Thickness scaling of NiAl thin films for alternative interconnect metallization

NiAl thin films have been studied as potential alternatives for the metallization of interconnects due to their relatively low bulk resistivity and high melting point. Stochiometric NiAl thin film of 56 nm thickness show an ordered B2 phase, low stress, and a resistivity of 13.9 µΩ cm after post-deposition annealing at 600
^°
C. Reducing the thickness leads however to an increasing resistivity due to the formation of a nonstoichiometric surface layer due to oxidation. As a consequence, ultrathin NiAl layers or scaled interconnects may require O and Al diffusion barriers to obtain low resistivity.