Substrate and manufacturing method thereof, and semiconductor device

A semiconductor device comprising:

• a base substrate including a processed portion processed by irradiation with an ultrashort-pulse laser light and an unprocessed portion which is not irradiated with the ultrashort-pulse laser light, the processed portion and the unprocessed portion are formed on a surface of the base substrate, the base substrate including on the surface thereof a first region in which a plurality of the processed portions are formed and a second region in which a plurality of the processed portions are formed with a higher density than in the first region;
• and
• a semiconductor crystal layer crystal-grown in the first region, the semiconductor crystal layer being not crystal-grown in the second region.

A manufacturing method of a substrate, the manufacturing method comprising:

• a laser processing process of irradiating a surface of a base substrate with an ultrashort-pulse laser light and thereby forming a processed portion on the surface of the base substrate;
• and
• a first crystal growth process of crystal-growing a semiconductor crystal layer on an unprocessed portion of the surface of the base substrate, the unprocessed portion being not irradiated with the ultrashort-pulse laser light.