Advanced Etching Techniques of LiNbO₃ Nanodevices.

Area of Science:

• Materials Science
• Nanotechnology
• Crystal Engineering

Background:

• Single Lithium Niobate (LiNbO₃ or LNO) crystals possess excellent electro-optic and piezoelectric properties, crucial for surface acoustic wave, optoelectronic, and ferroelectric memory devices.
• Current nanofabrication methods for LNO face limitations in achieving high etching rates and optimal sidewall angles, hindering broader applications.

Purpose of the Study:

• To investigate and compare various etching techniques for LiNbO₃ (LNO) nanofabrication.
• To identify methods that enhance etching rates and improve sidewall angles for LNO.

Main Methods:

• Exploration of diverse plasma densities using Reactive Ion Etching (RIE) and Inductively Coupled Plasma (ICP) dry etching.
• Investigation of proton exchange-enhanced etching and wet chemical etching post-high-temperature reduction.
• Evaluation of hybrid dry and wet etching approaches, including the use of SiO₂ masks.

Main Results:

• Reactive Ion Etching (RIE) combined with wet etching and reduction treatment yielded an etching rate of 10 nm/min with 90° sidewall angles.
• Inductively Coupled Plasma (ICP) dry etching achieved high etching rates of 79 nm/min with 83° sidewall angles.
• Utilizing SiO₂ masks with ICP resulted in an etching rate of 108 nm/min and a selectivity ratio of 0.86:1.

Conclusions:

• Optimized etching conditions provide multiple viable pathways for LNO nanofabrication.
• Achieved high etching rates and precise sidewall control pave the way for advanced LNO-based devices.
• The study offers practical solutions for overcoming LNO nanofabrication hurdles, enhancing its technological potential.