Hot-electron-induced MOSFET degradation—Model, monitor, and improvement

Abstract

Evidence suggests that MOSFET degradation is due to interface-states generation by electrons having 3.7 eV and higher energies. This critical energy and the observed time dependence is explained with physical model involving the breaking of the ≡ SisH bonds. The device lifetime τ is proportional toI_{sub}^{-2.9}I_{d}^{1.9}\Delta V_{t}^{1.5}. If Isubis large because of smallLor large Vd, etc., τ will be small. Isub(and possibly light emission) is thus a powerful predictor of τ. The proportionality constant has been found to vary by a factor of 100 for different technologies, offering hope for substantially better reliability through future improvements in dielectric /interface technologies. A simple physical model can relate the channel field Emto all the device parameters and bias voltages. Its use in interpreting and guiding hot-electron scaling are described. LDD structures can reduce Emand Isuband, when properly designed, reduce device degradation.