Atmospheric Dry Etching: A Water-Free Alternative For TOPCon

In solar cell manufacturing, most etching steps are still carried out with wet-chemical tools. However, alternative approaches are being developed to perform etching while reducing resource consumption. One such innovation comes from Nines Photovoltaics (Nines PV), which developed a proprietary process known as ADE, or Atmospheric Dry Etching. The company has been working on this technology since 2010. What sets it apart is that it enables dry texturing at atmospheric pressure using fluorine (F₂) as the etching gas. This eliminates the need for vacuum chambers and plasma, both typical components and major cost drivers in conventional dry-etching technologies. Importantly, the technology has no unusual adverse environmental impact.

While the use of fluorine as an etching gas might raise concerns about greenhouse gases, Nines PV CTO Laurent Clochard pointed out in his presentation "Atmospheric Dry Etching for TOPCon Solar Cells" at the TaiyangNews High Efficiency Solar Technologies Conference 2021 that the molecular fluorine employed in ADE has zero global warming potential, in stark contrast to SF6, a gas commonly used in other dry-etching processes. The key benefit of the technology is its high etching rates of 70 nm/s, while eliminating water usage.

The technology can also be applied to other wet bench applications such as SDE and texturing. In fact, the company has promoted its technology for these purposes in previous surveys. However, it has found its best fit in etching, particularly for removing silicon wraparound in TOPCon cells, which has now become the company’s primary focus. Nines PV’s CEO, Edward Duffy, shared key insights on the company’s technology. According to Duffy, water consumption is becoming a critical concern for solar cell producers, often only recognized during project planning when the sheer volume of water required for wet-chemical processes becomes apparent. This growing awareness is driving interest in Nines PV’s dry-etching technology, as it offers a way to eliminate water use entirely in the etching process. The company said it is in active discussions with several tier-1 manufacturers, particularly in India, and is receiving an increasing number of inquiries from both established players and new entrants. That said, financing remains a major hurdle – the challenge now is securing the funding needed to build and deliver the first machines for industrial production. Duffy emphasized that proving the technology’s industrial readiness is the next key milestone.

On the technology front, Nines PV continues to refine its platform to meet market needs, with a strong focus on selective and single-sided etching – capabilities that are becoming increasingly valuable as cell architectures grow more complex. The ability to use masks for selective etching and to form intricate structures is gaining traction. While Nines PV is collaborating with partners on back-contact cell projects, it does not have dedicated developments in that area yet. Duffy stressed that sustainability and selectivity remain at the core of the company’s approach, with ADE offering manufacturers a path to smaller, high-throughput machines that enable more efficient and cost-effective production.

Nines PV also points out that the case for dry-etching solutions like ADE is being strengthened by new policy developments in China. According to the company, the Ministry of Industry and Information Technology (MIIT) released an updated set of standards for PV manufacturing in 2024 that places much tighter limits on water use. For new or expanded n-type crystalline projects such as TOPCon, water consumption is capped at less than 360 tons per MWp, and at least 40% of that must come from recycled sources. Current TOPCon lines, however, are still consuming close to 550 tons per MW, according to data from CPIA. Nines PV’s solutions eliminate the water requirement in different etching applications, in particular removing silicon wraparound.

The text is an edited excerpt from TaiyangNews’ latest Market Survey on Solar Cell Production Equipment 2025, which can be downloaded for free here.