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Polishing Slurries with Varied Particle Size

IP.com Disclosure Number: IPCOM000050112D
Original Publication Date: 1982-Sep-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Kaplan, P: AUTHOR [+2]

Abstract

This method for formulating silicon chemical mechanical polishing slurries entails the use of bimodal particle size distributions to provide faster stock removal rates.

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Polishing Slurries with Varied Particle Size

This method for formulating silicon chemical mechanical polishing slurries entails the use of bimodal particle size distributions to provide faster stock removal rates.

Slurries used for chemical mechanical polishing of silicon wafers are generally comprised of colloidal dispersions of silicon dioxide in water, at pH values greater than 9. The solids content is normally in the range 8-15 weight percent SiO(2). Instead of using a conventional bell shaped particle size distribution, the particle size distribution of the colloidal silica used should be bimodal in nature. The physical distribution of the SiO(2) particles in our recommended formulation would consist of several distinct sizes, for instance, 10 weight percent blend of 60 and 30 or 90 and 30 millimicron sized SiO(2) particles. These mixtures will result in greater stock removal rates than a slurry mixture comprised of say, only 10 weight percent of 60 and 90 millimicron sized particles, respectively.

The basic mechanism of stock removal in chemical mechanical polishing is different when compared to mechanical polishing. In chemical mechanical polishing, accelerated removal rates occur using bimodal particle size distributions. Reaction product is more readily formed between the slurry and the workpiece surface with the smaller particles because they have more surface area than the larger particles. The larger particles are more efficient for the removal of the...