Nickel deposition behavior on n-type silicon wafer for fabrication of minute nickel dots

The present study is a part of our systematic development of mass-scale production processes of nanometer-scale arrays of metal dots on silicon wafer surfaces. Metallic Ni was deposited onto Si(100) wafer surfaces electrolessly or galvanostatically, for surveying appropriate methods for formation of minute structures. Within an electroless bath of simple NiSO₄-(NH₄)₂SO₄ solution, metallic Ni was deposited, accompanied by the oxidation of the Si surface. Wet pretreatment of the Si surfaces in HPM (HCl and H₂O₂ mixture) or in ethanol drastically improved the uniformity of Ni layer and the rate of deposition. The electrolytic deposition with applying a potential at the Si wafer resulted in formation of Ni deposit which were easily peeled off. Based on the knowledge obtained, a two-dimensional array of minute Ni dots (diameter ca. 270 nm) was successfully fabricated.