AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Selective Oxidation of Carbon on Silicon Kerf using Furnace Aerosol Reactor (FuAR) aided by TGA Kinetic Estimations
MIGUEL VAZQUEZ PUFLEAU, Tandeep Chadha, Gregory Yablonsky, Henry Erk, Pratim Biswas, Washington University in St. Louis
Abstract Number: 513 Working Group: Nanoparticles and Materials Synthesis
Abstract Silicon is the most widely used semiconductor in the electronics and photovoltaics (PV) industry. Current manufacturing processes are expensive and (for thin PV wafers) more than 40% of the silicon is lost during the cutting process as kerf. Efforts have been made to recycle kerf, but have been futile due to high impurities in the kerf. As a result, kerf is a disposed waste stream. A single-step route for recycling kerf is paramount to reduce the cost of PV wafers as well as eliminating a significant waste stream.
Previous studies have focused on removing the major contaminant, SiC, from the slurry-based cutting process. However, advanced diamond fixed-abrasive slicing process produces less waste and no free abrasive is used, hence it should be possible to recover silicon more easily. Chemical analysis shows that carbon (3.5%) is the main contaminant in this type of kerf. SEM and TEM characterization have shown that this kerf is composed of highly aggregated thin-layer flakes formed by the plastic deformation of Si into damaged and amorphized silicon.
In this work we used a furnace aerosol reactor (FuAR) process for selective carbon oxidation in kerf. Total organic carbon (TOC) measurements have shown that all carbon in kerf is in the organic form. Silicon oxidation and carbon elimination kinetics were studied using Thermo Gravimetric Analysis (TGA). Apparent kinetic orders of volatilization for carbonaceous compounds for air and nitrogen were found. Temperature dependences for total carbon reduction were presented and apparent activation energies were determined. The process mechanism was discussed qualitatively.