Method and apparatus for measuring and dispensing a wafer etchant

摘要

A tank is set up to hold a precise volume of acid by first adjusting an overflow pipe to establish a volume that is larger than the desired volume and then adjusting the vertical position of a volume occupying element that extends above and below the surface of the acid. The apparatus includes a drain pipe for directing the acid to a tank that holds deionized water that the acid is mixed with. The bath is used for etching a silicon dioxide layer on a semiconductor wafer.