Sputter yield and stoichiometry study of InGaZnO film in ion beam etching

Abstract

Although extensive research has been conducted on the characteristics of ion beam etching, studies focusing on sputtering yield at low ion energies and the effects of etching on material properties remain limited. In this study, the etching characteristics of InGaZnO4 (IGZO) thin films were investigated using Ar+ ion beams at various ion energies (50–800 eV) and incident angles (0°–87°). At ion energies below 100 eV, the sputter yield continuously increased with the incident angle across the entire range. This phenomenon differs from the established relationship observed at higher ion energies and may be attributed to surface collision dominating over ion reflection at low ion energies. To understand the impact of ion beam etching on IGZO materials, the chemical composition of IGZO was analyzed using x-ray photoelectron spectroscopy (XPS). An increase in the Ga percentage was observed after etching, accompanied by decreases in the In and Zn percentages, indicating that Ga is the most stable cation in these IGZO films under the ion beam etching etch process. After etching at high incident angles, the chemical composition of the IGZO thin films more closely resembled that of the as-deposited films compared to those processed at low incident angles. The O1s peak in XPS spectra was deconvoluted into three peaks: low binding energy (OL), medium binding energy (OM), and high binding energy (OH), and the ratio of OM to OL was employed to qualitatively assess the concentration of oxygen vacancies in IGZO films. An increase in the OM/OL ratio after the etching process indicates the formation of vacancies.