COVALENT BINDING OF PD CATALYSTS TO LIGATING SELF-ASSEMBLED MONOLAYERFILMS FOR SELECTIVE ELECTROLESS METAL-DEPOSITION

A new approach for the selective electroless (EL) metallization of sur faces is described. Surfaces are modified with a chemisorbed ligand-be aring organosilane film, and then catalyzed with an aqueous Pd(II) cat alyst solution. The catalyzed substrate is then immersed in an EL meta l deposition bath to complete the metallization process. The ligating surfaces are produced by molecular self-assembly of 2-(trimethoxysilyl )ethyl-2-pyridine (PYR) on silicon or silica substrates. The catalyst consists of chloride-containing aqueous Pd(II) solutions buffered at p H 5.0 to 6.4; oligomeric chloro and/or hydroxo-bridged Pd(II) complexe s act as the catalytic species at the surface. The activity of the cat alyst has been characterized and modeled as a function of solution pH, [CI-], and time from preparation. Adhesion of the Pd(II) EL catalyst to the substrate involves covalent bond formation with the surface lig and. An average minimum Pd(II) level on the surface of approximately 1 0(15) Pd atom cm2 is shown to be necessary to initiate EL metallizatio n of the substrate with an EL Co bath. This process involves fewer ste ps and displays improved selectivity compared to processes that involv e a conventional Pd/Sn catalyst. Fabrication of high resolution metal patterns using the new metallization chemistry in conjunction with dee p UV patterning of PYR films is demonstrated.