Generation of Solid-Source H2O Plasma and Its Application to Dry Etching of CaF2

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