Role of 1,2-benzisothiazolin-3-one (BIT) in the Improvement of Barrier CMP Performance with Alkaline Slurry

Role of corrosion inhibitors is one of the key factors affecting critical parameters including the materials removal rates (RRs) selectivity, defect performance, galvanic corrosion and step correction etc. during copper interconnect CMP process. In this paper, the effect of a new type inhibitor (BIT) on the above parameters in barrier layer CMP was researched by comparison with a typical inhibitor (BTA). In the H2O2-Based solutions, the corrosion current of copper was studied by electrochemical workstation, based on which the corrosion inhibition efficiency (IE) was calculated. The IE of 24mM BTA and 24mM BIT was up to 51% and 48.2%, respectively, indicating that both BTA and BIT are effective corrosion inhibitors of copper. On such basis, the defects map and SEM microscopic images of pattern wafer after barrier layer CMP were performed, which revealed that there was no residue like Cu-BTA on the pattern wafer after polished with BIT-contained slurry. Furthermore, XPS measurement of wafer surface was carried out, it was considered as the contamination caused by BIT can be partly removed with the presence of FA/O chelating agent under alkaline environment. At the same time, when 4mM BIT was added, the galvanic corrosion of copper and tantalum has reduced, the step height reduction efficiency (SRE) was up to 77.4%. On such basis, the corrosion inhibition mechanism of BIT was proposed, a two-dimensional film of Cu-BIT complex was formed and adsorbed on the surface by intermolecular force. (c) 2019 The Electrochemical Society.