Nano-Perforated Silicon Membrane with Monolithically Integrated Buried Cavity

Area of Science:

• Materials Science
• Nanotechnology
• Microfabrication

Background:

• Existing fabrication methods for nano-perforated membranes (NPMs) face challenges in mechanical robustness and complexity.
• There is a need for scalable and adaptable processes to create high-aspect-ratio (HAR) nanoporous structures.

Purpose of the Study:

• To develop a wafer-scale process for fabricating monolithically suspended NPMs with integrated support structures in silicon.
• To overcome limitations of existing methods regarding mechanical robustness and fabrication complexity.
• To enable tunable geometries for diverse applications.

Main Methods:

• Utilized a cyclic deposit, remove, etch, and multi-step (DREM) process for directional etching of nano-pores.
• Employed a buried cavity formation using an isotropic etch for thick NPMs.
• Integrated through-silicon-vias for macro-world connectivity.

Main Results:

• Successfully fabricated monolithically suspended NPMs with tunable thicknesses (4.5 µm, 6.5 µm, 12 µm).
• Achieved high-aspect-ratio (HAR) nano-pores (300 nm diameter, 700 nm pitch).
• Demonstrated a flexible and robust process adaptable to various structural parameters.

Conclusions:

• The developed DREM process offers a robust and scalable approach for fabricating advanced NPMs in silicon.
• The monolithic design allows for further functionalization and broadens application potential.
• NPMs are suitable for demanding applications like purification, separation, and corrosive environments.