Abstract: A semiconductor wafer includes a substrate, an aluminum layer on the substrate, an anti-reflection coating on the aluminum layer, a dielectric layer on the anti-reflection coating, and a via hole that passes through the dielectric layer and the anti-reflection coating down to a predetermined depth within the aluminum layer. A titanium layer is formed on the bottom and on the walls of the via hole. A physical vapor deposition process is then performed to form a first titanium nitride layer on the titanium layer. A chemical vapor deposition process is then performed to form a second titanium nitride layer on the first titanium nitride layer.