A first method is provided for forming a barrier layer on a substrate by sputter-depositing a tantalum nitride layer on a substrate having (1) a metal feature formed on the substrate; (2) a dielectric layer formed over the metal feature; and (3) a via formed in the dielectric layer so as to expose the metal feature. The via has side walls and a bottom, and a width of about 0.18 microns or less. The tantalum nitride layer is deposited on the side walls and bottom of the via and on a field region of the dielectric layer; and has a thickness of at least about 200 angstroms on the field region. The first method also includes sputter-depositing a tantalum layer on the substrate, in the same chamber. The tantalum layer having a thickness of less than about 100 angstroms on the field region. Other aspects are provided.