Development of coherent VUV Light Source for F_2 Laser Lithography

本课题旨在开发一种用于F_2激光光刻的检测工具。为此，采用两种方法在F_2激光波长（157.6nm）处研制出窄带宽（<0.01pm）、单模相干光源，即气态Xe中的2光子谐振、4波混频，非线性晶体KBBF中的二次谐波产生和和频混频。在方法(1)中，我们开发了波长分别为768 nm和681nm的单模Ti：蓝宝石激光器。157.6 nm的光是通过681 nm与与Xe6p共振的768 nm光的三次谐波混合而得到的[5/ 2,2]。得到的输出功率为0.6mW，谱宽为0.008pm，清洗了本项目的目标。该光源用于确定Gigaphoton公司F_2激光表征光谱仪的仪器功能。方法(2)采用中国科学院陈教授提供的KBBF晶体研制了光学接触棱镜耦合器件。上述钛蓝宝石激光器（680nm）的四次谐波产生了170 nm的光。该波长是由二次谐波产生（SHG）获得的最短波长。准连续波177nm光是由355 nm商用激光器的SHG实现的，现在被用于超高分辨率光电子能谱。156nm的辐射是由调至780nm的钛蓝宝石激光的五次谐波产生的。这是非线性晶体所能获得的最短波长。157.6nm处的输出功率为μ W级。

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.