Plasma-Enhanced Atomic Layer Deposition of Cobalt Films Using Co(EtCp) 2 as a Metal Precursor

摘要

For advanced Cu interconnect technology, Co films have been widely investigated to serve as the liner and seed layer replacement because of a better wettability to Cu than Ta. In this article, the Co films are grown by plasma-enhanced atomic layer deposition using Co(EtCp)~(2)as a precursor, and the influences of process parameters on the characteristics of the Co films are elaborately investigated. The results indicate that the process window is 125–225?°C with a growth rate of ~?0.073??/cycle. That is to say, the connection of Et group to Cp ligand can enable a stable film growth at 125?°C, while the corresponding temperature must be higher than 200?°C in terms of Co(Cp)~(2)and Co(MeCp)~(2). The deposited films contain N and O elements besides dominant Co and C. Furthermore, the prolongation of the NH~(3)pulse time significantly enhances the conductivity of the Co film and a low resistivity of 117?μΩ?cm can be achieved with a NH~(3)pulse time of 40?s. The root mean square roughness shows a smaller variation with the deposition temperature and maintains a low value of ~?0.3?nm, indicative of a flat Co film.