Generation of solid-source H2O plasma and its application to dry etching of CaF2

We demonstrate the discharge of H2O plasma generated by solid-source H2O placed in a process chamber. Also, we investigated the dry etching process of CaF2 Using solid-source H2O (ice) plasma. The average roughness of the etched surface was about 1 nm for an etching depth of in 2 mu m which satisfies the requirements for optical device fabrication. We believe that the proposed CaF2 etching process is suitable for the fabrication of optical devices such as gratings or Fresnel lenses. In addition, we think that the H2O plasma including OH radicals obtained by this proposed method may be useful for sterilization and as a new UV light source.