| 摘要 |
PROBLEM TO BE SOLVED: To improve both forward and reverse breakdown voltage characteristics in a high breakdown voltage semiconductor device. SOLUTION: On one surface of a first conductivity type first base layer having a first impurity concentration, a first conductivity type buffer layer having a second impurity concentration higher than the first impurity concentration is formed. On the other surface of the first base layer, a second conductivity type second base layer is formed. Also, on the side opposite to the first base layer of the buffer layer, a second conductivity type collector layer is formed. The buffer layer is formed so as to have a first thickness in a center region and have a second thickness less than the first thickness in a peripheral region surrounding the center region. The second base layer is formed in the center region. COPYRIGHT: (C)2009,JPO&INPIT
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