Identification and Implication of a Perimeter Tunneling Current Component in Advanced Self-Aligned Bipolar Transistors

Abstract

The identification of a perimeter tunneling current in the base-emitter junction of advanced “double-poly” self-aligned bipolar transistors has been verified by measuring base current as a function of temperature, bias voltage, and device perimeter to area ratio. The perimeter tunneling current at forward bias is found to be predominantly an excess tunneling that depends on the sidewall oxide interface properties, while that at reverse bias is due to band-to-band tunneling resulting from the emitter and extrinsic base profile overlap. Based on experimental results and an analysis of base leakage current trade-offs at forward and reverse bias, a device design concept has been developed to enhance device performance and processing yield in future scaled bipolar transistors. © 1988 IEEE