Optical Thin Film Formation with O₂Cluster Ion Assisted Deposition

Abstract

O2 cluster ion assisted deposition was demonstrated to form optical multilayer films for advanced optical communications. With O2 cluster ion assisted deposition, high refractive index 2.20 at 550 nm and very smooth surface (Ra=0.37 nm) of Ta2O5 films were realized. From a scanning electron microscope (SEM) image, dense film structure were observed without porous or columnar structures at the O2 cluster ion assisted layers. The surface and interface of Ta2O5/SiO2 multilayer films were very flat due to surface smoothing effect of cluster ion beams, and it can be realized even though the beneath surface was rough. The shift of a center wavelength of multilayer film was quite small after an environmental test.