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Rumyantsev AV, Borgardt NI, Volkov RL, Chaplygin YA. Level set simulation of focused ion beam sputtering of a multilayer substrate. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2024; 15:733-742. [PMID: 38952415 PMCID: PMC11216083 DOI: 10.3762/bjnano.15.61] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Accepted: 06/03/2024] [Indexed: 07/03/2024]
Abstract
The evolution of a multilayer sample surface during focused ion beam processing was simulated using the level set method and experimentally studied by milling a silicon dioxide layer covering a crystalline silicon substrate. The simulation took into account the redeposition of atoms simultaneously sputtered from both layers of the sample as well as the influence of backscattered ions on the milling process. Monte Carlo simulations were applied to produce tabulated data on the angular distributions of sputtered atoms and backscattered ions. Two sets of test structures including narrow trenches and rectangular boxes with different aspect ratios were experimentally prepared, and their cross sections were visualized in scanning transmission electron microscopy images. The superimposition of the calculated structure profiles onto the images showed a satisfactory agreement between simulation and experimental results. In the case of boxes that were prepared with an asymmetric cross section, the simulation can accurately predict the depth and shape of the structures, but there is some inaccuracy in reproducing the form of the left sidewall of the structure with a large amount of the redeposited material. To further validate the developed simulation approach and gain a better understanding of the sputtering process, the distribution of oxygen atoms in the redeposited layer derived from the numerical data was compared with the corresponding elemental map acquired by energy-dispersive X-ray microanalysis.
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Affiliation(s)
- Alexander V Rumyantsev
- National Research University of Electronic Technology - MIET, Bld. 1, Shokin Square, Zelenograd, Moscow, 124498, Russia
| | - Nikolai I Borgardt
- National Research University of Electronic Technology - MIET, Bld. 1, Shokin Square, Zelenograd, Moscow, 124498, Russia
| | - Roman L Volkov
- National Research University of Electronic Technology - MIET, Bld. 1, Shokin Square, Zelenograd, Moscow, 124498, Russia
| | - Yuri A Chaplygin
- National Research University of Electronic Technology - MIET, Bld. 1, Shokin Square, Zelenograd, Moscow, 124498, Russia
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Tong X, Chen Y, Mu C, Chen Q, Zhang X, Zeng G, Li Y, Xu Z, Zhao J, Zhen X, Mao C, Lu H, Tai R. A compound Kinoform/Fresnel zone plate lens with 15 nm resolution and high efficiency in soft x-ray. NANOTECHNOLOGY 2023; 34:215301. [PMID: 36745920 DOI: 10.1088/1361-6528/acb946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 02/06/2023] [Indexed: 06/18/2023]
Abstract
X-ray microscope as an important nanoprobing tool plays a prevailing role in nano-inspections of materials. Despite the fast advances of high resolution focusing/imaging reported, the efficiency of existing high-resolution zone plates is mostly around 5% in soft x-ray and rapidly goes down to 1%-2% when the resolution approaches 10 nm. It is well known that the rectangular zone shape, beamstop, limited height/width ratios, material absorption of light and structural defects are likely responsible for the limited efficiency. Although zone plates with Kinoform profile are supposed to be efficient, progress for achieving both high resolution (<30 nm) and high efficiency (>5%) have hardly been addressed in soft x-ray. In this work, we propose a compound Kinoform/Fresnel zone plate (CKZP) by combing a dielectric Kinoform zone plate with a 15 nm resolution zone plate. Greyscale electron beam lithography was applied to form the 3D Kinoform zone plate and atomic layer deposition was carried out to form the binary zone plate. Optical characterizations demonstrated 15 nm resolution focusing/imaging with over 7.8% efficiency in soft x-ray. The origin of the efficiency improvement behind the proposed compound lens is theoretically analyzed and discussed.
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Affiliation(s)
- Xujie Tong
- Nanolithography and Application Research Group, School of Information Science and Technology, Fudan University, Shanghai 200433, People's Republic of China
| | - Yifang Chen
- Nanolithography and Application Research Group, School of Information Science and Technology, Fudan University, Shanghai 200433, People's Republic of China
| | - Chengyang Mu
- Nanolithography and Application Research Group, School of Information Science and Technology, Fudan University, Shanghai 200433, People's Republic of China
| | - Qiucheng Chen
- Nanolithography and Application Research Group, School of Information Science and Technology, Fudan University, Shanghai 200433, People's Republic of China
| | - Xiangzhi Zhang
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, People's Republic of China
| | - Guang Zeng
- State Key Laboratory of ASIC and System, Shanghai Institute of Intelligent, Electronics & Systems, School of Microelectronics, Fudan University, Shanghai 200433, People's Republic of China
| | - Yuchun Li
- State Key Laboratory of ASIC and System, Shanghai Institute of Intelligent, Electronics & Systems, School of Microelectronics, Fudan University, Shanghai 200433, People's Republic of China
| | - Zijian Xu
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, People's Republic of China
| | - Jun Zhao
- Nanolithography and Application Research Group, School of Information Science and Technology, Fudan University, Shanghai 200433, People's Republic of China
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, People's Republic of China
| | - Xiangjun Zhen
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, People's Republic of China
| | - Chengwen Mao
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, People's Republic of China
| | - Hongliang Lu
- State Key Laboratory of ASIC and System, Shanghai Institute of Intelligent, Electronics & Systems, School of Microelectronics, Fudan University, Shanghai 200433, People's Republic of China
| | - Renzhong Tai
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, People's Republic of China
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Tong X, Chen Y, Xu Z, Li Y, Xing Z, Mu C, Zhao J, Zhen X, Mao C, Tai R. High-efficiency focusing and imaging by dielectric kinoform zone plate lenses with soft X-rays. JOURNAL OF SYNCHROTRON RADIATION 2023; 30:319-326. [PMID: 36891845 PMCID: PMC10000800 DOI: 10.1107/s1600577522012115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Accepted: 12/22/2022] [Indexed: 06/18/2023]
Abstract
With fast advances in enhancing the focusing/imaging resolution of Fresnel zone plate lenses toward sub-10 nm, low diffraction efficiency in connection with their rectangular zone shape still remains a big issue in both soft and hard X-ray microscopy. In hard X-ray optics, encouraging progress has recently been reported in our earlier attempts of high focusing efficiency by 3D kinoform shaped metallic zone plates, formed by greyscale electron beam lithography. This paper addresses our efforts towards high focusing/imaging efficiency by developing a novel dielectric kinoform zone plate lens for soft X-rays. The effects of the zone materials and zone shapes on the focusing/imaging quality were first theoretically investigated by a modified thin-grating-approximation method, revealing superior efficiencies of dielectric kinoform zone plates over rectangular ones in metals. Optical characterizations of replicated dielectric kinoform zone plates by greyscale electron beam lithography demonstrate a focusing efficiency of 15.5% with a resolution of 110 nm in the water window of X-rays. Apart from high efficiency, the novel kinoform zone plate lenses developed in this work exhibit significant advantages over conventional zone plates, i.e. simplified process, low cost and no need for a beamstop.
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Affiliation(s)
- Xujie Tong
- Nanolithography and Application Research Group, School of Information Science and Technology, Fudan University, Shanghai 200433, People’s Republic of China
| | - Yifang Chen
- Nanolithography and Application Research Group, School of Information Science and Technology, Fudan University, Shanghai 200433, People’s Republic of China
| | - Zijian Xu
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, People’s Republic of China
| | - Yijie Li
- Nanolithography and Application Research Group, School of Information Science and Technology, Fudan University, Shanghai 200433, People’s Republic of China
| | - Zhenjiang Xing
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, People’s Republic of China
| | - Chengyang Mu
- Nanolithography and Application Research Group, School of Information Science and Technology, Fudan University, Shanghai 200433, People’s Republic of China
| | - Jun Zhao
- Nanolithography and Application Research Group, School of Information Science and Technology, Fudan University, Shanghai 200433, People’s Republic of China
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, People’s Republic of China
| | - Xiangjun Zhen
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, People’s Republic of China
| | - Chengwen Mao
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, People’s Republic of China
| | - Renzhong Tai
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, People’s Republic of China
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Jidling C, Fleming AJ, Wills AG, Schön TB. Memory efficient constrained optimization of scanning-beam lithography. OPTICS EXPRESS 2022; 30:20564-20579. [PMID: 36224798 DOI: 10.1364/oe.457334] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Accepted: 05/16/2022] [Indexed: 06/16/2023]
Abstract
This article describes a memory efficient method for solving large-scale optimization problems that arise when planning scanning-beam lithography processes. These processes require the identification of an exposure pattern that minimizes the difference between a desired and predicted output image, subject to constraints. The number of free variables is equal to the number of pixels, which can be on the order of millions or billions in practical applications. The proposed method splits the problem domain into a number of smaller overlapping subdomains with constrained boundary conditions, which are then solved sequentially using a constrained gradient search method (L-BFGS-B). Computational time is reduced by exploiting natural sparsity in the problem and employing the fast Fourier transform for efficient gradient calculation. When it comes to the trade-off between memory usage and computational time we can make a different trade-off compared to previous methods, where the required memory is reduced by approximately the number of subdomains at the cost of more computations. In an example problem with 30 million variables, the proposed method reduces memory requirements by 67% but increases computation time by 27%. Variations of the proposed method are expected to find applications in the planning of processes such as scanning laser lithography, scanning electron beam lithography, and focused ion beam deposition, for example.
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Gao Y, Chen J, Chen G, Fan C, Liu X. Recent Progress in the Transfer of Graphene Films and Nanostructures. SMALL METHODS 2021; 5:e2100771. [PMID: 34928026 DOI: 10.1002/smtd.202100771] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 10/13/2021] [Indexed: 06/14/2023]
Abstract
The one-atom-thick graphene has excellent electronic, optical, thermal, and mechanical properties. Currently, chemical vapor deposition (CVD) graphene has received a great deal of attention because it provides access to large-area and uniform films with high-quality. This allows the fabrication of graphene based-electronics, sensors, photonics, and optoelectronics for practical applications. Zero bandgap, however, limits the application of a graphene film as electronic transistor. The most commonly used bottom-up approaches have achieved efficient tuning of the electronic bandgap by customizing well-defined graphene nanostructures. The postgrowth transfer of graphene films/nanostructures to a certain substrate is crucial in utilizing graphene in applicable devices. In this review, the basic growth mechanism of CVD graphene is first introduced. Then, recent advances in various transfer methods of as-grown graphene to target substrates are presented. The fabrication and transfer methods of graphene nanostructures are also provided, and then the transfer-related applications are summarized. At last, the challenging issues and the potential transfer-free approaches are discussed.
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Affiliation(s)
- Yanjing Gao
- School of Chemistry and Chemical Engineering, Frontiers Science Centre for Transformative Molecules, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Jielin Chen
- School of Chemistry and Chemical Engineering, Frontiers Science Centre for Transformative Molecules, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Guorui Chen
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Chunhai Fan
- School of Chemistry and Chemical Engineering, Frontiers Science Centre for Transformative Molecules, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Xiaoguo Liu
- School of Chemistry and Chemical Engineering, Frontiers Science Centre for Transformative Molecules, Shanghai Jiao Tong University, Shanghai, 200240, China
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Zhang X, Yang W, Zhang H, Xie M, Duan X. PEDOT:PSS: From conductive polymers to sensors. NANOTECHNOLOGY AND PRECISION ENGINEERING 2021. [DOI: 10.1063/10.0006866] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Xiaoshuang Zhang
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China
| | - Wentuo Yang
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China
| | - Hainan Zhang
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China
| | - Mengying Xie
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China
| | - Xuexin Duan
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China
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