Surface-Activation Process for Electroless Deposition of Adhesive Metal (Ni-B, Cu) Films on Si Substrates Using Catalytic Nanoanchors

Abstract

Autocatalytic electroless deposition, which is a conventional method to metalize nonmetallic substrates, requires catalyzation of substrates before deposition. For silicon (Si) substrates, obtaining adhesive metal films with conventional catalyzation pretreatment is difficult. In this study, we develop a new surface-activation process for the direct electroless deposition of adhesive metal films on Si substrates that consists of three steps: (1) metal nanoparticle formation by electroless displacement deposition; (2) Si nanopore formation by metal-particle-assisted hydrofluoric acid etching; and (3) metal filling in nanopores and metal-film formation on the whole Si surface by autocatalytic electroless deposition. The metal nanorods in the Si act as catalytic nanoanchors to promote autocatalytic electroless metal deposition and improve the adhesion of the metal films on the Si substrates. This process was successfully applied not only to nickel-boron alloy but also to copper film deposition on Si substrates.