Impact of alpha-radiation on power MOSFETs

In this paper it is shown how the impact of alpha particles in the gate oxide of a power MOSFET leads to a local reduction of the threshold voltage V
_th
. Evidence is presented that radioactive impurities in the solder material of the clip attach indeed are the root cause for such effects observed in long term measurements with electrical gate bias. Data show that alpha impacts have no negative influence on reliability and application performance of power MOSFETs.