Surface treatment of semiconductor substrates

This invention relates generally to the treatment of the surfaces of devices, especially semiconductor wafers and other electronic or electro-optical devices, at various stages of production. It relates more particularly to novel cleaning, chemical treatment and drying processes in which, instead of a condensed phase medium (liquid), a foam is used as a medium for the various operations such as cleaning, etching, neutralization and drying. Surface cleaning, chemical treatment and drying of semiconductor substrates is carried out using foam as a medium instead of a condensed phase liquid medium. In cleaning and chemical treatment, by introducing a foam into an overflow vessel the foam is caused to pass over the substrate in moving contact therewith. Drying of the substrate is carried out, using a water solution of carbon dioxide in a pressurizable vessel. By releasing the pressure in the vessel, a layer of foam is established on the surface of the solution. The solution is discharged from the vessel, causing the foam layer to pass over the substrate in moving contact therewith. The carbon dioxide reduces the surface tension of the water, thereby enabling the foam layer to be produced and also assisting in the elimination of water from the surface of the substrate. In both cases, the use of foam reduces materials requirements and also reduces the quantity of particles deposited onto the substrate in the treatment process.