Collector-base junction avalanche effects in advanced double-poly self-aligned bipolar transistors

Observation of base-current reversal induced by avalanche multiplication is reported in advanced self-aligned bipolar devices at a collector junction reverse bias less than 3 V. Temperature measurements were carried out to verify the avalanche mechanism, and the dependence on the collector doping profile and high-level injection effects was investigated both experimentally and by numerical simulations. The avalanche effect, which is expected to aggravate with scaling, will eventually threaten normal circuit operation if certain criteria for base-collector reverse bias cannot be maintained. >