A novel process for forming an ultra-thin oxynitride film with high nitrogen topping

We have proposed an approach to grow ultra-thin oxynitride film with high nitrogen concentration (≈13 at%) on the top and low interface state density (D_it=2×10¹⁰ cm^-2 eV^-1). In general, a high-nitrogen oxynitride film provides a rather reliable and higher dielectric constant. In this method, oxynitride growth included three process stages-chemical oxide growth, nitridation and subsequent dry oxidation. By this technique, the films demonstrate the desirable nitrogen concentration profile and excellent properties in terms of low D_it, low leakage current, and high endurance in stressing. Better controllability in film thickness may be achieved because the oxidation rate of the nitride-chemical oxide is much smaller than that of the conventional oxide. Most importantly, this process is simple and fully compatible with current process technology.