Photo-electrochemical Deposition of Platinum on TiO2 with Resolution of Twenty Nanometers using a Mask Elaborated with Electron-Beam Lithography

Abstract

We report the patterning of Pt on a TiO2-rutile single crystal (the fundamental absorption band starts at 396 nm) by direct deposition from a water solution of H2PtCl6 (10–20 mmol/dm3) using laser beam writing at 390–396 nm, or by Hg-lamp illumination (i-line at 365 nm). Pt deposition was corroborated by microchemical analysis. A resolution of the Pt patterning down to 20-30 nm was achieved. To create a Pt pattern with resolution of twenty nanometers, we employed a mask elaborated with electron-beam (EB) drawing lithography. The mask was transparent to the writing illumination. The Pt was reduced from the solution by laser beam scanning over resist-covered regions, while the pattern was formed in the openings of the resist. Separation of the growth and illumination regions, typically, by 0.5–2 µm, facilitates the deposition of reproducible, high-aspect-ratio patterns. It is demonstrated that Pt was deposited through a process of diffusion of the light-excited carriers. The possibility of fabrication of a three-dimensional Pt pattern by the overgrowth of the resist is discussed.