This review discusses the fundamentals of SiGe epitaxial base heterojunction bipolar transistor (HBT) technology that have been developed for use in analog and mixed-signal applications in the 1–20 GHz range. The basic principles of operation of the graded base SiGe HBT are reviewed. These principles are then used to explore the design optimization for analog applications. Device results are presented that illustrate some important trade-offs in device design. A discussion of the use of UHV/CVD for the deposition of the epitaxial base profile is followed by an overview of the integrated process. This process, which has been installed on 200 mm wafers in IBM's Advanced Semiconductor Technology Center in Hopewell Junction, N.Y., also includes a full range of support devices. The process has demonstrated SiGe HBT performance, reliability, and yield in a CMOS fabrication with the addition of only one tool for UHV/CVD deposition of the epi-base and, with minimal additional process steps, can be used to fabricate full BiCMOS designs. This paper concludes with a discussion of high-performance circuits fabricated to date, including ECL ring'oscillators, power amplifiers, low-noise amplifiers, voltage-controlled oscillators, and finally a 12-bit DAC that features nearly 3000 SiGe HBT devices demonstrating medium-scale integration.
