Impact of charging on breakdown in deep trench isolation structures [parasitic MOSFET example]

In this paper, the breakdown of a deep trench isolation structure has been analysed and modeled. In particular, it is shown that the breakdown voltage of the p-n junction in the silicon can be strongly affected by the presence of charges on the floating polysilicon within the trench. These charges might appear not only as process induced charges but also as a consequence of hot carrier injection during avalanche operation. The measured breakdown instabilities can be reproduced by TCAD simulations as well as by a simple theoretical model within which these results can be understood and predictions can be made.