A compact, solid-state, nanosecond laser system capable of generating 193-nm coherent light — a wavelength crucial for the fabrication of silicon wafers — could greatly enhance the efficiency and precision of semiconductor lithography and open new paths to advanced manufacturing techniques. The advance comes from a team at the Aerospace Information Research Institute of the Chinese Academy of Sciences and reportedly marks the first time that a 193-nm vortex beam has been produced with a solid-state laser. Deep ultraviolet (DUV) lasers, known for their high photon energy and short wavelengths, are used in many fields, including high-resolution spectroscopy, precision material processing, and quantum technology as well as semiconductor lithography. DUV lasers offer increased coherence and reduced power consumption compared to excimer or gas discharge lasers, enabling the development of more compact systems. The new laser system uses an inhouse-developed Yb:YAG crystal amplifier to produce a 1030-nm laser, which is divided into two parts. One part undergoes fourth-harmonic generation to create a 258-nm laser with an output power of 1.2 watts (W). The other part pumps an optical parametric amplifier (OPA) to generate a 1553-nm laser with an average output power of 700 milliwatts (mW). The researchers combined the beams in cascaded lithium triborate (LiB3O5) crystals to produce the desired 193-nm laser as well as a 221-nm laser, which exhibited an average power of 270 mW. The 193-nm laser exhibited an average power of 70 mW and a repetition rate of 6 kilohertz (kHz), corresponding to a pulse energy of over 10 microjoules (µJ). This laser had a linewidth of less than 880 megahertz (MHz), resulting in a full width at half-maximum of less than 0.11 picometers (pm). A DUV, solid-state laser with a compact setup generates a vortex at 193-nm wavelength. Courtesy of the Chinese Academy of Sciences/Hongwen Xuan. Before frequency mixing, the researchers introduced a spiral phase plate into the optical path of the 1553-nm beam, changing its Gaussian mode into a vortex beam carrying orbital angular momentum (OAM) with a topological charge of 1. They used the vortex beam as the pump source for frequency conversion, successfully transferring the OAM to the 193-nm and 221-nm lasers. They achieved a vortex beam at 193-nm with a topological charge of 2. To the best of the team’s knowledge, this is the first compact, 193-nm laser generation system using OPA and cascaded LBO crystals, and the first demonstration of a 193-nm vortex beam generated from a solid-state laser. The vortex beam could be used to seed hybrid argon-fluoride (ArF) excimer lasers, and has the potential to support applications in wafer processing, defect inspection, quantum communications, and optical micromanipulation. DUV light sources operating at the ArF excimer laser wavelength of 193 nm are important for high-resolution semiconductor lithography. Seeding an ArF excimer amplifier with a narrow-linewidth, solid-state laser could provide a way to simultaneously obtain high-power output and high spatial coherence, to achieve a higher coherence and higher machining accuracy in advanced interference lithography. With its high-power output and unusual vortex beam feature, the compact, solid-state, nanosecond-pulsed laser system, operating at 193 nm with a narrow linewidth, could unlock new possibilities for solid-state laser technology. The ability to generate a 193-nm vortex beam could lead to further advances in semiconductor lithography, potentially transforming the way electronic devices are produced. The research was published in Advanced Photonics Nexus (www.doi.org/10.1117/1.APN.4.2.026011).
