Nanopatterning Approach for Multiple-Height Metasurfaces with Absolute Lateral Spatial Precision.

Area of Science:

• Nanotechnology
• Photonics
• Materials Science

Background:

• Conventional lithography (DUV, EBL) excels in 2D patterning but struggles with 3D accuracy due to cumulative alignment errors in multi-step processes.
• Achieving precise 3D control in nanostructures is crucial for advanced optical and photonic applications.
• Existing methods face limitations in lateral alignment accuracy for multi-layered 3D nanostructures.

Purpose of the Study:

• To present a novel fabrication strategy for all-dielectric nanostructures with multiple discrete height profiles.
• To achieve absolute lateral alignment accuracy across different layers in 3D nanostructures.
• To enable the creation of truly 3D metasurfaces with deterministic spatial accuracy and enhanced optical functionality.

Main Methods:

• Combines single-step lithography with reactive ion etching (RIE).
• Utilizes on-demand, electrochemically controlled selective removal of metallic masks via atomic force microscopy (AFM).
• Eliminates repeated alignment procedures inherent to multistep lithography, ensuring nanometer-scale registration precision.

Main Results:

• Demonstrated fabrication of nanopillar arrays with three distinct height profiles over a 20 × 20 μm² area.
• Achieved no measurable lateral misalignment between different height profiles.
• Observed tunable optical responses directly correlated with controlled height variations.

Conclusions:

• The presented method offers a robust route for fabricating 3D metasurfaces with deterministic spatial accuracy.
• This technique enhances optical functionality by enabling precise control over nanostructure geometry.
• The approach is broadly applicable to fields like chiral nanophotonics, nanofluidics, data storage, and biosensing.