Time-dependent evolution of interface traps in hot-electron damaged metal/SiO2/Si capacitors

The interface traps in metal/SiO2/Si (MOS) capacitors generated by Fowler-Nordheim electron injection change with time after injection. Immediately after injection, a peak of the interface trap distribution appears above the midgap energy ( eV) in all of the samples studied. This peak, along with its background, increases or decreases with time at room temperature, depending on the gate bias polarity during injection, the initial damage level, the gate-induced stress, and the presence of certain chemical impurities in the gate oxide. In the cases when this peak decreases with time, a second peak below midgap ( eV) develops, and this peak grows with time at the expense of the first peak. The important factors that affect the time-dependent behavior of the interface traps are discussed.