Patent ID: 6472331
Filing Date: 2002-10-29
Classification: H01L

Abstract:
A method for forming an acid bath for etching a semiconductor wafer, comprising the following steps,providing a tank for holding the acid component of the bath, providing an overflow pipe for the tank and thereby establishing an overflow level at which an acid added to the tank overflows the pipe, the overflow level defining an overflow volume of acid that can be contained inside the tank below the overflow level, the overflow volume being larger than the volume of acid to be supplied to the bath, locating a volume occupying element inside the tank at a position where the volume occupying element extends above and below the overflow level, and adjusting the position of the volume occupying element with respect to the overflow level to provide said volume of acid to be supplied to the bath when the tank is filled to the overflow level, and emptying the tank into a bath containing the water component of the acid bath.