Ni-V(or Cr) Co-addition Cu alloy films with high stability and low resistivity

Abstract

In order to inhibit Cu, interconnecting in ultra-large-scale integration, from diffusing with surrounding dielectric materials and enhance its chemical inertness and maintain its excellent electrical performance as well. In this paper, the stable solid solution cluster-plus-glue-atom model was used to design the composition of Cu seed layers. In this model, insoluble element V (or Cr) was dissolved in Cu via Ni which is soluble both with Cu and V(or Cr), causing a certain degree of lattice distortion to improve the stability of Cu film. Cu-Ni-V(or Cr) alloy films were deposited directly on single crystal Si(100) substrates, without a designated barrier layer, subsequently annealed in vacuum. For the (V0.8/12.8Ni12/12.8)0.5Cu99.5 (at.%) film with the addition of large atomic radius element V, it showed the minimum electrical resistivity of 3.2 μΩ·cm after 500 °C/1 h annealing; after 500 °C/40 h annealing, no diffusion between Cu and Si was observed and the resistivity remained stable. Likewise, the (Cr1.4/13.4Ni12/13.4)0.4Cu99.6 film also remained a minimum resistivity of 3.0 μΩ·cm after annealing at 500 °C for 40 h. The greater the relative lattice distortion is in a single system, the higher the stability and the lower resistivity achieved. Obviously, the stability of Cu alloy film which satisfy the requirements of the microelectronics industry can be improved dramatically by the additive of Ni and V (or Cr) conform to the proportion of clusters.