Abstract: A silicon semiconductor substrate including a silicon semiconductor layer at one of upper and lower surfaces thereof, the silicon semiconductor layer being composed of polysilicon or noncrystal silicon and containing oxygen in the range of 2 atomic % to 20 atomic % both inclusive, nitrogen in the range of 4 atomic % to 20 atomic % both inclusive, or both nitrogen at 2 atomic % or greater and oxygen at 1 atomic % or greater. The polysilicon or noncrystal silicon semiconductor layer acts as a core for extrinsic gettering. In the silicon semiconductor substrate, the gettering performance is not deteriorated, even if the silicon semiconductor substrate experiences thermal treatment. Thus, it is possible to get rid of contamination caused by heavy metals in the silicon semiconductor substrate.