Vacuum-pressure-dispense system

PPDS works on the principle of metering pumps and employs diaphragm, bellows, centrifugal, or vacuum-pressure-dispense pumps. These systems may be used for slurries including shear-sensitive slurries and cause minimal recirculation during slurry usage and replenishment. 

J. P. Bare, B. Johl, and T. A. Lemke, Comparison of Vacuum-Pressure vs. Pump Dispense Engines for CMP Slurry Distribution, Proceedings of SEMlCONtWesl Contamination in Liquid Chemical Distribution Systems Workshop (July, 1998). 

Bare J, Johl B, Lemke T. Comparison of vacuum-pressure vs. pump dispense engines for CMP slurry distributionProceedings of SEMICON/West Contamination in Liquid Chemical Distribution Systems Workshop 1998 July. 

The typical cleaning sequence of a reusable cuvet and/or reaction vessel Involves aspiration of the reaction mixture out of the cuvet at an in situ wash station. A detergent, alkaline, or acid wash solution is then repeatedly dispensed into and aspirated out of the cuvet. The cuvet is rinsed several times with deionized water and dried by vacuum or pressurized air. Optical clarity is verified automatically in most systems (usually while the cuvets contain the water). If performance is unsatisfactory, the operator is alerted to replace individual cuvets. If the cuvets are not replaced promptly, the system cannot be used for analysis until they are replaced, the results for the unsatisfactory cuvets will be flagged. 

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