Photolithographic Plating of Platinum and Copper on Insulating Substrates

Abstract

Several micrometer thick layers of platinum or copper can be photolithographically deposited on Mylar or silica substrates by taking advantage of the photochemistry of [PtCl₆]²⁻ in alcohols. This reaction gives rise to a spatially well defined, but discontinuous deposit of platinum metal onto the illuminated areas of the substrate material. A conducting, adhesive, metallic film can be obtained by developing the photolyzed substrate in an electroless copper plating bath or a bath containing [PtCl₄]²⁻ and isopropanol, depending on the type of deposit required. Control over the rate of metallization and the spatial resolution of the deposit can be exerted by considering the detailed mechanistic chemistry associated with the metallization process.