End user reliability assessment of 1.2-1.7 kV commercial SiC MOSFET power modules

This paper is a first attempt to offer reliability evaluation of full SiC power modules where several dies are connected in parallel to increase power rating capability. Here, five different power modules with voltage rating from 1.2-1.7 kV and current rating from 120-800 A from three vendors have been tested. Fresh modules have been used for each type of test. The influence of temperature on the electrical parameters has been investigated. The switching losses have also been measured using a standard double pulse test setup. Following JEDEC and JEITA standards for Si based power devices, important reliability tests such as (i) High Temperature Gate Bias (HTGB) stress, (ii) High Temperature Reverse Bias stress (HTRB), (iii) High Humidity, High Temperature, High Bias (H3TRB) stress, and finally (iv) Thermal Cycling (TC) stress have been performed. Depending on the stress test type, the cause of failure and hence module survivability varies from vendor to vendor. With same voltage and current rating, spread in the leakage current was significantly high among various modules as a function of temperature. For one of the modules, the cause of failure during HTRB and H3TRB was the freewheeling diode, which is connected in parallel with the MOSFET chip. For another module, there has also been recorded a failure of the gate oxide during H3TRB.