Breakdown phenomena in MIS structure

An alternative to silicon dioxide applied to the gate dielectric in an MIS (metal-insulator-semiconductor) device is silicon nitride. Thin silicon nitride films (thickness <100 AA) were grown by LPCVD (low-pressure chemical vapor deposition) and were characterized by different measured values, such as BDV (distribution of breakdown voltage), TDDB (time-dependent dielectric breakdown), I-V, and C-V. BDV distributions of MNS (metal-nitride-semiconductor) (T/sub N/=5.8 approximately 8.3 nm) are concentrated in the field range of 7 to 8 MV/cm. In the MNS structure (T/sub N/=5.8 to 8.3 nm), two values are obtained from the results of TDDB characteristics, i.e. gamma =0.85 and E/sub a/=0.04 eV. The I-V characteristics of the MIS structure can be explained by mechanisms such as the Schottky effect, Fowler-Nordheim tunnel current, impact ionization, density to trap center, and breakdown. the high effective trap density would enhance the dielectric field strength of the insulating layer. The MNS structure has high permittivity and low V/sub FB/. The thin nitride film processed by LPCVD has relatively high dielectric breakdown strength in the insulating thickness range of 5.8 to 8.3 nm.<
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