Chemical Mechanical Polishing of Chemical Vapor Deposited Co Films with Minimal Corrosion in the Cu/Co/Mn/SiCOH Patterned Structures

This work describes the dissolution and corrosion of chemical vapor deposited (CVD) Co films determined using aqueous mixtures of H2O2, oxalic acid (OA) and nicotinic acid (NA) and the polishing behavior with added silica abrasives, all at pH 10. It was found that an aqueous solution containing 1 wt% H2O2, 40 mMOA and 80 mM NA at pH 10 is effective in minimizing the dissolution and corrosion currents of the Co films as well as the galvanic corrosion of Co and Cu. Addition of 3 wt% silica abrasives to this mixture yielded a desired removal rate of similar to 17 nm/min and similar to 20 nm/min for Co and Cu films, respectively, at 13.8 kPa (2 psi) polishing pressure, with good rate selectivity. The effect of OA and NA on the dissolution and corrosion behavior of Co is discussed based on contact angles and potentiodynamic polarization data. Finally, Cu/Co/Mn-based film/SiCOH patterned wafers with similar to 20 nm half pitch were polished with the 3 wt% silica based dispersion for 70 s at 13.8 kPa (2 psi) applied pressure. Cross-sectional TEM analysis showed excellent post-polish performance with no corrosion issues and no loss of Cu, Co liner and the Mn-based barrier. (C) The Author(s) 2017. Published by ECS. All rights reserved.