Interface State Generation in NMOS Transistors During Hot Carrier Stress at Low Temperatures

The generation of interface states in NMNOS transistors during hot carrier injection is investigated at temperatures between 300 and 75 K. It is found that hot carrier stress at low temperatures induces a higher number of interface states than at 300 K. The generation rate of interface states can be fitted with a power law as a function of stressing time with a value of the exponent which is independent of the stressing temperature. A similar dependence on the stressing gate voltage is found for hot carrier stress at 75 K and 300 K. The results suggest a temperature independent mechanism of interface state creation. The important role of oxide hole traps in the interface state generation at low temperatures is demonstrated using two-step experiments.