Thermal stability of polycrystalline silicon electrodes on ZrO2 gate dielectrics

Thermal stability of gate stack structures composed of ZrO2 gate dielectrics and silicon electrodes was investigated. The ZrO2 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 degreesC, but not in the room temperature PVD-electroded samples, even after gate annealing at 1050 degreesC. 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. (C) 2002 American Institute of Physics.