The real differentiator for the wet chemical process tool makers lies in their ability to deliver high process quality while maintaining cost and cell efficiency.
RENA, a European wet chemistry process tool maker with over 30 years of experience and more than 3,300 machines installed worldwide, offers a wide range of wet processing solutions across sectors including semiconductors, wafering, glass, medtech, and additive manufacturing.
Dr. Damian Brunner, Senior R&D Manager Solar & Battery at RENA Technologies, highlighted the company’s latest InEtchSide 4+ and Batch 3 N600 series wet chemical processing tool for TOPCon cell fabrication as part of his presentation at the TaiyangNews Solar Technology Conference India 2025 (STC.I 2025).
Wet benches for TOPCon
For TOPCon cell fabrication, RENA offers both batch and inline wet process tools for 3 key chemical process steps: texturing, boron emitter etching, and poly etching & cleaning. The texturing process addresses inherent defects in incoming wafers, such as saw damage, and transforms the surface into a pyramid structure for better light capture. Following the boron diffusion process, single-side oxide or BSG etching, boron emitter etching, and subsequent cleaning are carried out. However, after the deposition of the rear-side passivation layer, single-side PSG etching, poly-Si wraparound removal, and a subsequent cleaning process are carried out.
Batch tool
RENA’s Batch 3 N600 series batch type wet process tool, featuring 6 carriers per bath, is designed for texturing, edge isolation, and poly-Si wraparound removal. This wet bench supports carriers up to 710 mm in length and can handle up to 120 wafers per carrier (compatible with M10, G12R, or M12 wafer sizes), enabling a throughput of up to 15,000 wafers per hour (wph). Assuming the processing of TOPCon cells with up to 25.5% efficiency and an annual production time of 8,280 hours at a gross throughput of 16,000 wph, the tool can deliver up to 1,028 MW, 1,186 MW, and 1,369 MW of annual output for M10, G12R, and M12 wafer sizes, respectively. This makes producing 1 GW per line possible, which feeds 2 printing lines, added Dr. Brunner.
On the cost-optimization front, the use of ozone (O₃) as a cleaning agent reduces the consumption of KOH and HF, eliminates chemical waste, and lowers operational expenditure. However, this comes with a slight CapEx premium compared to Chinese counterparts that use H₂O₂-based cleaning, explained Dr. Brunner.
Inline tool
RENA’s brand-new InEtchSide 4+ series inline wet process tool features a long bath lifetime and RENA’s IP-protected RFL (RENA Functional Layer) technology – a water-capping solution that enhances optical yield and protects the front side of the wafer. The tool is designed for high-throughput, single-sided removal of silicon oxide layers or doped glasses (BSG) during boron emitter etching or PSG etching post rear side passivation.
With a compact < 20 m² footprint, the system is available in 2 configurations: a 12-lane layout for G12 and G12R wafer sizes, and a 14-lane layout for M10 wafers. Assuming the processing of TOPCon cells with 25.5% efficiency over 8,280 production hours annually, the 14-lane M10 configuration can achieve a production capacity of up to 1,100 MW at a gross throughput of 16,000 wph. In comparison, the 12-lane configuration yields up to 1,230 MW annually with G12 wafers at 13,500 wph and up to 1,200 MW with G12R wafers at 15,200 wph.
According to Dr. Brunner, the tool is commercially available starting Q4 2024.
