首页> 外文学位 >Two topics in surface science: Morphological changes of nickel-aluminumAl(111) induced by oxygen; secondary electron yield studies of ruthenium and titanium dioxide surfaces related to extreme ultraviolet lithography.
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Two topics in surface science: Morphological changes of nickel-aluminumAl(111) induced by oxygen; secondary electron yield studies of ruthenium and titanium dioxide surfaces related to extreme ultraviolet lithography.

机译:表面科学中的两个主题:氧诱导镍铝Al(111)的形态变化;与极紫外光刻相关的钌和二氧化钛表面的二次电子产率研究。

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摘要

This dissertation reports on two surface science projects: (1) one focuses on a study of oxygen-induced faceting of a NiAl(111) single crystal surface as a potential support for model catalysts; and (2) the other concerns secondary electron yield studies of TiO2(011) and Ru(0001), which are models of ruthenium and titanium dioxide capping layers on Mo/Si multilayer mirrors designed for applications in Extreme Ultraviolet Lithography (EUVL).;It is known that monolayer films of oxygen can induce faceting of some atomically rough but planar metal surfaces. We extend our knowledge from surfaces of elemental metals to atomically rough metal alloy surfaces, such as NiAl(111). We discovered that the NiAl(111) surface exhibits an unusual behavior upon interaction with oxygen, including nanometer scale facet formation and growth of micrometer scale dendritic features. A series of experiments aimed at understanding the adsorption of oxygen and oxygen-induced faceting of NiAl(111) employing a variety of ultrahigh vacuum surface characterization methods.;The atomically rough NiAl(111) surface remains planar at room temperature when exposed to oxygen. However, the oxygen-covered surface changes its morphology and forms nanometer scale facets upon annealing in the temperature range of ∼1050 K to 1200K. Covered with one monolayer-thick gamma-Al2O 3 film, three-sided facets of {110} orientation appear. These facets coexist with the planar (111) surface. The surface becomes planar upon annealing in UHV above ∼1250K.;After prolonged exposure to oxygen at elevated temperatures three dimensional features exhibiting three-fold symmetry erupted from the surface; their dimensions are several micrometers in length, and ∼300 nm high; their orientation is along low index 101> directions in the plane of the NiAl(111) substrate. SEM X-ray mapping and EDS measurements indicate that these are spinel (NiAl 2O4) structures; further investigation with SPEM revealed that these structures consist of gamma-Al2O3 and NiAl 2O4 oxides. Finally, TEM studies of the cross section of dendrites-covered NiAl(111) surface detected that gamma-Al2O 3 [131] is aligned with the NiAl[111] direction with a mismatch angle of 6°.;Ruthenium and titanium dioxide capping layers ∼2 nm thick protect and extend the lifetimes of Mo/Si multilayer mirrors (MLMs) used in EUVL. The magnitude of secondary electron yield (SEY) at EUV wavelengths (13.5nm) is a major factor in determining contamination rates of MLMs in EUV projection optics. Low energy secondary electrons (0 to ∼ 20 eV) cause dissociation of adsorbed hydrocarbons from the background gas, and lead to carbon film growth on MLM surfaces.;In this dissertation, we investigate SEY for model EUV optics cap layer materials -TiO2 and Ru single crystals (clean, O-covered, C-covered, air exposed) and compare them with measurements for Mo/Si multilayer films capped with Ru, TiO2, and RuO2. SEY measurements were performed using synchrotron radiation over the range 40 eV to 180 eV at three different beamlines (U4A, U5UA, and U3C) at NSLS.;For photon beams incident at 45°, the shapes of the curves for Ru MLMs, especially the maxima at ∼ 65 eV due to the Ru 4p excitation, are very similar to the data for pure Ru; such similarities are found also for a TiO2 crystal and TiO2-capped MLMs. The observation that the cap layer properties dominate the SEY characteristics agrees with theory. For near normal incidence, and for photon energies ∼92 eV, dramatic energy- and angle-dependent resonances in SEY are observed for the capped MLMs, with SEYs 2 to 3 times higher than off-resonance. Calculations show excellent correlations between the photon electric field strength on the surface of a cap layer and the angular-dependent SEYs.
机译:这篇论文报道了两个表面科学项目:(1)着重研究氧诱导的NiAl(111)单晶表面的刻面作为模型催化剂的潜在载体; (2)另一个涉及TiO2(011)和Ru(0001)的二次电子产率研究,这是设计用于极端紫外光刻(EUVL)的Mo / Si多层反射镜上钌和二氧化钛覆盖层的模型。众所周知,氧气的单层膜可以引起一些原子上粗糙但平坦的金属表面的刻面。我们将知识从元素金属的表面扩展到原子粗糙的金属合金表面,例如NiAl(111)。我们发现,NiAl(111)表面与氧相互作用时表现出不寻常的行为,包括纳米级小平面的形成和微米级树突状特征的生长。通过多种超高真空表面表征方法,旨在了解氧气的吸附和氧气诱导的NiAl(111)刻面的一系列实验。;原子粗糙的NiAl(111)表面在暴露于氧气时在室温下保持平坦。但是,在〜1050 K至1200K的温度范围内退火时,被氧气覆盖的表面会改变其形态并形成纳米级的小平面。用一层单层厚的γ-Al2O3膜覆盖,出现{110}取向的三面刻面。这些小平面与平面(111)表面共存。当在〜1250K以上的超高压中退火时,表面变为平面;在高温下长时间暴露于氧气后,表面呈现出三重对称的三维特征;它们的尺寸为几微米长,约300 nm高。它们的取向沿NiAl(111)衬底平面中的低折射率<101>方向。 SEM X射线作图和EDS测量表明它们是尖晶石(NiAl 2O4)结构。通过SPEM进行的进一步研究表明,这些结构由γ-Al2O3和NiAl 2O4氧化物组成。最后,用TEM研究树枝状晶体覆盖的NiAl(111)表面,发现γ-Al2O3 [131]与NiAl [111]方向对准,错配角为6°。钌和二氧化钛覆盖层约2 nm厚的膜可保护并延长EUVL中使用的Mo / Si多层反射镜(MLM)的寿命。 EUV波长(13.5nm)处的二次电子产率(SEY)的大小是确定EUV投影光学系统中MLM污染率的主要因素。低能二次电子(0到20 eV)引起从背景气体中分离出的碳氢化合物离解,并导致MLM表面的碳膜生长。;本文,我们研究了EUV光学模型盖层材料TiO2和Ru的SEY。单晶(干净,O覆盖,C覆盖,暴露于空气),并将它们与覆盖有Ru,TiO2和RuO2的Mo / Si多层膜的测量值进行比较。 SEY测量是在NSLS的三个不同光束线(U4A,U5UA和U3C)上使用40 eV至180 eV范围内的同步加速器辐射进行的;对于45°入射的光子束,Ru MLM的曲线形状,特别是由于Ru 4p激发,在〜65 eV时的最大值与纯Ru的数据非常相似;对于TiO2晶体和TiO2封端的MLM,也发现了这种相似性。盖层特性支配SEY特性的观察与理论相符。对于接近法线入射和约92 eV的光子能量,加盖的MLM在SEY中观察到剧烈的依赖于能量和角度的共振,其SEY较非共振高2至3倍。计算表明,盖层表面的光子电场强度与与角度有关的SEY之间具有极好的相关性。

著录项

  • 作者

    Loginova, Elena.;

  • 作者单位

    Rutgers The State University of New Jersey - New Brunswick.;

  • 授予单位 Rutgers The State University of New Jersey - New Brunswick.;
  • 学科 Physics Condensed Matter.
  • 学位 Ph.D.
  • 年度 2008
  • 页码 180 p.
  • 总页数 180
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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