Research Of Degradation Model And Lifetime Prognosis Method For Power MOSFET

Power MOSFET is key component of the circuits and electronic systems.According to statistical data, Power MOSFETs are of great failure rate of all.Degradation is regarded as the main method around the liefetime. In this paper, webuild the Power MOSFET degradation model influenced by multiple environmentalstress and time according to the degradation data, then predict lifetime by the model.At the same time, support vector machine is used to predict the remaining useful lifeof power MOSFET. The whole research has theoretical significance and practicalvalue.Failure mode and failure mechanism analysis of power MOSFET are finishedfirst. Threshold voltage and channel resistance are proved as sensitive parameters byfailure physics model and test. Power MOSFET degradation modeling and lifetimeprognosis overall research program is proposed here.Power MOSFET sensitive parameters degradation model is builded here.Accelerated degradation test with temperature voltage current conditions isdesigned. After that, data trend extraction method by wavelet analysis and stationarytime series analysis and normalization formula by temperatue are achieved.Threshold voltage and channel resistance model are established respectively.Precision of the model is acceptable by the test.Lifetime of power MOSFET is predicted by the model. Support vector machineand degradation data are used to predict the remaining useful life of powerMOSFET. The conparision between to methods shows that SVM prediction is moreaccuracy in the same condition. Therefore, modeling method is applicable forreliability design which has external tresses as input, while SVM prediction isapplicable for the specific conditions. Random process and normally distributed isused to calculate life distribution and reliability data like reliability rate and themedian life expectancy.Power MOSFET reliability test system is designed. Hardware includesdegradation circuit, signal conditioning circuit, test circuit and control circuit, etc.Software is built by hybrid programming of VC++and Matlab, which has thefunction of test control, regular monitoring of sensitive parameters, degradationmodeling, life prediction, etc.