| 摘要 |
<P>PROBLEM TO BE SOLVED: To increase a high breakdown voltage and decrease an on-state resistance for a semiconductor device having superjunction structure, even when a lateral pitch is narrow. Ž<P>SOLUTION: In a power MOSFET 70, a p-type pillar layer 2 and an n-type pillar layer 5 are periodically and alternately formed on an n<SP>+</SP>-type substrate 1, and a pillar layer used as a superjunction structure is prepared. On the p-type pillar layer 2 and at top side face of the n-type pillar layer 5 in contact with the p-type pillar layer 2, a p-type base layer 3 with a depth of 3 μm and a region having a constant impurity concentration up to 90% in the depth direction is prepared, using the silicon epitaxial method. Since elevated temperature thermal diffusion is not used for formation of the p-type base layer 3 for the power MOSFET 70, deterioration in the effective pillar density is suppressed. Thereby, the power MOSFET 70 has a region with an effective pillar density of 50% or more up to a diffusion length of 2 μm. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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