Patent ID: 6326313
Filing Date: 2001-12-04
Classification: H01L

Abstract:
A method by a valve controller coupled to drain a solution within a chemical bath for performing nitride strips of nitride on a plurality of wafers, the method comprising:initially filling the bath with fresh solution such that the bath contains a full volume; andperforming a two-step drain and replacement, comprising:partially draining diluted solution in the chemical bath so that the bath contains a partial volume;refilling the bath with a new volume of fresh solution after a nitride strip, wherein the new volume plus the partial volume substantially equal the full volume; andcompletely draining all of the solution in a chemical bath after one of a specified period of time has elapsed since the last complete drain, a specified number of strips has occurred since the last complete drain, or upon the detection of a process failure and filling the bath with a fill volume of fresh solution.