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

•A new reactor concept for wafer-level thin film deposition.•Simple, less volume, and maximal deposition area.•Numerical simulations that prove advantages.•Experimental results of Cu deposition.•Good film uniformity and film characteristics.

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 100 mm silica glass wafer using Cu(C9H12O2)2 (Cu(dibm)2) as a precursor. The average thicknesses were 75 nm at 185 °C and 182 nm at 200 °C,and the standard deviations were 19 nm and 14 nm, respectively. Basic film characterization was also performed.

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