New family of agents for high selectivity in ceria-based STI CMP

摘要

In the quest for more versatile agents to enhance selectivity for oxide to nitride removal, investigations prompted by chemical insights have uncovered an entirely novel family of compounds efficacious for high selectivity. These materials impart a nearly 98% reduction in blanket wafer silicon nitride removal and an oxide removal rate nearly 280 times faster than nitride. Functionality on the model compounds is responsible for inhibition of ceria's attack on the surface of silicon nitride. Five-carbon, six-carbon, and closed ring structural analogs of the model compound all show comparable ability to suppress nitride removal in ceria-based CMP. Even some polymeric forms of the similar compounds, possessing the crucial functionality, also exhibit suppression of nitride removal. Furthermore, the compounds' suppressant activity is displayed over a wide spectrum of pH, from about pH 4 to nearly pH 10. Analysis of surface roughness of LPCVD TEOS after polishing with this ceria-suppressant slurry shows an Ra value of only 0.259A value. An additional advantage offered by this type of compound is its ability to help stabilize the ceria slurry against hard-settling, a definite benefit vis-a-vis reduced defects and easier slurry-handling.