| 摘要 |
A completely integrated npn Darlington stage is provided using an n-type film deposited on an n+ substrate. A p-type boron base is first partially diffused into the n layer, then an oxide window is cut into the oxide formed during the base diffusion, in the area designated for the speedup transistor. A high temperature boron deposition is performed in the oxide window, and the base diffusion completed. The times of the base diffusion steps are chosen so that the penetration of the more lightly doped region slightly exceeds that of the heavily doped region. Oxide windows are then cut for the driver, output and speedup device emitters and the emitter diffusion performed in standard manner. Fabrication is completed using normal single diffused techniques. The effect of the heavy doping of the base region of the speedup transistor is to create a very low gain transistor which has a BVCEO nearly equal to the BVCEX rating. |
