【作者】 杨帆；

【导师】 金鹏；

【作者基本信息】 哈尔滨工业大学 ， 仪器科学与技术， 2016， 博士

【摘要】 随着微纳米加工技术和纳米光学技术的发展,加工周期性光学结构的方法在向着高精度、高分辨率和低成本的方向发展。其中,基于表面等离子干涉原理的微纳米加工技术发展迅速,拥有很大的应用潜力。运用该原理实现大面积、高深度、周期减小的光刻技术和加工工艺意义重大,是制造纳米级特征尺寸光学元件领域的热点和难点。本课题“基于表面等离子干涉原理的周期减小光刻技术研究”,对该技术领域存在的主要技术问题与科学问题进行了深入地理论分析、仿真模拟和实验验证。主要完成的工作如下:1.针对传统等离子干涉光刻时由于入射波与干涉波的重叠,无法实现周期减小光刻的问题,设计了一种基于双曲线超材料结构与表面等离子干涉效应的光刻方法。该方法利用双曲线超材料结构对透过光栅掩膜板的波段进行频率选择,屏蔽掉入射波对光刻图案的影响,从而实现周期减小光刻。根据该方法,设计含有铝-氧化铝双曲线超材料结构和700nm周期铝光栅的掩膜板,搭建曝光平台。利用405nm波长的UV激光光源对涂覆在弹性基底上的光刻胶进行曝光,得到了周期350nm(掩膜板周期1/2)、线宽100nm、区域面积15mm×15mm的均匀光栅图案。实验表明:使用该结构进行光刻不需要EUV光源和减震平台,利用普通UV光源就可以制作大面积的亚波长周期的光栅。2.为了提高基于等离子干涉原理的周期减小光刻的生产效率,优化超材料结构,提出了一种用近零折射率(ENZ)超材料多层膜结构与表面等离子干涉相结合的方法。通过对金属-非金属构成的多层膜在UV波段产生ENZ超材料特性和等离子干涉波在ENZ超材料中的传播进行分析,提出针对不同曝光波长和光栅掩膜周期实现周期减小光刻的优化设计方法;设计了SPP干涉激发结构,通过有限元仿真,分析了隔离层的厚度对干涉波的共振强度和波长的影响;计算得到掩膜板光栅周期与SPP干涉波周期的匹配条件,利用该方法可以实现1/n倍(n为偶数)掩膜板光栅周期的周期减小光刻;对多层膜拥有超材料特性所需层数的极限条件进行分析;计算入射光激发的表面等离子干涉波在垂直方向的波矢,根据波矢调节ENZ多层膜结构的透射波段实现频率选择;对构成ENZ双曲线超材料的条件进行了分析,给出了适合光刻结构的多层膜材料组合;对220nm周期的铝光栅掩膜和405nm波长的UV光源,通过建立的优化理论设计光刻结构,得到周期为掩膜板周期1/2(110nm)的光栅图案。3.设计了一种可以在高空间频率下得到超大曝光深度图案的等离子光刻方法,克服了传统等离子光刻中,由于表面等离子波离开金属表面后成指数衰减所导致的光刻图案浅的缺点。该结构利用了光栅的一阶衍射、表面等离子干涉和多层波导叠加的复合作用:利用空间频率选择原理设计光栅和多层波导,从而实现带通滤波的功能,只将金属光栅激发的一阶衍射光引入波导中,并在波导结构中产生谐振,使原本传播距离很短的倏逝波增强为传递波,实现周期减小的超大曝光深度光刻。由于受到一阶衍射光的限制,该方法只能产生1/2掩膜板周期的图案。使用周期为245nm的铝光栅掩膜板进行光刻实验,曝光显影后得到了周期122.5nm(掩膜板周期的1/2)、线宽55nm、深度超过100nm的均匀光栅图案。理论分析与实验结果证实了该方法可以实现大面积、高深度和周期减小的亚波长光刻。更多还原

【Abstract】 With the development of micro-nanofabrication technology and nano-optical technology, the production method of periodic optical structure towards high-precision, high-resolution and low-cost direction. Surface plasmon interference as a new near-field optical technology, which is developing rapidly, has great potential. But so far most of the studies have stayed in the theoretical analysis and simulation stages. There are still many problems to product large area optical devices by this technology.The project, "Research on period reduction lithography techniques based on surface plasmon interference", is about achieving period reduction lithography by surface plasmon interference effect which is excited by metal grating. It is theoretically analysised and experimentally verified.The main research contents and innovative works includes:1. Because for the traditional SPP interference lithography the incident light and interference wave overlap each other, and cannot produce grating patterns with reduced period. Therefore, a new lithography method based on hyperbolic metamatierals structure and SPP interference effect. This method uses frequency selection of hyperbolic metamatierals structure to choice transmitted wave of grating mask, and abandons the effect of incident light to achieve period reduction.According to this method, design and production mask which contains Al–Al2O3 hyperbolic metamaterials structure and Al grating with 700 nm period, set the exposure stage. Exposed photoresist on flexiable substrate by a UV laser source with 405 nm wavelength. A uniform grating pattern was produced with 350 nm period(half of the grating mask period), 100 nm line width, 1.5 cm × 1.5 cm area. The experimental results show: With this structure, EUV light source and damping platform are not necessary, a large area of subwavelength grating can be fabriced by a normal UV source.2. In order to improve the production efficiency of period reduction lithography and optimize the metamaterial multilayers structure, a method with combining Epsilon near zero(ENZ) metalmaterial multilayers structure with SPP interference is proposed. Through analyzing the characteristic of metal-dielectric multilayers in the UV band and propergation characteristic of SPP interference wace in ENZ metamaterial, a optimized design method of period reduction lithography for different wavelength of exposure source and period of grating mask is proposed: designing SPP interference excitation structure, and analyzing the effects of thickness of spacer layer on the resonance intensity of interference waves and wavelength through finite element simulation; calculating the matching conditions of grating mask period and SPP interference wavelength, period reduction lithography that produces grating with 1/n mask period(n is even) can be achieved by this method; analyzing the minimum number requirement of ENZ metamaterial multilayers; calculating the wave vector of SPP interference wave in the vertical direction; according to the wave vector, adjusting the transmission band of ENZ multilayers to Achieve frequency selection film structure to achieve frequency selection; analyzing the conditions of ENZ hyperbolic metamaterials and proposed the suitable combinations of materials for multilayers structure. A period reduction lithography structure is desighed by the optimization theory, with a Al grating mask with 220 nm period and a light source with 405 nm UV wavelength. It can produce grating pattern with period half of the grating mask(110nm).3. A high depth period reduction lithography method is designed. It overcome the defect of conventional plasma lithography, that lithography pattern is too shallow because surface plasmon wave decays exponentially after leaving metal surface. The structure utilizes the diffraction grating, SPP interference and multilayers waveguide: designing grating and multilayers waveguide with spatial frequency selection principle, to achieve bandpass filtering; guiding the 1st order diffraction wave into the waveguide, so the 1st order diffraction wave and SPP interference wave resonance in the waveguide structure. The evanescent wave with short propergrating distance is transferred to propergrating wave. Because the period of resulting pattern is restrited by the 1st order diffraction light, this method can only produce grating with 1/2 period of mask. Exposure experiments are achieved with Al grating mask with 245 nm period. The resulting patterns are uniform with 100 nm depth, 122.5nm period(half of the grating mask period), 61 nm linewidth. This method is theoretically and experimently proved that can achieve large area, high depth and period reduction subwavelength lithography.更多还原