Detection of precursor molecules in the Metal Chloride Reduction CVD of Cu

Chemical kinetics of a novel metal CVD method (Metal Chloride Reduction CVD; MCR-CVD) has been investigated. The MCR-CVD can be applied to thin-film deposition of copper and various other metals. In the MCR-CVD process of Cu, gaseous copper chlorides produced by chlorine-assisted etching of a copper surface serves as the precursors of copper thin-film deposition. On the substrate surface, the precursor (copper chlorides) are reduced to copper by the reaction of chlorine atoms. In the present study, chemical kinetics of etching processes has been investigated. Various products of the reaction of high-temperature copper plate and chlorine molecules were detected. In the gas phase, copper chlorides exist as CunCln (n = 1–5) molecules. CuCl could be detected by a laser induced fluorescence (LIF) method during the MCR-CVD process. It is found that Cl atom is not needed for the production of CuCl. CuCl is mainly produced by the reaction of Cl2 molecules with a hot copper surface. CunCln (n = 3, 4) molecules were also detected in the MCR-CVD process by using an electron impact-mass spectrometry (EI-MS).