The Etching of Crystallographically Determined Orifices in Sapphire

A process is described for etching arrays of orifices in the basal plane of sapphire using a Pt-Cr composite layer as a mask, and a mixture of H2SO4-H3PO4 as an etchant. The orifices are triangular shaped. Etching and masking studies are discussed, as is the relationship between the orifice size, the thickness of the starting substrate, and the diameter of the mask opening. © 1979, The Electrochemical Society, Inc. All rights reserved.