Oxide Membranes from Bulk Micro-Machining of SrTiO₃ Substrates

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Physics

Background:

• Suspended micro-structures of complex oxides are crucial for advanced devices.
• Current surface micro-machining methods limit physical access to these structures.
• A new bulk micromachining approach is needed for better fabrication and characterization.

Purpose of the Study:

• To develop a bulk micromachining protocol for fabricating suspended complex oxide micro-structures.
• To enable physical access to microstructures from both sides.
• To extend membrane technology beyond silicon-based compounds.

Main Methods:

• Developed a bulk micromachining protocol using anisotropic etching.
• Fabricated pass-through holes in strontium titanate (SrTiO₃) substrates.
• Calibrated etching rates to control aperture geometry.

Main Results:

• Successfully realized suspended oxide thin film devices with pass-through holes in SrTiO₃(100) and SrTiO₃(110) substrates.
• Demonstrated clamped membranes and trampolines using (La,Sr)MnO₃ thin films.
• Presented a suspended trampoline resonator fabricated from the SrTiO₃ substrate.

Conclusions:

• The developed bulk micromachining protocol allows predictable control over suspended complex oxide microstructures.
• This method overcomes limitations of surface micro-machining, enabling full device access.
• The protocol is applicable to a wide range of complex oxides, expanding membrane technology possibilities.