Accelerating 3D nanofabrication utilizing a delicate cationic photoresist

Two-photon laser direct writing lithography or TPL is a cutting-edge method used for creating nanoscale constructions. It really works by leveraging particular supplies often known as photoresists, which change their chemical properties when uncovered to mild. These supplies take in laser mild in a singular method, enabling exact management throughout publicity to laser beams.

In contrast to typical ultraviolet (UV) photolithography, which makes use of mild to create photos, TPL can instantly construct complicated three-dimensional (3D) shapes that embrace options like overhangs and suspended parts at a decision smaller than the width of a human hair. Nonetheless, the manufacturing velocity of TPL can’t match that of UV lithography. To hurry up the TPL course of, extremely delicate photoresists are important.

Up to now, the traditional SU-8 epoxy photoresist sequence stays a preferred alternative due to its quite a few advantages, comparable to a excessive depth-to-width ratio, minimal shrinkage, and no points with oxygen interference throughout processing. Nonetheless, cationic photoresists like SU-8 usually take longer to manufacture and end in much less detailed constructions in comparison with free-radical-based photoresists, which may restrict their purposes in creating intricate microdevices.

Lately, a analysis group headed by Professor Cuifang Kuang from the Zhejiang Lab at Zhejiang College made a major breakthrough by creating a brand new sort of cationic epoxy photoresist. This progressive materials exhibited round 600 instances better sensitivity to two-photon laser publicity than the normal SU-8 photoresist, due to a singular bimolecular sensitization system.

The findings are printed within the journal Superior Purposeful Supplies.

Professor Kuang explains, “We demonstrated the 3D fabricated constructions with advantageous options of lower than 200 nanometers (nm) and a quick writing velocity of 100 millimeters/second (mm/s) utilizing nanolattices to point out potential utility for high-throughput nanofabrication of microscopic 3D gadgets.”

The bimolecular photosensitized initiation system developed on this analysis successfully separates the processes of sunshine absorption and power switch, enhancing the fabric’s skill to soak up mild. The researchers launched 5-nitroacenaphthene, a photosensitizer that broadens the absorption spectrum, permitting it to seize mild wavelengths right down to 430 nm.

By combining this photosensitizer with pyrazoline-based sulfonium salt as a photoacid generator (PAG) and polyfunctional epoxy as a constructing block, the group created a brand new cationic photoresist known as TP-EO. This progressive materials can obtain a formidable lithography velocity of 100 mm/s and may produce advantageous options with a minimal width of about 170 nm. The efficiency of TP-EO when it comes to velocity and determination is healthier than different present cationic photoresists.

To exhibit the potential purposes of the TP-EO resin, the researchers efficiently fabricated a topological liquid diode with nanoscale options.

Professor Kuang says, “Such a high-performance TP-EO photoresist is appropriate for the scalable fabrication of complicated architectures for varied purposes, comparable to optical gratings, diffraction parts, micro-electromechanical methods, microfluidic gadgets, and tissue engineering scaffolds.”