| 摘要 |
PURPOSE:To obtain a gate turnoff thyristor having improved breaking capacity, by performing outdiffusion after diffusing P-type impurity atoms. CONSTITUTION:The temperature of a silicon wafer 1 is held at 1,250 deg.C and Ga is diffused at 990 deg.C. Then, outdiffusion is performed instead of Ga diffusion while the temperature of the silicon wafer is continuously held at 1,250 deg.C. In this manner, a P-type base layer 1b is provided with the conical diffusion profile exhibiting the impurity concentration peak PBP at the depth of X=XBP as measured from the surface. The sheet resistance rhoS of the P-type base layer 1b under an N-type emitter layer 1c is adjusted to a value as obtained by prior arts. In this manner, an avalanche voltage higher than those by prior arts can be obtained between the gate 4 and the cathode 5. In such a gate turnoff thyristor, controllable anode current is increased and the breaking capacity is improved.
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