Patent ID: 11972950
Assignee: FUJI ELECTRIC CO., LTD.
Field: Semiconductors (Electrical engineering)
Classification: CPC H | IPC H

Claim 20:
21. A method for manufacturing a semiconductor device including a semiconductor substrate that has an upper surface and a lower surface, the method for manufacturing comprising:
a first implantation step of implanting hydrogen at a first depth from the lower surface of the semiconductor substrate to form a hydrogen concentration peak;
a second implantation step of implanting helium at a second depth from the lower surface of the semiconductor substrate, the second depth being deeper than the first depth with respect to the lower surface, to form a helium concentration peak and a passed-through region through which the helium has passed; and
a diffusion step of heat treating the semiconductor substrate to diffuse, in the passed-through region, the hydrogen implanted at the first depth, so as to form a first donor concentration peak at the first depth and form a second donor concentration peak at the second depth, wherein
each concentration peak has an upward slope in which a concentration value increases from the lower surface toward the upper surface,
a value which is obtained by normalizing a gradient of the upward slope of the second donor concentration peak by a gradient of the upward slope of the helium concentration peak is smaller than a value which is obtained by normalizing a gradient of the upward slope of the first donor concentration peak by a gradient of the upward slope of the hydrogen concentration peak, and
in the semiconductor substrate heat treated in the diffusion step, a dose of hydrogen in the first implantation step is determined such that a minimum value of a donor concentration of the passed-through region is higher than a donor concentration of the semiconductor substrate into which the hydrogen is to be implanted.