Thermal Resistance Model for Multi-finger Trench-Isolated Bipolar Transistors on SOI Substrate

A simple predictive model to estimate the thermal resistance of a trench isolated multi-finger bipolar device on SOI substrate is proposed. The model shows very good agreement with 3-D electro-thermal simulations over a wide range of device parameters. The simulations have been verified with measurements. The model is virtually independent of critical device parameters such as trench depth, oxide layer thickness and emitter dimensions and serves as a useful tool to predict the thermal resistance of a multi-emitter device reasonably accurately, from the known thermal resistance of the corresponding single-emitter device.