Non-homogenous gamma process: Application to SiC MOSFET threshold voltage instability

The accelerated degradation tests provide the opportunity to assess the reliability of an electronic component for which only parametric degradation is observable. In the case of the silicon carbide MOSFETs, this approach makes it possible to study the impact of the threshold voltage phenomenon on the reliability of the devices. During the High Temperature Gate Bias tests, we have carried out, the threshold voltage of the ten devices under test have been monitored and their degradation modeled using a non-homogeneous Gamma process. The estimation of the degradation process parameters enable to estimate the distribution of the first hitting time to a degradation threshold which is considered as a failure criterion. Lastly, a criterion proposed by Tseng and Yu [1] has been used to provide a metric to stop these ageing tests while having relevant reliability data.