Effects of oxygen content on properties of silicon oxide films prepared at room temperature by sputtering-type electron cyclotron resonance plasma

Abstract

We present the study of the effects of gas-phase oxygen fraction on properties of silicon oxide films prepared in a sputtering-type electron cyclotron resonance plasma discharge. Dielectric breakdown characteristics of the films are considerably improved by an increase in oxygen flow rate, FO2, with a constant Ar gas flow rate of 16 sccm. Films prepared at FO2 of more than 6 sccm have good dielectric breakdown fields of 9–11 MV/cm, which are comparable with those of high quality thermally grown SiO2. Moreover, the increase of FO2 improved structural properties of the films. Detailed measurements of their composition and microstructure were carried out using ellipsometry, chemical etch rate measurement in a mixture of HF, H2O, and HNO3 (P etch), x-ray photoelectron spectroscopy (XPS), and infrared (IR) spectroscopy techniques. Ellipsometry and XPS measurements indicated that films prepared at FO2 of more than 3 sccm are stoichiometric. Dependence of the IR spectra and P etch rate on FO2 of more than 3 sccm indicated that distribution of Si–O–Si bond angle and Si–O bond strain in the films decreases with an increase of FO2. Based on the behavior of the Si–O–Si bond angle and refractive index of the films, we discuss the improvements in structural properties in terms of growth kinetics.