Preparation and etching processing of planar thin film of Pr3+-doped fluorozirconate glass

Planar thin-films of a 60ZrF₄ · 35BaF₂ · 5PrF₃ composition were successfully prepared from Zr(hfa)₄, Ba(hfa)₂(tg), Pr(fod)₃ and NF₃ by an electron cyclotron resonance plasma-enhanced chemical vapor deposition technique. The films obtained were colorless and amorphous. As etching processing of the prepared thin-film, dry etching was performed using Ar, CF₄, SF₆, Cl₂ and Cl₂-BCl₃ gases. The Ar etching in which no reactive ion-etching is anticipated exhibited the fastest etching rate. Wet etching was also performed using a ZrOCl₂-HCl etching solution. The etching rate was extremely fast compared with those of dry etching. In this etching, however, undesirable side-etching occurred. At the present stage, therefore, the most preferable etching processing is dry etching by an Ar gas.