Development of coherent VUV Light Source for F_2 Laser Lithography

本计画旨在研制一种适用于F_2雷射微影制程之检测工具。为此，窄带宽在F_2激光波长下，研制了单模（<0.01pm）相干光源（157.6nm）的二次谐波产生和混频。在（1）方法中，我们发展了单模Ti：蓝宝石激光器的波长分别为768和681 nm，157.6 nm的光是通过681 nm与768 nm光的三次谐波（与Xe6p共振）的混合获得的。获得的激光输出功率为0.6mW，光谱宽度为0.008pm，达到了本课题的目标。方法（2）采用中国科学院陈教授提供的KBBF晶体研制了光接触棱镜耦合装置，由上述钛宝石激光器的四次谐波（680nm）产生170nm的光。这个波长是二次谐波产生（SHG）所获得的最短波长。准CW 177 nm光是通过商用355 nm激光器的SHG获得的，目前正在用于超高分辨率光电子能谱。156 nm辐射是由调谐到780 nm的Ti：蓝宝石激光器的五次谐波产生的。在157.6nm处获得了μ W量级的激光输出。

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.