This work investigates the behavior of Si-SiO2 interface in n-channel MOSFETs when the device is subjected to high field injection. Devices of various groups were subjected to current stress (both gate injection and substrate injection) while the source and drain terminals were reverse biased by a screening potential followed by hot carrier stress. It was observed that the screening of the drain edge was effective for both gate injection and substrate injection at different screening potentials. The hot carrier lifetime is directly related to interface state density (Dit), measured by charge pumping method. The results suggest that hot electron degradation could be severe or mild for devices depending on their exposure to the level of screening potential. It was also observed that Si-H bond concentration varies based on the screening potential applied to the source and drain terminals. The interface state density (Dit), is found to have strong dependence on the concentration of the Si-H bonds. Hot carrier stress that significantly contributes to Si-H bond breaking confirmed the effective screening. The results indicate that Si-H bond breaking mechanism during screening is dependent on the polarity of the current stress and the screening potential applied.