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Znati S, Wharwood J, Tezanos KG, Li X, Mohseni PK. Metal-assisted chemical etching beyond Si: applications to III-V compounds and wide-bandgap semiconductors. NANOSCALE 2024; 16:10901-10946. [PMID: 38804075 DOI: 10.1039/d4nr00857j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Metal-assisted chemical etching (MacEtch) has emerged as a versatile technique for fabricating a variety of semiconductor nanostructures. Since early investigations in 2000, research in this field has provided a deeper understanding of the underlying mechanisms of catalytic etching processes and enabled high control over etching conditions for diverse applications. In this Review, we present an overview of recent developments in the application of MacEtch to nanomanufacturing and processing of III-V based semiconductor materials and other materials beyond Si. We highlight the key findings and developments in MacEtch as applied to GaAs, GaN, InP, GaP, InGaAs, AlGaAs, InGaN, InGaP, SiC, β-Ga2O3, and Ge material systems. We further review a series of active and passive devices enabled by MacEtch, including light-emitting diodes (LEDs), field-effect transistors (FETs), optical gratings, sensors, capacitors, photodiodes, and solar cells. By reviewing demonstrated control of morphology, optimization of etch conditions, and catalyst-material combinations, we aim to distill the current understanding of beyond-Si MacEtch mechanisms and to provide a bank of reference recipes to stimulate progress in the field.
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Affiliation(s)
- Sami Znati
- Microsystem Engineering, Rochester Institute of Technology, Rochester, NY 16423, USA.
- NanoPower Research Laboratories, Rochester Institute of Technology, Rochester, NY 14623, USA
| | - Juwon Wharwood
- NanoPower Research Laboratories, Rochester Institute of Technology, Rochester, NY 14623, USA
- Department of Electrical and Computer Engineering, Howard University, Washington, DC 20059, USA
| | - Kyle G Tezanos
- NanoPower Research Laboratories, Rochester Institute of Technology, Rochester, NY 14623, USA
- School of Materials Science and Chemistry, Rochester Institute of Technology, Rochester, NY 14623, USA
| | - Xiuling Li
- Department of Electrical and Computer Engineering, Microelectronics Research Center, The University of Texas at Austin, Austin, TX 78758, USA
| | - Parsian K Mohseni
- Microsystem Engineering, Rochester Institute of Technology, Rochester, NY 16423, USA.
- NanoPower Research Laboratories, Rochester Institute of Technology, Rochester, NY 14623, USA
- School of Materials Science and Chemistry, Rochester Institute of Technology, Rochester, NY 14623, USA
- Department of Electrical and Microelectronic Engineering, Rochester Institute of Technology, Rochester, NY 14623, USA
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2
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Surdo S, Barillaro G. Voltage- and Metal-assisted Chemical Etching of Micro and Nano Structures in Silicon: A Comprehensive Review. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2400499. [PMID: 38644330 DOI: 10.1002/smll.202400499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 03/12/2024] [Indexed: 04/23/2024]
Abstract
Sculpting silicon at the micro and nano scales has been game-changing to mold bulk silicon properties and expand, in turn, applications of silicon beyond electronics, namely, in photonics, sensing, medicine, and mechanics, to cite a few. Voltage- and metal-assisted chemical etching (ECE and MaCE, respectively) of silicon in acidic electrolytes have emerged over other micro and nanostructuring technologies thanks to their unique etching features. ECE and MaCE have enabled the fabrication of novel structures and devices not achievable otherwise, complementing those feasible with the deep reactive ion etching (DRIE) technology, the gold standard in silicon machining. Here, a comprehensive review of ECE and MaCE for silicon micro and nano machining is provided. The chemistry and physics ruling the dissolution of silicon are dissected and similarities and differences between ECE and MaCE are discussed showing that they are the two sides of the same coin. The processes governing the anisotropic etching of designed silicon micro and nanostructures are analyzed, and the modulation of etching profile over depth is discussed. The preparation of micro- and nanostructures with tailored optical, mechanical, and thermo(electrical) properties is then addressed, and their applications in photonics, (bio)sensing, (nano)medicine, and micromechanical systems are surveyed. Eventually, ECE and MaCE are benchmarked against DRIE, and future perspectives are highlighted.
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Affiliation(s)
- Salvatore Surdo
- Dipartimento di Ingegneria dell'Informazione, Università di Pisa, via G. Caruso 16, Pisa, 56122, Italy
| | - Giuseppe Barillaro
- Dipartimento di Ingegneria dell'Informazione, Università di Pisa, via G. Caruso 16, Pisa, 56122, Italy
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3
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Giulio F, Mazzacua A, Calciati L, Narducci D. Fabrication of Metal Contacts on Silicon Nanopillars: The Role of Surface Termination and Defectivity. MATERIALS (BASEL, SWITZERLAND) 2024; 17:1549. [PMID: 38612064 PMCID: PMC11012852 DOI: 10.3390/ma17071549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 03/22/2024] [Accepted: 03/25/2024] [Indexed: 04/14/2024]
Abstract
The application of nanotechnology in developing novel thermoelectric materials has yielded remarkable advancements in material efficiency. In many instances, dimensional constraints have resulted in a beneficial decoupling of thermal conductivity and power factor, leading to large increases in the achievable thermoelectric figure of merit (ZT). For instance, the ZT of silicon increases by nearly two orders of magnitude when transitioning from bulk single crystals to nanowires. Metal-assisted chemical etching offers a viable, low-cost route for preparing silicon nanopillars for use in thermoelectric devices. The aim of this paper is to review strategies for obtaining high-density forests of Si nanopillars and achieving high-quality contacts on them. We will discuss how electroplating can be used for this aim. As an alternative, nanopillars can be embedded into appropriate electrical and thermal insulators, with contacts made by metal evaporation on uncapped nanopillar tips. In both cases, it will be shown how achieving control over surface termination and defectivity is of paramount importance, demonstrating how a judicious control of defectivity enhances contact quality.
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Affiliation(s)
- Federico Giulio
- Department of Materials Science, University of Milano Bicocca, Via R. Cozzi 55, I-20125 Milan, Italy; (F.G.); (A.M.)
| | - Antonio Mazzacua
- Department of Materials Science, University of Milano Bicocca, Via R. Cozzi 55, I-20125 Milan, Italy; (F.G.); (A.M.)
| | - Luca Calciati
- Department of Physics ‘Giuseppe Occhialini’, University of Milano Bicocca, Piazza Della Scienza 3, I-20126 Milan, Italy;
| | - Dario Narducci
- Department of Materials Science, University of Milano Bicocca, Via R. Cozzi 55, I-20125 Milan, Italy; (F.G.); (A.M.)
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4
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Mascaretti L, Mancarella C, Afshar M, Kment Š, Bassi AL, Naldoni A. Plasmonic titanium nitride nanomaterials prepared by physical vapor deposition methods. NANOTECHNOLOGY 2023; 34:502003. [PMID: 37738967 DOI: 10.1088/1361-6528/acfc4f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 09/22/2023] [Indexed: 09/24/2023]
Abstract
Titanium nitride (TiN) has recently emerged as an alternative to coinage metals to enable the development of integrated plasmonic devices at visible and medium-infrared wavelengths. In this regard, its optical performance can be conveniently tuned by tailoring the process parameters of physical vapor deposition methods, such as magnetron sputtering and pulsed laser deposition (PLD). This review first introduces the fundamental features of TiN and a description on its optical properties, including insights on the main experimental techniques to measure them. Afterwards, magnetron sputtering and PLD are selected as fabrication techniques for TiN nanomaterials. The fundamental mechanistic aspects of both techniques are discussed in parallel with selected case studies from the recent literature, which elucidate the critical advantages of such techniques to engineer the nanostructure and the plasmonic performance of TiN.
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Affiliation(s)
- Luca Mascaretti
- Czech Advanced Technology and Research Institute, Regional Centre of Advanced Technologies and Materials, Palacký University Olomouc, Šlechtitelů 27, 77900 Olomouc, Czech Republic
| | - Cristina Mancarella
- Micro- and Nanostructured Materials Laboratory, Department of Energy, Politecnico di Milano, Via Ponzio 34/3, I-20133 Milano, Italy
| | - Morteza Afshar
- Czech Advanced Technology and Research Institute, Regional Centre of Advanced Technologies and Materials, Palacký University Olomouc, Šlechtitelů 27, 77900 Olomouc, Czech Republic
- Department of Physical Chemistry, Faculty of Science, Palacký University, 17. listopadu 1192/12, 77900 Olomouc, Czech Republic
| | - Štěpán Kment
- Czech Advanced Technology and Research Institute, Regional Centre of Advanced Technologies and Materials, Palacký University Olomouc, Šlechtitelů 27, 77900 Olomouc, Czech Republic
- CEET, Nanotechnology Centre, VŠB-Technical University of Ostrava, 17. listopadu 2172/15, Ostrava-Poruba 708 00, Czech Republic
| | - Andrea Li Bassi
- Micro- and Nanostructured Materials Laboratory, Department of Energy, Politecnico di Milano, Via Ponzio 34/3, I-20133 Milano, Italy
- Center for Nanoscience and Technology-IIT@PoliMi, Via Rubattino 81, I-20134 Milano, Italy
| | - Alberto Naldoni
- Czech Advanced Technology and Research Institute, Regional Centre of Advanced Technologies and Materials, Palacký University Olomouc, Šlechtitelů 27, 77900 Olomouc, Czech Republic
- Department of Chemistry and NIS Centre, University of Turin, Turin I-10125, Italy
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5
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Kim K, Choi S, Bong H, Lee H, Kim M, Oh J. Catalytic nickel silicide as an alternative to noble metals in metal-assisted chemical etching of silicon. NANOSCALE 2023; 15:13685-13691. [PMID: 37555310 DOI: 10.1039/d3nr02053c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/10/2023]
Abstract
Metal-assisted chemical etching (MACE) has received much attention from researchers because it can be used to fabricate plasma-free anisotropic etching profiles for semiconductors. However, the etching mechanism of MACE is based on the catalytic reaction of noble metals, which restricts its use in complementary metal oxide semiconductor (CMOS) processes. To obtain process compatibility, we developed catalytic Ni after alloying it with Si as a substitute for noble metals in the MACE of Si substrates. Nickel silicide is a material commonly used as a contact electrode in CMOS processes. When NiSi was used as the catalyst, the anisotropic etching of Si with a smooth surface was successfully demonstrated. Silicidation increased the standard reduction potential of the Ni alloy and enhanced the electrochemical stability in the MACE of Si. In contrast, when pure Ni was used as the catalyst, a rough-etched surface was fabricated because of the low standard reduction potential. Based on the experimental results, the factors affecting the MACE of Si were systematically analyzed to optimize the catalytic NiSi properties. The implementation of the NiSi alloy potentially eliminates the use of noble metals in MACE and allows the technology to be adopted in contemporary CMOS processes.
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Affiliation(s)
- Kyunghwan Kim
- School of Integrated Technology, Yonsei University, 85, Songdogwahak-ro, Yeonsu-gu, Incheon, 21983, Republic of Korea.
| | - Sunhae Choi
- School of Integrated Technology, Yonsei University, 85, Songdogwahak-ro, Yeonsu-gu, Incheon, 21983, Republic of Korea.
| | - Haekyun Bong
- School of Integrated Technology, Yonsei University, 85, Songdogwahak-ro, Yeonsu-gu, Incheon, 21983, Republic of Korea.
| | - Hanglim Lee
- SEMES, 1339, Hyohaeng-ro, Hwaseong-Si, Gyeonggi-do, 18383, Republic of Korea
| | - Minyoung Kim
- SEMES, 1339, Hyohaeng-ro, Hwaseong-Si, Gyeonggi-do, 18383, Republic of Korea
| | - Jungwoo Oh
- School of Integrated Technology, Yonsei University, 85, Songdogwahak-ro, Yeonsu-gu, Incheon, 21983, Republic of Korea.
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6
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Lidsky D, Cain JM, Hutchins-Delgado T, Lu TM. Inverse metal-assisted chemical etching of germanium with gold and hydrogen peroxide. NANOTECHNOLOGY 2022; 34:065302. [PMID: 35835063 DOI: 10.1088/1361-6528/ac810c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 07/13/2022] [Indexed: 06/15/2023]
Abstract
Metal-assisted chemical etching (MACE) is a flexible technique for texturing the surface of semiconductors. In this work, we study the spatial variation of the etch profile, the effect of angular orientation relative to the crystallographic planes, and the effect of doping type. We employ gold in direct contact with germanium as the metal catalyst, and dilute hydrogen peroxide solution as the chemical etchant. With this catalyst-etchant combination, we observe inverse-MACE, where the area directly under gold is not etched, but the neighboring, exposed germanium experiences enhanced etching. This enhancement in etching decays exponentially with the lateral distance from the gold structure. An empirical formula for the gold-enhanced etching depth as a function of lateral distance from the edge of the gold film is extracted from the experimentally measured etch profiles. The lateral range of enhanced etching is approximately 10-20μm and is independent of etchant concentration. At length scales beyond a few microns, the etching enhancement is independent of the orientation with respect to the germanium crystallographic planes. The etch rate as a function of etchant concentration follows a power law with exponent smaller than 1. The observed etch rates and profiles are independent of whether the germanium substrate is n-type, p-type, or nearly intrinsic.
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Affiliation(s)
- D Lidsky
- Sandia National Laboratories, Albuquerque, NM 87185, United States of America
| | - J M Cain
- Sandia National Laboratories, Albuquerque, NM 87185, United States of America
| | - T Hutchins-Delgado
- Sandia National Laboratories, Albuquerque, NM 87185, United States of America
| | - T M Lu
- Sandia National Laboratories, Albuquerque, NM 87185, United States of America
- Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, NM 87123, United States of America
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7
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Li S, Chen K, Vähänissi V, Radevici I, Savin H, Oksanen J. Electron Injection in Metal Assisted Chemical Etching as a Fundamental Mechanism for Electroless Electricity Generation. J Phys Chem Lett 2022; 13:5648-5653. [PMID: 35708355 PMCID: PMC9234978 DOI: 10.1021/acs.jpclett.2c01302] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Accepted: 06/14/2022] [Indexed: 06/15/2023]
Abstract
Metal-assisted chemical etching (MACE) is a widely applied process for fabricating Si nanostructures. As an electroless process, it does not require a counter electrode, and it is usually considered that only holes in the Si valence band contribute to the process. In this work, a charge carrier collecting p-n junction structure coated with silver nanoparticles is used to demonstrate that also electrons in the conduction band play a fundamental role in MACE, and enable an electroless chemical energy conversion process that was not previously reported. The studied structures generate electricity at a power density of 0.43 mW/cm2 during MACE. This necessitates reformulating the microscopic electrochemical description of the Si-metal-oxidant nanosystems to separately account for electron and hole injections into the conduction and valence band of Si. Our work provides new insight into the fundamentals of MACE and demonstrates a radically new route to chemical energy conversion by solar cell-inspired devices.
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Affiliation(s)
- Shengyang Li
- Engineered
Nanosystems Group, School of Science, Aalto
University, Tietotie 1, Espoo, 02150, Finland
| | - Kexun Chen
- Department
of Electronics and Nanoengineering, Aalto
University, Tietotie 3, Espoo, 02150, Finland
| | - Ville Vähänissi
- Department
of Electronics and Nanoengineering, Aalto
University, Tietotie 3, Espoo, 02150, Finland
| | - Ivan Radevici
- Engineered
Nanosystems Group, School of Science, Aalto
University, Tietotie 1, Espoo, 02150, Finland
| | - Hele Savin
- Department
of Electronics and Nanoengineering, Aalto
University, Tietotie 3, Espoo, 02150, Finland
| | - Jani Oksanen
- Engineered
Nanosystems Group, School of Science, Aalto
University, Tietotie 1, Espoo, 02150, Finland
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8
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Zhao ZJ, Shin SH, Lee SY, Son B, Liao Y, Hwang S, Jeon S, Kang H, Kim M, Jeong JH. Direct Chemisorption-Assisted Nanotransfer Printing with Wafer-Scale Uniformity and Controllability. ACS NANO 2022; 16:378-385. [PMID: 34978803 DOI: 10.1021/acsnano.1c06781] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Nanotransfer printing techniques have attracted significant attention due to their outstanding simplicity, cost-effectiveness, and high throughput. However, conventional methods via a chemical medium hamper the efficient fabrication with large-area uniformity and rapid development of electronic and photonic devices. Herein, we report a direct chemisorption-assisted nanotransfer printing technique based on the nanoscale lower melting effect, which is an enabling technology for two- or three-dimensional nanostructures with feature sizes ranging from tens of nanometers up to a 6 in. wafer-scale. The method solves the major bottleneck (large-scale uniform metal catalysts with nanopatterns) encountered by metal-assisted chemical etching. It also achieves wafer-scale, uniform, and controllable nanostructures with extremely high aspect ratios. We further demonstrate excellent uniformity and high performance of the resultant devices by fabricating 100 photodetectors on a 6 in. Si wafer. Therefore, our method can create a viable route for next-generation, wafer-scale, uniformly ordered, and controllable nanofabrication, leading to significant advances in various applications, such as energy harvesting, quantum, electronic, and photonic devices.
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Affiliation(s)
- Zhi-Jun Zhao
- Institute of Smart City and Intelligent Transportation, Southwest Jiaotong University, Chengdu 610032, China
| | - Sang-Ho Shin
- School of Electrical and Electronic Engineering, Nanyang Technological University, 639798 Singapore, Singapore
| | - Sang Yeon Lee
- School of Electrical and Electronic Engineering, Nanyang Technological University, 639798 Singapore, Singapore
| | - Bongkwon Son
- School of Electrical and Electronic Engineering, Nanyang Technological University, 639798 Singapore, Singapore
| | - Yikai Liao
- School of Electrical and Electronic Engineering, Nanyang Technological University, 639798 Singapore, Singapore
| | - Soonhyoung Hwang
- Nano-Convergence Mechanical Systems Research Division, Korea Institute of Machinery and Materials, Daejeon 34103, South Korea
| | - Sohee Jeon
- Nano-Convergence Mechanical Systems Research Division, Korea Institute of Machinery and Materials, Daejeon 34103, South Korea
| | - Hyeokjoong Kang
- Nano-Convergence Mechanical Systems Research Division, Korea Institute of Machinery and Materials, Daejeon 34103, South Korea
| | - Munho Kim
- School of Electrical and Electronic Engineering, Nanyang Technological University, 639798 Singapore, Singapore
| | - Jun-Ho Jeong
- Nano-Convergence Mechanical Systems Research Division, Korea Institute of Machinery and Materials, Daejeon 34103, South Korea
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9
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Kale P, Sahoo MK. Removal of Ag remanence and improvement in structural attributes of silicon nanowires array via sintering. Sci Rep 2021; 11:24189. [PMID: 34921206 PMCID: PMC8683431 DOI: 10.1038/s41598-021-03654-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 11/30/2021] [Indexed: 12/14/2022] Open
Abstract
Metal-assisted chemical etching (MACE) is popular due to the large-area fabrication of silicon nanowires (SiNWs) exhibiting a high aspect ratio at a low cost. The remanence of metal, i.e., silver nanoparticles (AgNPs) used in the MACE, deteriorates the device (especially solar cell) performance by acting as a defect center. The superhydrophobic behavior of nanowires (NWs) array prohibits any liquid-based solution (i.e., thorough cleaning with HNO3 solution) from removing the AgNPs. Thermal treatment of NWs is an alternative approach to reduce the Ag remanence. Sintering temperature variation is chosen between the melting temperature of bulk-Ag (962 °C) and bulk-Si (1412 °C) to reduce the Ag particles and improve the crystallinity of the NWs. The melting point of NWs decreases due to surface melting that restricts the sintering temperature to 1200 °C. The minimum sintering temperature is set to 1000 °C to eradicate the Ag remanence. The SEM-EDS analysis is carried out to quantify the reduction in Ag remanence in the sintered NWs array. The XRD analysis is performed to study the oxides (SiO and Ag2O) formed in the NWs array due to the trace oxygen level in the furnace. The TG-DSC characterization is carried out to know the critical sintering temperature at which remanence of AgNPs removes without forming any oxides. The Raman analysis is studied to determine the crystallinity, strain, and size of Si nanocrystals (SiNCs) formed on the NWs surface due to sidewalls etching. An optimized polynomial equation is derived to find the SiNCs size for various sintering temperatures.
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Affiliation(s)
- Paresh Kale
- Department of Electrical Engineering, NIT Rourkela, Odisha, 769008, India.
| | - Mihir Kumar Sahoo
- DST-IIT Bombay Energy Storage Platform On Hydrogen, IIT Bombay, Maharashtra, 410076, India
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10
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Srivastava RP, Khang DY. Structuring of Si into Multiple Scales by Metal-Assisted Chemical Etching. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2005932. [PMID: 34013605 DOI: 10.1002/adma.202005932] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 11/18/2020] [Indexed: 05/27/2023]
Abstract
Structuring Si, ranging from nanoscale to macroscale feature dimensions, is essential for many applications. Metal-assisted chemical etching (MaCE) has been developed as a simple, low-cost, and scalable method to produce structures across widely different dimensions. The process involves various parameters, such as catalyst, substrate doping type and level, crystallography, etchant formulation, and etch additives. Careful optimization of these parameters is the key to the successful fabrication of Si structures. In this review, recent additions to the MaCE process are presented after a brief introduction to the fundamental principles involved in MaCE. In particular, the bulk-scale structuring of Si by MaCE is summarized and critically discussed with application examples. Various approaches for effective mass transport schemes are introduced and discussed. Further, the fine control of etch directionality and uniformity, and the suppression of unwanted side etching are also discussed. Known application examples of Si macrostructures fabricated by MaCE, though limited thus far, are presented. There are significant opportunities for the application of macroscale Si structures in different fields, such as microfluidics, micro-total analysis systems, and microelectromechanical systems, etc. Thus more research is necessary on macroscale MaCE of Si and their applications.
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Affiliation(s)
- Ravi P Srivastava
- Soft Electronic Materials and Devices Laboratory, Department of Materials Science and Engineering, Yonsei University, Seoul, 03722, Korea
| | - Dahl-Young Khang
- Soft Electronic Materials and Devices Laboratory, Department of Materials Science and Engineering, Yonsei University, Seoul, 03722, Korea
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11
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Gayrard M, Voronkoff J, Boissière C, Montero D, Rozes L, Cattoni A, Peron J, Faustini M. Replacing Metals with Oxides in Metal-Assisted Chemical Etching Enables Direct Fabrication of Silicon Nanowires by Solution Processing. NANO LETTERS 2021; 21:2310-2317. [PMID: 33600718 DOI: 10.1021/acs.nanolett.1c00178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Metal-assisted chemical etching (MACE) has emerged as an effective method to fabricate high aspect ratio nanostructures. This method requires a catalytic mask that is generally composed of a metal. Here, we challenge the general view that the catalyst needs to be a metal by introducing oxide-assisted chemical etching (OACE). We perform etching with metal oxides such as RuO2 and IrO2 by transposing materials used in electrocatalysis to nanofabrication. These oxides can be solution-processed as polymers exhibiting similar capabilities of metals for MACE. Nanopatterned oxides can be obtained by direct nanoimprint lithography or block-copolymer lithography from chemical solution on a large scale. High aspect ratio silicon nanostructures were obtained at the sub-20 nm scale exclusively by cost-effective solution processing by halving the number of fabrication steps compared to MACE. In general, OACE is expected to stimulate new fundamental research on chemical etching assisted by other materials, providing new possibilities for device fabrication.
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Affiliation(s)
- Maxime Gayrard
- Laboratoire Chimie de la Matière Condensée de Paris (LCMCP), Collège de France, CNRS, Sorbonne Université, F-75005 Paris, France
| | - Justine Voronkoff
- Laboratoire Chimie de la Matière Condensée de Paris (LCMCP), Collège de France, CNRS, Sorbonne Université, F-75005 Paris, France
| | - Cédric Boissière
- Laboratoire Chimie de la Matière Condensée de Paris (LCMCP), Collège de France, CNRS, Sorbonne Université, F-75005 Paris, France
| | - David Montero
- Institut des Matériaux de Paris Centre (IMPC FR 2482), Sorbonne Université, UFR de Chimie Campus Jussieu, 75252 Paris, France
| | - Laurence Rozes
- Laboratoire Chimie de la Matière Condensée de Paris (LCMCP), Collège de France, CNRS, Sorbonne Université, F-75005 Paris, France
| | - Andrea Cattoni
- Centre de Nanosciences et de Nanotechnologies (C2N), CNRS UMR 9001, Université Paris-Saclay, 91120 Palaiseau, France
| | - Jennifer Peron
- ITODYS, CNRS, UMR 7086, Université de Paris, 15 Rue J-A de Baïf, F-75013 Paris, France
| | - Marco Faustini
- Laboratoire Chimie de la Matière Condensée de Paris (LCMCP), Collège de France, CNRS, Sorbonne Université, F-75005 Paris, France
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12
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Mallavarapu A, Ajay P, Barrera C, Sreenivasan SV. Ruthenium-Assisted Chemical Etching of Silicon: Enabling CMOS-Compatible 3D Semiconductor Device Nanofabrication. ACS APPLIED MATERIALS & INTERFACES 2021; 13:1169-1177. [PMID: 33348977 DOI: 10.1021/acsami.0c17011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The semiconductor industry's transition to three-dimensional (3D) logic and memory devices has revealed the limitations of plasma etching in reliable creation of vertical high aspect ratio (HAR) nanostructures. Metal-assisted chemical etch (MacEtch) can create ultra-HAR, taper-free nanostructures in silicon, but the catalyst used for reliable MacEtch-gold-is not CMOS (complementary metal-oxide-semiconductor)-compatible and therefore cannot be used in the semiconductor industry. Here, for the first time, we report a ruthenium MacEtch process that is comparable in quality to gold MacEtch. We introduce new process variables-catalyst plasma pretreatment and surface area-to achieve this result. Ruthenium is particularly desirable as it is not only CMOS-compatible but has also been introduced in semiconductor fabrication as an interconnect material. The results presented here remove a significant barrier to adoption of MacEtch for scalable fabrication of 3D semiconductor devices, sensors, and biodevices that can benefit from production in CMOS foundries.
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Affiliation(s)
- Akhila Mallavarapu
- NASCENT Engineering Research Center, University of Texas at Austin, Austin, Texas 78758, United States
| | - Paras Ajay
- NASCENT Engineering Research Center, University of Texas at Austin, Austin, Texas 78758, United States
| | - Crystal Barrera
- NASCENT Engineering Research Center, University of Texas at Austin, Austin, Texas 78758, United States
| | - S V Sreenivasan
- NASCENT Engineering Research Center, University of Texas at Austin, Austin, Texas 78758, United States
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Bower R, Loch DAL, Ware E, Berenov A, Zou B, Hovsepian PE, Ehiasarian AP, Petrov PK. Complementary Metal-Oxide-Semiconductor Compatible Deposition of Nanoscale Transition-Metal Nitride Thin Films for Plasmonic Applications. ACS APPLIED MATERIALS & INTERFACES 2020; 12:45444-45452. [PMID: 32960569 DOI: 10.1021/acsami.0c10570] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Transition-metal nitrides have received significant interest for use within plasmonic and optoelectronic devices because of their tunability and environmental stability. However, the deposition temperature remains a significant barrier to widespread adoption through the integration of transition-metal nitrides as plasmonic materials within complementary metal-oxide-semiconductor (CMOS) fabrication processes. Binary, ternary, and layered plasmonic transition-metal nitride thin films based on titanium and niobium nitride are deposited using high-power impulse magnetron sputtering (HIPIMS) technology. The increased plasma densities achieved in the HIPIMS process allow thin films with high plasmonic quality to be deposited at CMOS-compatible temperatures of less than 300 °C. Thin films are deposited on a range of industrially relevant substrates and display-tunable plasma frequencies in the ultraviolet to visible spectral ranges. Strain-mediated tunability is discovered in layered films compared to that in ternary films. The thin film quality, combined with the scalability of the deposition process, indicates that HIPIMS deposition of nitride films is an industrially viable technique and can pave the way toward the fabrication of next-generation plasmonic and optoelectronic devices.
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Affiliation(s)
- Ryan Bower
- Department of Materials, Royal School of Mines, Imperial College London, Exhibition Road, London SW7 2AZ, U.K
| | - Daniel A L Loch
- National HIPIMS Technology Centre - UK, Materials and Engineering Research Institute, Sheffield Hallam University, Howard Street, Sheffield S1 1WB, U.K
| | - Ecaterina Ware
- Department of Materials, Royal School of Mines, Imperial College London, Exhibition Road, London SW7 2AZ, U.K
| | - Andrey Berenov
- Department of Materials, Royal School of Mines, Imperial College London, Exhibition Road, London SW7 2AZ, U.K
| | - Bin Zou
- Department of Materials, Royal School of Mines, Imperial College London, Exhibition Road, London SW7 2AZ, U.K
| | - Papken Eh Hovsepian
- National HIPIMS Technology Centre - UK, Materials and Engineering Research Institute, Sheffield Hallam University, Howard Street, Sheffield S1 1WB, U.K
| | - Arutiun P Ehiasarian
- National HIPIMS Technology Centre - UK, Materials and Engineering Research Institute, Sheffield Hallam University, Howard Street, Sheffield S1 1WB, U.K
| | - Peter K Petrov
- Department of Materials, Royal School of Mines, Imperial College London, Exhibition Road, London SW7 2AZ, U.K
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Romano L, Stampanoni M. Microfabrication of X-ray Optics by Metal Assisted Chemical Etching: A Review. MICROMACHINES 2020; 11:E589. [PMID: 32545633 PMCID: PMC7344591 DOI: 10.3390/mi11060589] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 06/08/2020] [Accepted: 06/10/2020] [Indexed: 11/19/2022]
Abstract
High-aspect-ratio silicon micro- and nanostructures are technologically relevant in several applications, such as microelectronics, microelectromechanical systems, sensors, thermoelectric materials, battery anodes, solar cells, photonic devices, and X-ray optics. Microfabrication is usually achieved by dry-etch with reactive ions and KOH based wet-etch, metal assisted chemical etching (MacEtch) is emerging as a new etching technique that allows huge aspect ratio for feature size in the nanoscale. To date, a specialized review of MacEtch that considers both the fundamentals and X-ray optics applications is missing in the literature. This review aims to provide a comprehensive summary including: (i) fundamental mechanism; (ii) basics and roles to perform uniform etching in direction perpendicular to the <100> Si substrate; (iii) several examples of X-ray optics fabricated by MacEtch such as line gratings, circular gratings array, Fresnel zone plates, and other X-ray lenses; (iv) materials and methods for a full fabrication of absorbing gratings and the application in X-ray grating based interferometry; and (v) future perspectives of X-ray optics fabrication. The review provides researchers and engineers with an extensive and updated understanding of the principles and applications of MacEtch as a new technology for X-ray optics fabrication.
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Affiliation(s)
- Lucia Romano
- Institute for Biomedical Engineering, ETH Zürich, 8092 Zürich, Switzerland;
- Paul Scherrer Institut, Forschungsstrasse 111, CH-5232 Villigen, Switzerland
- CNR-IMM, Department of Physics, University of Catania, 64 via S. Sofia, 95123 Catania, Italy
| | - Marco Stampanoni
- Institute for Biomedical Engineering, ETH Zürich, 8092 Zürich, Switzerland;
- Paul Scherrer Institut, Forschungsstrasse 111, CH-5232 Villigen, Switzerland
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