Breakdown and hot carrier injection in deep trench isolation structures

In this paper, we propose intensive investigations of the electrical characteristics of a deep trench isolation structure for a new 0.35 μm CMOS based smart power technology. In particular, it is demonstrated, both experimentally and theoretically, that its blocking voltage can be strongly affected by the presence of charges in the floating polysilicon filling the trench. These charges are shown to appear as a consequence of hot carrier injection through the liner oxide during avalanche operation. The measured breakdown voltage instabilities are explained by TCAD simulation tools as well as by a simple theoretical model based on the capacitive coupling approach.