Alkaline Polishing for PERC and TOPCon

Alkaline Polishing for PERC and TOPCon

NOx-free edge isolation and polishing

The Alkaline Edge Isolation Inline System achieves a perfect edge isolation with an alkaline solution. One step horizontal inline system for PERC and TOPCon cell manufacturing without cassettes.

Product benefits

Significantly lower chemistry consumption and costs than in the case of an acid process

NOX-free process meets strict environmental requirements

Edge isolation and polishing for high-efficiency cells (e.g. PERC or TOPCon) in one system

Patented water mask

Shortest maintenance times due to good accessibility and easy cleaning


The alkaline polishing system combines several process steps into a modular system. On the one hand, the emitter layer on the rear side of the wafer, which is grown during the diffusion process, will be single-sided isolated from the front and on the other hand, the rear side of the cell is smoothed and prepared for a perfect surface passivation.

The machine can be converted at any time for the TOPCon process. This means that the doped glass on the front side is not removed for the TOPCon process. For the PERC process, the doped glass (PSG/BSG) on the front side will be removed. So, each PERC system is easily convertible into a TOPCon-ready production system.

Potassium hydroxide solution (KOH) is used instead of the expensive acid. The obvious advantages: No nitrogen oxide (NOX) is generated, which requires a complex exhaust and a subsequent costly disposal. This allows for easy compliance of increasingly strict environmental requirements. In addition, processing at approx. 80-90°C ensures a high Etching rate and a reduction of the footprint of the system with high throughput. During the edge isolation/polishing process, the emitter is protected by a water mask developed and patented by SCHMID.

Specially developed transport rollers ensure that the etching medium only wets the back of the cells, which leads to a reduction in chemical consumption. In addition, all necessary processes for polishing take place in one and the same machine. This makes it possible to dispense with further machinery with the associated automation and carriers.

Technical Data

Throughput (M12):

  • 5,000 wafers/h (5 tracks)
  • 10,000 wafers/h (10 tracks)
  • Further throughputs configurable

Wafer size:

  • M2 – M12

Breakage rate:

  • < 0,05 %

Process media:

  • HF
  • KOH
  • Additive

Other equipments for photovoltaics & glass


Surface finishing for glass
The AGTex offers innovative methods for processing and finishing glass surfaces. The technology is particularly suitable for the production of antireflection and antiglare coatings on glass.

Alkaline Texturing

Efficient texturing of mono-crystalline wafers
The Alkaline Texturing Inline System of SCHMID ensures the most efficient texturing of mono-crystalline wafers.

APCVD System

Low cost inline deposition of thin films
The 5500 series APCVD system is well suited for low cost high-volume processing for all cell architectures requiring single or multi-layer dielectric thin film deposition.

Edge Isolation & PSG Etching

Single-sided edge isolation for maximum efficiency
The Edge Isolation + PSG Etching Inline System fully automatically achieves a perfect edge isolation. In combination with the patented water mask the emitter is optimally isolated. 

Poly Silicon & BSG Etching

Poly Silicon & BSG Etch for TOPCon Manufacturing
The Alkaline Poly–Si and BSG Etching Inline System achieves a perfect cleaning of the sunny side for n-and p-doped polysilicon and Boron glass removal.


We look forward to getting to know you!

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Tracy Xie


Johnny Tseng


Jaho Kim