Patent ID: 7223691

Claim:
A method of improving contact resistance of a via opening formed in a low-k inter-level dielectric (ILD) layer to expose an underlying metal layer of Cu or alloys thereof, the method comprising: etching through said low-k ILD layer to form said via opening that exposes the underlying Cu metal layer, ion implanting Nitrogen at energies of less than 1 keV at a bottom of said via hole so as to concentrate Nitrogen at a surface of the underlying Cu metal layer and form a layer of CuN at a surface of said exposed Cu metal layer; and, depositing a thin refractory metal liner along a bottom and sidewall of said etched via opening, said formed layer of CuN enabling formation of a subsequent refractory metal liner having a reduced resistivity alpha-phase, wherein said ion implanting Nitrogen at energies of less Than 1 keV improves resistivity of a formed contact comprising the metal liner and said Cu metal layer.