High-frequency, low-noise Si bipolar transistor fabricated using self-aligned metal/IDP technology

A high-frequency, low-noise silicon bipolar transistor that can be used in over-10 Gb/s optical communication systems and wireless communication syste ms has been developed. The silicon bipolar transistor was fabricated using self-aligned metal/IDP (SMI) technology, which produces a self-aligned base electrode of stacked layers of metal and in-situ doped poly-Si (IDP) by lo w-temperature selective tungsten CVD. It provides a low base resistance and high-cutoff frequency. The base resistarlce is reduced to half that of a t ransistor with a conventional poly-Si base electrode. By using the SMI tech nology and optimizing the depth of the emitter and the link base, we achiev ed the maximum oscillation frequency of 80 GHz, a minimum gate delay in an ECL of 11.6 ps, and the minimum noise figure of 0.34 dB at 2 GHz, which are the highest performances among those obtained from ion-implanted base Si b ipolar transistors, and are comparable to those of SiGe base heterojunction bipolar transistors.