Effectively modeling the thermal behavior of trench-isolated bipolar transistors

The thermal behavior of trench-isolated bipolar transistors is thoroughly analyzed. Detailed 3-D numerical simulations are performed to investigate the impact of all technological parameters of interest. A novel strategy to analytically evaluate the temperature field is proposed, which is based on the reduction of the domain under analysis to a simplified structure subdivided into the silicon-only trench box with convective boundary conditions at lateral sidewalls and the silicon substrate. An extensive comparison with numerical results proves that the model is extremely accurate over the whole range of parameters, and can be adopted for a fast evaluation of the thermal resistance of a trench device as well as of the temperature gradients within the silicon box surrounded by trenches.