Patent ID: 8118988

Claim:
A method for analyzing a copper plating bath comprising copper ions and a bath complexing agent, comprising the steps of: (1) making a standard addition of a predetermined quantity of a strong complexing agent to a first sample of the copper plating bath so as to provide a first analysis solution of known volume contained in a first analysis cell, said predetermined quantity of the strong complexing agent being substantially greater than that needed to fully complex all of the copper ions present in the first analysis solution; (2) providing a first titrant solution comprising a first predetermined concentration of copper ions; (3) performing a back-titration by repeatedly adding an aliquot of a known volume of the first titrant solution to the first analysis solution and measuring a first Cu 2+ concentration parameter for the first analysis solution; (4) determining a back-titration endpoint corresponding to a substantial increase in the first Cu 2+ concentration parameter measured for the first analysis solution; (5) calculating the concentration of copper ions in the copper plating bath based on the back-titration endpoint; (6) providing a second analysis solution contained in a second analysis cell; (7) providing a second titrant solution comprising a second predetermined concentration of copper ions; (8) performing a titration by repeatedly adding an aliquot of a known volume of the second titrant solution to the second analysis solution and measuring a second Cu 2+ concentration parameter for the second analysis solution; (9) determining a titration endpoint corresponding to a substantial increase in the second Cu 2+ concentration parameter measured for the second analysis solution; and (10) calculating a concentration of the bath complexing agent based on the titration endpoint.