vol.%) was introduced into the processing chamber at a flow rate of 500 sccm. After adjusting the opening degree of the valve leading to the exhaust system, the pressure was set to 1.3×10 4 Pa, and then a negative voltage was applied to the substrate-side electrode and the substrate was exposed to plasma for 90 seconds to bias the surface of the intermediate layer 21 (that is, the surface of the single crystal Ir{111} film).

[0131] Subsequently, a single crystal diamond layer 31 (undoped diamond film) was heteroepitaxially grown by the microwave CVD method (step S14 in FIG. 6). Here, the underlayer substrate 20 subjected to the bias treatment was set in the chamber of the microwave CVD apparatus, and the base pressure was about 1.3×10 -4After exhausting the gas until it was below Pa, hydrogen-diluted methane (CH4 / (CH4+H2)=4.0 vol.%), the raw material gas, was introduced into the treatment chamber at a flow rate of 1000 sccm. The opening of the valve leading to the exhaust system was adjusted to set the pressure to 1.5 × 10⁻⁶. 4 After setting the temperature to Pa, a DC current was applied and film deposition was carried out for 80 hours. The substrate temperature during film deposition was measured with a pyrometer and was found to be 980°C.

[0132] The resulting single-crystal diamond layer 31 was a perfectly continuous film with no delamination across its entire 150 mm diameter. A schematic cross-sectional view of the single-crystal diamond laminated substrate 30 manufactured in this manner is shown in Figure 2.

[0133] A 2mm square was cut from this single-crystal diamond laminated substrate 30 to be used as an evaluation sample, and its film thickness and crystallinity were evaluated.

[0134] Regarding the film thickness, scanning electron microscopy (SEM) observation of the sample cross-section revealed that the total thickness of the diamond layer was approximately 100 μm. Compared to Example 1, a continuous film with a smooth surface was achieved despite its thinness. The dislocation defect density was also reduced.

[0135] The crystallinity of the film surface was measured using an X-ray diffraction (XRD) instrument (RIGAKU SmartLab). As a result, only a diffraction intensity peak attributed to diamond (111) at 2θ = 43.9° was observed, confirming that the diamond layer is an epitaxially grown single-crystal diamond {111} crystal. No twinning was observed.

[0136] Applying this single-crystal diamond {111} multilayer substrate to electronic and magnetic devices can yield high-performance devices. For example, high-performance power devices can be obtained.

[0137] Moreover, since it can be obtained on large-diameter substrates, it is possible to keep manufacturing costs low.

[0138] (Example 3) A double-sided polished single-crystal α-Al2O3 wafer with a diameter of 150 mm, a thickness of 1000 μm, a crystal plane orientation of {0001}, and an off-angle of 24° in the <11-20> direction was prepared as the initial substrate 11 (see initial substrate 11 in Figure 1) (step S11 in Figures 5 and 6).

[0139] Next, an Ir film was heteroepitaxially grown on the surface of the initial substrate 11 to form an intermediate layer 21 of the Ir film {111} (step S12 in Figures 5 and 6).

[0140] For the deposition of the Ir film, which is the intermediate layer 21, an RF (13.56 MHz) magnetron sputtering method was used, targeting an Ir target with a diameter of 8 inches (200 mm), a thickness of 5 mm, and a purity of 99.9% or higher. The substrate was heated to 850°C, evacuated with a vacuum pump, and the base pressure was approximately 8.0 × 10⁻⁶. -5 After confirming that the pressure was below Pa, Ar gas was introduced. The opening of the valve leading to the exhaust system was adjusted to 14 Pa, and then RF 1500W was applied for 30 minutes to deposit the film. The resulting film thickness was approximately 1 μm.

[0141] Crystallinity was measured from the outermost surface of the film using the pole method and out-of-plane method with an X-ray diffraction (XRD) instrument (RIGAKU SmartLab). As a result, there were no twinning components constituting Ir{111}, and only the main diffraction intensity peak and its multiple reflection peaks attributed to Ir(222) at 2θ=88.1° were observed, confirming that the intermediate layer is an epitaxially grown single-crystal Ir(111) crystal. The full width at half maximum of the rocking curve of the Ir(222) peak was 0.12°.

[0142] As described above, the base substrate 20 of the present invention was manufactured (see Figure 1).

[0143] Next, the base substrate 20 was subjected to a pretreatment (bias treatment) for diamond nucleation (step S13 in Figure 6). Here, the base substrate 20 on which the intermediate layer 21 was formed was set on a flat electrode, and the base pressure was approximately 1.3 × 10⁻⁶. -4After confirming that the pressure was below Pa, hydrogen-diluted methane (CH4 / (CH4+H2)=5.0 vol.%) was introduced into the treatment chamber at a flow rate of 500 sccm. The opening of the valve leading to the exhaust system was adjusted to set the pressure to 1.3 × 10⁻⁶. 4 After setting the temperature to Pa, a negative voltage was applied to the substrate-side electrode and the substrate was exposed to the plasma for 90 seconds to bias-treat the surface of the intermediate layer 21 (i.e., the surface of the single-crystal Ir{111} film).

[0144] Next, a single-crystal diamond layer 31 (undoped diamond film) was heteroepitaxially grown by microwave CVD (step S14 in Figure 6). Here, the bias-treated substrate 20 was set in the chamber of the microwave CVD apparatus, and the base pressure was increased to approximately 1.3 × 10⁻⁶ using a vacuum pump. -4 After exhausting the gas until it was below Pa, hydrogen-diluted methane (CH4 / (CH4+H2)=4.0 vol.%), the raw material gas, was introduced into the treatment chamber at a flow rate of 1000 sccm. The opening of the valve leading to the exhaust system was adjusted to set the pressure to 1.5 × 10⁻⁶. 4 After setting the temperature to Pa, a DC current was applied and film deposition was carried out for 80 hours. The substrate temperature during film deposition was measured with a pyrometer and found to be 980°C.

[0145] The resulting single-crystal diamond layer 31 was a perfectly continuous film with no delamination across its entire 150 mm diameter. A schematic cross-sectional view of the single-crystal diamond laminated substrate 30 manufactured in this manner is shown in Figure 2.

[0146] A 2mm square was cut from this single-crystal diamond laminated substrate 30 to be used as an evaluation sample, and its film thickness and crystallinity were evaluated.

[0147] Regarding the film thickness, scanning electron microscopy (SEM) observation of the sample cross-section revealed that the total thickness of the diamond layer was approximately 100 μm. Compared to Example 1, a continuous film with a smooth surface was achieved despite its thinness. The dislocation defect density was also reduced.

[0148] The crystallinity of the film surface was measured using an X-ray diffraction (XRD) instrument (RIGAKU SmartLab). As a result, only a diffraction intensity peak attributed to diamond (111) at 2θ = 43.9° was observed, confirming that the diamond layer is an epitaxially grown single-crystal diamond {111} crystal. No twinning was observed.

[0149] Applying this single-crystal diamond {111} multilayer substrate to electronic and magnetic devices can yield high-performance devices. For example, high-performance power devices can be obtained.

[0150] Moreover, since it can be obtained on large-diameter substrates, it is possible to keep manufacturing costs low.

[0151] In the comparative examples described below, the off-angle of the initial substrate 11 and the crystallinity of the intermediate layer 21 differ from those in the description of Examples 1-3, as shown in Figures 1 and 2. However, the general cross-sectional structure is the same as in Figures 1 and 2. Also, in Figures 5 and 6 used in the description of Examples 1-3, the process is the same except for the difference in the off-angle of the initial substrate prepared.

[0152] (Comparative example) A single-crystal α-Al2O3 wafer (without off-angle) with a diameter of 150 mm, a thickness of 1000 μm, and a crystal plane orientation of {0001}, polished on both sides, was prepared as the initial substrate 11 (corresponding to the initial substrate 11 with no off-angle in Figure 1 of the Example) (corresponding to step S11 in Figures 5 and 6 of the Example).

[0153] Next, an Ir film was heteroepitaxially grown on the surface of the initial substrate 11 to form an intermediate layer 21 of the Ir film {111} (corresponding to step S12 in Figures 5 and 6 of the example).

[0154] For the deposition of the Ir film, which is the intermediate layer 21, an RF (13.56 MHz) magnetron sputtering method was used, targeting an Ir target with a diameter of 8 inches (200 mm), a thickness of 5 mm, and a purity of 99.9% or higher. The substrate was heated to 850°C, evacuated with a vacuum pump, and the base pressure was approximately 8.0 × 10⁻⁶. -5After confirming that the pressure was below Pa, Ar gas was introduced. The opening of the valve leading to the exhaust system was adjusted to 14 Pa, and then RF 1500W was applied for 30 minutes to deposit the film. The resulting film thickness was approximately 1 μm.

[0155] Crystallinity was measured from the outermost surface of the film using the pole method and the out-of-plane method with an X-ray diffraction (XRD) instrument (RIGAKU SmartLab). The results showed that the pole method detected the {111} plane diffraction peak when the {111} plane was oriented in the direction normal to the main surface of the substrate, while the {111} plane diffraction peak was not detected when the {001} plane was oriented in the direction normal to the main surface of the substrate. Figure 9 shows the results of the pole method. The spot arrangement of the {111} diffraction peaks was consistent with the case where {111} is composed of twins.

[0156] Furthermore, the out-of-plane method revealed only the main diffraction intensity peak and its multiple reflection peaks at 2θ = 40.7°, which are attributed to Ir(111), confirming that the intermediate layer is an epitaxially grown single-crystal Ir{111} crystal. The results of the out-of-plane method are shown in Figure 10. The full width at half maximum of the rocking curve of the Ir{111} peak was 0.16°.

[0157] As described above, the base substrate 20 of the comparative example was manufactured (corresponding to the initial substrate 11 in Figure 1 of the example with a modified off-angle).

[0158] Next, the base substrate 20 was subjected to a pretreatment (bias treatment) for diamond nucleation (corresponding to step S13 in Figure 6 of the example). Here, the base substrate 20 on which the intermediate layer 21 was formed was set on a flat electrode, and the base pressure was approximately 1.3 × 10⁻⁶ -4 After confirming that the pressure was below Pa, hydrogen-diluted methane (CH4 / (CH4+H2)=5.0 vol.%) was introduced into the treatment chamber at a flow rate of 500 sccm. The opening of the valve leading to the exhaust system was adjusted to set the pressure to 1.3 × 10⁻⁶. 4After setting the temperature to Pa, a negative voltage was applied to the substrate-side electrode and the substrate was exposed to the plasma for 90 seconds to bias-treat the surface of the intermediate layer 21 (i.e., the surface of the single-crystal Ir{111} film).

[0159] Next, a single-crystal diamond layer 31 (undoped diamond film) was heteroepitaxially grown by microwave CVD (corresponding to step S14 in Figure 6 of the example). Here, the bias-treated substrate 20 was set in the chamber of the microwave CVD apparatus, and the base pressure was increased to approximately 1.3 × 10⁻⁶ using a vacuum pump. -4 After exhausting the gas until it was below Pa, hydrogen-diluted methane (CH4 / (CH4+H2)=4.0 vol.%), the raw material gas, was introduced into the treatment chamber at a flow rate of 1000 sccm. The opening of the valve leading to the exhaust system was adjusted to set the pressure to 1.5 × 10⁻⁶. 4 After setting the temperature to Pa, a DC current was applied and film deposition was carried out for 150 hours. The substrate temperature during film deposition was measured with a pyrometer and was found to be 980°C.

[0160] The obtained single-crystal diamond layer 31 was a perfectly continuous film with no delamination across its entire 150 mm diameter surface. The schematic cross-sectional view of the single-crystal diamond laminated substrate 30 manufactured in this manner was similar to the structure shown in Figure 2 of the example.

[0161] Next, the initial substrate 11, an α-Al2O3 wafer, was etched with thermal phosphoric acid. Furthermore, the intermediate layer 21, an Ir film, was removed by dry etching. This resulted in the acquisition of a single-crystal diamond {111} self-supporting substrate 35 (corresponding to step S15 in Figure 6 of the example).

[0162] Finally, a single-crystal diamond layer (additional single-crystal diamond layer 41) was heteroepitaxially grown again by microwave CVD (corresponding to step S16 in Figure 6 of the example). This additional single-crystal diamond layer 41 was formed under the same conditions as when the undoped diamond film was formed as described above.

[0163] The obtained single-crystal diamond layer was also a perfectly continuous film with no delamination across the entire 150 mm diameter. The schematic cross-sectional view of the single-crystal diamond self-supporting substrate 40, consisting of the single-crystal diamond layer 31 and the additional single-crystal diamond layer 41, was the same as the structure shown in Figure 4 of the example.

[0164] A 2mm square section was cut from this single-crystal diamond self-supporting substrate 40 and used as an evaluation sample. Film thickness and crystallinity were then evaluated.

[0165] Regarding the film thickness, a scanning secondary electron microscope (SEM) observation of the sample cross-section revealed that the total thickness of the diamond layer was approximately 400 μm.

[0166] Crystallinity was measured from the outermost surface of the film using an X-ray diffraction (XRD) instrument (RIGAKU SmartLab). The results showed a diffraction intensity peak attributed to diamond (111) at 2θ = 43.9°, confirming that the diamond layer was an epitaxially grown single-crystal diamond {111} crystal. Twining was present.

[0167] As explained above, in the comparative example, twinning components were present in the single-crystal diamond crystal, resulting in a lower-quality single-crystal diamond layer with more abnormal growth and dislocation defects compared to the example. When the single-crystal diamond {111} laminated substrate and self-supporting substrate of the comparative example are applied to electronic and magnetic devices, it is considered difficult to obtain high-performance devices compared to the example.

[0168] This specification includes the following embodiments: [1] In a substrate for a single-crystal diamond laminated substrate, An initial substrate which is one of the following: single crystal Si{111} substrate, single crystal Si{001} substrate, single crystal α-Al2O3{0001} substrate, single crystal α-Al2O3{11-20} substrate, single crystal Fe{111} substrate, single crystal Fe{001} substrate, single crystal Ni{111} substrate, single crystal Ni{001} substrate, single crystal Cu{111} substrate, and single crystal Cu{001} substrate. On the initial substrate, an intermediate layer consisting of a single layer or multilayer film containing at least one of a single crystal Ir film, a single crystal MgO film, a single crystal yttria-stabilized zirconia film, a single crystal SrTiO3 film, and a single crystal Ru film is provided. The initial substrate has the following characteristics: the outermost surface of the initial substrate has an off-angle in the direction of the crystal axis <-1-12> with respect to the cubic crystal plane orientation {111}, or has an off-angle in the direction of the crystal axis <10-10> or <11-20> with respect to the hexagonal crystal plane orientation {0001}, or the crystal axis <110> Those having an off-angle in the direction, or with respect to the hexagonal crystal plane orientation {11-20}, the crystal axis <10-10> or <0001> A substrate having an off-angle in the direction. [2]: The base substrate of the initial substrate, wherein the off-angle of the outermost surface of the initial substrate is in the range of +8.0 to +24.0° or -8.0 to -24.0°. [3]: The base substrate of [1] or [2] above, wherein the off-angle of the outermost surface of the initial substrate is in the range of greater than +15.0° and less than or equal to +24.0°, or greater than -15.0° and less than or equal to -24.0°. [4]: The outermost surface of the intermediate layer has an off-angle in the direction of the crystal axis <-1-12> with respect to the cubic crystal plane orientation {111}, or has an off-angle in the direction of the crystal axis <10-10> or <11-20> with respect to the hexagonal crystal plane orientation {0001}, or the crystal axis <110> Those having an off-angle in the direction, or with respect to the hexagonal crystal plane orientation {11-20}, the crystal axis <10-10> or <0001> The base substrate of [1], [2], or [3] described above, having an off-angle in the direction. [5]: The base substrate of [4], wherein the off-angle of the outermost surface of the intermediate layer is in the range of +8.0 to +24.0° or -8.0 to -24.0°. [6]: The substrate according to [4] or [5] above, wherein the off-angle of the outermost surface of the intermediate layer is in the range of greater than +15.0° and less than or equal to +24.0°, or greater than -15.0° and less than or equal to -24.0°. [7]: A single-crystal diamond laminated substrate having a single-crystal diamond layer on the intermediate layer of the base substrate described in [1], [2], [3], [4], [5] or [6] above. [8]: The single-crystal diamond laminated substrate according to [7], wherein the single-crystal diamond layer is a {111} crystal or a {001} crystal. [9]: A step of preparing an initial substrate which is one of the following: single crystal Si{111} substrate, single crystal Si{001} substrate, single crystal α-Al2O3{0001} substrate, single crystal α-Al2O3{11-20} substrate, single crystal Fe{111} substrate, single crystal Fe{001} substrate, single crystal Ni{111} substrate, single crystal Ni{001} substrate, single crystal Cu{111} substrate, and single crystal Cu{001} substrate, The process involves forming an intermediate layer on the initial substrate consisting of a single layer or a multilayer film containing at least one of a single crystal Ir film, a single crystal MgO film, a single crystal yttria-stabilized zirconia film, a single crystal SrTiO3 film, and a single crystal Ru film. A method for manufacturing a base substrate for a single-crystal diamond laminated substrate, As the initial substrate, the outermost surface of the initial substrate has an off-angle in the direction of the crystal axis <-1-12> with respect to the cubic crystal plane orientation {111}, or has an off-angle in the direction of the crystal axis <10-10> or <11-20> with respect to the hexagonal crystal plane orientation {0001}, or the crystal axis <110> Those having an off-angle in the direction, or with respect to the hexagonal crystal plane orientation {11-20}, the crystal axis <10-10> or <0001> A method for manufacturing a substrate using one of the following: having an off-angle in the direction.

[10] : The method for manufacturing the base substrate according to [9], comprising setting the off-angle of the outermost surface of the initial substrate to be in the range of +8.0 to +24.0° or -8.0 to -24.0°.

[11] : A method for manufacturing a substrate substrate according to [9] or

[10] , comprising setting the off-angle of the outermost surface of the initial substrate to be in the range of greater than +15.0 and less than or equal to +24.0°, or greater than -15.0 and less than or equal to -24.0°.

[12] : The outermost surface of the intermediate layer has an off-angle with respect to the cubic crystal orientation {111} in the direction of the crystal axis <-1-12>, or has an off-angle with respect to the hexagonal crystal orientation {0001} in the direction of the crystal axis <10-10> or <11-20>, or has an off-angle with respect to the cubic crystal orientation {001} in the direction of the crystal axis <110> Those having an off-angle in the direction, or with respect to the hexagonal crystal plane orientation {11-20}, the crystal axis <10-10> or <0001> A method for manufacturing the substrate substrate according to [9],

[10] , or

[11] , comprising having an off-angle in the direction.

[13] : A method for manufacturing the substrate substrate according to

[12] , comprising forming the intermediate layer such that the off-angle of the outermost surface of the intermediate layer is in the range of +8.0 to +24.0° or -8.0 to -24.0°.

[14] : A method for manufacturing a substrate substrate according to

[12] or

[13] , comprising forming the intermediate layer such that the off-angle of the outermost surface of the intermediate layer is in the range of greater than +15.0 and less than or equal to +24.0°, or greater than -15.0 and less than or equal to -24.0°.

[15] A method for manufacturing a single-crystal diamond laminated substrate, A step of preparing a substrate manufactured by the substrate manufacturing method described in [9],

[10] ,

[11] ,

[12] ,

[13] or

[14] above, A step of performing a bias treatment on the surface of the intermediate layer of the substrate for diamond nucleation, The process involves growing a diamond nucleus formed on the aforementioned intermediate layer to perform epitaxial growth and to form a single-crystal diamond layer. A method for manufacturing a single-crystal diamond laminated substrate containing [the specified material].

[16] : A method for manufacturing a single-crystal diamond laminated substrate according to

[15] , comprising using a {111} crystal or a {001} crystal for the single-crystal diamond layer.

[17] : A method for manufacturing a single-crystal diamond self-supporting structure substrate, comprising extracting only the single-crystal diamond layer from a single-crystal diamond laminated substrate manufactured by the method for manufacturing a single-crystal diamond laminated substrate described in

[15] or

[16] above, and manufacturing a single-crystal diamond self-supporting structure substrate.

[18] : A method for manufacturing a single crystal diamond self-supporting substrate, comprising forming an additional single crystal diamond layer on a single crystal diamond self-supporting substrate obtained by the method for manufacturing a single crystal diamond self-supporting substrate described in

[17] above.

[0169] It should be noted that the present invention is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of the present invention and achieves similar effects is included within the technical scope of the present invention.

Claims

1. In a base substrate for a single-crystal diamond multilayer substrate, Single crystal Si{111} substrate, single crystal α-Al ２ O ３ {0001} Substrate, single crystal α-Al ２ O ３ An initial substrate which is one of the following: {11-20} substrate, single crystal Fe{111} substrate, single crystal Ni{111} substrate, and single crystal Cu{111} substrate. On the aforementioned initial substrate, a single crystal Ir film, a single crystal MgO film, a single crystal yttria-stabilized zirconia film, and a single crystal SrTiO film are placed. ３ An intermediate layer consisting of a single layer or multilayer film containing at least one of a film and a single crystal Ru film, The initial substrate has the following characteristics: the outermost surface of the initial substrate has an off-angle with respect to the cubic crystal plane orientation {111} in the direction of the crystal axis <-1-12>, or an off-angle with respect to the hexagonal crystal plane orientation {0001} in the direction of the crystal axis <10-10> or <11-20>, or an off-angle with respect to the hexagonal crystal plane orientation {11-20} in the direction of the crystal axis <10-10> or <0001>, A base substrate characterized in that the off-angle of the outermost surface of the initial substrate is in the range of greater than +15.0° and less than or equal to +24.0°, or greater than -15.0° and less than or equal to -24.0°.

2. The substrate substrate according to claim 1, characterized in that the outermost surface of the intermediate layer has an off-angle in the direction of the crystal axis <-1-12> with respect to the cubic crystal plane orientation {111}, or has an off-angle in the direction of the crystal axis <10-10> or <11-20> with respect to the hexagonal crystal plane orientation {0001}, or has an off-angle in the direction of the crystal axis <10-10> or <0001> with respect to the hexagonal crystal plane orientation {11-20}.

3. The substrate substrate according to claim 2, characterized in that the off-angle of the outermost surface of the intermediate layer is in the range of +8.0 to +24.0° or -8.0 to -24.0°.

4. The substrate substrate according to claim 2, characterized in that the off-angle of the outermost surface of the intermediate layer is in the range of greater than +15.0° and less than or equal to +24.0°, or greater than -15.0° and less than or equal to -24.0°.

5. A single-crystal diamond laminated substrate, characterized in that it has a single-crystal diamond layer on the intermediate layer of the substrate according to any one of claims 1 to 4.

6. The single-crystal diamond laminated substrate according to claim 5, characterized in that the single-crystal diamond layer is a {111} crystal or a {001} crystal.

7. Single crystal Si{111} substrate, single crystal α - Al ２ O ３ {0001} substrate, single crystal α - Al ２ O ３ A step of preparing an initial substrate which is any one of a single crystal Fe{111} substrate, a single crystal Ni{111} substrate, a single crystal Cu{111} substrate, and a single crystal AlO{11 - 20} substrate, On the initial substrate, a single-crystal Ir film, a single-crystal MgO film, a single-crystal yttria-stabilized zirconia film, and a single-crystal SrTiO film are placed. ３ A step of forming an intermediate layer consisting of a single layer or a multilayer film containing at least one of a film and a single crystal Ru film. A method for manufacturing a base substrate for a single-crystal diamond laminated substrate, As the initial substrate, the outermost surface of the initial substrate is one in which the crystal axis has an off-angle in the direction of the crystal axis <-1-12> with respect to the cubic crystal plane orientation {111}, or an off-angle in the direction of the crystal axis <10-10> or <11-20> with respect to the hexagonal crystal plane orientation {0001}, or an off-angle in the direction of the crystal axis <10-10> or <0001> with respect to the hexagonal crystal plane orientation {11-20}. A method for manufacturing a substrate substrate, characterized in that the off-angle of the outermost surface of the initial substrate is in the range of greater than +15.0° and less than or equal to +24.0°, or greater than -15.0° and less than or equal to -24.0°.

8. The method for manufacturing a substrate substrate according to claim 7, characterized in that the outermost surface of the intermediate layer has an off-angle in the direction of the crystal axis <-1-12> with respect to the cubic crystal plane orientation {111}, or has an off-angle in the direction of the crystal axis <10-10> or <11-20> with respect to the hexagonal crystal plane orientation {0001}, or has an off-angle in the direction of the crystal axis <10-10> or <0001> with respect to the hexagonal crystal plane orientation {11-20}.

9. The method for manufacturing a substrate substrate according to claim 8, characterized in that the intermediate layer is formed with an off-angle of the outermost surface of the intermediate layer in the range of +8.0 to +24.0° or -8.0 to -24.0°.

10. The method for manufacturing a substrate substrate according to claim 8, characterized in that the intermediate layer is formed such that the off-angle of the outermost surface of the intermediate layer is in the range of greater than +15.0° and less than or equal to +24.0°, or greater than -15.0° and less than or equal to -24.0°.

11. A method for manufacturing a single-crystal diamond laminated substrate, A step of preparing a substrate manufactured by the substrate manufacturing method described in any one of claims 7 to 10, A step of performing a bias treatment on the surface of the intermediate layer of the substrate for diamond nucleation, The process involves growing a diamond nucleus formed on the aforementioned intermediate layer to perform epitaxial growth and to form a single-crystal diamond layer. A method for manufacturing a single-crystal diamond laminated substrate, characterized by including the following:

12. The method for manufacturing a single-crystal diamond laminated substrate according to claim 11, characterized in that the single-crystal diamond layer is made of {111} crystals or {001} crystals.

13. A method for manufacturing a single-crystal diamond self-supporting substrate, characterized by extracting only the single-crystal diamond layer from a single-crystal diamond laminated substrate manufactured by the method for manufacturing a single-crystal diamond laminated substrate described in claim 11, thereby manufacturing a single-crystal diamond self-supporting substrate.

14. A method for manufacturing a single-crystal diamond self-supporting substrate, characterized by forming an additional single-crystal diamond layer on a single-crystal diamond self-supporting substrate obtained by the method for manufacturing a single-crystal diamond self-supporting substrate described in claim 13.

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