Abstract

A model electronic device consisting of two sputter-deposited copper conducting lines on an α-alumina substrate has been exposed to electrochemical conditions that lead to failure by dendrite growth. The growth kinetics of copper dendrites have been determined for two types of experimental conditions. The model substrates in the first set of experimental conditions were fully immersed in bulk electrolytes, and in the second set of conditions, the model substrates were covered by thin layers (∼1.9 µ) of electrolyte. Sulfuric acid electrolytes (pH 1.0) containing various concentrations of dissolved copper were used for both types of experiments, which were conducted by applying a fixed cathodic potential using a potentiostat. The effect of varying the copper ion concentration and cathodic potential was examined, and a comparison was made between the behavior in the two types of experiments conducted, i.e., bulk and thin layer electrolytes. Experimentally measured dendrite growth rates have been compared with theoretical predictions based on a maximum velocity growth theory. While the theory correctly predicts general experimental trends, the predicted dendrite growth rates for the bulk solutions are approximately two orders of magnitude larger than those measured experimentally.

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