VLSI integration of SiGe epitaxial base bipolar transistors

Abstract

This paper presents the state-of-the-art concerning integrated Si/Si,,GeJSi Heterojunction Bipolar Transistors (SiGe HBTs), with special emphasis on what are the real strong points of the device, once integration constraints huve been accounted for. A review of some representative technologies is given, with a tentative classification according to the tradeof which has been chosen between performance, integrability and process complexity. Examples of low-cost integration of SiGe HBTs in an industrial BiCMOS technology are provided as an illustration.R,,, it is possible to get a smaller base resistance with a smaller device length (smaller current). In implanted