Diamond substrate and method for manufacturing diamond substrate
The crystal plane in the interior of the diamond substrate has a curvature higher than 0 km −1 and equal to or lower than 1500 km −1 by preparing a base substrate, forming a plurality of pillar-shaped diamonds formed of diamond single crystals on one side of the base substrate, causing diamond single crystals to grow from tips of each pillar-shaped diamond, coalescing each of the diamond single crystals grown from the tips of each pillar-shaped diamond to form a diamond substrate layer, separating the diamond substrate layer from the base substrate, and manufacturing the diamond substrate from the diamond substrate layer.
1. A method of manufacturing a diamond substrate, comprising:
preparing a base substrate;
forming a diamond layer formed from diamond single crystals on one side of the base substrate;
removing a part of the diamond layer to leave a plurality of pillar-shaped diamonds from the diamond layer, the plurality of pillar-shaped diamonds being spaced apart to each other;
causing the diamond single crystals to grow from tips of each pillar-shaped diamond while a space between the plurality of pillar-shaped diamonds are not fully filled and coalescing each of the diamond single crystals grown from the tips of each pillar-shaped diamonds to form a diamond substrate layer;
separating the diamond substrate layer from the base substrate; and
manufacturing the diamond substrate from the diamond substrate layer,
wherein a curvature of a crystal plane in an interior of the diamond substrate is set to higher than 0 km −1 and equal to or lower than 1500 km −1 .
2. The method according to claim 1 , wherein separation of the base substrate and the diamond substrate layer is performed by generating a stress in the pillar-shaped diamonds and destroying the pillar-shaped diamonds.
3. The method according to claim 2 , wherein the stress is generated by a lattice constant difference between the base substrate and the diamond substrate layer and/or a thermal expansion coefficient difference between the base substrate and the diamond substrate layer.
4. The method according to claim 1 , wherein an aspect ratio of each of the pillar-shaped diamond is equal to or higher than 5.
5. The method according to claim 1 , wherein a diameter and a pitch of the pillar-shaped diamond are set to be equal to or smaller than 10 respectively.
6. The method according to claim 1 , wherein a surface roughness Ra of the one side of the base substrate is equal to or lower than 10 nm.
7. The method according to claim 1 , wherein a height direction of the pillar-shaped diamond is set to be perpendicular to the plane (001) of the diamond single crystals used to form the pillar-shaped diamonds.
8. The method according to claim 1 , wherein the pillar-shaped diamond has a cylindrical shape, and
a diameter of a center portion of the pillar-shaped diamond in the height direction is thinner than a diameter of a tip portion.
9. The method according to claim 1 , wherein the curvature is set to be higher than 0 km −1 and equal to or lower than 400 km −1 .
10. The method according to claim 1 , wherein the curvature is set to be higher than 0 km −1 and equal to or lower than 200 km −1 .
11. The method according to claim 1 , wherein a shape of the diamond substrate in an in-plane is a circular shape or a circular shape having an orientation flat plane, and
a diameter of the diamond substrate is equal to or larger than 0.4 inches.
12. The method according to claim 11 , wherein the diameter is equal to or larger than 2 inches.
13. The method according to claim 11 , wherein the diameter is equal to or larger than 2 inches and equal to or smaller than 8 inches.