High temperature (1000°C) compatible Y-La-Si-O silicate gate dielectric in direct contact with Si with 7.7 Å equivalent oxide thickness

Abstract

Yttrium lanthanum silicate was formed in direct contact with silicon after a rapid thermal annealing at 1000°C in metal-oxide-semiconductor capacitors leading to an equivalent oxide thickness (EOT) of 7.7 Å. This represents one of the lowest EOT value reported for a gate-first process with non Hf-based dielectric. The silicate is formed by interdiffusion of La2 O 3 and YOx layers and interfacial SiO2 consumption. Yttrium incorporation reduces the leakage current density as well as the large negative flatband voltage (Vfb) shift that is associated with lanthanide-based dielectrics. The Vfb value can be appropriately tuned for n-type field-effect transistor operation by changing the silicate composition. © 2011 American Institute of Physics.