Improving reliability of IGBT surface electrode for 200 °C operation

The surface barrier effect due to nickel (Ni) film on aluminum (Al) surface electrode of insulated gate bipolar transistor (IGBT) via power cycling (P/C) test at the maximal junction temperature (Tjmax) of 200°C and thermal cycling (T/C) test in the -55°C to 200°C range has been carefully investigated. The difference of coefficient of thermal expansion (CTE) between Al and Ni and the stiffness of Ni played a key role to prevent mass transfer phenomena such as a migration of Al grain boundaries. We show that long P/C and T/C lifetime under high temperature operating condition can be achieved with the conventional IGBT module using our technique.