Electrothermal simulation of power semiconductor devices

TESSA, a program designed to simulate the coupled electrothermal behavior of semiconductor devices in two and three dimensions, is discussed. The equations used to capture the electrothermal physics and the algorithms used to solve them are described. Simulations are reported for a multifingered bipolar power transistor. These show that the characteristic form of the temperature distribution, within the transistor, is quite different for the saturated and unsaturated cases. The effect of temperature on the partitioning of current between emitter fingers is investigated. In addition, the components of heat generation, e.g., recombination heat, and their relative importance are calculated.>