Supercritical carbon dioxide etching of transition metal (Cu, Ni, Co, Fe) thin films.

Supercritical CO 2 is a promising zero-surface-tension, highly diffusive solvent, which creates a uniform reaction environment that dissolves low-volatility metal compounds. Here we report a novel etching technique for transition metal (Cu, Ni, Co, and Fe) thin films in supercritical CO 2 (scCO 2 ). The metals were removed by reacting with the chelating agent, hexafluoroacetylacetone, by dissolving the product compounds in scCO 2 . The operating temperatures were 100–250 °C and pressure was fixed at 10 MPa. The changes in the optical transmittance and thickness of the films indicated etching in the scCO 2 . Scanning electron microscope observation and surface probe microscope analysis confirmed that there was no significant film agglomeration, in particular, and that the Fe and Co films were uniformly etched. [ABSTRACT FROM AUTHOR]