Presentation of Silicon-Kerf recycling by CEA
Presentation of CEA and its role in the ICARUS project
CEA (Alternative Energies and Atomic Energy Commission) is a French Research and Technology Organization particularly committed to research and development on low-carbon energy (nuclear and renewable energies). In this theme, the unit contributing to ICARUS project is dedicated to solar photovoltaics, from materials to systems, through innovative PV cells and modules.
In ICARUS, CEA works on reduction of silicon kerf contamination during wafering (Work Package 2 – Pilot A), quality upgrading by refining processes of silicon kerf (WP4 – Pilot C) and PV application (WP6 – High-end applications).
Reduction of silicon kerf contamination during wafering: ICARUS’s results
Silicon kerf collected during the cutting of wafers is commonly contaminated by metal elements, in particular aluminum, and carbon. The former come, among others, from the sacrificial plate (beam) on which the silicon brick is glued, and carbon mainly comes from the organic cutting liquid. For WP2, CEA’s work focused on the selection of a low concentration (Carbon Oxygen Demand) cutting liquid and the development of new resin beams loaded with silicon power instead of aluminum compound. For this study, cuts were performed on an industrial wafering saw with an in-line wet kerf (cake) collection. The collected cake is dried immediately after cutting.
Industrial wafering saw
Cutting liquid flow during brick cutting
Wet cake
Dried silicon kerf
The developments have made it possible to select a cutting fluid that significantly reduces the carbon content of the raw silicon kerf (typically, in a ratio of more than 2) and beams that drastically decrease the residual aluminum concentration, compared to classical conditions. Ultimately, excluding light elements, a silicon kerf purity of 3N (99.9%) was achieved, instead of the usual 1N to 2N after cutting. It can be further improved up to 4N with simple chemical and thermal treatments.
Average Carbon and Aluminum concentration in raw silicon kerf
As part of the ICARUS project, the beams developed at CEA have been successfully tested on NORSUN’s industrial wafering equipment.
Beams tested on NORSUN’s industrial wafering equipment (length 840 mm)
More information regarding the recovery of Silicon-Kerf can be found in the video “Silicon-Kerf recovery & Mono crystalline ingot growth” realized by CEA and BENKEI in ICARUS: https://youtu.be/zVq8o9mgugc?si=arOalTH6pmyfZO3N.
CEA’s video on youtube
