Cyclic Voltammetric Stripping (CVS)
Nova’s chemical metrology products utilize cyclic voltammetric stripping (CVS) technology. CVS is an electrochemical method for measuring the concentration of organic additives in galvanic plating baths in order to deposit metals or alloys for interconnects and bumps on wafer structures. The additives are essential for optimizing the plating process and ensuring defect-free metallization.
With Cyclic Voltammetric Stripping techniques, metal is deposited by generating defined potential difference between the platinum rotating disk working electrode (WE) and a counter electrode (CE), in the presence of reference electrode (RE). Take, for example, the depositing of copper to a platinum rotating disk electrode followed by dissolving, or stripping, it back into the solution. The charge needed for the depositing process is measured and used for evaluation. The step is repeated several times under varying conditions, eventually leading to the organic additive concentration calculation, and delivering final measurement.
Multiple types of sweeps and scenarios of using Cyclic Voltammetric Stripping technique (the way and speed with which potential is varied during the measurement) are available for the analysis, and can deliver wide variety of plating process-relevant information, outside of simple concentration measurement. For example, CVS hardware setup can also be used for other voltammetric techniques such as bath plating condition and contaminant analysis.