Importance

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Abstract

A method of coating a thin layer of a liquid material on a substrate, in which the substrate is placed in an atmosphere saturated with the vapor of a solvent for the coating material, liquid coating material is deposited on the substrate, and then the substrate is spun to disperse the coating material into a thin film while causing the excess to run off. The vaporous solvent atmosphere is maintaind while the coating and run-off are completed. Then the substrate is isolated from the source of the solvent vapor and is heated in order to dry the coating. Apparatus for carrying out this method includes a coating chamber, a carrier adapted to receive and support the substrate, a turntable within the coating chamber for rotating the substrate carrier, and means in the coating chamber for generating the vaporous atmosphere. The apparatus also includes a separate drying chamber that is movable into or out of engagement with the coating chamber, and openings in both chambers which provide communication between them when they are in mutual engagement. Means are also provided to transfer the carrier from the coating chamber to the drying chamber, and at the same time sealing off the coating chamber to limit the amount of vaporous solvent flowing into the drying chamber. The apparatus also includes multiple drying chambers, multiple substrate carriers normally carried in corresponding ones of the drying chambers, and means for presenting the drying chambers in succession to the coating chamber so that while a newly coated substrate is being dried the next succeeding substrate can be transferred from its drying chamber into the coating chamber for coating.

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First Claim