Physical characterization of PECVD and PEALD Ru(-C) films and comparison with PVD ruthenium film properties
PECVD and PEALD of ruthenium films using RuEtcp(2) as a precursor and N-2/H-2/Ar plasma as a reducing agent were characterized. A self-adjusting process to overcome the previously reported inhibition of Ru PEALD on TaN substrates was investigated. Ellipsometric modelling of Ru films was demonstrated providing information on both film thickness and estimated Ru content. The physical properties of PECVD/PEALD Ru films were compared to characteristics of sputtered Ru films within the categories resistivity, impurites, crystal structure, conformity and Cu plating. As a result, ToFSIMS, ERDA and 3D atomprobe revealed the presence of carbon impurities in PECVD and PEALD Ru films, dependent on deposition temperature and plasma power. Nevertheless, highly conductive Ru-C films were produced via PECVD and PEALD achieving resistivities equal to PVD Ru. For all types of Ru films, the size effect played a significant role at thicknesses below 10 nm; Cu plating and crystallization behaviour appeared similar. Direct Cu fill potential of different Ru films was discussed for damascene structures and through silicon vias.