Density Functional Theory Study of Cu Adhesion

In this work, first-principles calculation based on the density functional theory was applied to study Cu adhesion on the surfaces of Rh(111), Ir(111), Pd(111), Ta(110), Mo(110), Co(0001), Os(0001), and Ru(0001), on which the adsorption energy, electron density difference, and geometrical structures of Cu were investigated. The analysis of the calculated and experimental results shows that the atomic chemical interaction, surface lattice mismatch, and crystal lattice type have marked effects on Cu adhesion on glue layers. Cu atoms on all the metal surfaces studied in this work are more likely to form the fcc structure with a quasi-(111) orientation. The coupling effect of the large surface lattice mismatch and the lattice type difference between Cu and the metal surface can greatly reduce Cu adhesion ability. Among all the studied metals, Ir and Os showed comparable adhesion ability to Ru and can be considered as promising Cu glue layers for Cu interconnects. (C) 2011 The Japan Society of Applied Physics