Solution delivery of Cu(hfac)2 for alcohol-assisted chemical vapor deposition of copper
We have applied the liquid delivery technique for the thermally activated chemical vapor deposition of copper using a solution of Cu(hfac)2 in isopropanol [H(hfac) = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione]. Using a substrate temperature of 300 °C and reactant partial pressures of 1.8 Torr Cu(hfac)2, 12 Torr isopropanol, and 40 Torr H2, we obtained a maximum growth rate of 6.7±0.5 mg cm-1 h-1 (ca. 125 nm min-1). There is an induction time of about 5 min, which correlates with the time required for the initial copper clusters to grow into contact with each other (i.e., as judged from scanning electron microscope images). Film resistivities lie in the range 2.5-5.0 μΩ cm (vs. 1.68 μω cm for bulk Cu). The scanning electron microscope images suggest these high values are caused by residual void volume between the clusters. Growth rates and resistivities can be improved by eliminating H2O from the starting Cu(hfac)2/isopropanol solution, by wet-etching the substrate or by increasing the substrate pretreatment time.
Publication Source (Journal or Book title)
Journal of the Electrochemical Society
Borgharkar, N., Griffin, G., Fan, H., & Maverick, A. (1999). Solution delivery of Cu(hfac)2 for alcohol-assisted chemical vapor deposition of copper. Journal of the Electrochemical Society, 146 (3), 1041-1045. https://doi.org/10.1149/1.1391718