Bipolar transistor with self-aligned lateral profile

This paper presents a new self-alignment concept for scaled-down bipolar transistors: the self-aligned lateral profile. Using this concept to form the impurity profile and combining it with a wraparound base contact to reduce the emitter-base contact spacing and an n+-poly-refractory metal emitter stack to reduce the emitter resistance, a high-performance and potentially high-yield device structure can be obtained. The device structure can be adapted to a CMOS or merged bipolar-CMOS process and can also be easily optimized for analog applications.