Wire-sawing defects on multicrystalline silicon wafers grown by a directional solidification method

In the industrial production of multicrystalline silicon (mc-Si) wafers used for solar cells, linear wire-sawing defects are sometimes generated on the surfaces of mc-Si wafers. The presence of such wire-sawing defects makes the mc-Si wafers unsuitable for the fabrication of solar cells. In this work, we first studied the nature of the linear wire-sawing defects on the mc-Si wafers, and then investigated how these wire-sawing defects were generated during the wire-sawing process. It has been found that the linear wire-sawing defects are sawing ridges and ditches on the wafer surfaces, and direct evidence has suggested that they are generated due to the presence of SiC particles embedded within mc-Si. The SiC particles form an obstacle to the movement of the sawing wire during the wire-sawing process, and the sawing wire tends to climb over the SiC obstacle, resulting in the generation of the wire-sawing defects. A model for the generation of the wire-sawing defects has been proposed. This work will be of much practical interest to the commercial mc-Si wafer production communities for solar cells.