Applied Physics and ‡Department of Electrical Engineering and Computer Science, University of Michigan , Ann Arbor, Michigan 48109, United States.
ACS Nano. 2017 Oct 24;11(10):9863-9868. doi: 10.1021/acsnano.7b03584. Epub 2017 Oct 5.
In this work, a special hyperbolic metamaterial (HMM) metamaterial is investigated for plasmonic lithography of period reduction patterns. It is a type II HMM (ϵ < 0 and ϵ > 0) whose tangential component of the permittivity ϵ is close to zero. Due to the high anisotropy of the type II epsilon-near-zero (ENZ) HMM, only one plasmonic mode can propagate horizontally with low loss in a waveguide system with ENZ HMM as its core. This work takes the advantage of a type II ENZ HMM composed of aluminum/aluminum oxide films and the associated unusual mode to expose a photoresist layer in a specially designed lithography system. Periodic patterns with a half pitch of 58.3 nm were achieved due to the interference of third-order diffracted light of the grating. The lines were 1/6 of the mask with a period of 700 nm and ∼1/7 of the wavelength of the incident light. Moreover, the theoretical analyses performed are widely applicable to structures made of different materials such as silver as well as systems working at deep ultraviolet wavelengths including 193, 248, and 365 nm.
在这项工作中，研究了一种特殊的双曲超材料（HMM）超材料，用于等离子体光刻的周期缩减图案。这是一种类型 II HMM（ϵ < 0 和 ϵ > 0），其介电常数 ϵ的切向分量接近于零。由于类型 II 近零 ε（ENZ）HMM 的各向异性很高，只有一种等离子体模式可以在具有 ENZ HMM 作为其芯的波导系统中以低损耗水平传播。这项工作利用由铝/氧化铝薄膜组成的类型 II ENZ HMM 以及相关的异常模式，在专门设计的光刻系统中暴露光致抗蚀剂层。由于光栅的三阶衍射光的干涉，实现了半周期为 58.3nm 的周期性图案。线宽为 700nm 掩模版周期的 1/6 和入射光波长的 1/7。此外，进行的理论分析广泛适用于由不同材料（如银）制成的结构以及在包括 193、248 和 365nm 在内的深紫外波长下工作的系统。
