High-Performance Nitrided Oxides Fabricated by Very-Low-Pressure Nitridation Technique

Abstract

A novel and simple method is proposed to produce high-performance nitrided oxides. Thin oxides nitrided only in NH3 at 900° C for 1 h at 0.1 Torr have excellent interface stability, few electron traps, and excellent reliability. Although the nitrogen concentration [N] at the dielectric/Si substrate interface is kept at a low value, the hydrogen concentration [H] has been shown to be comparable to that of pure oxide at the beginning of the nitridation. Consequently, a high ratio of [N]/[H], which reflects the stable interface, can be attained at the initial stage of the very-low-pressure nitridation (VLPN). This is very different from the case of conventional low-pressure nitridation. The retarded formations of the interfacial Si3N4 and the surface nitrogen-rich oxynitrides are conjectured to be the main cause of reduction in the hydrogen content in the dielectrics during VLPN. Due to the simplicity and wide process window, VLPN is promising for the future ultra-large-scale-integration (ULSI) technology.