Ultraviolet Metalenses Mass Produced. Will Enable Future AI Chips

Extreme Ultraviolet lithography for computer chips have been critical to letting us efficiently get better than 14 nanometer computer chips. Deep ultraviolet lithography were used for 14 nanometer feature sizes. China chip companies do not have access to EUV lithography equipment and have pushed deep ultraviolet lithography to 7 nanometer feature sizes.

Metalenses are 10,000 times thinner than regular lenses. However, it is possible that UV metalenses could be used to overcome the physical diffraction limit. UV metalenses that could go beyond the diffraction limit would enhance (deep) ultraviolet lithography to be able do things previously exclusive to extreme ultraviolet lithography. This could be done at the right costs. China’s methods for pushing deep ultraviolet lithography while successful come with efficiency and cost penalties.

Metalenses control light properties through nanometer-scale patterns or structures on lens surfaces. With the ability to reduce the thickness of conventional lenses by a factor of 10,000, they hold significant promise in medical devices that are inserted in the body and wearable devices. Ongoing active research aims to achieve mass production and commercialization of metalenses.

Researchers have devised a technique for the mass production of large-area metalenses tailored for use in the ultraviolet region.

Ultraviolet light poses challenges as it is absorbed by most materials due to its high energy level.

The team used a nano-imprinting process that engraves the pattern like a stamp. They achieved the rapid and inexpensive production of metalenses that are 20,000 times larger than conventional ones.

Metalenses have outstanding light-modulating performances, and studies have been conducted on them to not only replace conventional bulky and heavy refractive lenses but also to expand on them. However, their operating wavelengths have rarely covered the ultraviolet (UV) regime since UV-transparent materials are scarce and nanopatterning techniques have a small patterning area, high cost, and low throughput.

These limitations are overcome in this study, and centimeter-scale and highly efficient UV metalenses are successfully mass-produced. The UV metalens is designed to operate at a wavelength of 325 nm, with a numerical aperture of 0.2. Argon fluoride photolithography is used to fabricate an 8-inch master stamp in which 300 metalenses are patterned in an array with a high resolution. The fabricated master stamp can be duplicated repeatedly using wafer-scale nanoimprint lithography. To improve efficiency, we developed a zirconium dioxide–polymer hybrid material that is scalable, easily manufacturable, UV-transparent, and high-index material. The experimental results confirm that the mass-produced metalenses operate as ideal imaging systems, exhibiting an average measured efficiency of 45.1 %.