NOX-free etching for edge isolation and polishing as well as poly-Silicon removal along with PSG or BSG cleaning

The Alkaline Edge Isolation Inline System combines several process steps in a modular system.

With the single side and immersion Alkaline Inline System, SCHMID has the state of the art solution for PERC and TOPCon manufacturing. It is operated without any nitric acid (HNO3). Alkaline 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 to easily meet increasingly stringent environmental requirements. In addition, processing at about 90 °C ensures a high etching rate and thus a small footprint of the system. It can be combined with any required acidic etching step, e.g. also for junction isolation. Due to the modular SCHMID system design any require process combination can be realized.

During the etching process the emitter or any other layer underneath is protected by the water mask developed and patented by SCHMID. Special transport rollers ensure that the chemistry comes into contact exclusively with the rear side, thus reducing the chemistry consumption.

• Significantly lower chemistry 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) in one system
• Patented water mask
• Stable process without cooling unit
• Shortest maintenance times due to good accessibility and easy cleaning

Throughput:

• Up to 10.000 wph M12
• Further throughputs configurable

Wafer size:

• M2 – M12

Breakage rate:

• < 0.05 %

Process media:

• HF
• KOH