US 7,598,587 B2Granted

Semiconductor device

AssigneeMitsubishi Denki Kabushiki Kaisha

InventorTomohide Terashima

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Abstract

A semiconductor layer of n− type is formed on a semiconductor substrate of p− type. A first buried impurity region of n+ type is formed at an interface between the semiconductor substrate and the semiconductor layer. A second buried impurity region of p+ type is formed at an interface between the first buried impurity region and the semiconductor layer. Above the first and second buried impurity regions, a first impurity region of n type is formed in an upper surface of the semiconductor layer. Above the first and second buried impurity regions, a second impurity region of p type is also formed apart from the first impurity region in the upper surface of the semiconductor layer. When the second impurity region becomes higher in potential than the first impurity region, the second impurity region and the second buried impurity region are electrically isolated from each other by a depletion layer.

Claims19

Dependent claims

A semiconductor device comprising:

a semiconductor substrate of p type;
a semiconductor layer of n type provided on said semiconductor substrate;
a first buried impurity region of n type provided at an interface between said semiconductor substrate and said semiconductor layer;
a second buried impurity region of p type provided at an interface between said semiconductor layer and said first buried impurity region;
a first impurity region of n type provided in an upper surface of said semiconductor layer above said second buried impurity region;
and
a second impurity region of p type provided apart from said first impurity region in said upper surface of said semiconductor layer above said first buried impurity region so as to surround said first impurity region in a perspective view from said upper surface toward said semiconductor substrate therebelow,
wherein, upon applying a higher potential to said first impurity region than to said second impurity region, said second impurity region and said second buried impurity region are electrically isolated from each other by a depletion layer, and said first impurity region and said first buried impurity region are electrically isolated from each other by a depletion layer.

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Dependencies are inferred from the claim text.