Technique for fabricating a sidewall base contact with extrinsic base-on-insulator

摘要

The disclosure relates to a bipolar transistor having reduced base-collector capacitance and a method of making the transistor by forming a sidewall base contact with polycrystalline silicon-on-insulator. The structure is achieved by using differential oxidation to grow thicker oxide over heavily doped N+ regions in a sacrificial polycrystalline silicon layer with the sidewall base region being protected from doping by a sidewall oxide and limited anneal of the N+ dopant. Both NPN and PNP bipolar transistors with minimum collector-base capacitance can be fabricated using this technique.