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Andy Yang, ProMOS Technologies Inc. Hsinchu, Taiwan, R.O.C.

ABSTRACT

Airflow rate and FFU coverage were the major topic considerations to control contamination before designing cleanroom construction. As a result, the initial investment and cost of ownership would become essential factors in determining the economic success of semiconductor production facility. An empirically based recommendation had now been used for many years in calculating the required airflow rate design to achieve a certain classification of cleanliness from the international standards. Cleanliness will actually be influenced by a combination of interactions between obstructions, the layout of equipment, contamination sources and exhaust ventilation. In order to refine cleanroom design in terms of operating costs, capital costs and overall performance, a simple calculation was used to explain the relationship between many variables such as process contamination generation rates, make- up air fraction, make-up air concentration, the filtration system efficiency, cleanliness, FFU coverage, etc. Overdesign can be avoided, thus providing a suitable manufacturing environment with minimized levels of contamination.