Growing process and reaction mechanism of electroless Ni–Mo–P film on SiO2 substrate

The diffusion barrier Ni–Mo–P film for Cu interconnects was prepared on SiO2/Si substrate using electroless method. The surface morphology and composition during the formation process of electroless Ni–Mo–P film were investigated through analyzing samples of different deposition time. Induced nucleation, induced co-deposition, and self-induced growth mechanisms involved in electroless process were confirmed by field-emission scanning electron microscopy (FE-SEM), energy dispersive spectrometry and atomic force microscopy (AFM). Firstly, the preceding palladium particles as catalysts induce the nucleation of nickel. Secondly, the nickel particles induce the deposition of molybdenum and phosphorus, which attributes to induced co-deposition. Thirdly, former deposited Ni–Mo–P induces deposition of the latter Ni–Mo–P particles. Moreover, the reaction mechanism was proposed with the oxydate of PO3−4.