Reliability of 4H-SiC Devices Passivation Layer in High Humidity Environment for Power Electronic Applications

The 4H-SiC (Four Hexagon) devices create innovative technology for power electronic design and pulsed power applications to improve energy efficiency and reliability. The 4H-SiC material includes a higher bandgap and thermal conductivity than the current commercial Si material devices. The 4H-SiC material devices have become more suitable for high-power applications for long-term reliability. However, the 4H-SiC devices show a critical failure in the H3TRB (High Temperature, High Humidity, and High Field) test. This test places a semiconductor transistor in an extreme environmental condition to challenge a device’s long-term reliability. The passivation over the die inside the package and on top of the device becomes compromised by the chemical reaction of the water particles and the impurity’s containment from the package. The change of reaction creates a water tree line that would eventually become a short circuit across the surface of passivation. That could enhance serious long-term reliability issues for the wide-bandgap semiconductor device market. In this dissertation, the paper will cover the 4H-SiC TO-247 package devices’ failure mechanism from the H3TRB test and the physics simulation model for the failure mechanism. This paper divides into three parts of the research: background, devices’ test results, and simulation results. The first two chapters cover the introduction and background of the wide bandgap semiconductor materials, current 4H-SiC devices (Diode and MOSFET), static characterization on the devices, TO-247 package, passivation on the die, the H3TRB test industry standard and the COMSOL multiple level software backgrounds. The third chapter presents the 4H-SiC device results of the static characterization and internal layer of SEM images from the H3TRB test. The fourth chapter presents the semiconductor physics equations, 4H-SiC JBS diode design and simulation of the static characterization, and the field in the COMSOL multiple-level physic software. The fifth chapter covers the insulation physic equations, water tree description, and the simulation of the short circuit phenomenon in the COMSOL multiple-level software. Semiconductor covers the conclusion and the contribution in the semiconductor device reliability research in power electronic and pulsed power applications.

Embargo status: Restricted until 09/2173. To request the author grant access, click on the PDF link to the left.