Importance

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Abstract

A liquid pumping and filtering system for use in dispensing materials such as photoresist used to make semiconductors. A positive displacement diaphragm pump is used to draw source liquid from a source bottle. A pump valve is activated to direct fluid from the pump to a main dispensing line which includes a filter. A suckback line bridges the dispense line. The suckback line and the dispense line are each connected to a final dispense line, and the flow of liquid is controlled by a filter valve, which alternative causes fluid to flow through the suckback line or the dispense line, depending upon the mode of operation of the system. The use of an independent suckback line allows the quick withdrawal of fluid away from the dispense nozzle in the final dispense line. As a result, liquid in the dispensing line on opposite sides of the filter is generally maintained at constant pressure. Air bubbles trapped in the filter, which are generally unavoidable because of the construction thereof, are not allowed to expand and therefore do not distort measurements of liquid being dispensed.

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First Claim