Patent ID: 6716298
Filing Date: 2004-04-06
Classification: H01L

Abstract:
Apparatus for supplying a first predetermined volume of an acid to a second predetermined volume of deionized water to form a bath of a preselected concentration for etching a semiconductor wafer comprising,a tank adapted to hold the acid and having a volume larger than the first predetermined volume of the acid to be supplied to the bath, an overflow pipe establishing an overflow level for receiving acid from the tank when the acid supplied to the tank reaches the overflow level, the volume of the tank below the overflow level being larger than the first predetermined volume of acid to be supplied to the bath and a volume occupying element located in the tank and extending above and below the overflow level, the volume occupying element being adjustable with respect to the overflow level for adjusting the volume of acid contained below the overflow level to said first predetermined volume, and a first pipe and a first valve for controlling the flow of acid from the tank to the bath.