Jiang Kexin, Xie Mingliang, Tang Zhe, Zhang Xiren, Yang Dongxu
School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 610054, China.
College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences, Beijing 100049, China.
Sensors (Basel). 2025 Sep 21;25(18):5906. doi: 10.3390/s25185906.
Micro- and nanopatterning is crucial for advanced photonic, electronic, and sensing devices. Yet achieving large-area periodic nanostructures with a 75 nm half-pitch on low-cost laboratory systems remains difficult, because conventional near-ultraviolet laser interference lithography (LIL) suffers from Gaussian-beam non-uniformity and a narrow exposure latitude. Here, we report a cost-effective deep-ultraviolet (DUV) dual-beam LIL system based on a 266 nm laser and diffractive flat-top beam shaping, enabling large-area patterning of periodical nanostructures. At this wavelength, a moderate half-angle can be chosen to preserve a large beam-overlap region while still delivering 150 nm period (75 nm half-pitch) structures. By independently tuning the incident angle and beam uniformity, we pattern one-dimensional (1D) gratings and two-dimensional (2D) arrays over a Ø 1.0 cm field with critical-dimension variation < 5 nm (1σ), smooth edges, and near-vertical sidewalls. As a proof of concept, we transfer a 2D pattern into Si to create non-metal-coated nanodot arrays that serve as surface-enhanced Raman spectroscopy (SERS) substrates. The arrays deliver an average enhancement factor of ~1.12 × 10 with 11% intensity relative standard deviation (RSD) over 65 sampling points, a performance near the upper limit of all-dielectric SERS substrates. The proposed method overcomes the uneven hotspot distribution and complex fabrication procedures in conventional SERS substrates, enabling reliable and large-area chemical sensing. Compared to electron-beam lithography, the flat-top DUV-LIL approach offers orders-of-magnitude higher throughput at a fraction of the cost, while its centimeter-scale uniformity can be scaled to full wafers with larger beam-shaping optics. These attributes position the method as a versatile and economical route to large-area photonic metasurfaces and sensing devices.
微纳图案化对于先进的光子、电子和传感设备至关重要。然而，在低成本实验室系统上实现半间距为75 nm的大面积周期性纳米结构仍然很困难，因为传统的近紫外激光干涉光刻（LIL）存在高斯光束不均匀性和曝光宽容度窄的问题。在此，我们报告了一种基于266 nm激光和衍射平顶光束整形的经济高效的深紫外（DUV）双光束LIL系统，能够对周期性纳米结构进行大面积图案化。在这个波长下，可以选择适中的半角来保持较大的光束重叠区域，同时仍能实现周期为150 nm（半间距为75 nm）的结构。通过独立调整入射角和光束均匀性，我们在直径为1.0 cm的区域上对一维（1D）光栅和二维（2D）阵列进行图案化，关键尺寸变化<5 nm（1σ），边缘光滑，侧壁近乎垂直。作为概念验证，我们将二维图案转移到硅中，以创建用作表面增强拉曼光谱（SERS）基底的无金属涂层纳米点阵列。该阵列在65个采样点上的平均增强因子约为1.12×10，强度相对标准偏差（RSD）为11%，其性能接近全介质SERS基底的上限。所提出的方法克服了传统SERS基底中热点分布不均匀和制造工艺复杂的问题，实现了可靠的大面积化学传感。与电子束光刻相比，平顶DUV-LIL方法以成本的一小部分提供了高几个数量级的吞吐量，同时其厘米级的均匀性可以通过更大的光束整形光学元件扩展到整个晶圆。这些特性使该方法成为制造大面积光子超表面和传感设备的通用且经济的途径。
