| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing a semiconductor device, in which punch-through breakdown voltage can be increased, without making the well deep. SOLUTION: The method for manufacturing a semiconductor device comprises a step for implanting boron ions into a silicon substrate 1 at a high acceleration energy, a step for forming a P-type well 9 in the silicon substrate 1 and a silicon oxide film 15 on the surface thereof, by heat treating the silicon substrate 1 in oxygen atmosphere, a step for implanting N-type impurity ions into the P-type well 9, and a step for forming an N-type well in the P-type well 9 by heat treating the silicon substrate 1.
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