High Humidity, High Temperature and High Voltage Reverse Bias - A Relevant Test for Industrial Applications

In this article, the importance of the High Humidity, High Temperature and High Voltage Reverse Bias test (H3TRB-HVDC) for semiconductor reliability is shown. With the test methodology presented here, long term ruggedness of SiC-based semiconductors to harsh environmental conditions is assessed. To demonstrate the importance of the test method, results from different devices are presented and discussed. Results of commercially available 1:7 kV SiC MOSFETS from two well-established suppliers packaged in TO-247 are shown. In addition, results of two different 1200 V industrial silicone gel filled modules are presented. In the first case, benchmarking of different suppliers can be obtained with this test method, in the latter case, end-of-life equal to electrical short is reached for one of the device type. The test conditions are based on the Temperature Humidity Bias (THB) reliability test standard. In order to be closer to the application profile and to address both chip level degradation as well as package related issues, the stress voltage level is increased from the generally used 80 V to 80% of the device rated voltage (i.e. 1360 V and 960 V, respectively for 1700 V and 1200 V rated devices). The results underline the importance of the H3TRB-HVDC to become a common test for SiC semiconductor suppliers as humidity ruggedness of power devices is an essential feature for industrial applications.