An advanced PSA process for high speed bipolar VLSI

A structure, fabrication processes and performances of the bipolar transistor with 1 µm wide emitter are presented. An advanced polysilicon self-aligned (APSA) technology (1) is applied in order to realize high speed bipolar VLSI. The remarkable feature of the APSA technology is its overlapping structure of emitter electrodes using the second layer of polysilicon. Consequently, 1 µm wide emitter and a spacing of about 1 µm between the edges of the emitter diffused layer and the base contact windows can be realized at a time. Further, the shallow base junction can be controlled arbitrarily because intrinsic base is fabricated just before forming emitter. By using the APSA technology, we have realized low power CML (LCML) structure with 1×3 µm²emitter transsistors leading to the maximum propagation delay time of 0.29 ns/gate and a speed power product of 0.18 pJ/gate in low current region.