Abstract: A vacuum transfer system for transferring food grade products. A biased ball in a cage with a substantially uninterrupted cage wall is utilized as a check valve. The ball may be biased by a weight to float in a predictable orientation relative to the cage. The biased ball assures that a certain portion of the ball will consistently engage with an aperture. The biased ball also minimizes chattering of the ball in the cage under high flow conditions.

Abstract: 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.