Reduction of Copper Oxide by Water Vapor Plasma at Low Pressure

Abstract

As a new and safe reduction method for copper oxide, we propose the use of water vapor plasma at low pressure instead of conventional hydrogen plasma. Although hydrogen plasma is the established method to reduce copper oxide at low temperature, hydrogen is flammable and requires safety equipment. In this study, oxidized copper film was treated with water vapor plasma and its reduction process was compared with hydrogen plasma's. Surface, cross-section structure and thickness of oxidized and reduced copper film were measured and analyzed by FE-SEM (Field Emission-Scanning Electron Microscope), FIB (Focused Ion Beam), XRD (X-Ray Diffraction) and XPS (X-ray Photoelectron Spectroscopy). Using water vapor plasma, oxidized copper film was reduced without any oxygen remaining. During the reduction process, induction period and S-shaped curve were observed to be the same as hydrogen plasma. Furthermore, the reduction rate of water vapor plasma was more than twice that of hydrogen plasma.