Thermo-mechanical reliability analysis of flip-chip bonded silicon carbide Schottky diodes

Abstract

This paper presents the thermo-mechanical reliability analysis of a novel chip-scale wire bondless packaging technique for a SiC Schottky diode that leads to lower parasitics, higher reliability, lower costs, and lower losses. The proposed approach uses a flip-chip solder ball array to make connections to the anode. A copper connector was used to make contact with the bottom cathode, thus reconfiguring the bare die into a chip-scale, flip-chip capable device. Thermo-mechanical analysis in a finite element software showed that the proposed approach could better manage Coefficient of Thermal Expansion (CTE) mismatch stresses arising at the critical module interfaces as compared with a conventional wire bonded module. A detailed analysis of the flip-chip structure is presented and contrasted with a state-of-the-art wire bonded module. Different design parameters were explored for the drain connector to be able to make an optimized decision. However, keeping production costs low was prioritized without compromising significant performance. The fabrication process for manufacturing a flip-chip schottky diode module was also demonstrated along with preliminary test results to demonstrate functionality.