Patterning of ZnS-SiO2 by laser irradiation and wet etching

Generally, ZnS-SiO2 thin film is used as a protective layer in phase-change optical media. The wet etching characteristics of ZnS-SiO2 have been investigated, and it was found that ZnS-SiO2 can be patterned by laser irradiation and wet etching. Convex patterns of ZnS-SiO2 with steep taper profiles were formed. The minimum size of ZnS-SiO2 dots was 90 nm, and the minimum width of ZnS-SiO2 lines was 100 nm. These pattern sizes were approximately one-fourth of the laser beam spot from a 405 nm laser diode (LD) with an objective lens of 0.85 numerical aperture (NA). The pattern edges of ZnS-SiO2 dots and lines were clear and smooth. These results prove that ZnS-SiO2 is a useful material for forming nanometer-scale patterns.