Technology

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The manufacturing of solar cells requires single-side etching steps, where silicon material is removed from only one surface of the wafer. The ADE technology provides a low cost, low footprint, yet high throughput process to carry out the single-side etching steps, with low environmental impact.

> Atmospheric Dry Etching - ADE

Nines Photovoltaics has developed a novel UNIVERSAL silicon etching technology designed to meet the specific requirements of the PV solar cell manufacturing industry. A unique, cost effective industrial dry etching solution.

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> HOW IT WORKS

The solar silicon wafers are continuously loaded on a conveyor and processed in an in-line fashion. They pass through a heated, open ended ADE reactor.  The etching gas  showers the wafers while they are pasing through.  The reactor is engineered to create the required etch depth, texture and uniformity. The gases are contained through purge curtains on eather sides of the reactor. Only the top side of the wafer is etched. This decoupling ensures that each side of the wafer can receive a specific treatment, as required in most advanced solar cell architectures. 

ADE reactor with belt

> WHY IS IT DIFFERENT ?

The ADE technology provides a new way of carrying out  dry gaseous etching without the limitations of other common vacuum plasma based technologies (typically Reactive ion etching, RIE). This makes ADE suitable for application in industrial solar cell processing.

The ADE process works at atmospheric pressure (no vacuum) and does not require a plasma. The etching process is purely chemical, without any ions involved.ADE delivers superior etching rates and its specific cost of ownership is highly competitive for capacity production scenarios. Due to high etch rate, the tool footprint is very small. Furthermore, the gas chemistry does not use any green house gases (GHG).

It provides the solar cell manufacturing industry with a viable alternative to the long standing incumbent wet etching process, enables the high throughput production of solar cells while reducing the environmental impact of the etching process steps. 

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ADE reactor Roll-to-roll configuration

> FAST ETCHING AND TEXTURING

The ADE process is carried out at atmospheric pressure, allowing for very high etching rate. Typically, a wafer can be etched in less than a minute using 30%  concentrated Fluorine (F2) and in a few seconds using 100% F2,(as compared to 1 to 20 minutes for a wet etch tool) in a very small reactor. This impressive etch rate combined with the open design of the Nines reactor enables the ADE technology to deliver a high wafer throughput that can meet the current and future requirements of the PV industry. The ADE reactor technology can easily be scaled, without any of the constraints associated with vacuum based plasma systems. It is also by design compatible with roll to roll configuration.

> HIGH ETCHING SELECTIVITY

The ADE process is highly selective. Etch selectivity is the ratio of etch rates between materials. Using ADE, Silicon is typically etched at least a 100 times faster than silicon oxide layers, or silicon nitride layers. This specific process property makes it very useful for applications where sacrificial layers need to be removed, or for process using masking and patterning technics. This high selectivity is another strong differenciation from a  typical reactive ion etching process (RIE).

> FLEXIBLE & GREEN PROCESS

ADE is compatible with any type of silicon wafer and does not require specific chemistries; one tool is suitable for all substrates (mono,multi, quasi-mono, diamond wire-cut or slurry cut), including low cost substrates and thin epitaxial or deposited layers (a-Si, etc,...).  ADE provides a dry etch solution, faster and cheaper than RIE. Furthermore, the etching chemistry does not produce nor use any green house gases (GHG), and there is no water consummed in the process.

"ADE is the ideal process to start moving away from water-hungry wet processes, and reduce your etch process water and environmental footprint "
EIT