Fuji Electric Co., Ltd.

National Space Development Agency of Japan

Saburo Tagami

Takashi Kobayashi

Satoshi Kuboyama

Fumiaki Kirihata

In a power MOSFET, on an Ndrain layeras a substrate, a second N base layerand a first Nbase layerare deposited in the order by epitaxial growth. In a surface portion of the layer, there are selectively formed a P base region, in a surface portion of which an Nsource regionis selectively formed. On a channel region in the P base region, a gate electrodeis formed with a gate insulator filmheld between. A source electrodeand a drain electrodeare formed on the Nsource regionand on the back of the substrate, respectively. The layeris made to have a thickness equal to or more than &#xbc; of that of the first Nbase layer, and an averaged impurity concentration between 1&#xd7;10/cmand 3&#xd7;10/cm. The thickness can be alternatively given as equal to or more than &#xbd; of a difference between the thickness x shown as x(&#x3bc;m)=V(V)/8 and that of the layer, where Vis an SEB(Single Event Burnout) voltage of the layer. This makes positive feed back hard to occur between latch-up of a parasitic npn transistor and dynamic avalanche near the substrate to enhance the SEB voltage, allowing the MOSFET to be applied to space use.

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Matsumoto, Japan

Saburo Tagami