A titanium-tantalum barrier layer film for use in conjunction with an interconnect film such as copper and a method for forming the same provides a relatively titanium rich/tantalum deficient portion adjacent the interface it forms with a dielectric film and a relatively tantalum rich/titanium deficient portion adjacent the interface it forms with a conductive interconnect film formed over the barrier layer film. The titanium rich/tantalum deficient portion provides good adhesion to the dielectric film and the tantalum rich/titanium deficient portion forms a hetero-epitaxial interface with the interconnect film and suppresses the formation of inter-metallic compounds. A single titanium-tantalum film having a composition gradient from top-to-bottom may be formed using various techniques including PVD, CVD, sputter deposition using a sputtering target of homogeneous composition, and sputter deposition using multiple sputtering targets. A composite titanium-tantalum film consists of two separately formed films.