pH-controlled selective etching of Al2O3 over ZnO

Area of Science:

• Materials Science
• Surface Chemistry
• Nanotechnology

Background:

• Atomic Layer Deposition (ALD) is crucial for thin-film fabrication.
• Selective etching is essential for patterning ALD films.
• Understanding material interactions in etching solutions is key.

Discussion:

• Alkaline aqueous solutions with pH 9-12 selectively etch Al2O3 over ZnO.
• Spectroscopic ellipsometry quantifies film thickness changes during etching.
• Optimized conditions achieve high selectivity (>400:1) and etch rates (~50 nm/min).

Key Insights:

• pH control is critical for selective etching of Al2O3 vs. ZnO.
• A pH 12 solution at 60°C provides efficient and highly selective Al2O3 removal.
• This method minimizes damage to the underlying ZnO layer.

Outlook:

• Potential applications in microelectronics and semiconductor device fabrication.
• Further research into other ALD materials and etching chemistries.
• Integration into advanced patterning techniques for complex device architectures.