|A true-colour image containing around 8 × 105 RGB subpixels directly photopatterned using Cs2N3– capped quantum dots. Scale bar, 5 mm. Courtesy: D Talapin|
Topics: Applied Physics, Nanotechnology, Optical Physics, Semiconductor Technology, Quantum Dots, Quantum Mechanics
Photolithography is an important manufacturing process widely used in the semiconductor industry that employs photoresists (usually made from polymers) whose solubility change when illuminated with ultraviolet light. Although it is precise and can generate patterns with nanoscale resolution, it is limited in that it cannot easily pattern nanomaterials such as quantum dots (which are increasingly being used in flat-panel displays, for example). A new photoresist-free technique, developed by researchers at the University of Chicago and the Argonne National Laboratory, both in Illinois in the US, could help overcome this problem.
“Our new technique, dubbed DOLFIN (for Direct Optical Lithography of Functional Inorganic Nanomaterials) can be used to optically pattern a variety of inorganic materials, including metals, semiconductors, catalysts and magnetic materials without using photoresists,” explains team leader Dmitri Talapin. “No residual polymer-based impurities are present in the patterned layers, which means that they have good electronic and optical properties. Indeed, their conductivity, carrier mobility, dielectric and luminescence properties are on a par with those of state-of-the-art solution-processed materials.”
DOLFIN involves first preparing patternable materials in the form of nanoparticles with the desired size and shape. Next, the surface of these nanoparticles is decorated with special molecules designed to decompose when they are illuminated with UV light.
Optical lithography goes photoresist-free, Belle Dumé, Nanotechweb.org