Suck back valve for use during semiconductor wafer processing controls pilot pressure fluid, flowing through ON/OFF valve based on comparison of detected amount variation and preset amount of variation

摘要

A pair of ports are formed on both ends of a coupler (24). A condom back mechanism (28) has valve (26) opened or closed by pilot pressure. The amount of variation of diaphragms (56,80) is detected by a detector. A controller performs feedback control of variation velocity of valve and amount of attraction of coating liquid based on comparison result of detected and preset amount of variation.