Reoxidation after NH₃ Plasma Nitridation for Multiple-Thickness Oxynitrides

Abstract

A novel manufacturable multiple gate oxynitride thickness technology is proposed in this work. An ultrathin dielectric film (E OT=2.5 nm) of lower oxidation growth rate than conventional films was fabricated by NH3 plasma nitridation. Oxide thickness was reduced by about 80% for samples treated by NH3 plasma nitridation. However, the thickness limitation is 1.3 nm for NH3 plasma nitridation. This is believed to be due to nitrogen incorporated in the silicon surface to form a nitridelike thin film, which retarded oxide growth. The effects of NH3 plasma nitridation were systematically studied, and the rapid thermal N2O reoxidation of an NH3 plasma sample was also demonstrated in this work. This novel process improves the gate oxide reliability, decreases bulk trap densities, provides better SILC immunity, and produces less charge trapping and a higher Q bd.

Complete prevention of reaction at HfO2/Si interfaces by 1nm silicon nitride layer

“…The nitrogen concentration of the SiN layer (i.e., N/(N + O) = 0.65) formed in the present study is much higher than that for SiON layers formed by NH 3 -plasma and N 2 O-plasma [13,14,19]. The complete prevention of the interfacial reaction even at 400°C (cf.…”

“…[14,19,20]. In the case of NH 3 plasma, high concentration hydrogen atoms are incorporated, resulting in the formation of high density interfacial trap states [19][20][21].…”

“…[14,19,20]. In the case of NH 3 plasma, high concentration hydrogen atoms are incorporated, resulting in the formation of high density interfacial trap states [19][20][21]. Ultrathin SiON buffer layers formed by NH 3 and N 2 O plasma nitridation cannot prevent the interfacial reaction completely, leading to the formation of an Hf silicate interfacial layer [14].…”