Effect of secondary inhibitors on material removal rate and nano-roughness of Cu chemical mechanical planarization

We have reported chemical mechanical planarization (CMP) performance aspects of nanoscale colloidal silica based Cu CMP slurries with a focus on the interdependent effect of various slurry ingredients like inhibitor, oxidant, chelating agent, dispersant and stabilizer. The CMP performance was mainly evaluated in terms of material removal rate and nanoscale wafer surface uniformity. The use of heterocyclic organic compounds and non-ionic surfactant—as secondary inhibitors—has been explored in formulating the slurry to enhance the CMP performance. The nanoscale roughness was ascertained by using high resolution atomic force microscopy. It is concluded that the addition of the commercial surfactant Triton X-100 in the slurry plays a key role in realizing high material removal rate outcome (i.e., higher than 6000 Å/min) and fittingly low wafer surface uniformity at nanoscale. The speculative mechanism for the enhanced Cu CMP performance with respect to addition of Triton X-100 has been also proposed by using tools like X-ray photoelectron spectroscopy, high resolution atomic force microscopy and contact angle measurements.