| 摘要 |
PURPOSE:To provide a device with high-speed turn-off characteristics and a sufficiently wide safe operating region, by a method wherein the lifetime of carriers in a second region is set at a prescribed value or lower by radiation and the device is provided with a fifth region having a part, which is formed in contact with a third region and whose second conductivity type impurity concentration is higher than that of the second region. CONSTITUTION:An N<+> buffer region 102 is set in an impurity concentration of 10<17>atm/cc and in a thickness of 15mum and an N<-> drain region 103 is set in an impurity concentration of 2X10<14>atm/cc and in a thickness of 50mum. Then, the surface of the region 103 of a silicon wafer is oxidized, region where active regions are respectively formed are opened and an N-type impurity is selectively diffused in the regions. Phosphorus is used as the impurity and is implanted at a dose of 1X10<12>atm/cm<2>. After that, the surface is again covered with an oxide film, an impurity is previously diffused for several hours or thereabouts at 1100 deg.C and an N-type region 1001 is formed. Electron beam irradiation is performed on the formed region 1001 by 6 Mrd and the lifetime of carriers is controlled to about 50ns.
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