Patent ID: 7112865

Claim:
A diode comprising: a first-conductivity-type first region having a first impurity concentration; a first-conductivity-type second region placed on said first region and having a second impurity concentration that is lower than said first impurity concentration; a generally ring-like second-conductivity-type third region formed in a surface layer of said second region; a second-conductivity-type fourth region formed in a surface layer of said second region located inside said third region; a first-conductivity-type fifth region formed in contact with a portion of said first region that is located below said fourth region surrounded by said third region, said fifth region having a lower resistivity than said second region; a first main electrode formed in contact with said first region; and a second main electrode formed in contact with said fourth region, wherein said fifth region is formed only inside a vertical projection of said third region, and said second region includes a first portion located on said fifth region, and a second portion located under said third region, said first portion having a smaller thickness than said second portion.