Distributed Model For Thermal Characterization Of Oxide Isolated Silicon Germanium Heterojunction Bipolar Transistors

Abstract

Demand for high-speed and cost-effective devices has resulted in the development of smaller, high frequency devices. Since semiconductor devices are getting smaller, self-heating effects have become more important. This is especially true in BJTs/HBTs since the base-emitter voltage and hence collector current are sensitive to temperature variations. Self-heating increases the temperature of the devices and results in variations in the electrical properties of the circuit in which these devices are used. Hence, it is important to accurately characterize the self-heating effects and develop reliable models, so that these effects can be taken into consideration in the simulations during the design process. With the development of Silicon on Insulator (SOI) technology, self-heating is even more dominant because the oxide is a poor conductor of heat, and the heat tends to get trapped within the device resulting in much longer time constants. This work deals with the development of the Vertical Bipolar Inter-Company (VBIC) model parameters to characterize self-heating in SOI SiGe transistors which have been fabricated by National Semiconductors (NSC).