Investigation on the sawing of solar silicon by application of wires of 100 µm diameter

In the wafering process of silicon ingots up to 50% of the silicon is lost due to the sawing process. In order to increase the wafer yield the manufacturers reduced the wafer thickness from 300 µm down to 180 µm in the past years. Developments for achieving reductions of kerf loss by reducing the wire diameter are much less advanced because of the difficulties to keep the actual standards for the wafer properties and the sawing process (e.g. high feed rate). The purpose of this work was to apply thin wires of 100 µm diameter in the sawing process and to analyze influences of different sawing parameters, e.g. distributions of SiC particles as abrasives in slurries and forces effective during sawing on quantities like wire lifetime, wafer roughness, and wafer strength. The sawing experiments were performed by application of an experimental single wire saw. The results of the investigations show that compared to the use of SiC abrasive grains having a coarse particle size distribution (PSD) SiC of a fine PSD together with a wire of 100 µm diameter may lead to a reduced roughness of the wafers and an increase of the wafer strength.