Self heating modeling of SiGe heterojunction bipolar transistor

A model of heat transfer in a SiGe heterojunction bipolar transistor (HBT) at the macro scale is established, that leads to an analytical solution. Modelling is based on the use of integral transforms as the Fourier and Laplace ones. The heat source is assumed as a heat flux applied at the base-collector junction. It is shown that the thermal behaviour of the transistor at the highest frequencies is perturbed by the deep-trench insulation of the device. Finally, it is shown the interest of this model to identify the thermal conductivity of the back-end layer which is treated as a homogeneous medium.