title: Carbon elimination from silicon kerf: Thermogravimetric analysis and mechanistic considerations.
abstract: 40% of ultrapure silicon is lost as kerf during slicing to produce wafers. Kerf is currently not being recycled due to engineering challenges and costs associated with removing its abundant impurities. Carbon left behind from the lubricant remains as one of the most difficult contaminants to remove in kerf without significant silicon oxidation. The present work enables to better understand the mechanism of carbon elimination in kerf which can aid the design of better processes for kef recycling and low cost photovoltaics. In this paper, we studied the kinetics of carbon elimination from silicon kerf in two atmospheres: air and N2,under a regime of no-diffusion-limitation. We report the apparent activation energy in both atmospheres using three methods: Kissinger, and two isoconversional approaches. In both atmospheres, a bimodal apparent activation energy is observed, suggesting a two stage process. A reaction mechanism is proposed in which (a) C-C and C-O bond cleavage reactions occur in parallel with polymer formation; (b) at higher temperatures, this polymer fully degrades in air but leaves a tarry residue in N2that accounts for about 12% of the initial total carbon.
authors.affiliation: Aerosol and Air Quality Research Laboratory Department of Energy, Environmental &Chemical Engineering Washington University in St. Louis St. Louis, MO 63130, USA.
authors.forename: Miguel
authors.initials: M
authors.lastname: Vazquez-Pufleau
authors.affiliation: Aerosol and Air Quality Research Laboratory Department of Energy, Environmental &Chemical Engineering Washington University in St. Louis St. Louis, MO 63130, USA.
authors.forename: Tandeep S
authors.initials: TS
authors.lastname: Chadha
authors.affiliation: Parks College Department of Chemistry Saint Louis University St. Louis, MO 63103, USA.
authors.forename: Gregory
authors.initials: G
authors.lastname: Yablonsky
authors.affiliation: Aerosol and Air Quality Research Laboratory Department of Energy, Environmental &Chemical Engineering Washington University in St. Louis St. Louis, MO 63130, USA.
authors.forename: Pratim
authors.initials: P
authors.lastname: Biswas