脉冲激光辐照液滴锡靶等离子体极紫外辐射的实验研究

摘要

采用波长13.5 nm的极紫外光作为曝光光源的极紫外光刻技术是最有潜力的下一代光刻技术之一，它是半导体制造实现10 nm及以下节点的关键技术.获得极紫外辐射的方法中，激光等离子体光源凭借转换效率高、收集角度大、碎屑产量低等优点而被认为是最有前途的极紫外光源.本文开展了脉冲TEA-CO2激光和Nd：YAG激光辐照液滴锡靶产生极紫外辐射的实验，对极紫外辐射的谱线结构以及辐射的时空分布特性进行了研究.实验发现：与TEA-CO2激光相比，较高功率密度的Nd：YAG激光激发的极紫外辐射谱存在明显的蓝移；并且激光等离子体光源可以认为是点状光源，其极紫外辐射强度随空间角度变化近似满足Lambertian分布.%Extreme ultraviolet lithography (EUVL), which uses the extreme ultraviolet radiation at a wavelength of 13.5 nm, is the leading candidate of next generation lithography addressing not only the 10 nm half-pitch nodes, but several nodes beyond that. Among all the methods for getting EUV radiation, laser-produced plasma (LPP) light source is the most promising EUV light source because of its high conversion efficiency (CE), large collect angle and low debris output. In this paper, pulsed TEA-CO2 laser and Nd:YAG laser are used to irradiate tin droplets to obtain plasma EUV emission, and the properties of EUV radiation from the plasma are studied. Results show that the EUV emission spectra induced by Nd:YAG laser have an obvious blueshift as compared with those by CO2 laser. In addition, the LPP sources are point light sources, so that the angular distribution of EUV emission from LPP can be described by Lambertian distribution.