EFFECTS OF NITROGEN INCORPORATION IN LANTHANUM-BASED DIELECTRIC FILMS

ABSTRACT

Thermal stability, electrical and structural properties induced by nitrogen incorporation in lanthanum-based high-k dielectrics were investigated. Thermal growth of a thin silicon oxynitride previously to LaAlO₃ deposition induced higher dielectric constant, lower equivalent oxide thickness, and better interfacial stability during post-deposition annealing of MOS structures. But it also degraded others electrical and structural properties such as leakage current and charges densities, and interfacial roughness. Deposition of LaAlON films, either by reactive sputtering in Ar/N₂ plasma, or by thermal nitridation in ammonia of LaAlO₃, reduced partially several thermal instabilities after post-deposition annealing in ¹⁸O₂, such as metallic losses, silicon diffusion and substrate oxidation.

Keywords:

• High-k dielectrics
• nitrided barrier
• thermal nitridation
• isotopic substitution

ACKNOWLEDGMENT

This work has the financial support from the CAPES-COFECUB (Brazil-France) scientific cooperation program.