A New Effective Methodology for Semiconductor Power Devices HTRB Testing

An advanced high-temperature reverse bias (HTRB) testing procedure for performing reliability tests on power transistors is reported. The main target is to monitor continuously the degradation trend of tested devices. Therefore, the total HTRB test time is divided into short stress cycles. Thanks to a purposely designed miniature heater, which controls the individual case temperature of devices under test (DUTs), electrical characterization, at low or high temperature, can be performed at the end of each stress period automatically. In this way, DUT's electrical parameters can be periodically measured to identify early warnings of failure, and test can be stopped for the sole out-of-specification devices. In addition, thanks to the fast thermal control, thermal runaway processes can be inhibited, freezing the degradation state to a presettled level, in order to perform appropriate postfailure analysis. Finally, the new HTRB methodology allows for evidencing anomalous behaviors, which are not considered as failures, and the application of low frequency noise measure techniques provides the evidence of the effects of the applied thermo-electrical stress. The proposed HTRB methodology together with low frequency noise measurements are presented as well as the results obtained from the experimental application of the procedure on silicon power MOSFETs.