Microstructure and Pattern Size Dependence of Copper Corrosion in Submicron-Scale Features.

The effects of grain size and pattern geometry on the etching rate were investigated by using our invented pattern, and each pattern has a same height of electrodeposits regardless of pattern size after electroplating. It was found out that the logarithmic value of the etching rate is inversely linear with the pattern width at self-annealed specimen. In other words, as the pattern width decreases, the etching rate increases exponentially. Such tendency of the etching rate is owing to the result that the interfacial energies of pattern surface and grain boundary per unit volume increase by the decrease of pattern width. In contrast, the as-deposited sample shows a flat etching rate for pattern sizes. In addition, at the narrow patterns with a pattern width of below 220 nm, the etching rate in the nanocrystalline structure of the as-deposited sample is lower than in the grain grown structure of the self-annealed sample. It can be surmised that the stresses caused by interfacial energies may be relaxed by the nanocrystalline structure in the as-deposited sample. [ABSTRACT FROM AUTHOR]