| 摘要 |
PROBLEM TO BE SOLVED: To provide a high breakdown-strength semiconductor element where fine working and high-integration are allowed, while higher breakdown-strength is made possible with no thicker protective film for the flat part of a P-N junction part. SOLUTION: A channel 16 of a desired depth is dug at a joint part between a P-type diffusion layer 14 and an N-type silicon substrate 11, and while the channel 16 is filled with a silicon oxide film 17, a silicon oxide film 17' is formed on the surfaces of the P-type diffusion layer 14 and the N-type silicon substrate 11, so that the entire is flat. With this structure, the thickness of such part of the silicon oxide film 17 as the electric field intensity at the joint part is high is substantially thicker, while that of the silicon oxide film 17' in other region is normal. Thus, a semiconductor element of higher breakdown- strength is provided, without having to make the thickness of silicon oxide film 17' at the flat part larger. Since the silicon oxide films 17 and 17' grow in the same direction, the width of the channel 16 is desirably twice or less the thickness of the silicon oxide film 17'.
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