| 摘要 |
PROBLEM TO BE SOLVED: To reduce a switching loss in an IEGT, and to enable application even to an IGBT, a power MOS-FET, an MCT, etc., by forming a polysilicon layer to which impurities have been doped, on the internal surface of a silicon oxide film. SOLUTION: Doping impurities such as phosphorus for example, etc., onto a silicon oxide film 17, SiH4 and POCl3 gases are reacted by the use of CVD for example, etc., and a high-concentration polysilicon gate electrode 19 is grown and fills up a trench 16. Furthermore, the gate oxide film 17 and the upper surface of the gate electrode 19 are removed using RIE for example, etc. Finally, an insulating film 20 is deposited and patterning is performed. From the rear a collector electrode 21 is formed, and from the upper surface an emitter Al electrode 22 is formed. Accordingly, it becomes possible to deal with quick switching, when the frequency of switching is increased when the device is used for an induction heater IH for example, etc.
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