| 摘要 |
PURPOSE:To reduce Qrr by softening the reverse recovery characteristic by a method wherein the lifetime is made ununiform in the region with lower impurity concentration of two regions of different conductivity which form P-N junctions where most of reverse voltage is impressed at the time of turn-off operation. CONSTITUTION:An N type Si is put into the P-N-P three layer structure with a P-emitter 12, an N-base 11, and a P-base 13 by diffusing a P type impurity from both surfaces. Next, an N-emitter 14 is formed on the base 13 by diffusion of POCl3, etc. At the time of diffusing a lifetime killer, the lifetime killer is enabled to reach only part of the base by controlling the time and the diffusion temperature; then, only a region in the base 11 close to the emitter 12 is provided with a region where the lifetime decreases. Such a manner causes less accumulation of carriers at the time of on-operation, and they are swiftly exhausted. As a result, the reverse recovery characteristic is softened without deteriorating the ON-characteristic; further, Qrr can be reduced. |
