Oblon, Spivak, McClelland, Maier & Neustadt, L.L.P.
Power semiconductor device and method for manufacturing the power semiconductor device
In a power semiconductor device that switches at a high speed, a displacement current flows at a time of switching, so that a high voltage occurs which may cause breakdown of a thin insulating film such as a gate insulating film. A semiconductor device includes: a semiconductor substrate of a first conductivity type; a drift layer of the first conductivity type formed on a first main surface of the semiconductor substrate; a first well region of a second conductivity type formed in a part of a surface layer of the drift layer; a second well region of the second conductivity type formed in a part of the surface layer of the drift layer at a distance from the first well region, the second well region having a smaller area than that of the first well region when seen above an upper surface thereof; a low-resistance region of the first conductivity type formed in a surface layer of the first well region, the low-resistance region having a higher impurity concentration than that of the first well region; a gate insulating film formed on and in contact with a surface of the first well region; and a gate electrode formed on and in contact with a surface of the gate insulating film.
Mitsubishi Electric Corporation
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Naruhisa Shoyu Shuhei
Miura Watanabe Nakata