AN ADVANCED BSG SELF-ALIGNED (A-BSA) TRANSISTOR TECHNOLOGY FOR HIGH-SPEED IC IMPLEMENTATION

This paper reports on a high-speed silicon bipolar transistor with an f(T) and J(MAX) of over 40 GHz, we call it the Advanced Boro-silicated -glass Self-Aligned (A-BSA) transis tor. In basic BSA technology, a CV D-BSG him is used not only as a diffusion source to form the intrinsic base and the link base regions but also as a sidewall spacer between the emitter and the base polysilicon electrodes. An A-BSA transistor o ffers three advancements to this technology: (I) a graded collector pr ofile underneath the intrinsic base region to suppress the Kirk effect ; (2) an optimized design of the link base region to prevent the trade -off effect between f(T) and base resistance; and (3) a newly develope d buried emitter electrode structure, consisting of an N++-polysilicon layer, a platinum silicide layer, and a CVD tungsten plug, to prevent the emitter plug effect. Furthermore, our transistor uses a BPSG fill ed trench isolation to reduce parasitic capacitance and improve circui t performance. In this paper, we describe device design, process techn ology and characterization of the A-BSA transistor, with it we have pe rformed several application ICs, operating at 10 Gb/s and above. The A -BSA transistor achieved an f(T) of 41 GHz and an J(MAX) of 44 GHz und er optimized conditions.