A robust diffusion barrier and metallization liner technology are critical for the realization of a functional and reliable interconnect structure. While copper barrier materials and processes have evolved significantly since the onset of copper-based metallization, the extendibility of existing barrier/liner solutions for use in emerging nanoscale interconnect structures faces a number of significant challenges related to the continued scaling of IC feature sizes. A key element in addressing these challenges includes developing an understanding of the mechanisms that lead to barrier failure and subsequent interconnect reliability deficiencies, and identifying how such mechanisms differ in the nanoscale regime from their counterparts at the microscale regime. In this respect, it is important that these distinctions serve as baseline in establishing the factors that determine the relevance and applicability of potential barrier solutions. Furthermore, it is critical to understand how these factors have evolved as barrier layers scaled to thicknesses of a few atoms. Accordingly, the current report outlines short-and long-term trends for these technologies.