Patent ID: 6863079

Claim:
A semiconductor wafer washing system comprising: a washing solution supply section including chemical storage tanks each containing a respective chemical for use in washing semiconductor wafers, supply piping comprising respective supply pipes extending from the tanks, and flow control means comprising at least one flow control valve disposed in said supply piping for controlling the flow of chemicals from the tanks through the supply pipes, and a filter disposed in said supply piping for filtering one of the chemicals; a washing tank connected to said plurality of tanks of said washing solution supply section via respective portions of the supply piping thereof so as to receive chemicals from the washing solution supply section at a rate set by said flow control means, wherein a washing solution for washing wafers is formed in the washing tank; a discharge section including a drain, and discharge piping comprising respective discharge pipes separately connecting said washing solution supply section and said washing tank to said drain, and flow control means for controlling the flow of chemicals through said discharge pipes, one of said discharge pipes being directly connected to said filter such that impurities filtered out of said one of the chemicals can be discharged to said drain from said washing solution supply section; and a controller operatively connected to said flow control means so as to issue control signals thereto that control the flow of the chemicals from said chemical tanks to said washing tank, the flow of the chemicals from said washing solution supply section to said drain as by-passing said washing tank, and the flow of chemicals from the washing tank to said drain.