The DW Pre Tex diamond-wire sawing for wafers and cells is a one-step, inline wet process that achieves an R< 23% reflection value.
Compared to cutting by a slurry saw, diamond wire sawing is significantly cheaper since it is a quicker process and wastes less silicon. However, the diamond wire leaves a smooth surface that cannot be textured with the standard acid texture process. Previously presented methods were either too expensive, environmentally harmful or have failed to meet quality requirements.
Schmid has developed a cost-effective solution—relying on materials that are commonly used in the PV industry—for texturing of diamond-wire-cut multi-wafers. The DW PreTex is based on an inline wet process which roughens the relatively smooth surface of the wafers so that they can be processed afterwards with the standard HF/HNO3 texture. It achieves uniform surfaces with a reflection value of R< 23%. This process can be integrated into existing production lines as the last step in a wafer fab, or as the first process step in cell manufacturing fabs.
Figure 1: DW PreTex is a modular wet process system that can be integrated into the existing production line as the last step in a wafer fab without additional requirements.
As a significant economical advantage in the highly competitive photovoltaic market, diamond-wire-cut wafers can be produced at €0.06 to €0.08 lower, boosting demands for 500MW and 5GW middle of this year.