【作者】 田丰；

【导师】 白剑； 杨国光；

【作者基本信息】 浙江大学 ， 测试计量技术及仪器， 2010， 博士

【摘要】 本论文在国内外首次提出了利用微纳光纤进行微触式直写曝光的新技术。实验结果表明,微纳光纤直写的分辨率可达350nm,如果是在不充分曝光的情况下,线宽则可达100nm,小于曝光波长(442nm)的四分之一。直接写入技术是无掩模的表面微纳结构制造方法。目前,开发分辨率更高、工艺更简单、性价比更高的直写新技术是亟待解决的问题。微纳光纤具有极强的光场约束、低的传输损耗、高比例的倏逝场分量、场增强作用等特点,近年来在科研领域引起了广泛关注,而它的这些特点对直写曝光都是非常有利的。首先,极强的光场约束有利于提高曝光分辨率；其次,低传输损耗和场增强作用保证了曝光的光能量；第三,高比例的倏逝场分量可以很容易地被耦合到光刻胶层中。基于这些特点,本论文提出了一种利用微纳光纤进行直写曝光的新技术,微纳光纤通过微接触将光能量导入到光刻胶层中,这就类似于一个装满墨水的钢笔在纸上写字。本文提到的直写用微纳光纤与传统的微纳光纤是有区别的,传统微纳光纤一般被用来制作诸如光纤光栅、Mach-Zehnder干涉仪、滤波器、环形谐振腔、结形激光器等微纳光子器件,它们都是利用了微纳光纤的波导特性,而直写用微纳光纤是一种截断式的微纳光纤,它利用了微纳光纤输出端的点光源特性。另外,直写用微纳光纤与传统的用来做传感、滤波、光镊等的光纤探针也是不同的,直写用微纳光纤的锥角非常小,它的直径是逐渐过渡到亚微米量级的。本论文详细展示了这一利用微纳光纤点光源特性和微接触模式的直接写入新技术。首先,我们展示了微纳光纤的传播特性和端面光场特性,并利用时域有限差分(FDTD)方法分析了微纳光纤直写模型的光场分布。其次,我们详细说明了微纳光纤直写的实验系统、工艺方法和操作步骤。接着,我们计算了微纳光纤直写的曝光模型,展示和分析了实际的直写实验结果。实验结果表明微纳光纤直写技术具有独特的优势：分辨率高、写入范围大、工艺简单以及线宽可控,另外,通过改变线条的写入方向还可以制作出结构复杂的图形。最后,我们还提出将表面等离子体技术引入到微纳光纤直写中的新方法,模拟分析表明通过激发表面等离子体,微纳光纤直写的分辨率还可以进一步地得到提高。更多还原

【Abstract】 We firstly reports a novel direct writing technique using micro-and nanofiber worldwide, which adopts the micro touch model during the exposure. The experiment results show that the writing resolution can be up to 350 nm. In the condition of inadequate exposure, the 100-nm-lines are achieved, which is lower than one quarter of exposure wavelength (442 nm).Direct writing techniques allow maskless definition of surface micro-and nanostructures, and it is necessary to develop the simpler, more cost-effective and higher resolution direct writing technique. Optical micro-and nanofibers have attracted much attention due to their advantages, such as tight optical confinement, low optical loss, high fraction of evanescent fields, strong field enhancement. All these attractive properties make the micro-and nanofiber suitable for maskless lithography. First, tight optical confinement can provide high exposure resolution. Second, low optical loss and strong field enhancement ensure exposure power. Third, high fraction of evanescent fields can be easily coupled into photoresist layer. Based on these properties, this dissertation presents a novel direct writing technique utilizing the micro-and nanofibers. Herein, the fiber probes are similar to an inked pen, transferring a laser "ink" from the probe tip to a photoresist layer through direct micro touch. However, there are some differences between the direct writing fiber probes and the usual micro-and nanofibers. The usual micro-and nanofibers are used to fabricate a variety of micro-and nanophotonic components or devices, such as fiber gratings, Mach-Zehnder interferometers, filters, ring resonators, knot lasers, etc, where they act as waveguides. Contrary to the above-mentioned uninterrupted micro-and nanofibers, the micro-and nanofiber probes are interrupted and serve as submicron-dimension point sources. They are also different from usual fiber tapers, which have some applications, such as sensors, filters, optical tweezers, etc. The fiber probes for direct writing gradually change its diameter to a submicron tip, so their cone angles are much smaller than those of usual fiber tapers.In this dissertation, the direct writing technique using micro-and nanofibers is described in detail. The micro-and nanofiber serves as a tightly confined point source and it adopts micro touch mode in the process of writing. Firstly, the propagation and endface pattern of micro-and nanofiber are theoretically shown. The energy distribution of direct writing model is analyzed by Three-Dimension Finite-Difference Time-Domain method. Secondly, the system and operation of laser direct writing using micro-and nanofiber are carefully established. Thirdly, the exposure model is caculated and the experimental results are presented. Experimental results demonstrate that micro-and nanofiber direct writing has some advantages:simple process, high resolution, large writing area, and controllable width of lines. In addition, by altering writing direction of lines, complex submicron patterns can be fabricated. In the end of this dissertation, the surface plasmons technique is introduced to this direct writing approach, and the simulation shows that the writing resolution is further improved via the excitation of surface plasmons.更多还原