Stabilization of removal rate of silica glass on catalystreferred etching by cleaning catalyst surface

Inhalt:
A novel planarization method termed catalyst-referred etching (CARE) was developed, in which platinum and pure water were respectively employed as a catalyst and an etchant to create highly ordered surfaces with a step terrace structure on oxide materials, such as quarts, sapphire, and zinc oxide substrates. The step heights were in good agreement with the theoretical single-bilayer thickness. However, the removal rate of the etching process gradually decreased with the processing time. This decrease in the removal rate was attributed to degradation of the catalyst via the adsorption of silicic acid produced during the CARE process on the catalyst surface. Two methods were employed to remove the silicic acid: control of the potential of the Pt surface and cleaning of the catalyst pad with H2 water. The removal rate was maintained by using both methods. In both methods, the potential of the Pt surface was set at the H generation level. It is proposed that the generated hydrogen atoms broke the Pt-O bonds, thereby maintaining the reactivity of the catalyst surface. Keywords: Catalyst-referred etching, Planarization, SiO2, Potential control, H2 water