Crystal Growth on Cathode Sputtered Copper Films by Pairs of Double Spiral Mechanisms Analogous to Frank-Read Sources

Abstract

Unique crystal growth patterns with closed loops, partly concentric and partly eccentric, with very large step heights between the ledges were observed on microblisters of copper films sputtered onto glass substrate. While the primary cause for the generation of the blisters is explained as due to diffusion-oil deposits present on the glass substrate and to heat from secondary electrons released by the target producing a high vapor pressure underneath the sputtered film, the generation of the loop patterns on the flat circular surface of the blisters is considered to be caused by alternative slips induced by the inside pressure which affect a triangular part of the {111} surface with two sides of {111} slip planes, one in radial <110> direction and the other in a <110> direction along the rim of the blister. Two alternately generated monatomic radial steps on the flat part of the blister produce two superposing spirals of opposite sense each due to one-half of two Frank-Read sources and create by repetition of this process the observed patterns with very large step heights of the ledges.