Improvement of 1/f noise in advanced 0.13 µm BiCMOS SiGe:C Heterojunction Bipolar Transistors

In this study, we present recent low frequency noise results obtained on Si/SiGe:C Heterojunction Bipolar Transistors (HBTs) associated with a 0.13 μm BiCMOS technology. The HBTs are supplied by STMicroelectronics Crolles and present unity current gain frequencies (f_T) and maximum oscillation frequencies (f_max) in the 250s of GHz. The 1/f noise sources are found to be located in the intrinsic emitter-base (E-B) region. The 1/f noise figure of merit, K_B, is found to be close to 1.5 10^-10 μm². This excellent result is at least one decade better than the initial development of this 0.13 μm BiCMOS technology. Moreover, in order to take into account the improvement of the high frequency parameters (f_T and f_max) associated to this technological evolution, we have studied the ratio f_C/f_T, figure of merit that links LF Noise and transistor speed. We have analyzed the 1/f noise improvement from different technological aspects related to the emitter-base process, for instance the surface cleaning (prior to the polysilicon deposition) and the epitaxial regrowth of the polysilicon.