| 摘要 |
PROBLEM TO BE SOLVED: To prevent re-release of a contaminated impurities which was gettered during manufacturing process from a getter layer. SOLUTION: On the rear side of a p-type silicon substrate 1, polycilicon layers 2, 3 and 4 where boron was doped and a silicon oxide film 5 are stacked alternately, and baron concentration is made higher as approaching the third polysilicon layer 4, thus a semiconductor substrate is manufactured. Then, by performing gettering heat treatment with the semiconductor substrate, more contaminated impurities are gettered as approaching the third polysilicon layer 4, then, before the heat treatment process wherein gettered contaminated impurities might be re-released, the third polysilicon layer 4 is removed.
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