Method of controlling additives in copper plating baths

The present invention relates to monitoring and ultimately controlling organic additives and particularly the accelerator and suppressor components of the additives in copper plating baths. The copper plating baths can be used to deposit copper interconnections for semiconductor chips. Organic addition agents in copper plating baths are monitored by diluting a sample of the bath with sulfuric acid and hydrochloric acid and optionally a cupric salt. The diluting provides a bath having conventional concentrations of cupric ion, sulfuric acid and hydrochloric acid; and adjusted concentrations of the organic addition agents of 1/X of their original values in the sample; where X is the dilution factor. CVS techniques are used to determine concentrations of organic addition agents.