Uniform Thin Film Electrodeposition onto Large Circular Wafer Substrates

Abstract

A wafer-scale electrochemical flow cell specially suited for uniform thin-film electrodeposition is presented. The cell consists of a porous disk injector set parallel and coaxial to a working disk electrode with a narrow separation gap between them. The porous injector was designed to supply a uniform axial flow of electrolyte onto the surface of the working disk electrode. The mass transfer characteristics of the cell and the current distribution on the working disk electrode were studied for various operating conditions, geometric parameters and bath chemistries. The experimental results confirmed the simple scaling properties that were theoretically predicted. It has also been shown that this cell can provide nearly uniform current distribution on the working electrode under conditions of both migration and convective-diffusive mass transfer control. The results indicate that this cell is suitable for uniform thin-film electrodeposition onto large circular wafer substrates.