物理学报2017，Vol.66Issue(14)：223-231,9.DOI:10.7498/aps.66.148101
基于双表面等离子激元吸收的纳米光刻
Nanolithography based on two-surface-plasmon-polariton-absorption
摘要
Abstract
Lithography is one of most important technologies for fabricating micro- and nano-structures. Limited by the light diffraction limit, it becomes more and more difficult to reduce the feature size of lithography. Surface plasmon polariton (SPP) is due to the interaction between electromagnetic wave and oscillation of free-electron on metal surface. For the shorter wavelength, higher field intensity and abnormal dispersion relation, the SPP would play an important role in breaking through the diffraction limit and realizing nanolithography. In this paper, we theoretically and experimentally study the optical nonlinear effect of SPP (two-SPP-absorption) in the photoresist and its application of nanolithography with large field. First, the concept and features of two-SPP-absorption are introduced. Like two-photo-absorption, the two-SPP-absorption based lithography is able to realize nanopatterns beyond the diffraction limit: 1) the absorption rate quadratically depends on the light intensity, which can further squeeze the exposure spot; 2) the pronounced power threshold provides a possibility for precisely controlling the linewidth by manipulating the illumination power. Nevertheless, unlike the two-photo-absorption lithography which focuses light onto a single spot and scans point by point, the two-SPP-absorption method could obtain the subwavelength field pattern by simply illuminating the plasmonic mask. The subwavelength field pattern due to the short wavelength of SPP would further result in the overcoming-diffraction-limit resist pattern. Besides, the highly concentrated SPP field leads to the strong electromagnetic field enhancement at the metal-dielectric interface, which could reduce the input power density of exposure source or enlarge the exposure area. Then the two-SPP absorption is realized under the illuminations of femtosecond lasers with vacuum wavelengths of 800 nm and 400 nm. Meanwhile, the interference periodic patternis realized and it is observed that the linewidth could be adjusted by controlling the exposure dose. The minimum linewidth of resist pattern is only one tenth of the vacuum wavelength. By utilizing the features of two-SPP-absorption, namely shorter wavelength, enhanced field and threshold effect, the lithography field could be of millimeter size, which is about four to five orders of magnitude larger than the characteristic size of nanostructure. Therefore, this two-SPP-absorption scheme could be used for large-area plasmonic lithography beyond the diffraction limit with the help of various plasmonic structures and modes.关键词
表面等离子激元/纳米光刻/光学非线性/衍射极限Key words
surface plasmon polariton/nano-lithography/nonlinear optics/diffraction limit引用本文复制引用
刘仿,李云翔,黄翊东..基于双表面等离子激元吸收的纳米光刻[J].物理学报,2017,66(14):223-231,9.基金项目
国家重点基础研究发展计划 (批准号: 2013CBA01704) 和国家自然科学基金 (批准号: 61575104, 61621064) 资助的课题. Project supported by the National Basic Research Programs of China (Grant No. 2013CBA01704) and the National Natural Science Foundation of China (Grant Nos. 61575104, 61621064). （批准号: 2013CBA01704）
