INTERFACE STATE DENSITY REDUCTION AND EFFECT OF OXIDATION TEMPERATUREON FLUORINE INCORPORATION AND PROFILING FOR FLUORINATED METAL-OXIDE SEMICONDUCTOR CAPACITORS

The effect of fluorine incorporation on the as-grown Si-SiO2 interface state density of the metal/SiO2/Si system was investigated using MOS capacitors with fluorinated oxide dielectrics grown by NF3-enhanced ox idation as test structures. A dear reduction of the interface trap den sity, attributed to fluorine-induced passivation of interfacial dangli ng bonds, weak bonds, and weak interactions, was shown for NF3, additi ons in the parts-per-million range as compared to dry oxides. Fluorine incorporation in the oxide was investigated with SIMS profiling. The application of a pulsed oxidation process in which the NF3-fluorine so urce is added to the oxidant in intervals within the total oxidation t ime demonstrated that the variation of NF3-enhanced oxidation processi ng parameters strongly influences the resulting fluorine profile. A tw o-peak pattern of the fluorine profile, with one peak in the interfaci al area and the other corresponding to the oxide area grown during the NF3-enhancement step, was observed. This pattern was strongly depende nt on the oxidation temperature, with the interfacial fluorine accumul ation more pronounced with increasing temperature. The pronounced infl uence of the oxidation temperature on the fluorine profile resulting f rom NF3-enhanced oxidation was ascribed to a thermally activated repla cement reaction of bonded fluorine by oxygen.