| 摘要 |
PROBLEM TO BE SOLVED: To reduce the density of crystal defects by forming the surface consisting of an atom step and a terrace on silicon base material, and making the surface porous, and then, forming a nonporous film. SOLUTION: The manufacture of semiconductor base material is as follows: silicon base material 1 whose surface 10 shows granular morphology is prepared, and surface treatment is performed by hydrogen annealing, etc., and the surface 10 presenting granular morphology is changed to the surface substantially consisting of an atom step 11 and a terrace 12. Next, this surface consisting of the step 11 and the terrace 12 is made porous by anode formation or the like, and a porous layer 2 is made on the surface side at least of the silicon base material 1. A nonporous layer 3 is made by CVD or the like on the surface of the porous layer 2. As a result, the hole size distribution of the porous layer 2 can be narrowed as compared with the case of the making the surface without a step and a terrace porous, so it becomes possible to reduce the density of the crystal defects such as stack defects introduced in the nonporous layer 3, dislocation, twin, etc.
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