Laser-induced Thermal Etching of Metal and Semi-conductor Surfaces

Chalmers et al.1, Hendrickson and Machlin2, and others3–5 have demonstrated the possibility of thermally etching metals by evaporation. Thermal etching has been investigated most extensively in silver although it has been observed on other metals. It has been generally established that the etching is characterized by two mechanisms, namely, (a) the formation of grooves at the grain boundaries of polycrystalline metals, and (b) terrace or striation formation on the surface of single crystals. Grooving usually occurs at a lower temperature than that at which striation structure forms. The formation of a terrace structure, at least on the surfaces of copper and silver single crystals, may depend on the presence of oxygen during annealing. This communication reports a further consequence of thermal etching in air, namely, the formation of etch hillocks. This phenomenon has now been established for a number of metals and semiconductors.