Material analysis with EUV/XUV radiation using a broadband laser plasma source and optics system
Material analysis with EUV/XUV radiation using a broadband laser plasma source and optics system
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DOI：
10.1117/12.822585
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发表时间：
2009-04
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影响因子：
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通讯作者：
A. Bayer;F. Barkusky;J. Dette;S. Döring;B. Flöter;C. Peth;K. Mann
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文献类型：
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作者：
A. Bayer;F. Barkusky;J. Dette;S. Döring;B. Flöter;C. Peth;K. Mann
受半导体行业发展路线图的推动，近年来极紫外（EUV）光源和高质量EUV光学薄膜的开发取得了巨大进展，开辟了微光刻以外的新应用领域，如计量学、高分辨率显微镜或表面分析。哥廷根激光实验室开发了一种激光驱动等离子体源，用于产生光谱范围为2... 20纳米。将Nd：YAG激光（1064 nm，800 mJ，6 ns）聚焦到气体靶中，形成等离子体，然后发射特征软X射线辐射。因此，主要焦点在于13.5 nm左右的波长（“EUV”-未来的光学光刻）和所谓的水窗（2.2 nm... 4.4 nm -“XUV”）区域。根据所采用的目标气体，可以获得窄带（例如，用于EUV的O2，用于XUV的N2）以及宽带（例如，用于EUV的Ar，用于XUV的Kr）光谱。为了聚焦，开发了灵活的Kirkpatrick-Baez光学器件，由于掠入射反射而提供宽带光转向。该装置的碳涂层反射镜由弯曲的硅晶片切片形成，允许连续调谐到所需的曲率。作为这样一个设置的应用程序，在碳K边的近边X射线吸收精细结构光谱（NEXAFS）的结果将被提交。研究的系统范围从合成聚合物（PMMA，PI）到有机物质（腐殖酸）到生物物质（脂质），为每种化合物提供独特的光谱。因此，使用桌面XUV源的NEXAFS光谱可以被建立为用于化学分析的高表面灵敏度指纹方法。
Triggered by the roadmap of the semiconductor industry, tremendous progress has been achieved in the development of Extreme Ultraviolet (EUV) sources and high-quality EUV optical coatings in recent years, opening up also new fields of applications apart from microlithography, such as metrology, high-resolution microscopy, or surface analysis. The Laser-Laboratorium Göttingen has developed a laser-driven plasma source for generation of soft X-rays in the spectral range 2...20 nm. A Nd:YAG laser (1064 nm, 800 mJ, 6 ns) is focused into a gas-target leading to the formation of a plasma which in turn emits characteristic soft X-ray radiation. Hereby the main focus lies on wavelengths around 13.5 nm ("EUV" - future optical lithography) and the so called water window (2.2 nm...4.4 nm - "XUV") region. Depending on the employed target gas, narrow-band (e.g. O2 for EUV, N2 for XUV) as well as broad-band (e.g. Xe for EUV, Ar, Kr for XUV) spectra can be obtained. For focusing a flexible Kirkpatrick-Baez optics was developed, providing broad-band light steering due to grazing-incidence reflection. The carbon-coated mirrors of this device are formed by bent silicon wafer slices allowing continuous tuning to the desired curvatures. As an application of such a setup, results on near-edge X-ray absorption fine structure spectroscopy (NEXAFS) at the carbon K-edge will be presented. The investigated systems range from synthetic polymers (PMMA, PI) over organic substances (humic acids) to biological matter (lipids), delivering unique spectra for each compound. Thus NEXAFS spectroscopy using a table-top XUV source could be established as a highly surface sensitive fingerprint method for chemical analysis.