Patent ID: 6392417
Filing Date: 2002-05-21
Classification: G05D,H01L

Abstract:
Arrangement for detecting the end of life of an aqueous bath utilized in semiconductor processing, said bath comprising water, an amount of hydrogen peroxide and an amount of a predetermined chemical species, which is either an acid or a base, the arrangement being provided to:a plurality of pumps for adding a predetermined additional amount of said hydrogen peroxide and/or said predetermined chemical species at predetermined time intervals; a conductivity measurement unit and a pH measurement unit, wherein both said units coupled to a processor which measures at least one parameter of the aqueous bath, thereby obtaining a measured parameter value, said at least one parameter being selected from a set of parameters comprising bath pH and bath conductivity; a timer generates a timing signal coupled to said plurality of pumps, and not coupled to said processor; the processor reads a predicted value of said at least one parameter from a memory coupled to said processor for storing a curve of predicted values of said at least one parameter as a function of time, said curve depending on said predetermined additional amount of said hydrogen peroxide and/or said predetermined chemical species, and depending on said predetermined time intervals; the processor establishes the end of life of said aqueous bath on the basis of a predetermined deviation between said measured parameter value and said predicted value.