Electrochemical and Fill Studies of a Multicomponent Additive Package for Copper Deposition

Abstract

An acid-copper plating bath containing chloride ions, polyethylene glycol (PEG), bis(3-sulfopropyl) disulfide (SPS), and Janus Green B (JGB) has been characterized by electrochemical methods and by fill studies on electrode surfaces patterned with trenches ranging in size from 200 to 600 nm, with aspect ratios between 2 and 4. The electrochemical methods employed include linear sweep voltammetry (LSV), chronoamperometry (CA), and cyclic voltammetric stripping (CVS) on a rotating disk electrode. Comparison of the methods shows that in all the cases an analysis of LSV and CA gives consistent estimates of an effective surface coverage of additives. CVS results are consistent with the other results only in baths that are free of JGB. The ability to produce void-free deposits of a bath containing all of the additives can be understood in part with LSV and CA results. However a very good superfilling can also be obtained from a plating bath containing chloride ions, PEG, SPS, but no JGB. This observation cannot be easily interpreted with measurements within the context of established leveling theories. © 2001 The Electrochemical Society. All rights reserved.