The rinsing process of silicon wafers is normally carried out in an "overflow" bath in which water flows past the wafers at average velocity of 1 cm/s. But the velocity is zero at the wafer surface. The efficiency of rinsing is limited by the rate at which contaminants diffuse away from the silicon surface and into the flow stream. This paper reports the improvement in rinsing efficiency gained by repeating a 1-min cycle of first allowing the contaminants to diffuse into the stagnant layer and then "dumping" the rinse tank to remove most of the contaminated stagnant layer. A further 10-fold improvement in rinsing efficiency per rinse cycle can be achieved by spinning the wafer and using centrifugal force to remove a greater fraction of the stagnant layer. This allows the complete removal of soluble contaminants with a 20-fold reduction in water usage compared to present immersion techniques.

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