Side-wall oxide isolation self-aligned technique for SiGe/Si HBTs

A low temperature side-wall oxide isolation self-aligned technique for SiGe/Si HBTs has been developed, by which the SiGe/Si HBTs with advanced performances have been fabricated. Its current gain is about 70 at 300 K and is more than 2000 at 77 K. It also has superior saturation characteristics with Early voltage over 200 V. Moreover, using this technique, the transverse base resistance is reduced by 50%, resulting in the cutoff frequency and the maximum frequency of oscillation being increased considerably. N/sub F/ is reduced by 3 dB, compared with those devices fabricated by the conventional Si techniques.