Lithography-free surface modification by self-masking during glassdry-etching

摘要

Glass surface roughness with defined morphologies is realized by a two step lithography-free process: first sputter deposition of an around 10 nm thin unstructured metallic layer onto the surface, second reactive ion etching in an Ar/CF_4 high density plasma. During the etch step metal atoms and etch gas constituents build hardly volatile metal halogen compounds resulting in self-masking of the glass. Several metals like Ag, Al, Au, Cu, In, and Ni can be employed as the metallic seed layer in this technology. Within the second process step the sacrificial metal layer is completely removed from the surface. Due to the locally varying etch velocity further etching causes formation of pits and elevations with typical height and lateral dimensions on the order of 0.5 urn. Surface morphology is influenced by choice of seed layer material and etch parameters, resulting in a multitude of different morphologies. Hence optical scattering characteristics of the glass can be tuned almost arbitrarily over a wide range. The dosed extents of light scattering could possibly be used advantageously for specific classes of applications, e.g. lighting engineering, efficiency enhancement of thin film solar cells or organic light emitting diodes.