Analysis of structured wire wafering processes to predict optimized process settings by varying particle size and wire diameter
The dominating slurry based wafering technology for cutting multi crystalline silicon into photovoltaic wafers will be replaced by the diamond wire technology over the next years. Though, the slurry technology is still in use for manufacturing microelectronic and photovoltaic wafers, if wafer manufacturers are forced by different reasons to use their slurry based wire saws. The development of an enhanced slurry based process is still required. A Design of Experiments was performed varying two major wafering parameters, the wire diameter of structured wire as well as the silicon carbide particle size. Additionally, the table speed was subdivided in several process sequences to analyze its impact. As a result, the slurry particle size shows the major influence to the cutting efficiency and the wafer geometry. The F600 slurry shows the highest Preston coefficient, equal to a high efficient silicon removal, but also the highest standard deviation of wafer thickness. The F800 and F1000 show an equal silicon removal but the F800 causes the best geometry in combination with the investigated wire diameters. Nevertheless, different effects were observed that indicate a need for more detailed process analysis. The impact of the wire structure and its loss of structure due to the cutting process is not observed, yet.