Etching properties of ZnS thin films in Cl2/CF4/Ar plasma

Abstract The manganese-doped zinc sulfide (ZnS:Mn) films were investigated in terms of etch rates and selectivity with inductively coupled plasma (ICP). The changes of volume density of etching species in Cl2/CF4/Ar plasma were investigated with optical emission spectroscopy (OES). OES analysis indicated that the maximum Cl emission intensity was obtained with the gas mixture of 10% addition to CF4(20%)/Ar(80%) plasma. The changes of chemical states on the surface were analyzed with X-ray photoelectron spectroscopy (XPS). XPS study indicated that Zn was formed non-volatile etch by products and remained on the surface after etching of ZnS:Mn (0.39 wt.%) in Cl2/CF4/Ar plasma. The etch rate of ZnS was gradually increased up to 10% addition of Cl2 then decreased furthermore with increasing Cl2 contents from 20 to 30%. The increase of etch rate can be explained by the effect of chemical and physical etching process.