Electrical characterization of electron beam induced damage on sub-10 nm n-channel MOS transistors using nano-probing technique

Abstract

Electron beam induced damage on sub-10 nm n-channel MOS transistors was evaluated using an atomic force microscopy-based nano-probing technique. After electron beam irradiation, all the device parameters shifted including threshold voltage (Vth), saturation current, sub-threshold slope and transistor leakage current. A negative shift in Vth occurred at low electron beam acceleration voltage (Vacc) because of the increase in oxide trapped holes generated by excited plasmons. At high Vacc, however, a positive Vth shift was observed because of an increased contribution of interface trap generation caused by the deeper electron penetration depth. In addition, interface trap generation not only degraded the sub-threshold slope due to the additional capacitance from the generated interface traps, but also increased transistor leakage current due to changes in junction characteristics. Our studies show that it is critical to avoid electron beam exposure before electrical characterization on sub-10 nm devices even in the range of less than 1.0 kV of Vacc using nano-probe systems.