Abstract
In order to investigate whether recycling of a metal-organic chemical vapor deposition (MOCVD) precursor, bis(ethylcyclopentadienyl)ruthenium (Ru(EtCp)2), is possible, impurities of used Ru(EtCp)2 collected in a cold trap were analyzed. It became clear that several kinds of organic impurities containing ruthenium (Ru) are contained when analyzing used Ru(EtCp)2 by gas chromatography (GC) mass and liquid chromatography (LC) mass technology. The organic impurities were generated during the course of Ru film formation. When trapped Ru(EtCp)2 was reused as a MOCVD precursor, the surface of the Ru film was somewhat rough. We presumed that organic impurities included in the trapped Ru(EtCp)2 might affect the surface roughness of the Ru film. To remove the impurities, the trapped Ru(EtCp)2 was purified using a purification technology with a 70% recycle rate. The refined Ru(EtCp)2 was found to have a purity and a vapor pressure that were equivalent to those of fresh Ru(EtCp)2. The root-mean-square (rms) roughness value of the Ru film prepared using the refined Ru(EtCp)2 was similar to that of the fresh Ru(EtCp)2. In this paper, we propose that recycling of Ru(EtCp)2, as a MOCVD precursor, is possible.