World premiere: SCHMID develops a cost-effective process for the texturing of diamond-wire cut multi-wafers that easily can be integrated into existing production lines. The first systems will be shipped in Q2. With “DW PreTex“ SCHMID presents a worldwide novelty to the photovoltaic industry: a cost-effective process for texturing of diamond-wire-cut multi-wafers based on an inline wet process. SCHMID’s process roughens the relatively smooth surface of the wafers so that they can be processed afterwards with the standard HF/HNO3 texture. This allows DW PreTex to be easily integrated into the existing production lines. The process can be implemented as the last step in a wafering fab or as the first process step in cell manufacturering fab.
“We have processed samples for all leading wafer and cell manufacturers in our Technology Center,” explains Dr. Christian Buchner, head of the business unit Photovoltaics at SCHMID. “With DW PreTex, our customers achieve more uniform surfaces than by texturing slurry-cut wafers – at operating costs of less than 0.01 Euro per wafer.” This is a significant economical advantage in the highly competitive PV market. With diamond wire saws, wafers can be produced at 0.06 – 0.08 Euros lower cost. Therefore the demand for DW PreTex is high. First orders for industrial mass production with 500 MW have already been placed and an additional 5 GW are expected by the middle of the year.
The background: So far multicrystalline wafers have mostly been separated from the ingot with slurry saws. Diamond wire sawing is significantly cheaper since it is faster and wastes less silicon. However, the diamond wire leaves a smooth surface that cannot be textured with the standard acid texture process. Processes that have been presented so far were either too expensive, environmentally harmful or failed to meet quality requirements. The solution from SCHMID is different: DW PreTex requires only one process step to allow the processing of diamond-wire cut multi-wafers with the proven standard texture HF/HNO3. The innovative solution relies on materials that are commonly used in the PV industry. So DW PreTex can be integrated into the existing production as a modular wet process system without additional facility requirements. The process achieves uniform surfaces with a reflection values of R < 23 % at lowest operating costs.