Inductive couple plasma reactive ion etching characteristics of TiO2 thin films

• Reactive ion etching of TiO2 films under HBr, C2F6, and Cl2 gases was studied.
• Etch rate and etch profile of TiO2 films were investigated under each gas chemistry.
• The highest degree of anisotropy was achieved at 25% C2F6/Ar.
• Strong etch conditions at 25% C2F6/Ar increased etch rate and degree of anisotropy.
• X-ray photoelectron spectroscopy revealed the existence of F-containing etch residues.

Changes in the inductively coupled plasma reactive ion etching characteristics of TiO2 thin films in response to the addition of HBr, Cl2 and C2F6 to Ar gas were investigated. As the HBr, Cl2 and C2F6 concentration increased, the etch rate increased; however, the etch profile degree of anisotropy followed a different trend. As HBr concentration increased, the greatest anisotropic etch profile was obtained at 100% HBr, while the greatest anisotropic etch profile was obtained at concentrations of 25% when etching was conducted under C2F6 and Cl2. Field emission scanning electron microscopy revealed that 25% C2F6 generated the greatest vertical etch profile; hence, etch parameters were varied at this concentration. The effects of rf power, dc-bias voltage and gas pressure on the etch rate and etch profile were also investigated. The etch rate and degree of anisotropy in the etch profile increased with increasing rf power and dc-bias voltage and decreasing gas pressure. X-ray photoelectron spectroscopy analysis of the films etched under a C2F6/Ar gas mixture revealed the existence of etch byproducts containing F (i.e. TiFx) over the film. CxFy compounds were not detected on the film surface, probably due to contamination with atmospheric carbon.