Annealing-free adhesive electroless deposition of a nickel/phosphorous layer on a silane-compound-modified Si wafer

• Annealing-free nickel/phosphorus film on silicon wafer with super-tight adhesion is prepared by electroless deposition.
• Silane compound equipped with 3 amino-moieties is introduced to modify the surface of silicon wafer.
• Pull-off adhesion test improves 4 times using our materials and recipe.

In this study, a post-annealing-free, adhesive nickel/phosphorous (Ni/P) layer was deposited on a 3-[2-(2-aminoethylamino)ethylamino] propyl-trimethoxysilane-modified (ETAS-modified) silicon (Si) surface through an electroless deposition process catalyzed by a novel polyvinylpyrrolidone-capped palladium nanocluster (PVP-nPd). ETAS was covalently bonded on the Si surface, whereas the amino groups on ETAS bridged with the palladium core in the PVP-nPd clusters. Because of the mentioned two effects, the deposited Ni/P layer showed superior adhesion on the Si wafer without the requirement of conventional annealing treatment. Compared with the Ni/P films deposited on bare and ETAS-modified Si surfaces by using commercial Sn/Pd colloids, the adhesion of the Ni/P film catalyzed by PVP-nPd on the ETAS-modified Si wafer improved 4- and 2-fold, respectively.