| 摘要 |
PURPOSE:To improve turn-off characteristics and increase the maximum controllable current by a method wherein a narrow rectangular cathode is formed on an N-type emitter layer surrounded by recessed parts and a region which reduces the DC current amplification factor of a transistor, composed of an N-type emitter layer, a P-type base layer and an N-type base layer, is provided beneath the neighborhood of the center axis of the cathode. CONSTITUTION:A P-type emitter layer 2 is formed on one of the main surfaces of a substrate 1 by diffusion and an anode 3 is formed. A P-type base layer 4 is formed on the other main surface by diffusion and further an N-type emitter layer 5 is formed on the surface of the P-type base layer 4 by diffusion. Recessed parts 6 are formed in the N-type emitter layer 5 and the recessed parts 6 reach the P-type base layer 4 to divide the N-type emitter layer 5 into a plurality of cathode regions 10. Gate electrodes 7 are formed on the bottom surfaces of the recessed parts 6 with high impurity concentration layers 8 for ohmic contact in between. A cathode 9 is formed on each narrows rectangular cathode region 10 and a P-type impurity is diffused from the surface near the center axis of the cathode 9 to form a low impurity concentration N-type region 11. |
