A low-complexity 62-GHz fT SiGe heterojunction bipolar transistor process using differential epitaxy and in situ phosphorus-doped poly-Si emitter at very low thermal budget

Abstract

A low-complexity SiGe heterojunction bipolar transistor process based on differential epitaxy and in situ phosphorus doped polysilicon emitter technology is described. Silane-based chemical vapor deposition at reduced pressure was used for low-temperature SiGe epitaxy. Following SiGe epitaxy, the process temperature budget was kept very low with 900°C for 10 s as the highest temperature step. A very high current gain of almost 2000 and cut-off frequency of 62 GHz were achieved for a uniform 12% Ge profile. The breakdown voltage BV CEO and forward Early voltage were equal to 2.9 and 6.5 V, respectively.