由于光波衍射特性,传统光学光刻面临分辨力衍射极限限制,成为传统光学光刻技术发展的原理性障碍。表面等离子体(surface plasmon,SP)是束缚在金属介质界面上的自由电子密度波,具有突破衍射极限传输、汇聚和成像的独特性能。近年来,通过研究和利用SP超衍射光学特性,科研人员提出和建立了基于SP的纳米干涉光刻、成像光刻、直写光刻等方法,在紫外光源和单次曝光条件下,获得了突破衍射极限的光学光刻分辨力。目前,基于SP成像结构,实验中获得了22 nm(-1/17波长)最高SP成像光刻线宽分辨力水平。SP将为发展高分辨、低成本、高效、大面积纳米光学光刻技术提供重要方法和技术途径。本文系统综述了SP光学光刻技术研究发展情况,总结和分析了技术发展现状、存在问题,并对其发展趋势和前景进行了展望。
Due to the light's diffraction feature, conventional optical lithography methods have been suffering from the diffraction limit of resolution, which imposes great obstacles for obtaining nano patterns with ultra-violet and deep ultra-violet light source. Surface plasmons(SPs) are the free electron density waves confined at the interface of metal and dielectric medium, which exhibits unique sub-diffraction optical characteristic in SP propagation, focusing and imaging performances. In recent years, benefiting from SPs' features beyond the diffraction limit, researchers have proposed a variety of SP lithography methods in the manner of interference, imaging and direct writing, demonstrating both in theoretical simulations and experiments that the sub-diffraction resolution could be readily obtained in SP lithography just using ultra-violet light source and single exposure process. The SPs interference lithography is simple and easy to realize nano periodic patterns with short wavelength of SPs, but usually deliver some shortcomings, like greatly restricted interference area size and complex fabrications of exciting structures. Bulk plasmon polaritons formed by greatly coupled SPs was proposed and demonstrated in our work for deep subwavelength large area interference lithography without the necessity of subwavelength exciting structures. SPs lithography in direct writing manner mainly originates from localized surface plasmon resonance behaviors of nano particles or metallic tips, further investigations of bow-tie structure and SP focusing lens with specific nano structures deliver enhanced resolution and intensity efficiency and help to realize point to point writing lithography with much more flexibility. Plasmonic lens imaging lithography seems to be particular interesting for applications as projecting nano irregular patterns in one exposure step. Superlens, as a simplified version of perfect lens, provides the physical prototype of SP imaging lithography. Further, the contributions of metal-dielectric-