Study on thermal stability of electroless deposited Ni-Co-P alloy thin film

The Ni-P and Ni-Co-P alloy thin films were deposited on silicon substrates with electroless technique. The solid state metallurgical reactions were investigated with silicon for the viewpoint of Co co-deposition effect. The alloy film kept amorphous state with increasing Co content even though the P content decreased. The films become more amorphous, and the thermal stability increased with increment of Co content in the deposit. The Co content was varied from 11.013 to 45.068 wt% while P content was decreased from 9.340 to 6.491 wt% by varying the concentration of components in electroless deposition baths. The thermal stability was examined by X-ray diffractometer (XRD), four probe, and atomic force microscopy (AFM). The results indicated the Ni-Co-P alloy films with lower P content show the higher thermal stability then the ordinary Ni-P films and prevent the silicidation at low temperature because the Ni crystallization formation suppressed by the co-deposition of Co.