Low-Voltage Hot-Electron Currents and Degradation in Deep-Submicrometer MOSFET's

Hot-electron currents and degradation in deep submicrometer MOSFET's at 3.3 V and below are studied. Using a device with Leff = 0.15 μm and Tox = 7.5 nm, substrate current is measured at a drain bias as low as 0.7 V; gate current is measured at a drain bias as low as 1.75 V. Using the charge-pumping technique, hot-electron degradation is also observed as drain biases as low as 1.8 V. These voltages are believed to be the lowest reported values for which hot-electron currents and degradation have been directly observed. These low-voltage hot-electron phenomena exhibit similar behavior to hot-electron effects present at higher biases and longer channel lengths. No critical voltage for hot-electron effects (such as the Si-SiO2 barrier height) is apparent. Established hot-electron degradation concepts and models are shown to be applicable in the low-voltage deep submicro-meter regime. Using these established models, the maximum allowable power supply voltage to insure a 10-year device life-time is determined as a function of channel length (down to 0.15 μm) and oxide thicknesses.