高性能193nm光学薄膜的制备与性能研究
文献类型：学位论文
| 作者 | 孙建 |
| 学位类别 | 博士 |
| 答辩日期 | 2014 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 邵建达 |
| 关键词 | 193nm 氟化物 增透膜 高反膜 膜厚均匀性 |
| 其他题名 | High performance optical coatings at 193nm |
| 中文摘要 | 光刻技术的不断进步推动着半导体工业的发展，其中193nm 光刻技术不仅是32nm特征线宽节点的主流技术，也有望大规模应用于22nm节点光刻成产。薄膜元件是光刻系统的重要组成部分，直接影响着系统的整体性能，因此设计与制备高性能的193nm光学薄膜并对其性能进行研究对推进光刻技术的发展至关重要。 本文围绕着193nm波段常用的几种材料展开，分析工艺参数对其性能的影响，由此制备了增透膜和高反膜，并实现了球面和非球面光学元件上膜厚的均匀性修正。 针对不同性质的薄膜，通过三种不同的方法用以计算薄膜的光学常数。对于折射率均匀的弱吸收薄膜，使用包络法可以快速稳定的得到薄膜光学常数。对于折射率均匀的强吸收薄膜，使用迭代反演法是更好的选择。对于折射率非均匀的弱吸收薄膜，通过一种改进的包络法，可以同时得到薄膜的折射率非均匀性信息和消光系数。 研究了工艺参数对AlF3，MgF2, LaF3 和Al2O3的光学、结构、组分、机械性质等的影响。氟化物材料从真空暴露至空气中时，性质会发生变化。对于AlF3¬和MgF2，相比于真空中，在空气中折射率随温度变化规律会发生反转现象，这种现象是氧化物的形成和吸水共同导致的。氟化物薄膜的吸收也受其中形成的氧化物的影响。电子束蒸发MgF2膜薄膜性质上相对于电阻热蒸发膜表现出一个相对的基底温度提高量，这种提高小于50℃。对于Al2O3薄膜，氧分压升高一方面可以改善化学计量比减少吸收，另一方面又会减少蒸发分子能量而减少折射率。 针对ArF光刻系统中应用最多的增透膜和高反膜，从膜料的选择、工艺参数的优化出发，设计制备了多种增透膜和高反膜。使用LaF3和AlF3两种材料，分别使用HL膜系和2LHL膜系制备了193nm增透膜。HL膜系增透膜在193nm处透射率和剩余反射率分别为98.32%和0.08%。2LHL膜系宽角谱增透膜在入射角0-47.5°范围内剩余反射率小于0.5%，并且Rs-Rp小于0.2%。制备了Al2O3/MgF2、Al2O3/AlF3、LaF3 /AlF3、以及Al2O3/AlF3和LaF3 /AlF3组合高反膜四种高反膜。其中，Al2O3/AlF3和LaF3 /AlF3组合高反膜在193nm处反射率可达98.8%。 针对光刻系统内非平面光学元件镀膜的需求，建立了行星转动系统镀膜机内球面和非球面光学元件膜厚均匀性修正模型。通过计算机快速优化出固定式修正挡板的形状与安装位置。使用抛物线型挡板理论上将球面光学元件在通光口径(CA)与曲率半径(RoC)比值CA/RoC=-1.9~1.9范围内，实验上在CA/RoC=-1.65~1.85范围内膜厚均匀性修正至97.5%以上。对于CA较小，且CA/RoC绝对值较大的凹球面光学元件，使用高斯型挡板可以达到更好的效果。 |
| 英文摘要 | The development of semiconductry is being drived by the progress of lithography. 193nm immersion lithography optics is the mainstream technology serving 32nm feature size node and expected to serve 22nm node on the ITRS roadmap. As important parts of lithographic systems, 193nm optical films determine the whole performance of the systems. Therefore, preparation and researchment of high performance 193nm optical coatings are important for the improvement of 193nm lithographic techniques. The research work focusd on several ultraviolet materials and analyzed the process parameters on the properties of the single films. Several antireflection coatings and high-reflectivity mirrors were prepared. A model is developed to improve thickness uniformity of coatings on spherical and aspherical substrates rapidly and automatically using fixed shadow masks in a planetary rotation system. Optical constants were calculated through three different methods according to different materials. For softly absorbing films which have homogeneous refractive index, the envelop method were used to calculate the optical constants. For strongly absorbing films which have homogeneous refractive index, an iterative inversion method were used to get better results. For softly absorbing films which have inhomogeneous refractive index, an improved envelop method were used to get the optical constants. The influence of process parameters on the properties of AlF3，MgF2, LaF3 and Al2O3. When fluorides were exposed to air from vacuum, the properties are changed. For AlF3 and MgF2, a non-monotonic change trend of the refractive index with substrate temperature was observed due to adsorbed water and oxide formed in the films. The oxide formed in the fluoride films alse affected the absorption. For MgF2 films, electron beam evaporation was a better method than resistive heating evaporation for higher density and less absorption. For Al2O3 films, higher oxygen partial pressure made films less absorptive but more porous. Several kinds of antireflection coatings and high-reflectivity mirrors at 193nm were prepared according to the substrates, materials and process parameters. Antireflection coatings of HL and LHL designs were prepared using LaF3 and AlF3. The transmittance and reflectance of the coatings of HL design were 98.32% and 0.08%. The reflectance of the coatings of 2LHL design was lower than 0.5% from 0-47.5° and Rs-Rp was lower than 0.2%. Al2O3/MgF2 mirrors、Al2O3/AlF3 mirrors、LaF3 /AlF3 mirrors and Al2O3//LaF3 /AlF3 mirrors were prepared. The reflectance of Al2O3//LaF3 /AlF3 mirrors could achieve 98.8% at 193nm. A model is developed to improve thickness uniformity of coatings on spherical and aspherical substrates rapidly and automatically using fixed shadow masks in a planetary rotation system. Using a type of masks with parabolic contours, the thickness uniformity of spherical substrates of CA/RoC from –1.9 to 1.9 could be improved to higher than 97.5% theoretically and the thickness uniformity of spherical substrates of CA/RoC from –1.65 to 1.85 could be improved to higher than 97.5% experimentally. For concave spherical substrates whose CA was small and |CA/RoC| was large, the Gaussian mask was a better choice. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15860]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 孙建. 高性能193nm光学薄膜的制备与性能研究[D]. 中国科学院上海光学精密机械研究所. 2014. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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