MEMORY CHARACTERISTICS OF MNOS CAPACITORS FABRICATED WITH PECVD SILICON-NITRIDE

The memory performance of metal-nitride-oxide-silicon (MNOS) capacitors, fabricated with 'as-deposited' PECVD silicon nitride, have been evaluated using high-frequency, capacitance-voltage characteristics. A 4. 2v memory window was achieved for a programming field of 6 multiplied by 10**6v/cm and a pulse width of 1 mu s. Decay rates varied between 0. 1 and 1. 0v per decade of time in seconds depending on nitride deposition conditions and initial window size. Devices endurance cycled to 10**8 suffered a small decrease in window size and a slight shift in memory window center. Retention data taken following endurance cycling to 10**7 showed a negligible degradation of decay rate. Vertical scaling of the nitride layer to approximately 100 angstroms yielded devices which could be programmed with 5-8v. Nitride films were annealed at temperatures of 400-800 degree C. Fourier Transform Infrared analysis revealed a loss of hydrogen for temperatures above 400 degree C. Memory performance of the films degraded in parallel with loss of hydrogen.