The effect of RF power and deposition temperature on the structure and electrical properties of Mg 4Ta 2O 9 thin films prepared by RF magnetron sputtering

Abstract

Mg 4Ta 2O 9 thin films were deposited on p-type Si(1 0 0) substrates by reactive RF magnetron sputtering with various RF powers and deposition temperatures. The crystallinity and electrical properties of the films were investigated. The microstructure and surface morphology characteristics analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM) were related to deposition parameters, such as RF power (100, 200, and 300 W) and deposition temperature (250, 350, and 450 °C). Highly oriented Mg 4Ta 2O 9 (1 0 4) and (1 1 6) perpendicular to the substrate surface were identified at an RF power of 300 W and a deposition temperature of 450 °C. The electrical properties were also measured using capacitance–voltage ( C– V) and current–voltage ( I– V) measurements on a metal–insulator–semiconductor (MIS) capacitor structure. The leakage current increased with increasing RF power and substrate temperature. At an RF power of 300 W, a substrate temperature of 450 °C, a deposition pressure of 5 mTorr, and an Ar/O 2 ratio of 100/0, the Mg 4Ta 2O 9 films with 4.82 μm thickness possess a dielectric constant of 13.2 ( f=10 MHz) and a leakage current density of 1.59×10 −9 A/mm 2 at 5 V.