【作者】 朱明轩；

【导师】 李海华；

【作者基本信息】 上海交通大学 ， 微电子与固体电子学， 2010， 硕士

【摘要】 光刻技术是当前半导体元器件加工业应用最为广泛的一项技术。随着大规模集成电路和微结构光子学元器件的迅速发展,对光刻技术的精度和分辨率要求越来越高,但是由于光学衍射极限的存在,传统光刻技术的分辨率存在无法突破的极限。为了突破这一极限,许多新型的光刻技术涌现出来,例如远紫外激光光刻法、电子束刻蚀法等等,但是这类光刻技术成本过高,无法应用到成规模的工业生产中。表面等离子体激元具有近场局域增强和纳米聚焦的突出特性,这为高分辨率的光刻技术开辟了一条新的途径。基于表面等离子体激元的光刻技术已成为一个热点研究方向。本文研究了金属表面等离子体增透特性,并在此基础上进行了光刻技术研究。首先介绍了表面等离子体发展的历史以及其在光刻领域的应用,接着详细讨论了四种模拟复杂周期性纳米金属结构的数值算法,为本文随后的数值仿真打下了理论基础。然后,从Kretschmann棱镜激发表面等离子体的原理出发,讨论了在电介质-金属-电介质三层膜结构激发表面等离子体的机理,接着,利用时域有限差分方法(FDTD)模拟了光刻过程中电磁场的分布。最后,讨论了表面等离子光刻实验。文章从入射光频率、光刻胶介电常数、银膜厚度、入射光角度四个方面讨论了实验过程中的工艺条件对于表面等离子体增强的透射率的影响。数值模拟结果显示这种方法光刻分辨率可以达到32纳米。我们先用FDTD方法模拟了一系列一维周期光栅结构的电场场强的分布,周期性光栅模板具有三角形的脊,整个模板覆盖了一层银,接着讨论了三角形底角角度变化对于透射率和分辨率的影响。当角度在57-64度之间变化时,三角形脊部有透射增强现象产生,最大透射振幅是入射光的4.2倍,分辨率在30±5nm之间变化。因为凹槽部分透射光强度很小,因此,具有很好的分辨率。通过对比周期和非周期边界条件下模拟的结果,三角形脊的形状是产生透射增强现象的原因。实验结果表明用1500纳米周期的光栅模板激发表面等离子体波,能够很好的将模板周期性结构转移到光刻胶上,可以得到线宽为500纳米的光栅结构。更多还原

【Abstract】 Photolithography has been a key technique in semiconductor nano-facture and micro-fabrication for several decades, with the development of Super Large Scale Integration (SLSI) and integrated optics; high resolution photolithography has become more and more important. However the traditional photolithography is limited by the illuminating wavelength due to the optical diffraction limit. Many nano-scale lithography techniques like the electron beam lithography and deep ultraviolet (UV) lithography have been applied to achieve high resolution, but these techniques require quite expensive equipment and cannot meet the industrial mass fabrication needs. The recent discovery of extraordinary transmission through perforated metal films shows that the surface plasmon polaritons (SPPs) on the metal surface can greatly enhance the light transmission and redistribute the electromagnetic field in nanometer scale. These give us a novel method of photolithography beyond the diffraction limit.In this paper first from the principle of Kretschmann prism, the mechanism is discussed to excite surface plasmon polaritons in dielectric-metal-dielectric three layers system. And then the experimental technique to enhance transmission is analyzed from four perspectives of incident light frequency, dielectric constant of photoresist, depth of Ag film, angle of incident light.Finite Difference Time Doman (FDTD) method is employed to simulate the electromagnetic field distribution in the process of lithography based on surface plasmon polaritons. The numerical simulation indicates that this SPPs method can achieve the feature size of 32nm. In this paper first it is simulated by FDTD method that the electromagnetic field of a one-dimension periodical gratings with triangular ridges and planar grooves covered by a silver membrane. And then the analysis of transmission and resolution is given as the base-angle of ridges changes. When the base-angle varies from 57 to 64 degree, the enhanced transmission is found at the area under the ridges and the maximum of amplitude reaches 4.2 times compared with the incident light. The resolution size changes within 30±5nm. At the same time the transmission from grooves of the mask is quite little. Therefore a good contrast is achieved. The comparison between the non-periodical and periodical boundary conditions suggests that the enhanced transmission is the result of the shape of ridges instead of the periodical conditions At last the experiment result is discussed. The pattern of 1500nm periodical gratings is perfectly transferred on the photoresist and the resolution is 500nm.更多还原