Liquids: A Cleaning Overview

Abstract

Once the cleanroom operation is defined and in good order, airborne particulate contaminants are usually reduced to minor problems. The major contamination problems are then the emissions from personnel and processing tool actions (discussed previously) and the contamination transferred to products from process fluids. The particle concentration in most reactive process liquids is normally orders of magnitude greater than that in the ambient air or in a compressed gas supply. Because so many high-technology products either are produced using liquid processing materials or are cleaned by liquids, contamination transfer from the supposedly clean liquid to the product must be controlled. Production of a modern finished integrated-circuit component may require the use of as much as 150 gallons of water for all of the processing steps (Iscoff 1986). A study of the mechanisms involved in transfer of particles from liquids to solid surfaces has shown some of the important processes that control deposition and retention of particles from liquids to solid surfaces (Michaels et al. 1988). These processes are similar in nature to those in deposition from air suspension, but particle transfer across the liquid-solid and liquid-air interfaces is also important.