In some embodiments, a method of forming an interconnect structure includes selectively depositing a barrier layer atop a substrate having one or more exposed metal surfaces and one or more exposed dielectric surfaces, wherein a thickness of the barrier layer atop the one or more exposed metal surfaces is greater than the thickness of the barrier layer atop the one or more exposed dielectric surfaces. In some embodiments, a method of forming an interconnect structure includes depositing an etch stop layer comprising aluminum atop a substrate via a physical vapor deposition process; and depositing a barrier layer atop the etch stop layer via a chemical vapor deposition process, wherein the substrate is transferred from a physical vapor deposition chamber after depositing the etch stop layer to a chemical vapor deposition chamber without exposing the substrate to atmosphere.