Methods of forming a conductive metal layer over a dielectric layer using plasma enhanced atomic layer deposition (PEALD) are provided, along with related compositions and structures. A plasma barrier layer is deposited over the dielectric layer by a non-plasma atomic layer deposition (ALD) process prior to depositing the conductive layer by PEALD. The plasma barrier layer reduces or prevents deleterious effects of the plasma reactant in the PEALD process on the dielectric layer and can enhance adhesion. The same metal reactant can be used in both the non-plasma ALD process and the PEALD process.