An ultra-low thermal-budget SiGe-base bipolar technology

A new self-aligned bipolar transistor structure with self-aligned implanted collector and si!icided extrinsic base contact has been presented. The structure allowed the intcgration of a SiGe-base with very high doping and a low-doped implanced emitter because the dominant thermal cycle was only 880 °C for 15 seconds. Transistors have been fabricated by using the new device structure and SiGe-base layers grown by APCVD epitaxy in a commercial reactor. Typical fT of 35 GHz and fmax of 34 GHz have been achieved for transistors with RB=50 Ω for an emitter area AE=0.6x19.1 μm2. Transistors with an estimated base width of 30 nm and high base resistance had an f7- higher than 60 GHz and ideal device characteristics, which demonstrated the excellent quality of the APCVD SiGe epitaxial films.