One-Step Mask-Based Diffraction Lithography for the Fabrication of 3D Suspended Structures

Area of Science:

• Materials Science
• Optics
• Nanotechnology

Background:

• Fabricating complex three-dimensional (3D) suspended structures is challenging.
• Existing methods often involve multiple steps and complex lithography.

Purpose of the Study:

• To introduce a novel one-step exposure method for fabricating 3D suspended structures.
• To demonstrate the versatility of the method for creating various 3D patterns.
• To explore the potential of derived 3D carbon structures in advanced applications.

Main Methods:

• Utilizing the diffraction of mask patterns with small line width for one-step exposure.
• Building an optical model based on Fresnel-Kirchhoff diffraction formulation.
• Calculating the 3D light intensity distribution within the photoresist.
• Achieving pyrolysis of SU-8 photoresist structures to form carbon materials.

Main Results:

• Successfully fabricated various 3D suspended photoresist structures, including beams, meshes, word patterns, and multilayer designs.
• Obtained suspended and free-standing 3D carbon structures after pyrolysis.
• Demonstrated the feasibility of the one-step diffraction method for complex 3D fabrication.

Conclusions:

• The proposed one-step exposure method offers an efficient route to fabricate intricate 3D suspended structures.
• The derived 3D carbon materials show significant promise for applications in transparent electrodes, semitransparent solar cells, and energy storage devices.