Phase control of magnetron sputtering deposited Gd 2O 3 thin films as high-κ gate dielectrics

Abstract

Gd 2O 3 thin films as high-κ gate dielectrics were deposited directly on Si(001) substrates by magnetron sputtering at a pressure of 1.3 Pa and different temperatures. X-ray diffraction results revealed that all the films grown from 450 to 570 °C were crystalline, and the Gd 2O 3 thin films consisted of a mixture of cubic and monoclinic phases. The growth temperature was a critical parameter for the phase constituents and their relative amount. Low temperature was favorable for the formation of cubic phase while higher temperature gave rise to more monoclinic phase. All the Gd 2O 3 thin films grown from different temperatures exhibited acceptable electrical properties, such as low leakage current density ( J L) of 10 −5 A/cm 2 at zero bias with capacitance equivalent SiO 2 thickness in the range of 6–13 nm. Through the comparison between films grown at 450 and 570 °C, the existence of monoclinic phase caused an increase in J L by nearly one order of magnitude and a reduction of effective dielectric constant from 17 to 9.