GENERATION OF HOLE TRAPS IN THIN SILICON-OXIDE LAYERS UNDER HIGH-FIELD ELECTRON INJECTION

The letter reports an observation of a new degradation mechanism in th ermal silicon dioxide layers on silicon, namely generation of hole tra ps under high-held stressing of metal-oxide-semiconductor (MOS) struct ure. Excess hole trapping due to newly generated hole traps is observe d by substrate hot-hole injection in 9 nm oxide of p-channel MOS trans istors after high-field Fowler-Nordheim stress followed by standard po st-metallization annealing in nitrogen. The concentration of generated traps has a weak stress-polarity dependence and increases with electr on fluence during degrading stress. Relaxation behavior under switchin g oxide fields indicates that the nature of hole trapping sites is dif ferent from anomalous positive charge centers. (C) 1996 American Insti tute of Physics.