Synthesis of Fe metal precipitated colloidal silica and its application to W chemical mechanical polishing (CMP) slurry

Precipitation of Fe metal ions on colloidal silica particle for the application of W CMP process. The objective of this paper is to develop a new method of Fe (metal) precipitation on colloidal silica to overcome the stability problem, which would be responsible in producing defects, with commercial...

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Bibliographic Details
Published in:Journal of colloid and interface science 2010-09, Vol.349 (1), p.402-407
Main Authors: Kang, Young-Jae, Prasad, Y. Nagendra, Kim, In-Kwon, Jung, Seok-Jo, Park, Jin-Goo
Format: Article
Language:English
Subjects:
Chemical-mechanical polishing
Chemistry
Colloidal state and disperse state
Colloids
Defects
Electrochemistry
Exact sciences and technology
Fe precipitation on colloidal silica
Fumed silica
General and physical chemistry
Iron
Physical and chemical studies. Granulometry. Electrokinetic phenomena
Precipitation
Removal rate
Selectivity
Silicon dioxide
Slurries
Slurry stability
W CMP
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Summary:Precipitation of Fe metal ions on colloidal silica particle for the application of W CMP process. The objective of this paper is to develop a new method of Fe (metal) precipitation on colloidal silica to overcome the stability problem, which would be responsible in producing defects, with commercially available fumed silica slurry containing Fe ions. The slurry was developed by using sodium silicate (Na 2SiO 3) as a raw material and the concentration of precipitation of metal was controlled by addition of Fe salt (Fe(NO 3) 3). To compare the concentration of precipitated Fe with directly added Fe ions in slurry solutions, static electrochemical and peroxide decomposition experiments were performed. Although the performance of the Fe precipitation appeared to be lower than Fe ion addition during these experiments, nearly equal removal rate was observed due to the dynamic condition during polishing. The Fe precipitated colloidal silica particles at the concentration of 52 ppm showed the similar W removal rate and selectivity of W to TEOS (tetraethylorthosilicate) to commercially available fumed silica slurry containing externally added Fe ions. The introduction of Fe particle precipitation on colloidal silica particles would result in a longer shelf life time and hence lower defect level in W CMP.
ISSN:0021-9797
1095-7103
DOI:10.1016/j.jcis.2010.04.083