Method for manufacturing diamond single crystal substrate, and diamond single crystal substrate

A diamond single crystal substrate, in which a diamond single crystal is grown on a diamond single crystal seed substrate by vapor phase synthesis and the growth width in the lateral direction from the seed substrate in a single crystal layer obtained by vapor phase synthesis is greater than the growth width upward from the seed substrate.

A diamond single crystal substrate which is constructed from a plurality of diamond single crystal seed substrates of uniform planar orientation lined up and integrated overall by growing diamond single crystals on the seed substrates by vapor phase synthesis, wherein a planar orientation of a main surface of all of the plurality of seed substrates but one has an inclination of less than 1 degree relative to a {100} plane, a planar orientation of a main surface of the remaining one seed substrate has an inclination of not more than 8 degrees relative to the {100} plane, the diamond single crystal substrate having been manufactured by a method comprising forming a plurality of planes of different orientation which are inclined in an outer peripheral direction of the main surface relative to the main surface on one side of the one seed substrate, by machining;

• lining up the plurality of seed substrates so as to surround the one seed substrate by the remaining plurality of seed substrates;
• and then growing diamond single crystals by vapor phase synthesis, whereby the diamond single crystal grown from this one seed substrate is made to cover the diamond single crystals grown on the other seed substrates and cause integrating.