Patent ID: 8535504

Claim:
A method for determining the concentration of an auxiliary leveler additive in an acid copper electroplating bath also containing a suppressor additive, an anti-suppressor additive and a leveler additive, comprising the steps of: (1) cycling the potential of a rotating disk electrode between a predetermined negative potential limit and a predetermined positive potential limit in the oxygen evolution region positive of 1.9 V vs. SSCE/M in a background electrolyte of the acid copper electroplating bath comprising predetermined concentrations of sulfuric acid (H 2 SO 4 ), copper ion (Cu 2+ ), chloride ion (Cl − ), the suppressor additive, the anti-suppressor additive and the leveler additive; (2) measuring the current response as the potential of the rotating disk electrode is cycled in step (1) so as to produce a normalization cyclic voltammogram; (3) selecting a baseline current a (I baseline ) that is smaller than a maximum current (I max ) measured for the rotating disk electrode at the predetermined positive potential limit in step (2); (4) integrating the portion of the current in the normalization voltammogram that is greater than the baseline current so as to determine an A r (0) parameter; (5) cycling the potential of the rotating disk electrode between the predetermined negative potential limit and the predetermined positive potential limit in a plurality of calibration solutions comprising the background electrolyte and different predetermined concentrations of the auxiliary leveler additive; (6) measuring the current response as the potential of the rotating disk electrode is cycled in step (5) so as to produce a plurality of calibration cyclic voltammograms; (7) integrating the portion of the current in each of the calibration cyclic voltammograms that is greater than the baseline current so as to determine a plurality of A r (calibration) parameters; (8) plotting the ratio A r (calibration)/Ar(0) as a function of the corresponding concentrations of the auxiliary leveler additive in the calibration solutions so as to generate a calibration curve; (9) cycling the potential of the rotating disk electrode between the predetermined negative potential limit and the predetermined positive potential limit in a measurement solution comprising predetermined volume fractions of the supporting electrolyte and a sample of the acid copper electroplating bath; (10) measuring the current response as the potential of the rotating disk electrode is cycled in step (9) so as to produce a measurement cyclic voltammogram; (11) integrating the portion of the current in the measurement cyclic voltammogram that is greater than the baseline current so as to determine an A r (measurement) parameter; and (12) comparing the ratio A r (measurement)/A r (0) with the calibration curve to determine the concentration of the auxiliary leveler additive in the acid copper electroplating bath.