Electrical and Reliability Studies of 'Wet $N_2O$' Tunnel Oxides Grown on Silicon for Flash Memory Applications

摘要

In this paper, we report the electrical characteristics and reliability studies on tunnel oxides fabricated by "wet $N_2O$" oxidation of silicon in an ambient of water vapor and $N_2O$ at a furnace temperature of $800^oC$. Tunnel oxides that have an equivalent oxide thickness of $67 AA$ are subjected to a constant-current stress (CCS) amount of $-100 mA/cm^2$ using a MOS capacitor to obtain information on stress-induced leakage current (SILC), interface, and bulk trap generation. The obtained results clearly demonstrate the superior performance features of the present tunnel oxides with reduced SILC, lower trap generation, minimum change in gate voltage, and higher charge-tobreakdown during CCS studies. X-ray photoelectron spectroscopy depth profile studies of the tunnel oxide interfaces have shown that the improved performance characteristics and reliability can be attributed to the incorporation of about 8.5% nitrogen at the oxide–silicon interface of the samples formed by the "wet $N_2O$" process that involves low-temperature oxidation and annealing at $800^oC$.