Modeling of gate dielectric breakdown due to drain avalanche injection in MOSFET's

In this work, the drain avalanche breakdown due to infinite multiplication and substrate current feedback effect as well as their influence on the gate oxide breakdown are discussed and modeled. Results show that at drain avalanche breakdown the gate oxide can break down twice at a low oxide electric field (<1.2 MV/cm). The first breakdown happens simultaneously with the drain avalanche breakdown whereas the second breakdown occurs beyond the drain breakdown. It is further identified that the gate oxide breakdown is governed by the thermionic emission of hot electrons at low oxide fields (<1.0 MV/cm). This thermionic current can be retarded by increasing the gate voltage and a revised thermionic equation is developed. On the other hand, the gate current at second breakdown can be fitted very well with the Fowler-Nordheim equation.