| 摘要 |
PROBLEM TO BE SOLVED: To suppress the increase of the leakage current of a PT-IGBT. SOLUTION: An n+-type buffer layer 8 and a p+-type collector layer 9 satisfying the relation d2/d1>1.5 are made. Here, d1 shows the depth of the peak of the concentration of the n-type impurities within the n+-type buffer layer 8 from the backside of the p+-type collector layer 9, and d2 shows the first depth where the activation rate (a) of the n-type impurities within the n+-type buffer layer 8 becomes 0.3 in a region deeper than the d1 of the n+-type buffer layer 8. The activation rate (a) is defined by 'the concentration of the activated n-type impurities obtained by SR analysis/the concentration of the n-type impurities obtained by SIMS analysis'.
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