物理学报2024，Vol.73Issue(11)：110-121,12.DOI:10.7498/aps.73.20240335
基于匀光管的极紫外消相干和光强均匀化仿真研究
Simulation study of decoherence and light intensity uniformization for extreme ultraviolet of uniform light pipe
摘要
Abstract
Free electron laser(FEL)is a high-quality laser source with wavelengths ranging from short-wave X-ray to long-wave infrared ray.Extreme ultra-violet(EUV)radiation at λ=13.5 nm emitted by FEL can be used in manufacturing integrated circuit,such as EUV lithography exposure and mask defect inspection.However,the high spatial coherence characteristics and similar Gauss intensity profile distribution of FEL source has a negative effect on imaging,and cannot meet the requirements of imaging applications in EUV lithography.In this work,a newly light pipe for decoherence and intensity uniformity in an EUV spectral range is designed through the simulation calculations.The new light pipe consists of two pairs of tilted elements which are symmetrically distributed in the y-z plane and x-z plane,respectively.In this way,the beam transmission divergence in two dimensions can be widened at the same time,and the disturbance of the ray transmission track and spatial phase distribution is increased,so as to achieve the uniformization of light intensity and the reduction of spatial coherence. The simulation results show that for an EUV Gaussian beam at λ=13.5nm,with a diameter of 200 μm,and a divergence of 20 mrad,the newly designed light pipe has more significant decoherence and illumination field uniformity than the conventional light pipe structure.When the new light pipe has an inner diameter of 1mm,a total length of not less than 600 mm,and a tilt angle of 10mrad,a basically uniform illumination field can be obtained,the coherence is completely disordered,and the non-uniformity of light intensity distribution in the illumination field decreases to 0.97 from 28.38 achieved by conventional cylindrical light pipe.At the same time,the light power transmission efficiency is about 37.6%and the maximum transmission efficiency is about 44.58%.The uniformity can be further improved by increasing the number of reflections.When the inner diameter and tilted angle of the light pipe are unchanged,the length of the light pipe increases to 1m,the non-uniformity of intensity distribution at the illumination field further decreases to 0.90,and the light power transmission efficiency is about 22.35%.The results show that the newly designed light pipe structure can meet the application requirements of decoherence and improve the uniformity of illumination field at EUV wavelength range,and it has great application prospects in EUV lithography and other imaging applications.关键词
极紫外光源/自由电子激光/匀光管/相位/光强均匀性Key words
extreme ultraviolet source/free electron laser/light pipe/phase/intensity uniformity引用本文复制引用
李慧,谭芳蕊,尹皓玉,马钺洋,吴晓斌..基于匀光管的极紫外消相干和光强均匀化仿真研究[J].物理学报,2024,73(11):110-121,12.基金项目
国家自然科学基金(批准号:62071464)和中国科学院前瞻战略科技先导项目(A类先导项目)资助的课题. Project supported by the National Natural Science Foundation of China(Grant No.62071464)and the Foresight Strategic Science and Technology Pilot Project of the Chinese Academy of Sciences(Class A Pilot Project). （批准号:62071464）
