Spensley Horn Jubas & Lubitz
Semiconductor device and method of producing semiconductor device
 A semiconductor device composed of: a semiconductor substrate of a first conductivity type having a first impurity concentration; a belt-shaped impurity layer of the first conductivity type which is formed in the substrate so as to be spaced apart from a surface of the substrate and which has a second impurity concentration which is higher than the first concentration at a first depth from the surface of the substrate; a gate electrode formed on the substrate via a first insulating film; a second impurity layer of a second conductive type which is formed in the substrate on both sides of the gate electrode such as to be spaced apart from each other and has a third impurity concentration at a second depth from the surface of the semiconductor substrate, whose lower surface abuts against the first impurity layer or is present thereabove, the second impurity layer having a configuration projecting downward of the gate electrode at a portion thereof adjacent to the first impurity layer; side wall insulating films each formed on a side wall of the gate electrode; and a third impurity layer of the second conductivity type which is formed in the second impurity layer laterally of the side wall insulating film and has a fourth concentration higher than the third concentration. 
Seiko Epson Corporation
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inventional additional inventional inventional
Masahiro
Takeuchi