基于介质光子晶体结构的近场超分辨光刻器件研究

Blocked by the diffraction limit, the resolution of traditional photolithography is limited at the level of half the working wavelength. The near-field photolithography can break through the diffraction limit and produce deep subwavelength patterns by employing the evanescent waves, which carry the high spatial frequency information of the structure. However, the current well-researched plasmonic photolithography has the problems of high transmission loss, long exposure time, and poor patterns quality caused by the unwanted waves, which severely obstruct its application in market. This project proposes a new way for regulating the evanescent waves by utilizing dielectric photonic crystal, and develops a near-field super-resolution photolithography device with the properties of low loss and low noisy waves. In this project, the principle of photonic crystal in controlling the evanescent waves and the mechanism of spatial frequency filtering will be deeply investigated. Besides, the physical model of the multilayer system composed of mask and photonic crystal will be studied. The design method for super-resolution photolithography device based on dielectric photonic crystal structures will be formed. Next, the controllable and high-precision preparation technology for nano-films will be breached. The novel device for super-resolution photolithography will be fabricated. Furthermore, the super-resolution photolithography will be explored to produce varieties of complex patterns. Therefore, this project will solve the problems of high transmission loss and poor quality of patterns for near-field super-resolution photolithography. It will provide a new theory and a new way for developing novel nanolithography technology. In addition, it is meaningful for pushing the research of subwavelength optics and promoting the breakthrough in nano-fabrication technology.

受衍射极限制约，传统光刻系统的图形分辨力被限制在半波长水平。近场光刻利用携带空间结构高频信息的倏逝波可突破衍射极限，获得深亚波长光刻图形。然而，目前广泛研究的表面等离子体近场光刻存在倏逝波传输损耗大、曝光时间长、由杂散波引起的光刻图形质量低等问题，严重制约了其推广应用。本项目提出基于介质光子晶体的倏逝波调控新方法，研制一种低损耗、低杂散波的近场超分辨光刻器件。项目将深入研究光子晶体对倏逝波的调控机理和空间频谱滤波机制；研究掩模-光子晶体膜系的物理模型，形成基于介质光子晶体的超分辨光刻器件设计方法；突破高精度纳米多层膜结构的可控制备工艺，研制出新型超分辨光刻器件，探索多样化复杂图形的超分辨光刻实现方法。本项目将解决基于现有近场超分辨光刻传输损耗大、图形质量低等难题，为纳米光刻技术的发展提供新原理、新方法，对推动亚波长光学研究和促进纳米制造技术突破具有重要意义。

基于倏逝波调控突破传统衍射极限是实现超分辨光刻的重要途径。但因为倏逝波的指数衰减特性，以及传播过程中的材料吸收和界面散射，目前近场超分辨光刻技术存在传输损耗大、曝光时间长、由杂散波引起的光刻图形质量低等问题，严重制约了该技术的发展和实际应用。本项目以构建低损耗、低杂散波的超分辨光刻器件为目标，研究光子晶体对倏逝波的调控机理和空间频谱滤波机制，形成基于纳米复合薄膜的超分辨光刻器件设计方法，探索光刻图形质量和分辨力的限制因素和改善途径。主要成果包括：1）研究了介电常数近零超材料对倏逝波的选频调控机理，提出了一种长焦深超分辨直写光刻器件，获得了半高宽约80 nm（~λ/5）、焦深达500 nm的倏逝波贝塞尔光针，有效解决了目前的近场光刻器件传输损耗大、焦深短的问题。2）建立了紫外波段负折射率超材料的传输模型，完成了一种基于负折射率超材料的亚波长光刻器件实验验证。在用非偏振光照明情况下，其空气工作距可以拓展到100 nm，且光刻图形保真度高、无旁瓣，图形深度达160 nm，单次曝光即可获得任意构型的大面积亚波长二维图形，该工作为拓展近场光刻工作距离、提高光刻图形质量提供了解决方案。3）揭示了全介质光子晶体对倏逝波的空间滤波机制，提出一种基于缺陷层增强倏逝波的全介质光子晶体超分辨光刻器件，其能在空气工作距大于100 nm的情况下，获得半周期32 nm（~λ/6）的超分辨干涉光刻图形，该设计方法规避了金属材料损耗和颗粒污染、提高了传输效率、降低了杂散波负面影响。4）分析了一种基于全介质超表面的超分辨聚焦器件，在距离该器件纵向2.8λ ~ 3.3λ范围内，其聚焦光斑半高全宽均低于衍射极限，且旁瓣比均低于30%，该理论探索为新型光刻器件设计奠定了基础。本项目的研究结果为低损耗、低杂散波的近场超分辨光刻器件设计提供了新思路，为纳米光刻技术的发展提供了新原理、新方法，对推动亚波长光学研究和促进纳米制造技术突破具有重要意义。