Self-aligned BJTs for VLSI using a new diffusion technique for shallow base formation

A method of using selectively deposited and selectively removed 'polycrystalline' Si/sub x/Ge/sub 1-x/ as a diffusion source for the fabrication of narrow-base self-aligned BJTs (bipolar junction transistors) is described. The transistors showed excellent quality emitter-base and base-collector junction characteristics. In addition, this process was found to be completely compatible with current double polysilicon self aligned technology.