| 摘要 |
PROBLEM TO BE SOLVED: To cause a semiconductor device to have a high avalanche resistance and to make the surface concentration at a channel region unchanged when operated, by causing a buried diffusion region composed by diffusing second conductivity impurities buried in a substrate into a drain region to form a high-concentration second conductivity semiconductor region. SOLUTION: In an N-channel power MOSFET 20, sources 6 are completely covered with P-dot diffusion regions 4, by forming the diffusion regions 4 in a first epitaxial growth layer 2 by burying diffusion, forming P wells 5 and compensating diffusion regions 7 in a second epitaxial growth layer 3 from its surface, and diffusing the sources 6 into the P wells 5. Accordingly, a part having a high amplification factor of a parasitic transistor is difficult to be formed. Besides, avalanche resistance on the occasion of a reactance load is increased, since the MOSFET 20 has the compensating regions 7 for bringing source electrodes 10 into ohmic contact with the P wells 5 between sources 6, and the regions 7 are in touch with the diffusion regions 4.
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