三硼酸锂晶体上1064 nm,532 nm,355 nm三倍频增透膜的设计

采用矢量法设计了三硼酸锂晶体上1064 nm、532 nm和355 nm三倍频增透膜,结果表明1064 nm、532 nm和355 nm波长的剩余反射率分别为0.0017%、0.0002%和0.0013%。根据误差分析,薄膜制备时沉积速率精度控制在 5.5%时,1064 nm、532 nm和355 nm波长的剩余反射率分别增加至0.20%、0.84%和1.89%。当材料折射率的变化控制在 3%时,1064 nm处的剩余反射率增大为0.20%,532 nm和355 nm处分别达0.88%和0.24%。与薄膜物理厚度相比,膜层折射率对剩余反射率的影响大。对膜系敏感层的分析表明,在1064 nm和355 nm波长,从入射介质向基底过渡的第二层膜的厚度变化对剩余反射率的影响最大,其次是第一膜层。在532 nm波长,第一和第三膜层是该膜系的敏感层。同时发现,由于薄膜材料的色散,1064 nm5、32 nm和355 nm波长的剩余反射率分别增加至0.15%、0.31%和1.52%。     

组合倍率极紫外光刻物镜梯度膜设计EI北大核心CSCD

10nm以下光刻技术牵引极紫外(EUV)光刻物镜向超高数值孔径(NA)、组合倍率设计形式发展,物镜系统的入射角和入射角范围因此急剧增大,传统规整膜和横向梯度膜难以满足该类物镜系统反射率及像质要求。为此,提出了横纵梯度膜组合法,用横向梯度膜提高反射率,用纵向梯度膜提高反射率均匀性,并补偿横向梯度膜引入的像差。应用该方法对一套NA为0.50的组合倍率EUV光刻物镜进行膜层设计,设计结果表明,在保证系统成像性能不变的情况下,平均每面反射镜的反射率大于60%,各反射镜的反射峰谷值均小于3.5%,满足光刻要求,验证了横纵梯度膜组合法的可行性。     

基于传输矩阵法的多层介质膜反射特性研究

薄膜干涉是大学物理波动光学教学的重要内容,也是薄膜光学的理论基础.薄膜干涉的一个重要应用是用于设计减反膜和高反膜.本文基于传输矩阵法,定量计算了多层介质膜的反射率.以BK7玻璃为例,无镀膜时在可见光范围内,其反射率约为4%.利用薄膜的相消干涉可以减少表面的反射率.镀一层减反膜时,对设计波长550 nm其反射率下降为1.3%,一旦偏离设计波长减反效果变差;镀两层减反膜时,在470 nm～670 nm范围内,减反效果明显改善,反射率均低于1.3%.利用薄膜的相长干涉可以增加表面的反射率.以熔石英为例,镀一层薄膜时,对设计波长1500 nm其反射率可由未镀膜时的3.3%提高到30%;镀七组薄膜时在1360 nm～1660 nm范围内其反射率均可达99%以上.通过这些定量计算,让学生更加深刻地理解所学理论知识在实际中的应用,培养工程意识,提高学习兴趣.     

30.4 nm波长处Mg基多层膜反射镜

太阳光谱中重要的He-Ⅱ谱线(波长30.4 nm)的观测对于研究太阳活动和日地空间环境具有重要意义,实现空间极紫外太阳观测需要采用多层膜作为反射元件.研究了工作在30.4 nm的Mg基多层膜.以反射率最高为评价函数设计了多层膜,采用直流磁控溅射技术制备了SiC/Mg,B4C/Mg和C/Mg多层膜,用X射线衍射仪测量了多层膜的结构.研究表明虽然B4C/Mg多层膜理论反射率最高,但实际制备结果显示,SiC/Mg多层膜的成膜质量最好,反射率最高.同步辐射反射率测量表明:在入射角10°时实测的SiC/Mg多层膜反射率为44.6%.     

组合倍率极紫外光刻物镜梯度膜设计

10nm以下光刻技术牵引极紫外(EUV)光刻物镜向超高数值孔径(NA)、组合倍率设计形式发展,物镜系统的入射角和入射角范围因此急剧增大,传统规整膜和横向梯度膜难以满足该类物镜系统反射率及像质要求。为此,提出了横纵梯度膜组合法,用横向梯度膜提高反射率,用纵向梯度膜提高反射率均匀性,并补偿横向梯度膜引入的像差。应用该方法对一套NA为0.50的组合倍率EUV光刻物镜进行膜层设计,设计结果表明,在保证系统成像性能不变的情况下,平均每面反射镜的反射率大于60%,各反射镜的反射峰谷值均小于3.5%,满足光刻要求,验证了横纵梯度膜组合法的可行性。     

组合倍率极紫外光刻物镜系统梯度膜设计方法

随着极紫外(EUV)光刻物镜的设计朝着组合倍率物镜系统的方向发展,物镜系统需要同时具有大视场和高数值孔径(NA),因而产生了物镜的光线入射角及入射角范围急剧增大的问题,需要研究适用于组合倍率极紫外光刻物镜系统的膜层设计的新方法。提出了渐进优化膜层的设计方法,该方法提高了镀制膜层的物镜系统的反射率,保证了组合倍率物镜系统的成像质量。利用该方法对NA为0.6的组合倍率物镜系统进行了膜层设计,设计结果表明,含膜极紫外光刻物镜系统的平均反射率大于65%,各反射镜的反射率峰谷值均小于3.35%,反射率均匀性良好。     

在19.5 nm处高反在30.4 nm处抑制的双功能薄膜

 研究了极紫外波段的双功能光学元件。采用周期膜叠加的思想,运用遗传方法优化设计了在19.5 nm处高反,在30.4 nm处抑制的双功能多层膜。采用磁控溅射技术制备了多层膜,利用X射线衍射仪测试了多层膜的结构,在国家同步辐射实验室测试了双功能多层膜的反射特性。结果表明：制备出的双功能膜性能与设计相符,在入射角13°,19.5 nm处的反射率达到33.3%,接近传统的19.5 nm周期高反膜的反射率,并且在30.4 nm附近将反射率由1.1%降到9.6×10^-4。     

GaSb基激光器腔面膜的材料选取及膜系设计

为了提高GaSb基激光器腔面膜的反射率,根据有关薄膜设计理论并借助薄膜设计软件,设计出激光器腔面膜膜系。使高反膜在2.0~3.5μm波段的理论反射率高于95%;增透膜在波长为2.5μm处的理论透射率高于99%。并经过反复实验操作比较了实验与理论设计反射率曲线,结果表明,实验所得反射率能达到实际应用的要求。除此之外,还通过比较各种材料的特性,讨论了薄膜材料的选取。     

低原子序数材料窄带多层膜的研制

为研制极紫外波段窄带多层膜反射镜,采用低原子序数材料组合设计了30.4 nm波长处Mg/SiC,Si/SiC,Si/B4C和Si/C多层膜反射镜,并与极紫外波段传统的Mo/Si多层膜反射镜进行对比。采用直流磁控溅射技术制备了这些多层膜,在国家同步辐射实验室辐射与计量光束线完成了多层膜反射率测量,测量结果表明:Mg/SiC多层膜的带宽最小,为1.44 nm,且反射率最高,为44%;而Mo/Si多层膜的反射率仅为24%,带宽为3.11 nm。实验结果证明了采用低原子序数材料组成的多层膜的带宽要比常规多层膜窄,该方法可以应用于极紫外波段高分辨研究。     

157 nm氟化物光学薄膜制备

为了研制低损耗、高性能的157 nm薄膜,研究了常用的六种宽带隙氟化物薄膜材料.制备和研究了六种氟化物单层膜,并以不同高低折射率材料对,设计制备了157 nm高反膜和增透膜|讨论和比较了不同氟化物材料对所组成的高反膜和增透膜的反射率、透射率、光学损耗等特性.结果表明,采用NdF3/AlF3 材料对设计制备的157 nm高反膜的透过率为1.7%,反射率接近93%,散射损耗为2.46%,已经与吸收损耗相当|以AlF3/LaF3材料对设计制备的157 nm增透膜的剩余反射率低于0.17%.     

极紫外多层膜技术研究进展

在极紫外波段,任何材料都表现出极强的吸收特性,因此,采用多层膜实现高反射率是构建正入射式光学系统的唯一途径。本文总结了极紫外多层膜的发展进程,叙述了制备极紫外多层膜的关键技术(磁控溅射、电子束蒸发、离子束溅射)以及它们涉及的相关设备。由于多层膜反射式光学元件主要应用于极紫外光刻与极紫外天文观测,文中重点讨论了极紫外光刻系统对多层膜性能的要求,镀膜过程中的面形精度和热稳定性等问题;同时介绍了极紫外天文观测中使用的多层膜的特点,特别讨论了多层膜光栅的制备技术和亟待解决的问题。     

多层膜聚光镜对Schwarzschild显微镜成像均匀性的影响

 提出了利用多层膜聚光镜提高Schwarzschild显微镜成像均匀性的方法。设计了聚光镜的光学结构,使80%的等离子体辐射能量会聚在约0.8 mm直径的范围内。根据成像系统的工作波长和光线在聚光镜表面的入射角度,设计了Mo/Si周期多层膜,制备了聚光镜光学元件,膜层周期厚度为9.64 nm,周期数为30,对18.2 nm波长的峰值反射率为51.7%。利用所设计的聚光镜作为照明系统,对Schwarzschild物镜进行了网格成像实验。结果表明:在1.2 mm视场内可以实现2.5 μm的空间分辨力,并且完全消除了物镜中心遮拦所造成的像面光强分布不均匀性。     

Development of Al-based multilayer optics for EUV

We report on the development of multilayer optics for the extreme ultra-violet (EUV) range. The optical performance of Al-based multilayer mirrors is discussed with regard to promising reflectivity and selectivity characteristics and the problems of the interfacial roughness for this type of multilayers. We demonstrate a possibility to reduce the average roughness by introducing additional metal layer (W or Mo) rather than depositing a buffer layer at each interface. We have prepared and tested Al/SiC, Al/W/SiC and Al/Mo/SiC multilayers of various periods for the spectral range from 15 to 40 nm, which is the range of increasing interest for high-order harmonic generation, synchrotron radiation and astrophysics. The structure of the three-component systems has been optimized in order to obtain the best reflectivity for each wavelength within the spectral range. We have shown that introduction of refractory metal in Al-based periodic stack can improve the optical performance of multilayer reflecting coatings designed for the EUV applications.     

The thermal stability of Al(1%wtSi)/Zr EUV mirrors

Six Al(1%wtSi)/Zr multilayers are deposited on Si substrates by using the direct-current magnetron sputtering system, and annealed from 100?°C to 500?°C temperature in a vacuum furnace for 1?h. To evaluate the thermal stability of Al(1%wtSi)/Zr multilayers, the multilayers were characterized by grazing incidence X-ray reflectance, X-ray diffraction, X-ray emission spectroscopy, and near-normal incident extreme ultraviolet (EUV) reflection. The symmetric and asymmetric interlayer models are used to present the interfacial structure before and after 300?°C. The Al(1%wtSi)/Zr multilayer annealed up to 200?°C maintains the initial symmetric multilayer structure, and keeps almost the similar EUV reflectivity as the nonannealed sample. From 300?°C, interdiffusion is much greater at the Zr/Al interface compared with the Al/Zr interface. And the interfacial phases of Al-Zr alloy transform from amorphous to polycrystalline, which induces the deterioration of multilayer structure and the decrease of EUV reflectivity. However, up to 500?°C, the polycrystalline Al-Zr compound does not destroy the multilayer completely.     

Metrologies for the phase characterization of attosecond extreme ultraviolet optics

Extreme ultraviolet (EUV) optics play a key role in attosecond science since only with higher photon energies is it possible to achieve the wide spectral bandwidth required for ultrashort pulses. Multilayer EUV mirrors have been proposed and are being developed to temporally shape (compress) attosecond pulses. To fully characterize a multilayer optic for pulse applications requires not only knowledge of the reflectivity, as a function of photon energy, but also the reflected phase of the mirror. We develop the metrologies to determine the reflected phase of an EUV multilayer mirror using the photoelectric effect. The proposed method allows one to determine the optic's impulse response and hence its pulse characteristics.     

帽层对极紫外多层膜反射特性影响分析

介绍了在极紫外波段，利用帽层材料来减少多层膜反射镜因外部环境干扰而造成的反射率降低，使多层膜光学元件能够长时间稳定工作.计算了在139nm波长处Mo/Si极紫外多层膜反射镜在表面镀制不同帽层材料时的理论最大反射率，利用单纯形调优法，对帽层和多层膜的周期厚度进行优化，同时把分层理论用于多层膜帽层优化,可使多层膜的反射率得到进一步提高.分析了在加入帽层前后多层膜外层电场强度的分布变化情况. 关键词： 多层膜 反射率 帽层 极紫外     

中心波长为13．9nm的正入射Mo／Si多层膜

用由铜靶激光等离子体光源等组成的反射率计对自行设计的周期厚度为7.14nm的120层Mo/Si多层膜进行极紫外(EUV)波段反射率测量。由于多层膜层数增加所引起的吸收、膜层界面之间的扩散以及镀膜过程中的膜厚控制误差或表面被氧化(污染)等原因,正入射Mo/Si多层膜在13.9nm处的反射率低于理论计算值73.2%,最后用原子力显微镜(AFM)测量其表面粗糙度为σ=0.401nm。     

Reflective phase shift measurement of the Mo/Si multilayer mirror in extreme ultraviolet region

The reflective phase shift of multilayer mirror is one important property required in EUV lithography and attosecond pulses experiments. The reflective phase shift of the periodic Mo/Si multilayer mirror was characterized by combining the reflectivity with total electron yield signal at the synchrotron radiation in Hefei. The multilayer was fabricated using direct current magnetic sputtering method. Using the wavelet transform approach, the period and each layer thickness were obtained, the small angle X-ray reflective data from X-ray diffractometer were fitted using these data as the mutilayer's initial structure. The TEY signal of the multilayer is coincided with the surface electron field of the multilayer. A thick Si layer was used to eliminate the effect of the multilayer's surface layer on the TEY signal. The retrieved difference in reflected phase from the incident phase was obtained combining the reflectivity with the total electron yield signal and it is similar with the calculated phase shift of the multilayer.     

Design and performance of two-channel EUV multilayer mirrors with enhanced spectral selectivity

In this paper, we present a study on two-channel multilayer mirrors which can operate at two wavelengths in Extreme Ultraviolet (EUV) spectral range. We propose a new method to design two-channel EUV multilayer mirrors with enhanced spectral selectivity. The mirror structure is a stack of two periodic multilayers separated by a buffer layer. We have defined the main parameters which allow adjustment of the distance between different order Bragg’s peak and of wavelength positions of reflectivity minima. Two mirrors have been designed and deposited for solar EUV telescope applications by using this method. The first mirror reflects Fe IX–X line (17.1 nm) and Fe XVI (33.5 nm) lines with attenuation of the He II line (30.4 nm). The second mirror reflects Fe IX–X and He II lines with attenuation of Fe XV (28.4 nm) and Fe XVI lines. Measurements with synchrotron radiation source confirm that, in both cases, for these mirrors, we are able to adjust reflectivity maxima (Bragg peak position) and minima. Such multilayers offer new possibilities for compact design of multi-wavelength EUV telescopes and/or for high spectral selectivity.