Aqueous HF-(HCl)-Cl2 Mixtures for Saw-Damage Removal and Spray Texturing of Monocrystalline Silicon Solar Cells

A new approach for the texturing of monocrystalline silicon solar wafers was developed. By using a spray etching process with aqueous HF-HCl-Cl₂ mixtures, textured wafers were generated and processed to PERC solar cells and compared to cells textured by a conventional alkaline texturing process. Also, a novel saw damage removal (SDR) process using aqueous HF-Cl₂ mixtures was tested against the typical NaOH SDR. A possible dependency of cell parameters on the wafer reflectivity is discussed. The etch rates of the spray etching process are compared to other chlorine-containing hydrofluoric acid-based processes and alkaline potassium hydroxide-based mixtures. Computational fluid dynamic analyses were performed to identify possible reasons for marks occurring on the spray textured wafers. The influence of the marks on the electrical properties were examined with electroluminescence measurements. As cell performance data show promising results, we discuss whether the spray etching process with HF-HCl-Cl₂ mixtures is a viable way for the implementation of an inline texturing process for solar cell production.