Supercritical CO2 reactor for wafer-scale thin film deposition: reactor concept, numerical results, and Cu depositio.

Abstract

Supercritical fluid chemical deposition, frequently abbreviated SFCD, is a thin film deposition technique that employs supercritical fluids. In this deposition technique, a thin film is synthesized from a precursor dissolved in a fluid, along with a reaction reagent if necessary. This paper proposes a novel wafer-scale tool for SFCD. The reactor has a flat cylindrical interior, and the fluid is supplied at the center of the upper face. A porous plate is placed on the bottom face, at the center of which a small fluid outlet is opened. A wafer is placed directly on the porous plate without a holding device, and the diameter of the porous plate is slightly larger than that of the wafer. This reactor has a minimal interior volume and realizes radial and unidirectional flow over the entire wafer. Furthermore, the in-plane pressure distribution is completely uniform, allowing a uniform flow distribution, which was verified by computational fluid dynamics simulations. Cu films were deposited on a 100mm silica glass wafer using Cu(C9H12O2)2 (Cu(dibm)2) as a precursor. The average thicknesses were 75nm at 185°C and 182nm at 200°C,and the standard deviations were 19nm and 14nm, respectively. Basic film characterization was also performed.