Development of coherent VUV Light Source for F_2 Laser Lithography

本课题旨在研制一种F_2激光光刻检测工具。为此，窄带(&lt；利用两种方法，(1)双光子谐振，气体Xe中的四波混频，(2)非线性晶体KBBF中的二次谐波和和频，分别获得了波长分别为768和681 nm的单模掺钛蓝宝石激光器，其中681 nm的光与与Xe6P[5/2，2]共振的768 nm光的三次谐波混频，获得了157.6 nm的光。获得的输出功率为0.6 mW，光谱宽度为0.008 pm，达到了本项目的设计指标。方法(2)用中科院陈教授提供的KBBF晶体研制了光学接触式棱镜耦合装置，用上述钛宝石激光器(680 Nm)的四次谐波产生170 nm的光。这个波长是由二次谐波(SHG)获得的最短波长。准连续177 nm激光由商用355 nm激光器倍频获得，目前正在用于超高分辨率光电子能谱，其中156 nm辐射是由钛宝石激光器的五次谐波调谐到780 nm产生的。该波长是由非线性晶体获得的最短波长，在157.6 nm处的输出功率达到了μW的水平。

This project aims at the development of an inspection tool for F_2 laser lithography. For this purpose, the narrow bandwidth (<0.01pm), single mode, coherent light source was developed at the F_2 laser wavelength (157.6nm) by two methods, (1) 2-photon resonant, 4-wave mixing in gaseous Xe, (2) Second harmonic generation and sum frequency mixing in a nonlinear crystal KBBF.In the method (1), we developed single mode, Ti : sapphire lasers with the wavelengths of 768 and 681nm respectively.The 157.6-nm light was achieved by the mixing of 681 nm with the third harmonic of the 768-nm light which is in resonance to Xe6p[5/2, 2]. The obtained output power and spectral width were 0.6mW and 0.008pm, cleaning the target of this project. This light source was used to determine the instrumental function of the spectrometer for the characterization of F_2 laser in Gigaphoton inc.In the method (2) the optically contacted, prism-couple device was developed by a KBBF crystal supplied from Prof. Chen in Chinese Academy of Science.The 170-nm light was generated by the 4th harmonic of the above-mentioned Ti : sapphire laser (680nm). This wavelength is the shortest ever obtained by second harmonic generation (SHG). The quasi CW 177-nm light was achieved by SHG of a commercial 355-nm laser and is now being used for ultra high-resolution photoelectron spectroscopy.The 156-nm radiation was generated by the 5th harmonic of the Ti : sapphire laser tuned to 780nm. This wavelength is the shortest ever obtained by nonlinear crystals.The output power at 157.6nm was at a level of μ W.