A resolution enhancement method for line gratings based on inverse calculation of diffraction fringes
-
摘要:
本研究构建了一套基于桌面级高次谐波产生（High-Harmonic Generation, HHG）源与反射式干涉仪的光刻评估系统，可用于低成本、高效率表征EUV光刻胶。光束线采用515 nm飞秒激光激发氩气产生高次谐波，经轮胎镜聚焦和闪耀光栅分光后，由狭缝选取第11阶谐波（46.8 nm）作为EUV光源。以磺酸肟酯修饰的聚苯乙烯（PSOS）非化学放大型光刻胶为测试对象，分别采用劳埃镜和对称双镜进行干涉曝光。针对样品面与对称双镜间的对准难题，提出了一种基于衍射条纹反演计算的光学测距方法，实现了对称双镜的精确定位。实验结果表明：采用劳埃镜可获得周期125 nm，高对比度的清晰线栅图案，完成待测材料百纳米级分辨率的表征；经衍射条纹反演法精确定位后，利用对称双镜可制备出周期为60 nm的线栅图案，显著提升了系统的分辨能力。本研究展示的评估系统为光刻胶材料的快速筛选、分辨率极限研究及相关工艺开发提供了一个成本低、可推广的实验平台。
Abstract:To enable low-cost and efficient characterization of EUV photoresists, a lithographic evaluation system based on a tabletop high-harmonic generation (HHG) source and a reflective interferometer was developed. High-order harmonics were generated using a 515 nm femtosecond laser to excite argon gas. After focusing by a toroidal mirror and spectral dispersion by a blazed grating, the 11th harmonic (46.8 nm) was selected through a slit as the EUV source. Nonchemically amplified photoresists based on oxime sulfonate-functionalized polystyrene (PSOS) were used as the test material, and interference exposure was performed with a Lloyd’s mirror and a symmetric dual-mirror configuration. To solve the alignment problem between the sample plane and the symmetric dual-mirror interferometer, an optical ranging method based on diffraction-fringe inversion was proposed, enabling precise positioning of the symmetric dual-mirror interferometer. The results show that the Lloyd’s mirror produces clear high-contrast line-space patterns with a period of 125 nm and enables characterization of the tested resist at the 100 nm scale. After precise positioning by diffraction-fringe inversion, the symmetric dual-mirror configuration produces line-space patterns with a period of 60 nm, significantly improving the system resolution. This evaluation system provides a low-cost and scalable experimental platform for rapid screening of photoresist materials, investigation of resolution limits, and development of related lithographic processes.
-
Key words:
- high-order harmonics /
- lithography /
- interference exposure /
- extreme ultraviolet
-
图 1 由金属膜、轮胎镜、闪耀光栅以及狭缝组合的单色仪
Figure 1. Monochromator composed of a metal film, a toroidal mirror, a blazed grating, and a slit
图 2 (a)劳埃镜干涉光刻中几何关系图；(b)对称双镜干涉光刻中几何关系图
Figure 2. Geometric configurations in (a) Lloyd’s-mirror and (b) symmetric dual-mirror interference lithography
图 4 实现相位匹配后，铝膜后300 mm处的EUV光斑形貌
Figure 4. EUV beam profile at 300 mm behind the aluminum film after phase matching
图 7 对称双镜装置图，
$ {l}_{0}、{l}_{{i}} $ 分别为镜面边缘与光刻胶平面的初始距离和理想距离Figure 7. Schematic diagram of the symmetric dual-mirror setup, where
$ {l}_{0} $ and$ {l}_{{i}} $ denote the initial and ideal distances, respectively, from the mirror edge to the photoresist plane
图 8 (a)、(b)劳埃镜（
$ \theta =10{\text{°}} $ ）制备的线栅；(c)劳埃镜（$ \theta =20{\text{°}} $ ）制备的线栅；(d)对称双镜（$ \theta =10{\text{°}} $ ）制备的线栅Figure 8. Line gratings fabricated by (a), (b) Lloyd’s mirror (
$ \theta =10{\text{°}} $ ), (c) Lloyd’s mirror ($ \theta =20{\text{°}} $ ) and (d) symmetric dual-mirror ($ \theta =10{\text{°}} $ )
图 10 劳埃镜（
$ \theta =10{\text{°}}、20{\text{°}} $ ）和对称双镜（$ \theta =10{\text{°}} $ ）所制备的线栅周期数据Figure 10. Measured periods of line gratings fabricated by Lloyd’s mirror (θ = 10°, 20°) and symmetric dual-mirror interferometer (θ = 10°)
图 11 (a)调节距离后,对称双镜装置（
$ \theta =10{\text{°}} $ ）中，镜面边缘引发的衍射条纹；(b)$ l=104.8~\text{μm} $ 时，所获得菲涅耳直边衍射条纹的仿真结果Figure 11. (a) Diffraction fringes induced by the mirror edge in the symmetric dual-mirror setup(
$ \theta =10{\text{°}} $ ) after distance adjustment; (b) simulated Fresnel straight-edge diffraction fringes at$ l=104.8~ $ μm -
[1] BASU P, VERMA J, ABHINAV V, et al. Advancements in lithography techniques and emerging molecular strategies for nanostructure fabrication[J]. International Journal of Molecular Sciences, 2025, 26(7): 3027. doi: 10.3390/ijms26073027 [2] RAYLEIGH N. XXXI. Investigations in optics, with special reference to the spectroscope[J]. The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, 1879, 8(49): 261-274. [3] CAO H B, YUEH W, ROBERTS J, et al. EUV resist patterning performance from the Intel microexposure tool (MET)[J]. Proceedings of SPIE, 2005, 5753: 459-466. [4] BROSE S, DANYLYUK S, TEMPELER J, et al. Enabling laboratory EUV research with a compact exposure tool[J]. Proceedings of SPIE, 2016, 9776: 97760R. [5] BUITRAGO E, YILDIRIM O, VERSPAGET C, et al. Evaluation of EUV resist performance using interference lithography[J]. Proceedings of SPIE, 2015, 9422: 94221S. [6] 韦亚一. 超大规模集成电路先进光刻理论与应用[M]. 北京: 科学出版社, 2016.WEI Y Y. Theory and Application of Advanced Lithography for Large Scale Integrated Circuits[M]. Beijing: Science Press, 2016. (in Chinese) . [7] GRONHEID R, SOLAK H H, EKINCI Y, et al. Characterization of extreme ultraviolet resists with interference lithography[J]. Microelectronic Engineering, 2006, 83(4-9): 1103-1106. doi: 10.1016/j.mee.2006.01.149 [8] EKINCI Y, SOLAK H H, PADESTE C, et al. 20 nm Line/space patterns in HSQ fabricated by EUV interference lithography[J]. Microelectronic Engineering, 2007, 84(5-8): 700-704. doi: 10.1016/j.mee.2007.01.213 [9] ISOYAN A, CHENG Y C, JIANG F, et al. Progress in extreme ultraviolet interferometric lithography at the University of Wisconsin[J]. Proceedings of SPIE, 2008, 6921: 69212R. [10] 赵俊, 杨树敏, 薛超凡, 等. 上海光源极紫外光刻胶检测平台[J]. 应用化学, 2021, 38(9): 1168-1174. doi: 10.19894/j.issn.1000-0518.210190ZHAO J, YANG SH M, XUE CH F, et al. Extreme ultraviolet photoresist inspection platform in Shanghai synchrotron radiation facility[J]. Chinese Journal of Applied Chemistry, 2021, 38(9): 1168-1174. (in Chinese). doi: 10.19894/j.issn.1000-0518.210190 [11] GIANNOPOULOS I, MOCHI I, VOCKENHUBER M, et al. Extreme ultraviolet lithography reaches 5 nm resolution[J]. Nanoscale, 2024, 16(33): 15533-15543. doi: 10.1039/D4NR01332H [12] 李逵, 孟润宇, 李睿晅, 等. 基于高次谐波的高功率高稳定13.5 nm极紫外光源[J]. 中国激光, 2024, 51(7): 0701011. doi: 10.3788/CJL231507LI K, MENG R Y, LI R X, et al. High power and high stability 13.5 nm extreme ultraviolet light source driven by high-order harmonics[J]. Chinese Journal of Lasers, 2024, 51(7): 0701011. (in Chinese). doi: 10.3788/CJL231507 [13] WANG X L, KAZAZIS D, TSENG L T, et al. High-efficiency diffraction gratings for EUV and soft X-rays using spin-on-carbon underlayers[J]. Nanotechnology, 2022, 33(6): 065301. doi: 10.1088/1361-6528/ac328b [14] KIM H S, BAKSH P, ODSTRCIL M, et al. Lloyd’s mirror interference lithography with EUV radiation from a high-harmonic source[J]. Applied Physics Express, 2016, 9(7): 076701. doi: 10.7567/APEX.9.076701 [15] DORNEY K, CASTELLANOS S, LARSEN E, et al. Lloyd’s mirror interference lithography below a 22-nm pitch with an accessible, tabletop, 13.5 nm high-harmonic EUV source[J]. Proceedings of SPIE, 2021, 11610: 1161011. [16] YAMAMOTO H, DINH T H, KOZAWA T, et al. Evaluation of inorganic-organic hybrid resist materials with ultrafast coherent high harmonic generation (HHG) EUV system developed in QST[J]. Journal of Photopolymer Science and Technology, 2025, 38(3): 217-221. doi: 10.2494/photopolymer.38.217 [17] FLORES E, MOHANTY S, MITCHELL R, et al. Photoresist characterization using a tabletop extreme ultraviolet source at 30 nm wavelength[J]. Journal of Vacuum Science & Technology B, 2025, 43(6): 064003. doi: 10.1116/6.0004950 [18] CORKUM P B. Plasma perspective on strong field multiphoton ionization[J]. Physical Review Letters, 1993, 71(13): 1994-1997. doi: 10.1103/PhysRevLett.71.1994 [19] AN H W, CHEN J P, ZENG Y, et al. Increasing the sensitivity of nonchemically amplified resists by oxime sulfonate-functionalized polystyrene[J]. ACS Applied Polymer Materials, 2024, 6(9): 5374-5384. doi: 10.1021/acsapm.4c00573 [20] WERNER W S M, GLANTSCHNIG K, AMBROSCH-DRAXL C. Optical constants and inelastic electron-scattering data for 17 elemental metals[J]. Journal of Physical and Chemical Reference Data, 2009, 38(4): 1013-1092. doi: 10.1063/1.3243762 [21] 王莉, 杨会静, 段芳芳. 用MATLAB模拟菲涅耳直边衍射[J]. 唐山师范学院学报, 2008, 30(5): 131-132.WANG L, YANG H J, DUAN F F. The simulation of Fresnel straight edge diffraction by MATLAB[J]. Journal of Tangshan Teachers College, 2008, 30(5): 131-132. (in Chinese). -
下载:
计量
- 文章访问数: 403
- HTML全文浏览量: 195
- PDF下载量: 26
- 被引次数: 0
