【作者】 郭小伟；

【导师】 杜惊雷；

【作者基本信息】 四川大学 ， 光学， 2007， 博士

【摘要】 近年来，空间光调制器(SLM)无掩模光刻技术受到微电子及相关领域的广泛关注。SLM作为无掩模光学光刻系统的图形发生器，可便捷、灵活、并行、低成本和高速地产生曝光图形，在小批量高精度掩模制作和微光学器件生产中发挥了重要作用，在高分辨集成电路制作上也表现出极其诱人的应用前景。目前，发展SLM光刻技术已成为国际光刻系统制造领域的一个重要研究内容，基于SLM的无掩模光刻系统有望成为下一代微纳加工的一个重要工具。为满足我国对纳米加工技术日益增长的应用需求，促进我国微电子和MOEMS技术的快速发展，本论文以开展SLM光刻成像理论和研制SLM无掩模光刻系统为目标，对作为数字图形发生器应用于无掩模光刻中的MEMS微镜的光学特性、成像特性、基于SLM的无掩模光刻成像质量及相关问题进行了深入、系统的理论研究和实验探索。研究内容包括：1．系统地阐述和总结部分相干成像和抗蚀剂曝光显影理论，针对用于无掩模光刻的几种空间光调制器的特点进行了深入细致地研究。通过数学建模以分析倾斜型、活塞型和数字微反镜的光学特性，通过比较它们作为光刻系统的数字掩模的成像效果的差异，总结各种MEMS微镜的光刻成像特点，进而建立适于描述无掩模光刻成像的理论模型、数字灰度成像计算机仿真算法，并编写光学光刻过程的计算仿真软件。为SLM无掩模光刻成像分析、作为数字掩模的MEMS器件参数确定和无掩模光刻成像光路设计提供理论依据。2．分析集成电路制作对SLM无掩模光刻成像特性和质量的要求，探索提高SLM光刻分辨率的有效途径。研究表明，SLM用于光刻系统中，在线宽调制、线边缘和线条位置定位、改善成像质量方面比传统掩模有特色、更灵活。针对SLM光刻成像对离焦量较为敏感问题，提出通过微镜的排列方式改善成像系统焦深，探讨光学邻近效应校正技术改善SLM成像质量的可行性，并发展了用优化偏转微镜的偏转量来改善光刻图形质量的牛顿—拉普森算法。3．探讨数字灰度光刻技术，采用DMD搭建数字灰度光刻系统，开展数字灰度光刻制作微光学器件的理论和实验研究，提出用DMD灰度曝光装置制作微光学器件曝光方式及改善器件加工质量的方法，包括衍射栅格消除、数据传输量、边缘畸变校正等问题。针对脉宽调制编码方法对连续对称图形易引起周期性的表面起伏问题，采用通过调整照明源相干性技术或预优化SLM掩模图形技术来加以校正；通过成像系统结构和曝光显影工艺的优化，制作出多种面形的微光学元件，为快速，方便地制作微结构元件提供了一种新思路。4．目前，纳米加工技术和表面等离子激元(SPP)技术是学界国际上关注的热点，而探索无掩模超衍射极限纳米光刻技术也一直是我们的追求目标。论文最后一章试图把SPP技术应用于无掩模光刻，通过深入分析SPP形成的物理机理与特点，提出利用宽光束照明全内反射激发SPP实现大面积无掩模纳米干涉光刻的方案，并进一步提出利用厚金属SPP共振透射机制实现准周期性、非周期光刻或任意纳米图形的加工。若把这一思想与SLM相结合，有可能发展成一种新型无掩模光刻装置用于制作任意形状纳米结构。更多还原

【Abstract】 In recent years, optical maskless lithography technique based on spatial light modulator(SLM) has been attracted wide attentions. SLM is adopted as pattern generator in maskless lithography because of its convenience, programmable control and parallel print. SLM-based maskless lithography technique plays a very important role in the fabrication of high-quality mask and micro optical elements(MOE), especially for low-volume runs, and further provides potential application in high-resolution integrated circuits(IC) fabrication. Now it is an important target to develop SLM-based maskless lithography technique in lithographic community. To meet the continuously increasing requirement of nanofabrication and promote the rapid development of microelectronic and MOEMS techniques in China, and aiming at developing the imaging theory of SLM lithography and building SLM-based maskless lithography system, we made a comprehensive and systemic study on MEMS mirror’s optical features, the imaging quality of SLM-based maskless lithography and its applications in this dissertation.1. The partial coherent imaging theory used in lithographic system with the exposure and development theories in resist was academically summarized, and the peculiarities of several SLMs for lithography were studied in detail. Following the build of their mathematical models, the optical characteristics of tilting mirrors, piston mirrors and digital micro device(DMD) were analyzed, and then their differences in imaging effect were compared to obtain their imaging features, and further the theoretic model and emulation algorithm suitable for depicting the imaging process of SLM-based maskless lithography were built, and finally a program was developed to simulate SLM-based optical lithography process, which provide the theoretic base for analyzing the imaging of SLM-based maskless lithography, choosing the parameters of MEMS mirrors as digital mask and designing the optical path in SLM-based maskless lithography system.2. The conditions of SLM-based maskless lithography for the fabrication of IC were analyzed, and the methods for the improvement of lithographic resolution were explored. The study results show that there are some advantages in SLM-based maskless lithography such as basic CD adjustment, edge positioning with grayscaling, arbitrarily placing minimum features with good imaging quality, and so on. According to the shortcoming of the sensitivity to defocus, we presented to use different mirrors’ arrangement tricks to correct it. We also studied the optical proximity effects in SLM-based maskless lithography and develop Newton-Raphson algorithm for adjusting the deflection quality of MEMS mirrors to improve the imaging quality.3. DMD-based gray-tone lithography technique was discussed, and the theoretical and experimental studies of the fabrication of MOE with the technique were performed. We explored the exposure methods for fabricating MOE and the methods for improving MOE fabrication quality in detail which involves removing grid effect, deducing data delivery and correcting edge aberration, etc. Due to the data delivery technique of pulse width modulation easily bringing surface aberrations in fabricating MOE, we presented two methods to solve it, namely, to adjust the coherence of illumination source and optimize the mask design. Through the modification of the imaging system and the process parameters, we fabricated some MOEs with good profile, which gives out a new path to fabricate microstructure elements.4. Now nanofabrication and surface plasmon polariton(SPP) techniques are being explored, and meanwhile it is our pursuit purpose to develop maskless nanofabrication technique beyond the diffraction limit. We try to apply SPP to maskless lithography in the lattermost chapter. Through the in-depth analysis of the physical forming mechanism and the characteristics of SPP, we presented to use wide beam illumination with ATR coupling mode to realize large-area interference lithography, and further presented to use SPP resonance transmission in thick metal film to fabricate quasi-periodic, non-periodic and arbitrary nanostructures, which is expected to be a new nanofabrication tool when combining with SLM maskless lithographic technique.更多还原