Remote Plasma Nitridation of In-Situ Steam Generated (ISSG) Oxide

Abstract

Electrical performance of in-situ steam generated (ISSG) oxide nitrided using remote plasma nitridation (RPN) has been evaluated. An equivalent oxide thickness (EOT) of 1.6 nm with gate leakage current around 5×10−3 A/cm2 (at −1.5V) has been achieved. The leakage current of remote plasma nitrided ISSG oxide is lower than that of ISSG only, where more than one order of magnitude leakage current reduction (at the same EOT) has been achieved for some RPN conditions. Moreover, it is observed that the extent to which the RPN process conditions modify device parameters such as EOT, flatband voltage (VFB), and time-to-breakdown (tbd) increases with decreasing ISSG thickness. The thinner ISSG oxides appear to be more susceptible to plasma damage and accumulation of positively charged nitrogen atoms at the oxide/Si interface. Therefore, RPN processes that use lower temperature and shorter time are preferred for very thin oxides. The nitrogen content and profile in the samples evaluated using SIMS analysis, indicate that RPN offers higher nitrogen content and better nitrogen profile compared to conventional nitrogen incorporation methods such as NO annealing [1].

Characterization of ultrathin gate dielectrics formed by in-situ steam generation with nitrogen postprocessing

“…9,10 The lowest EOT of 1.6 nm was measured for the ISSG ϩ RPN film; the ISSG ϩ NO film exhibited an EOT ϳ 2.2 nm, while the ISSG and RTO films were of comparable thicknesses (EOT ϳ 2.4 nm). 11 In all cases, hysteresis of the The flat band voltages, V FB , for all films in this experiment were approximately Ϫ0.9 V, which is close to the theoretical value for the substrate type; substrate and polydoping levels used in our experiments at International SEMATECH and have been published.…”

Investigation of boron penetration through decoupled plasma nitrided gate oxide using backside secondary ion mass spectrometry depth profiling

“…1,2 Plasma nitridation of silicon dioxide has been shown to introduce sufficient nitrogen with a controlled concentration profile within the SiO 2 layer. 3,4 Without a heavily nitrided oxide, the high thermal budget needed to fully activate the polysilicon dopant will cause boron penetration through the thin gate oxide. 5 Decoupled plasma nitridation ͑DPN͒ of pure oxide can incorporate a high level of nitrogen into very thin gate oxides ͑Ͻ2 nm͒ with higher nitrogen concentration at the oxide/polysilicon gate interface, resulting in less boron piling up within the oxide after annealing.…”