Electrical properties of silicon dioxide films grown by inductively coupled R.F. plasma anodization

Abstract

The effect of growth conditions on the electrical properties of silicon dioxide grown in oxygen/argon plasma at 500°C are described. The two process parameters whose effects were studied in detail were: gas pressure in plasma and anodization current density. MOS capacitors were fabricated with these oxides. These were subjected to a post oxidation anneal at 800°C for 20 min and a post-metallization anneal at 450°C for 30 min. Measurements on these capacitors indicated that the growth parameters have a marked effect on the density of interface states, fixed oxide charge and the electron trap density in plasma oxides. A qualitative model based on the mechanism of plasma oxidation is presented which explains the dependence of oxide properties over process conditions. Measurements on the thickness of oxides grown at various distances from the plasma have also been presented. It has been pointed out that our oxidation data are not in agreement with various growth kinetics models existing in literature. Hence, a suitable mechanism of plasma oxidation is required which must explain the dependence of electrical properties of plasma oxides on growth parameters.