Comparison of dielectric wear-out between oxides grown in O/sub 2/ and N/sub 2/O

Electrical and reliability properties of MOS gate oxides prepared by furnace oxidation of Si in an N/sub 2/O ambient have been studied. The thickness uniformity of N/sub 2/O oxides is comparable to that of the control oxides grown at the same temperature. Time-zero breakdown tests reveal similar breakdown field distributions for both oxides. Devices with N/sub 2/O gate oxides are less susceptible to charge trapping, interface state generation, and transconductance degradation under electrical stressing than devices with gate oxides grown in O/sub 2/. Significant improvement in time-to-breakdown (t/sub BD/) and charge-to-breakdown (Q/sub BD/) under substrate electron injection was observed for N/sub 2/O oxides. Under gate injection, Q/sub BD/ and t/sub BD/ values of both N/sub 2/O and control oxides are comparable. This stress polarity dependence is explained by the nitrogen pile-up at the SiO/sub 2//substrate interface.<
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