Recognizing the industrial importance of optimizing copper/copper oxide etching processes, we investigate the specific process of abstracting a copper atom, from a theoretical perspective. Copper etchants/etching processes generating products with high volatility are still being sought, but most of the experimental work on copper etching have involved halogen-based reactants, and have achieved useful etch rates with these agents. In this part of our group’s metal/metal oxide surface etching studies [1], the abstraction of copper by halogen atoms is investigated as benchmark systems representing halogen-based etchants. The calculation model is straightforward: a halogen atom impinges toward the metal surface from the gas phase (initial state), momentarily adsorbs on the metal/metal oxide surface (intermediate state), grabs one metal surface atom, and together proceeds into the vacuum region, leaving behind a single vacancy on the surface (final state). Potential energy surfaces describing the reactions are created from energy calculations as a function of the desorbed copper-halogen center of mass, and their interatomic separation. Initial results show that fluorine etching of the copper surface is the most reactive among the three halogen-based processes. Trends are the same on both surfaces, although the Cu atom abstraction is a more favored process for the oxide. Results for a dynamics treatment of these etching reactions and a discussion with respect to experimental data [2] will be detailed at the meeting.
References:
[1] S. Watanabe, W.A. Diño, H. Nakanishi, H. Kasai, H. Akinaga, Jpn. J. Appl. Phys. 44 (2005) 893-894.
[2] X.R. Chen, K. Wagemann, J. Wanner, W. Brenig, S. Küchenhoff, Surf. Sci. 224 (1989) 570-580.
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