Anisotropic Deposition of Electroless Nickel Bevel Plating

Wet chemical processes such as etching or plating are generally isotropic. Although anisotropic wet etching can be achieved using single-crystalline substrates or a duplex resist, anisotropic metal deposition seems a difficult task. However, we show here that anisotropic deposition of Ni has been accomplished in an acid electroless Ni bath to which an appropriate level of Pb 2+ has been added. Since the edges of a given pattern experience an additional contribution from nonlinear diffusion, mass transport to these edges is enhanced compared to the bulk of a substrate. As a result the surface concentration of the adsorbed stabilizer is also higher at the edges