16 nm-resolution lithography using ultra-small-gap bowtie apertures.

Area of Science:

• Nanotechnology
• Optical Engineering
• Materials Science

Background:

• Photolithography is essential for semiconductor manufacturing but limited by light diffraction.
• Near-field scanning optical lithography (NSOL) offers a low-cost alternative, with resolution dependent on near-field localization.
• Existing NSOL techniques require further advancements to improve resolution for nanoscale fabrication.

Purpose of the Study:

• To enhance the resolution of near-field scanning optical lithography (NSOL).
• To develop a fabrication method for improved NSOL apertures.
• To demonstrate a new photolithography scheme for advanced nanotechnology applications.

Main Methods:

• Fabrication of bowtie apertures with sub-15 nm gaps using a novel backside milling technique.
• Excitation of localized surface plasmon and nanofocusing within the tapered gap to generate a confined electric near field.
• Demonstration of contact lithography using the fabricated bowtie apertures.

Main Results:

• Achieved a record resolution of 16 nm (Full Width at Half Maximum) in contact lithography.
• Demonstrated highly confined electric near fields due to bowtie aperture design and plasmon excitation.
• The backside milling method effectively created sub-15 nm gaps for enhanced NSOL performance.

Conclusions:

• The developed backside milling method for fabricating sub-15 nm bowtie apertures significantly improves NSOL resolution.
• This high-resolution photolithography technique holds promise for applications in data storage, high-speed computation, and energy harvesting.
• The study presents a viable pathway for overcoming diffraction limits in optical lithography for nanotechnology.