• Wettability and adhesion of Cu From an experimental perspective, a large variety of analysis methods are available to determine barrier and liner performance. However, it is usually not feasible to focus on more than one specific aspect of the system, such as the failure mechanism of the diffusion barrier. Additionally, there is overwhelmingly more literature on the topic of diffusion barriers than there is for liner materials, and there are few studies that examine a barrier and a liner material together, or test a material for both barrier and liner properties. Some of the materials studied as combined barrier/liner materials include NiP alloy , Cr , RuMo alloy , CoWB , Ru , MoC doped Ru , Ru(P) , RuCo , Co , Co(W) , MnN and Ti . There is also some precedence for building upon existing knowledge by combining known diffusion barrier and liner materials. Chakraborty et al. studied mixed-phase RuTaN. Eisenbraun used plasma enhanced ALD (PEALD) to create mixed phase barrier/liner materials by layering known barrier (TaN, WCN) and liner materials (Ru, Co), starting with the barrier and ending with a liner layer. These materials showed comparable barrier properties to TaN. Additionally, the ratios of metals in the material can be used to further tune the material to have low resistivity and good wettability while maintaining strong barrier properties. This type of work also includes our work on Ru-doped TaN which demonstrated that Cu wetting can be promoted on TaN surfaces by incorporating a known liner material and provides the foundation for the work presented in this paper. While the work on combined barrier/liner materials is relatively limited, there is even less work on using theoretical methods to screen for potential barrier, liner or barrier/liner materials. Just as a wide variety of experimental methods is needed to study all aspects of a potential barrier and liner material, theory also requires a range of methods to attempt to study all of the above properties. This is usually not feasible and therefore it is reasonable to select the primary properties of interest and focus on modelling these. Adhesion is the property that is most easily studied using theoretical methods. Activation energy for atom diffusion can be determined using nudged elastic band calculations and can give insight into surface mobility of atoms as well as the diffusion barrier properties. Ab initio molecular dynamics calculations can be used to gain some insight into thermal stability as well as wettability and growth processes. Additionally, electronic properties such as density of states (DOS), atomic charges and electron density can be studied, which give useful insight into conductivity and band gap of the material and can also reveal trends that drive the formation of favourable structures. These are useful in determining the basic material properties such as conductivity and band gap. Models have also been developed to screen for materials based on their electronic properties. These are particularly useful when combined with experimental methods. Additionally, machine learning can now be applied to modelling the overall performance of interconnects which can save valuable time and resources during the development process. Overall, theoretical studies make up only a small fraction of the research on advancing interconnect manufacturing leaving plenty of room to gain further insight into growth mechanisms and material interactions relevant for application in interconnect technology.