Thermal transient behavior of silicon-on-glass BJTs

Calibrated 3-D numerical simulations are employed to quantify the influence of design parameters like emitter area, aspect ratio, distance to trenches, and thickness of AlN heatspreaders on the thermal transient behavior of silicon-on-glass (SOG) bipolar transistors. A larger silicon island enclosed in the trenches reduces the thermal resistance at the expense of a slower thermal response of the system to a unitary power step. Conversely, the integration of AlN heatspreaders lowers both the thermal resistance and the rise time of the thermal impedance. An in-house custom code is adopted to extract an optimized Foster network for the description of the dynamic transistor behavior, thereby allowing the analysis of the thermal frequency response.