软X射线多层膜与衰减膜研究

本文采用随机数的方法,发展了一种普适的多层膜设计方法,这种方法除可设计一般的周期多层膜,更重要的是它可以根据选定的评价因子,设计不同要求的非周期多层膜。用磁控溅射方法完成软X射线多层膜制备,X射线衍射、卢瑟福背散射、俄歇电子谱和反射率的相对测试用来表征多层膜结构和特性,所得结果说明多层膜的结构完整,周期参数正确。用离子束溅射方法成功地制备了有一定反射率和透过率的软X射线半反半透分束镜;分析了Ag和Zr衰减膜中的杂质含量与分布及其对衰减膜特性的影响,并对衰减系数进行了修正,为实验提供优质的衰减膜。     

制备长波段X射线多层膜的新方法

叙述用离子束溅射镀膜机OXFORD进行X射线长波段多层膜实验及制备X射线多层膜光学元件方面的工作。简述离子束油射镀膜机的工作原理,X射线多层膜的制备过程,主要工艺参数,以及用X射线小角衍射仪对制备样品周期结构的检测和用软X射线反射率计测反射率的部分结果。     

23.4nm软X射线多层膜反射镜研制

为了满足类氖-锗X射线激光研究的需要,设计制备了23.4 nm软X射线多层膜反射镜.依据多层膜选材原则并考虑材料的物理化学特性选择新的材料Ti与Si组成材料对.设计优化材料多层膜的周期厚度(d),材料比例(Γ),周期数(N),计算出Ti/Si反射率曲线.通过实验优化各种镀膜工艺参数,制备出了23.4 nm的Ti/Si多...     

用不同的Mo靶溅射功率制备Mo/Si多层膜

 用磁控溅射法制备了周期厚度和周期数均相同的Mo/Si多层膜,用原子力显微镜和小角X射线衍射分别研究了Mo靶溅射功率不相同时,Mo/Si多层膜表面形貌和晶相的变化。随后在国家同步辐射实验室测量了Mo/Si多层膜的软X射线反射率。研究发现,随着Mo靶溅射功率的增大,Mo/Si多层膜的表面粗糙度增加,Mo的特征X射线衍射峰也增强,Mo/Si多层膜的软X射线峰值反射率先增大后减小。     

用不同的Mo靶溅射功率制备Mo/Si多层膜

用磁控溅射法制备了周期厚度和周期数均相同的Mo/Si多层膜,用原子力显微镜和小角X射线衍射分别研究了Mo靶溅射功率不相同时,Mo/Si多层膜表面形貌和晶相的变化。随后在国家同步辐射实验室测量了Mo/Si多层膜的软X射线反射率。研究发现,随着Mo靶溅射功率的增大,Mo/Si多层膜的表面粗糙度增加,Mo的特征X射线衍射峰也增强,Mo/Si多层膜的软X射线峰值反射率先增大后减小。     

多层膜优化设计方法

传统多层膜设计所用的全局寻优法的速度非常慢，有时还很难得到理想的膜系。根据Frensnel反射系数公式计算多层膜的反射率，利用单纯形法对软X射线和X射线波段多层膜进行调优，可在短时间内优化出最接近目标光学性能的多层膜膜系结构。计算了不同波长软X射线周期性多层膜的最高理论反射率。单纯形调优算法在保证优化结果与随机搜索法优化结果近似相同的基础上，使优化计算速度提高了十倍以上。同时还用单纯形调优法优化设计了X射线超反射镜，得到了非常理想的非周期膜系。     

溅射气压对X射线多层膜反射率的影响

本文在不同的溅射气压的情况下制备了具有相同结构参量的Mo/Si多层膜,测出了其对应的小角度X衍射曲线,在北京同步辐射实验室测量了多层膜的软X射线反射率.小角X射线衍射谱表明:随着溅射气压升高,多层膜的小角X射线衍射曲线的高次峰的峰高急剧变小,半峰宽变大.反射率测量结果也表明:多层膜的X射线反射率随溅射气压的升高而急剧降低.     

研究扩散屏障层对Mo/Si多层膜软X射线反射率影响的模拟

在特定波长下,用四层结构模型模拟了Mo/Si多层膜的软X射线反射率.研究了扩散屏障层dMo-on-Si和dSi-on-Mo对Mo/Si多层膜软X射线反射率的影响.研究发现,扩散屏障层并不总是损害Mo/Si多层膜的光学性能,通过合理设计dMo-on-Si和dSi-on-Mo厚度,增加dMo-on-Si与dSi-on-Mo的比值,也能提高多层膜的软X射线反射率.     

Mo/Si软X射线多层膜的界面粗糙度研究

用磁控溅射法分别制备了以Mo膜层和Si膜层为顶层的Mo/Si多层膜系列, 利用小角X射线衍射确定了各多层膜的周期厚度。以不同周期数的Mo/Si多层膜的新鲜表面近似等同于同一多层膜的内界面,通过原子力显微镜研究了多层膜界面粗糙度随膜层数的变化规律。并在国家同步辐射实验室测量了各多层膜的软X射线反射率。研究表明：随着膜层数的增加,Mo膜层和Si膜层的界面粗糙度先减小后增加然后再减小,多层膜的峰值反射率先增加后减小。     

4.48 nm正入射软X射线激光用Cr/C多层膜高反射镜的研制

针对4.48nm类镍钽软X射线激光及其应用实验,设计制备了工作于这一波长的近正入射多层膜高反射镜。选择Cr/C为制备4.48nm高反射多层膜的材料对,通过优化设计,确定了多层膜的周期、周期数以及两种材料的厚度比。模拟了多层膜非理想界面对高反射多层膜性能的影响。采用直流磁控溅射方法在超光滑硅基片上实现了200周期Cr/C多层膜高反射镜的制备。利用X射线衍射仪测量了多层膜结构,在德国BessyⅡ同步辐射上测量了在工作波长处多层膜反射率,测量的峰值反射率达7.5%。对衍射仪测量的掠入射反射曲线和同步辐射测量的反射率曲线分别进行拟合,得到的粗糙度和厚度比的结果相近。测试结果表明,所制备的Cr/C多层膜样品结构良好,在指定工作波长处有较高的反射峰,达到了设计要求。     

13.9nm软X射线激光用大面积多层膜分束镜研制

 基于分束镜反射率和透射率的乘积为衡量标准的原则,设计了13.9nm软X射线激光干涉测量所需的多层膜分束镜，用磁控溅射法在有效面积达10mm×10mm，厚100nm的氮化硅窗口上镀制Mo/Si多层膜,实现了分束镜制作。用表面轮廓仪实测分束镜面形精度达到nm量级，同步辐射反射率计测试表明,分束镜的反射率和透射率乘积约4%。     

13.9nm软X射线激光用大面积多层膜分束镜研制

基于分束镜反射率和透射率的乘积为衡量标准的原则,设计了13.9nm软X射线激光干涉测量所需的多层膜分束镜,用磁控溅射法在有效面积达10mm×10mm,厚100nm的氮化硅窗口上镀制Mo/Si多层膜,实现了分束镜制作。用表面轮廓仪实测分束镜面形精度达到nm量级,同步辐射反射率计测试表明,分束镜的反射率和透射率乘积约4%。     

Structural stability of heat-treated Co/C soft X-ray multilayers fabricated by dual-facing-target sputtering

Thermal stability of Co/C multilayers prepared by a dual-facing-target sputtering system was studied. A picture of the thermally induced changes in the microstructure was obtained using complementary measurement techniques including low-angle and high-angle X-ray diffraction, transmission electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. It was found that the period expansion, reflectivity change and compound formation, that were observed after annealing are caused by structural changes both in the sublayers and at the interfaces. Below 400°C, the period expansion is mainly caused by the graphitization of the amorphous carbon layers, and a significant increase in the reflectivity at grazing incidence was observed. By 500°C, the crystallization and agglomeration of Co layers induce an enormous period expansion and a serious decrease in reflectivity. A small amount of carbide is found to form at this temperature. Our results imply that new multilayer structures, e.g., compound multilayers will have to be developed for use at high temperatures or under high X-ray incident flux.     

极紫外多层膜制备工艺研究

介绍了用平面磁控溅射方法制备极紫外多层膜的研究工作。围绕极紫外多层膜技术 ,重点探讨了多层膜膜厚定标和工艺过程对多层膜结构和内部成分的影响。为深入研究多层膜制备工艺指明了方向。     

Influence of interface roughness on reflectivity of tungsten/boron-carbide multilayers with variable bi-layer number by X-ray reflection and diffuse scattering

Infuence of interface roughness on the reflectivity of Tungsten/boron-carbide （W/B4C） multilayers varying with bi-layer number, N, is investigated. For W/B4C multilayers with the same design period thickness of 2.5 nm, a real-structure model is used to calculate the variation of reflectivities with N = 50, 100, 150, and 200, respectively. Then, these multilayers are fabricated by a direct current （DC） magnetron sputtering system. Their reflectivity and scattering intensity are measured by an X-ray diffractometer （XRD） working at Cu Kα line. The X-ray reflectivity measurement indicates that the reflectivity is a function of its bi-layer number. The X-ray scattering measured results show that the interface roughness of W/B4C multilayers increases slightly from layer to layer during multilayer growing. The variation of the reflectivity and interface roughness with bi-layer number is accurately explained by the presented realstructure model.     

X-ray scattering study of interfacial roughness in Nb/PdNi multilayers

Specular and diffuse X-ray scattering are used to study interfacial roughness in Nb/Pd_0.81Ni_0.19 multilayers deposited by dc UHV sputtering. The data are analyzed to extract information about the correlated behavior of interface roughness in both the lateral and vertical directions. X-ray reflectivity is treated quantitatively by computer-aided simulation and modelling in order to extract values also for the layers thickness. From the analysis of the diffusive spectra of the reflectivity maps the roughness correlation has been evaluated.     

Influence of working gas pressure on the performance of W/Si multilayers

The effect of Ar pressure on the performance of W/Si multilayers is investigated. W/Si multilayers were deposited by a high vacuum DC magnetron sputtering system. The Ar pressure was changed from 1.0 to 5.0 mTorr with an interval of 1.0 mTorr during the deposition process. Electron probe microanalysis and Rutherford backscattering are performed to determine the Ar content incorporated within these multilayers. The results demonstrate that less Ar is incorporated within the sample when more Ar is used in the plasma, which could be explained by the increase of the collision probability and the decrease in the kinetic energy of Ar ions arriving at the substrate when more Ar exists. The grazing incident X-ray reflectivity (GIXR) at 0.154 nm is used to determine the structural parameters of the layers. The results show that the structures of these multilayers prepared at different Ar pressure are very similar and that the interface roughness increases quickly when the Ar pressure is higher than 3.0 mTorr. The measurements of the extreme ultraviolet (EUV) reflectivity indicate that the reflectivity decreases when Ar pressure increases. The fitting results of GIXR and EUV reflectivity curves indicate that with an increase of Ar pressure, the density and decrement of the refractive index are increased for W and decreased for Si, which is mainly due to (1) the decrease in Ar content incorporated within these multilayers which affects their performance and (2) the increase of collision probability for sputtered W and Si, the decrease of their average kinetic energy arriving at the substrate, and thus the loosing of their layers.