An aspect of the present disclosure relates to a method of forming a barrier layer on a semiconductor device. The method includes placing a substrate into a reaction chamber and depositing a barrier layer over the substrate. The barrier layer includes a metal and a non-metal and the barrier layer exhibits an as-deposited thickness of 4 nm or less. The method further includes densifying the barrier layer by forming plasma from a gas proximate to said barrier layer and reducing the thickness and increasing the density of the barrier layer. In embodiments, during densification 300 Watts or less of power is applied to the plasma at a frequency of 350 kHz to 40 MHz.