Challenges of the multi wire sawing process for thin wafers below 120 µm thickness

The photovoltaic sector is still dominated by silicon solar cells based on wafers cut by multi wire saws with slurry based on silicon carbide. The thinner the wafer and the wire get, the more important are the influence of the sawing processes in neighbouring sawing channels on wafer geometry and the wire wear which indicates the safety margin against rupture. The purpose of this work is to investigate the limitations of wire sawing of wafers below 120 ?m thickness by analysis of local thickness distribution of the wafers and the wire wear during the sawing process. The results of detailed wafer thickness measurements show a significant influence of the sawing processes in neighbouring channels on wafer geometry. Tensile tests of new and used wires show that the wire breakage force declines with reduced wire diameter. However, stress-strain analysis shows that the abrasively reduced wire has a similar slope as new wire of same diameter. The thickness measurements show that the abrasion rate of the wires and the wire loading are dependent on each other.