Investigation on etch characteristics of FePt thin films using a H2O/Ar plasma

Abstract

• Development of a H 2 O/Ar gas to etch FePt magnetic films. • Films etched by inductively coupled plasma reactive ion etching. • Etch mechanism of FePt films in H 2 O/Ar plasma. • Etching of FePt films with high degree of anisotropy without redeposition or etch residue. The etch characteristics of FePt thin films patterned with a TiN hard mask were investigated using inductively coupled plasma reactive ion etching (ICPRIE) in a H 2 O/Ar plasma. As the H 2 O concentration increased, the etch rates of the FePt films and TiN hard mask decreased gradually, but the etch profile improved with a high degree of anisotropy without redepositions or etch residues. The improvement of etch profiles was attributed to the formation of a protective layer containing hydrogen species on the sidewall of the patterns and the formation of metal oxides during etching. The optical emission spectroscopy of H 2 O/Ar plasma revealed an increase of [H]/[Ar] and [O]/[Ar] ratios with increasing H 2 O concentration. As the ICP rf power and dc-bias voltage increased, and the gas pressure decreased, the etch rates of the FePt films increased and more vertical etch slopes were obtained. X-ray photoelectron spectroscopy of etched FePt films confirmed the existence of Fe oxide compounds formed by the etching. Overall, the results indicated that the etching of FePt films in a H 2 O/Ar plasma follows a chemically-affected sputtering etching mechanism.