Enhancement of hot-carrier induced degradation under low gate voltage stress due to hydrogen for NMOSFETs with SiN films

For transistors with a SiN film on the gate electrode, a new degradation mode has been found where hot-carrier induced degradation is maximum when the gate voltage during stress is lower than that of the substrate current maximum. This degradation is increased with increasing amounts of hydrogen in the SiN film. This degradation mode is considered to be caused by hydrogen diffusion from SiN into the gate oxide during high temperature annealing such as BPSG reflow.