Development of an SiC multichip phase-leg module for high-temperature and high-frequency applications

This article presents a 1,200-V, 120-A silicon carbide metal-oxide-semiconductor field-effect transistor (SiC MOSFET) phase-leg module capable of operating at 200°C ambient temperature. Paralleling six 20-A MOSFET bare dice for each switch, this module outperforms the commercial SiC modules in higher operating temperature and lower package parasitics at a comparable power rating. The module's high-temperature capability is validated through the extensive characterizations of the SiC MOSFET, as well as the careful selections of suitable packaging materials. Particularly, the sealed-step-edge technology is implemented on the direct-bonded-copper substrates to improve the module's thermal cycling lifetime. Though still based on the regular wire-bond structure, the module is able to achieve over 40% reduction in the switching loop inductance compared with a commercial SiC module by optimizing its internal layout. By further embedding decoupling capacitors directly on the substrates, the module also allows SiC MOSFETs to be switched twice faster with only one-third turn-off overvoltages compared with the commercial module.