A fracture mechanics approach to enhance product and process sustainability in diamond wire sawing of silicon wafers for solar cells through improved wire design

By decreasing the subsurface damage in silicon wafers produced by diamond wire sawing, the mechanical strength of wafers can be increased, and the amount of silicon to be etched in subsequent manufacturing steps can be minimised, enhancing both product and process sustainability. Apart from the sawing process parameters, the subsurface damage in as-sawn silicon wafers is influenced by the design of the diamond wire. We present a fracture mechanics approach for the design of fixed abrasive diamond wires used in wire sawing of silicon wafers for solar cells. Starting from an allowable damage (crack) depth, indentation fracture mechanics and contact analysis are used to determine the wire design parameters, namely the grit protrusion and peripheral distribution of diamond abrasives. The improved wire design can reduce subsurface damage and thereby improve the surface integrity (product sustainability), and reduce the processing time and chemicals used in the subsequent saw-damage removal step (process sustainability).