Ultra-Thin Zirconium Oxide Films Deposited by Rapid Thermal Chemical Vapor Deposition (RT-CVD) as Alternative Gate Dielectric

Abstract

ABSTRACTZrO2 ([.kappa]∼ 18) was deposited on Si(100) wafers by rapid thermal chemical vapor deposition (RT-CVD) process to replace SiO2 as the gate dielectric material in metal-oxide- semiconductor devices for its high dielectric constant, good thermal stability on silicon, and large bandgap. The deposited films are nearly stoichiometric, amorphous, uniform, and highly smooth, as determined by X-ray photoemission spectroscopy, X-ray diffraction, ellipsometry, and atomic force microscopy. The high resolution transmission electron microscopy (TEM) image shows an interfacial ZrSiO4 layer between ZrO2 and the silicon substrate, and this interfacial layer is verified by thermodynamic calculations and etching resistance measured at the interface. Excellent step coverage was observed for depositing ZrO2 on nanometer scale features with an aspect ratio of 4. The dielectric constant of RTCVD ZrO2 was 15-18, with small C-V hysteresis and low leakage current.