Modeling and design of silicon-germanium heterojunction bipolar transistors for reliability-aware circuit design

Abstract

The objective of this work is to analyze the mechanisms of breakdown and aging in silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) devices to help maximize the deliverable, reliable performance of high-frequency SiGe HBT circuits and systems. Conventional circuit design methodologies follow conservative and overly simplistic guidelines when considering reliability, but with a more detailed understanding of device reliability, these conventional design limitations may be pushed to enhance performance. This broad objective is explored primarily in three separate approaches, namely the investigation of SiGe HBT aging mechanisms, the development of predictive aging models, and the design of novel SiGe HBT devices with enhanced breakdown performance. It is the intention of the author that device engineers may obtain an enhanced understanding of the physics of aging in SiGe HBTs and that circuit designers may obtain an appreciation of the benefits of "reliability-aware'' circuit design methodologies. Building a link between these two groups to leverage an understanding of physics to enhance circuit and system design methodologies is the overall goal of this work.