Researchers at the Chinese Academy of Sciences (CAS) have developed a solid-state deep ultraviolet (DUV) laser that emits 193nm light in lab conditions—a wavelength critical for semiconductor lithography. Although still in the early research phase and not ready for commercial applications, its emergence has been viewed as a potential challenger to the excimer laser systems currently used in chip production.
A report from the International Society for Optics and Photonics (SPIE), cited by Tom's Hardware and Eetop.cn, suggests the experimental solid-state laser could be used in future lithography systems, potentially reducing reliance on gas-based excimer lasers.
The solid-state advantage over conventional systems
DUV lithography systems from ASML, Canon, and Nikon currently use argon fluoride (ArF) excimer lasers that produce 193nm light by exciting a gas mixture of argon and fluorine. These lasers deliver short, high-energy pulses with power ranging from 100W to 120W and frequencies of 8kHz to 9kHz, which are then directed through optics and a photomask to expose semiconductor wafers.
By contrast, the CAS system is entirely solid-state. It begins with a custom Yb crystal amplifier that generates a 1,030nm laser beam, which is then divided into two separate optical paths for nonlinear wavelength conversion.
One optical path uses the fourth harmonic generation (FHG) to convert the 1,030nm beam into 258nm, delivering 1.2W of power. The other path applies optical parametric amplification (OPA) to shift the wavelength to 1,553nm, generating 700mW.
The two beams—258nm and 1,553nm—are then mixed in a cascaded lithium triborate (LBO or LiB3O5) crystal to produce 193nm laser output. The system achieves an average power of 70mW at a 6kHz pulse rate, with a linewidth under 880MHz—specifications that approach the spectral purity of commercial excimer systems.
Performance gap remains significant
In terms of performance, the CAS prototype still lags behind commercial excimer systems. Its 70mW power and 6kHz pulse rate are far below ASML's ArF lasers, which exceed 100W and 9kHz—performance levels essential for high-volume semiconductor production.
Even so, the development marks early progress toward moving beyond gas-based laser technology. If engineers can improve output power and system stability, solid-state DUV lasers could eventually become a viable option for semiconductor manufacturing. Continued research and engineering refinements will be key to bridging this performance gap in the coming years.
Article translated by Levi Li and edited by Jerry Chen
