Direct evidence of multiple vibrational excitation for the Si–H/D bond breaking in metal–oxide–semiconductor transistors

Experiments based on substrate hot-electron generation due to impact ionization are designed to reveal whether the hydrogen/deuterium (H/D) isotope effect is caused by the density of electrons or their energy. It is found that the H/D isotope effect for hot-electron degradation is strongly dependent on the density of hot electrons presented at the interface. This suggests that the multiple vibrational excitation (heating) plays a major role in hot-carrier degradation of metal–oxide–semiconductor (MOS) transistors. Because of the unique nature of multiple vibrational excitation (heating), low-energy electrons are able to break Si–H/D bonds in MOS devices. This implies that hot-electron degradation is still an important reliability issue even if the drain voltage is scaled down to below 1 V.