The Changing Effect of N 2 / O 2 Gas Flow Rate Ratios on Ultrathin Nitrogen-Enriched Oxynitride Gate Dielectrics

We report the growth of an ultrathin 1.0 nm (equivalent oxide thickness = 0.86 nm) oxynitride gate dielectric by rapid thermal processing (RTP) in high-N 2 but low-O 2 gas flow ambient. The effect of the changing N 2 /O 2 gas flow ratio on the characteristics of oxynitride films was investigated. High-quality oxynitride film could be formed by RTP in an optimum N 2 /O 2 gas flow ratio of 5/1. Detailed characterization (transmission electron microscopy, J-E capacitance-voltage, stress-induced leakage current, charge-trapping properties) demonstrated the high quality of the oxynitride dielectric and showed that low leakage current density J g = 0.1 A/cm 2 at I V, was 1.85 orders of magnitude lower than that of SiO 2 . These improvements are attributed to the presence of nitrogen at the interface and in the hulk of the oxynitride.