太赫兹增透窗口设计与制作

发布时间：2018-04-04 21:42

本文选题：太赫兹　切入点：亚波长结构　出处：《电子科技大学》2017年硕士论文

【摘要】：随着大规模集成电路工艺水平的进一步发展,采用二元光学技术能够制作的图形尺寸越来越小以及线条的精细程度也随之提高。基于二元光学技术制造的亚波长结构给太赫兹增透窗口设计提供了新的思路,因此也吸引了很多从事光学透过率研究学者的关注。亚波长增透结构是一种周期性浮雕结构,该结构的特征尺寸与特定工作光波的波长大小相当甚至更小的。它的最大特点就是其周期结构尺寸足够小时,器件仅存在零级反射衍射和透射衍射,因此衍射效率高于一般的衍射光学器件。该结构的另一特点就是可以通过改变浮雕结构的周期大小、占空比大小和高度大小等特征尺寸参数改变其透过率和反射率。本文结合等效介质理论和严格耦合波理论对亚波长增透结构进行优化设计,并且通过实验制作了太赫兹增透窗口,有效的提高了太赫兹频率为1.7T时的窗口通过率。本文的主要内容简述如下:(1)介绍了太赫兹波的概念和太赫兹传感器,以及二元光学的发展。介绍了研究亚波长增透结构的理论方式,并指出标量衍射理论不再适用于亚波长结构,应该采用矢量衍射理论。(2)介绍了等效介质理论,并采用该理论推导出一维、二维亚波长的零级等效折射率和二级等效折射率。讨论了亚波长结构仅存在零级衍射时的周期阈值。介绍了严格耦合波理论,并采用该理论推导出二维亚波长柱状体结构的透过率和反射率。(3)结合等效介质理论和严格耦合波理论,利用MATLAB编程进行仿真,得到理论上反射率最低的双面太赫兹增透窗口结构,使用L-Edit绘制对应的图形并制作掩膜版。整个计算过程为今后的太赫兹增透窗口设计提供有价值的参考。(4)介绍了光刻流程。详细说明了太赫兹增透窗口的具体制作步骤以及工艺流程。由于刻蚀深度比较深,光刻胶不足以充当掩膜层,提出可增镀一层氮化硅作为刻蚀硅的掩膜层,采用ICP进行深硅刻蚀,采用RIE对氮化硅进行刻蚀。整个制作过程为微细加工工艺提供了一些可靠的参考。(5)使用太赫兹时域光谱仪(THz-TDs)对制作好的单面、双面增透结构进行透过率测试。通过分析测试结果,测试结果表明:当太赫兹频率为1.7T时,单面二元光学增透结构透过率达到了57.52%;双面二元光学增透结构透过率达到了68.15%,较本体硅片都有一定的提高。
[Abstract]:With the further development of large-scale integrated circuit (LSI) technology, the size of the graphics that can be produced by binary optics becomes smaller and smaller, and the fine degree of the lines is also improved.The subwavelength structure based on binary optics technology provides a new idea for the design of terahertz antireflection window, and therefore attracts the attention of many researchers engaged in optical transmittance research.The subwavelength antireflection structure is a kind of periodic relief structure. The characteristic size of the structure is equivalent to or even smaller than the wavelength of a specific working light wave.Its biggest characteristic is that its periodic structure size is small enough, the device only exists zero order reflection diffraction and transmission diffraction, so the diffraction efficiency is higher than that of the ordinary diffraction optical device.Another characteristic of the structure is that the transmittance and reflectivity can be changed by changing the characteristic dimension parameters such as the period size duty cycle and height of the relief structure.In this paper, the subwavelength antireflection structure is optimized by combining the equivalent medium theory and the strict coupling wave theory, and the terahertz antireflection window is made through experiments, which effectively improves the window pass rate when the terahertz frequency is 1.7 T.The concept of terahertz wave, terahertz sensor and the development of binary optics are introduced.This paper introduces the theoretical method of studying subwavelength antireflection structure, and points out that the scalar diffraction theory is no longer suitable for subwavelength structure, and the equivalent medium theory should be introduced by vector diffraction theory.The zero-order equivalent refractive index and the second-order equivalent refractive index of the second wave length are obtained.The periodic threshold of the subwavelength structure with only zero order diffraction is discussed.The theory of strictly coupled wave is introduced, and the transmittance and reflectivity of the cylindrical structure of the two-dimensional wavelength are derived by using this theory. Combining with the theory of equivalent medium and the theory of strictly coupled wave, the simulation is carried out by using MATLAB programming.A double-sided terahertz antireflection window structure with the lowest reflectivity in theory is obtained. The corresponding figure is drawn by using L-Edit and the mask plate is made.The whole calculation process provides a valuable reference for future terahertz antireflection window design.Detailed description of the terahertz antireflection window of the specific manufacturing steps and technological process.Because the etching depth is deep, the photoresist is not enough to be used as the mask layer. A layer of silicon nitride can be added as the mask for etching silicon. ICP is used for deep silicon etching and RIE is used for etching silicon nitride.The whole fabrication process provides some reliable reference for the micromachining process. THz-TDs are used to test the transmittance of the single and double-sided antireflection structures made by the THz time domain spectrometer (THz-TDs).The results show that when the terahertz frequency is 1.7 T, the transmittance of one-sided binary optical antireflection structure reaches 57.52, and that of double-sided binary optical antireflection structure reaches 68.15, which is higher than that of bulk silicon wafer.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O441;TN402

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