In the ever-evolving world of science and technology, the utilization of coherent light sources in the deep ultraviolet (DUV) region plays a vital role in various applications such as lithography, defect inspection, metrology, and spectroscopy. The traditional high-power 193-nanometer (nm) lasers have been instrumental in lithography but have faced challenges in coherence limitations, particularly in applications requiring high-resolution patterns.
The introduction of the hybrid ArF excimer laser, which integrates a narrow linewidth solid-state 193-nm laser seed in place of the ArF oscillator, has revolutionized the field. This innovative approach enhances coherence and narrow linewidth, thereby improving performance in high-throughput interference lithography. The hybrid ArF excimer laser not only enhances pattern precision but also accelerates lithography speed. Additionally, its heightened photon energy and coherence allow for direct processing of various materials with minimal thermal impact, highlighting its versatility in diverse fields like lithography and laser machining.
To optimize seeding for an ArF amplifier, the linewidth of the 193-nm seed laser must be meticulously controlled, ideally below 4 gigahertz (GHz). This specification is crucial for interference and can be achieved through solid-state laser technologies. A recent breakthrough from researchers at the Chinese Academy of Sciences has propelled this field forward by achieving a remarkable 60-milliwatt (mW) solid-state DUV laser at 193 nm with a narrow linewidth using a sophisticated two-stage sum frequency generation process employing LBO crystals.
The research conducted by the Chinese Academy of Sciences, as reported in Advanced Photonics Nexus, showcases impressive results in generating DUV lasers. The setup involving pump lasers at 258 and 1553 nm, derived from a Yb-hybrid laser and an Er-doped fiber laser, respectively, culminates in a 2mm×2mm×30mm Yb:YAG bulk crystal for power scaling. The output DUV laser, along with its 221-nm counterpart, exhibits an average power of 60 mW, a pulse duration of 4.6 nanoseconds (ns), and a repetition rate of 6 kilohertz (kHz) with a linewidth of approximately 640 megahertz (MHz).
This groundbreaking research not only sets new benchmarks in efficiency values but also underscores the immense potential of LBO crystals in generating DUV lasers at various power levels. Prof. Hongwen Xuan, the corresponding author for the work, highlights the importance of this research in demonstrating the viability of pumping LBO with solid-state lasers for the reliable generation of narrow-linewidth lasers at 193 nm. This advancement not only pushes the boundaries of DUV laser technology but also holds promise for revolutionizing applications across scientific and industrial domains.
The advancements in deep ultraviolet laser technology have opened up new possibilities for enhancing precision, speed, and efficiency in various applications. The integration of hybrid ArF excimer lasers and the breakthroughs in solid-state laser technology showcase the continuous evolution and innovation in the field of DUV lasers. The future holds exciting prospects for further advancements and discoveries in this realm, paving the way for transformative developments in science and technology.
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