Method for adjusting the current gain of polysilicon emitter bipolar transistors

摘要

The existing upper surface oxide on the monosilicon is removed. It is then placed in an oxygenated atmos. of sufficiently low temp. to avoid further oxidn.. The equipment is then made airtight. Using a measured time (at least one min.) and temp. (of at least 500 degrees C) the oxide film is built up to a specific thickness in the oxygen atmos. on the upper surface so that the current gain of the transistor is narrowly determined to a desired value. The equipment is then evacuated and polysilicon is then deposited of the oxide film.