Etchant Solutions for the Removal of Cu(0) in a Supercritical CO2-Based “Dry” Chemical Mechanical Planarization Process for Device Fabrication

The microelectronics industry is focused on increasing chip complexity, improving the density of electron carriers, and decreasing the dimensions of the interconnects into the sub-0.25 μm regime while maintaining high aspect ratios. Water-based chemical mechanical planarization or polishing (CMP) faces several technical and environmental challenges. Condensed CO2 has significant potential for replacing current CMP solvents as a “dry” etching medium because of its unique properties. In working toward a condensed CO2-based CMP process, we have successfully investigated the oxidation and chelation of solid copper metal in liquid and supercritical CO2 using ethyl peroxydicarbonate and a β-diketone chelating agent.