Multiple Technique Characterization of the Physical and Chemical Properties of Silica Abrasives Used in Chemical-Mechanical Planarization

Abstract

The performance of chemical-mechanical planarization (CMP) slurries in the commercial fabrication of integrated circuits depends critically on the physical and chemical properties of abrasive particles used in CMP slurries. A host of analytical methods are used for characterizing the properties of CMP abrasive particles including spectroscopic,1,2 sedimentation,3 viscometric4 and fractionation5 techniques. One particular method, fluorescence correlation spectroscopy (FCS),1 has demonstrated significant versatility in this application due to its ability to simultaneously analyze the particle size distribution and the surface chemistry of abrasive particles in aqueous mixture containing small molecule CMP additives. The need for further characterization of these properties, especially the surface chemistry, is the product of the increasing use of nano-abrasives with reduced hydrodynamic diameters (< 20 nm) in CMP slurries in order to minimize surface defect creation during CMP processes. Incorporation of nano-abrasives in CMP slurries will promote surface chemistry-driven CMP additive adsorption on abrasive particles due to the increase in the total particle surface area as the hydrodynamic diameters of nano-abrasives decrease. The use of FCS in conjunction with the application of complementary techniques, such as dynamic light scattering and fluorescence lifetime analysis, is described in the presentation for the comprehensive characterization of the physical and chemical properties of representative silica abrasives used in CMP slurries.1. Jacobson, L.M.; Turner, D.K.; Wayman, A.; Rawat, A.; Carver, C.T..; Moinpour, M.; Remsen, E.E. “Characterization of Particle Size and Surface Adsorption for SiO2 Abrasives Used in Chemical Mechanical Planarization via Fluorescence Correlation Spectroscopy”, ECS J. Solid State Sci. Tech. 2015, 4, P5053-P5057.2. Marsh, J.L.; Wayman, A.E.; Smiddy, N.M.; Campbell, D.J.; Parker, J.C.; Bosma, W.B.; Remsen, E.E. “Infrared Spectroscopic Analysis of the Adsorption of Pyridine Carboxylic Acids on Colloidal Ceria”, Langmuir 2017, 33 , 13224-13233.3. Kamiti, M.; Boldridge, D.; Ndoping, L.M.; Remsen, E.E. “Simultaneous Absolute Determination of Particle Size and Effective Density of sub-Micron Colloids by Disc Centrifuge Photosedimentometry”, Anal. Chem. 2012, 84, 10526−10530. 4. Boldridge, D.; Kamiti, M.; Remsen, E.E. “Avoiding the Spherical Particle Assumption: Fractal Particle Density, Size and Structure Characterization through Combined Sedimentation and Viscometry Measurements”, Anal. Chem. 2020, 92, 15034-15041.5. Williams, S.K.R.; Park, I.; Remsen, E.E.; Moinpour, M. “New Particle Metrology for CMP Slurries”, Mater. Res. Soc. Symp. Proc. 2007, 991, 249-251.