Thermal stability of polycrystalline silicon electrodes on ZrO2 gate dielectrics

Abstract

Thermal stability of gate stack structures composed of ${\mathrm{ZrO}}_2$ gate dielectrics and silicon electrodes was investigated. The ${\mathrm{ZrO}}_2$ films were deposited by atomic layer deposition, while the polycrystalline silicon electrodes were deposited using different variants of chemical (CVD) and physical vapor deposition (PVD). Zirconium silicide formation was noted in all CVD-electroded samples after subsequent annealing treatments at temperatures above 750 °C, but not in the room temperature PVD-electroded samples, even after gate annealing at 1050 °C. The dependence of zirconium silicide formation on the Si deposition process was explained using thermodynamic arguments which explicitly include the effects of oxygen deficiency of the metal oxide films.