Following texturing, the emitter for the cell is attached by means of diffusion. After it has been diffused in a parasitic process, the emitter needs to be removed from the back of the cell by means of so-called chemical edge isolation, and the etched surface has to be smoothed (“polished”). Cleaning strategies are also playing an ever more important role in this edge isolation process, particularly for advanced cell concepts like TOPCon.
With its InOxSide, RENA boasts years of experience in this segment. Whilst earlier edge isolation systems still used an easily manageable but environmentally and economically questionable mixture of hydrofluoric and nitric acid to perform the etching, the new InOxSide Blue does this completely using environmentally friendly hot potash, without any additives, and achieves an unbeatable polishing quality on the etched surface.
The InOxSide Fusion is a hybrid form that melds both etching strategies. It combines the benefits of acidic and alkaline etching with the ability to adapt the etching process easily to suit different wafer materials. At the same time, it also uses over 50% less nitric acid than the acidic process and produces maximum reflection on the back of the cell.