Fe-substituted silica via lattice dissolution–reprecipitation replacement for tungsten chemical mechanical planarization

Abstract

Chemical mechanical planarization (CMP) is indispensable for processing of integrated circuit semiconductordevices to attain globally planarized surfaces. One of the critical consumables in the CMP processis a slurry containing abrasives like colloidal silica (SiO2). However, there is a limit to the use of CMP slurriescontaining SiO2 under acidic conditions due to deterioration of colloidal stability, resulting in defectson the planarized surfaces. Herein, we developed an Fe-substituted SiO2 consisting of single-atom Fe(III),enabling improved colloidal stability over universal pH regions for low-defect tungsten CMP applications. The facile and unique single-atom modification process is proposed by controlling the lattice dissolution–reprecipitation replacement of Fe3+ and Si4+ ions. The physicochemical states of Fe atoms in the surficiallattice of Fe-substituted SiO2 were confirmed through Raman spectroscopy, electron microscopy, x-rayabsorption spectroscopy, and energy-dispersive x-ray spectroscopy. Consequently, enhanced performancein W CMP was achieved using Fe-substituted SiO2. Regarding defect performance, defects werereduced from 11 scratches to 0 and 94 other defects to only 7. Additionally, the removal rate increasedfrom 67 to 122 Å/min, and the surface topography improved from 6.6 to 2.9 nm.