Electro-thermal Modeling Method of Protection Power Diodes Using TCAD 3D / 2D approach

This paper introduces a new model for predicting the electro-thermal behaviour and the failure of transient-voltage-suppression (TVS) diodes by finite elements with the TCAD suite Sentaurus from Synopsys^©. A two-heat source description (3D simulation), based on the dissipated power distribution (2D simulation) in the diode is proposed to report on the non-uniformity of the dissipated power along the TVS junction. First, the properties of different numerically obtained diodes were successfully compared to experimental ones. 10/1000 μs electrical overstress was then applied for each diode and the corresponding maximum reached current and voltage confronted to experimental surge characterization data. The model provides a limit temperature and can be extended to different breakdown voltages and active surfaces at which failure happens. We found out that this limit is due to the melting of the die attach layer at a current intensity depending on the diode structure.