Article
Nanoscience & Nanotechnology
Dorte R. Danielsen, Anton Lyksborg-Andersen, Kirstine E. S. Nielsen, Bjarke S. Jessen, Timothy J. Booth, Manh-Ha Doan, Yingqiu Zhou, Peter Boggild, Lene Gammelgaard
Summary: This study explores the effects of anisotropic etching with sulfur hexafluoride (SF6) on multilayer 2D materials, showing that it induces hexagonal features in transition metal dichalcogenides. Furthermore, it demonstrates that anisotropic SF6 reactive ion etching process can downsize nanostructures significantly below the resolution limit of electron beam lithography for smooth edges, sharp corners, and feature sizes.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Chemistry, Multidisciplinary
Julian A. Michaels, Lukas Janavicius, Xihang Wu, Clarence Chan, Hsieh-Chih Huang, Shunya Namiki, Munho Kim, Dane Sievers, Xiuling Li
Summary: This paper presents a plasma-free, open-circuit, photo-induced metal-assisted chemical etch method for fabricating micro and nanoscale features on Silicon carbide without causing high energy ion-related surface damage. The comprehensive exploration of parameter space demonstrates the controllability and versatility of this technique in producing ordered arrays of micro and nanoscale SiC structures with porous or solid sidewalls, while elucidating the etching mechanism.
ADVANCED FUNCTIONAL MATERIALS
(2021)
Article
Thermodynamics
Nguyen Van Toan, Keisuke Ito, Truong Thi Kim Tuoi, Masaya Toda, Po -Hung Chen, Mohd Faizul Mohd Sabri, Jinhua Li, Takahito Ono
Summary: This study demonstrates a micro-heat sink based on silicon nanowires formed by metal-assisted chemical etching (MACE) to enhance heat dissipation and improve the performance of a micro-thermoelectric generator (mu-TEG). By increasing the surface-to-volume ratio, the micro-heat sink effectiveness was improved, resulting in a significant enhancement of mu-TEG performance, with the maximum output power increasing from 18.5 μW to 93 μW.
ENERGY CONVERSION AND MANAGEMENT
(2022)
Article
Materials Science, Multidisciplinary
Shaffy Garg, Sanjeev Gautam, Jitendra Pal Singh, Mandeep Kaur, Anshu Gupta, Ramcharan Meena, Suvankar Chakraverty, Young Hwa Jung, Navdeep Goyal
Summary: This study focuses on using a single target system for multilayer formation and dissolving impurity phases by swift heavy ion irradiation to improve the in-situ system for metallic multilayer thin films used for magnetic tunnel junction (MTJ), thus reducing the cost.
Article
Chemistry, Physical
Doo San Kim, Yun Jong Jang, Ye Eun Kim, Hong Seong Gil, Hee Ju Kim, You Jin Ji, Hyung Yong Kim, In Ho Kim, Myoung Kwan Chae, Jong Chul Park, Geun Young Yeom
Summary: In this study, a dual exhaust system was implemented in a reactive ion beam etcher (RIBE) to control the radical flux relative to ion flux during the etching process. The additional exhausting of radicals through the inductively coupled plasma (ICP) source chamber decreased both the ICP source chamber pressure and the ratio of radical flux to ion flux. This control of the radical flux is believed to be beneficial for anisotropic etching of nanoscale features in the next generation RIBE.
APPLIED SURFACE SCIENCE
(2022)
Review
Chemistry, Multidisciplinary
Ravi P. Srivastava, Dahl-Young Khang
Summary: Metal-assisted chemical etching (MaCE) is a simple, low-cost, and scalable method for producing silicon structures of various dimensions. Careful optimization of parameters is crucial for successful fabrication of silicon structures. MaCE enables bulk-scale structuring of silicon with significant opportunities for applications in various fields.
ADVANCED MATERIALS
(2021)
Article
Materials Science, Multidisciplinary
Sk. Ziaur Rahaman, Yao-Jen Chang, Yu-Chen Hsin, Shan-Yi Yang, Hsin-Han Lee, I. -Jung Wang, Guan-Long Chen, Yi-Hui Su, Jeng-Hua Wei, Shyh-Shyuan Sheu, Wei -Chung Lo, Duan-Li Deng, Shih-Chieh Chang
Summary: The generation of torques in heavy metal and ferromagnet heterostructures in SOT-MRAM makes them attractive for magnetic memory technology. However, the current manufacturing tools present major challenges for etching in SOT-MRAM. In this study, we experimentally investigated two different etching recipes, CF-Etch and NH-Etch, and their effects on the performance of Ta/CoFeB/MgO/Ta magnetic film stacks for SOT-MRAM development.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Shahnawaz Uddin, Md Roslan Hashim, Mohd Zamir Pakhuruddin
Summary: This study investigated the fabrication of b-Si absorber using the AACE process for the first time, and found that b-Si fabricated with a 12 nm thick aluminum film exhibited the lowest Ravg and highest broadband light absorption. The findings demonstrate the potential of the AACE process for producing b-Si with superior broadband light absorption, which is important for photovoltaic applications.
MATERIALS CHEMISTRY AND PHYSICS
(2021)
Article
Green & Sustainable Science & Technology
A. Palomino, J. Marty, S. Auffret, I. Joumard, R. C. Sousa, I. L. Prejbeanu, B. Ageron, B. Dieny
Summary: STT-MRAM, with its unique combination of properties, is expected to play a key role in IoT and information communication technologies. Recent studies have focused on critical materials in magnetic random access memory, with potential significant reductions in energy requirements and global warming potential by substituting Co/Pt multilayers.
SUSTAINABLE MATERIALS AND TECHNOLOGIES
(2021)
Article
Chemistry, Multidisciplinary
Qi Wang, Kehong Zhou, Shuai Zhao, Wen Yang, Hongsheng Zhang, Wensheng Yan, Yi Huang, Guodong Yuan
Summary: This paper demonstrates a damage-free, rapid metal-assisted chemical etching (MacEtch) method for anisotropic deep trenching of GaN, providing a new approach for GaN-based devices fabrication. The optimized etchant is studied to restrain disorder accumulation of excessive Cu particles and ensure continuous etching result, showing promise for promoting evolution of GaN-based device fabrication.
Article
Chemistry, Physical
Ziyuan Liu, Lei Tao, Yan-Fang Zhang, Jinbo Pan, Shixuan Du
Summary: Through high-throughput calculations, we have identified 39 two-dimensional ferroelectric materials with low switching barriers and large polarization. These materials include alpha, beta, and gamma phases. Seven of them exhibit ferroelectric switching barriers below 0.3 eV/f.u., polarization larger than 2 x 10(-10) C/m, and high thermodynamic stability. We have also found that larger electronegativity differences result in larger ferroelectric polarization.
Article
Nanoscience & Nanotechnology
Ju Eun Kim, Doo San Kim, You Jung Gill, Yun Jong Jang, Ye Eun Kim, Hanna Cho, Bok-Yeon Won, Oik Kwon, Kukhan Yoon, Jin-Young Choi, Jea-Gun Park, Geun Young Yeom
Summary: In this study, the etching of MTJ materials using a mixture of H-2 and NH3 in a RIBE system showed higher etch rates and selectivities compared to etching with pure H-2 or NH3. No significant damages were observed on the etched magnetic materials surfaces, and the technique is believed to be suitable for the etching of MTJ materials for future generation STT-MRAM devices.
Article
Nanoscience & Nanotechnology
Wataru Kubota, Ryoya Yamaoka, Toru Utsunomiya, Takashi Ichii, Hiroyuki Sugimura
Summary: The vapor-phase etching assisted by graphene oxide enhances the etching reaction without the formation of a porous layer, and microcontact printing of graphene oxide can be combined with silicon etching to form micrometer-sized pores in desired areas.
ACS APPLIED NANO MATERIALS
(2022)
Article
Chemistry, Physical
F. Hoelzel, D. Rolon, J. Bauer, J. Kober, S. Kuehne, F. Pietag, D. Oberschmidt, T. Arnold
Summary: Investigated the reactive ion beam finishing process of rapidly solidified aluminum (RSA) 501 using CF4 and N2 gasses to improve the surface roughness for UV optics. Found that surface modification can prevent grain orientation-dependent etching and adjusting ion incidence angle can reduce the protrusion of precipitates after UP-machining. Achieved a surface roughness value of Sq = 0.9 nm +/- 0.1 nm in the micro-roughness range using collimated ion beams with CF4 process gas at 40 degrees and 80 degrees angle of incidence.
SURFACES AND INTERFACES
(2023)
Article
Chemistry, Multidisciplinary
Alexander Sagar Grossek, Anna Niggas, Richard A. Wilhelm, Friedrich Aumayr, Christoph Lemell
Summary: We provide the first qualitative description of the atomic dynamics in 2D materials induced by slow, highly charged ions. By combining classical molecular dynamics simulation and Monte Carlo model, we investigate the impact of charge transfer velocity and extracted electron number on the stability of 2D structure and nanopore formation due to Coulomb repulsion.
Article
Nanoscience & Nanotechnology
Gyo Wun Kim, Won Jun Chang, Ji Eun Kang, Hee Ju Kim, Geun Young Yeom
Summary: This study compared the radiation damage to EUV resist during etching of hardmask materials using CF4 gas between neutral beam etching (NBE) and ion beam etching (IBE). The results showed that NBE reduced the line edge roughness increase and critical dimension change of EUV resist compared to IBE. NBE also had a lower root mean square surface roughness value of EUV resist and higher etch selectivity for materials such as Si3N4 and SiO2 over EUV resist.
Article
Chemistry, Physical
Dain Sung, Long Wen, Hyunwoo Tak, Hyejoo Lee, Dongwoo Kim, Geunyoung Yeom
Summary: The etching properties of C6F6/Ar/O-2 in ICP and CCP systems were evaluated. In the ICP system, lower O-2/C6F6 ratio and higher SiO2 etch rate were required, while in the CCP system, tapered SiO2 etch profiles were observed.
Article
Chemistry, Analytical
Ki Seok Kim, You-Jin Ji, Ki-Hyun Kim, Ji-Eun Kang, Albert Rogers Ellingboe, Geun Young Yeom
Summary: Low-hydrogen-containing amorphous silicon (a-Si) was successfully deposited at a low temperature using a 162 MHz VHF plasma system. The use of smaller multi-split electrodes resulted in a high ion density plasma, leading to a high deposition rate and uniformity. Increasing the RF power reduced the hydrogen content in the deposited silicon film. The a-Si could be crystallized through UV irradiation without the need for dehydrogenation. Transmission electron microscopy revealed that the a-Si deposited by the VHF plasma system had a nanocrystalline-like structure, which could be significantly increased in size with UV irradiation.
Article
Multidisciplinary Sciences
Won Oh Lee, Ki Hyun Kim, Doo San Kim, You Jin Ji, Ji Eun Kang, Hyun Woo Tak, Jin Woo Park, Han Dock Song, Ki Seok Kim, Byeong Ok Cho, Young Lae Kim, Geun Young Yeom
Summary: This study investigates fast and selective isotropic etching of SiNx over SiOy using CIF3/H-2 remote plasma in an inductively coupled plasma system. The addition of H-2 increases etching selectivity and reduces the etch rate of both oxide and nitride.
SCIENTIFIC REPORTS
(2022)
Article
Nanoscience & Nanotechnology
Ki Seok Kim, Ji Eun Kang, Peng Chen, Sungkyu Kim, Jongho Ji, Geun Young Yeom, Jeehwan Kim, Hyun S. Kum
Summary: Epitaxial lift-off techniques are important for the fabrication of lightweight and flexible devices. This study presents a new approach, using direct growth of thick graphene on the target substrate followed by atomic layer etching, to improve the yield and quality of remote epitaxy.
Article
Chemistry, Multidisciplinary
Seunghwan Seo, Jeong-Ick Cho, Kil-Su Jung, Maksim Andreev, Ju-Hee Lee, Hogeun Ahn, Sooyoung Jung, Taeran Lee, Byeongchan Kim, Seojoo Lee, Juncheol Kang, Kyeong-Bae Lee, Ho-Jun Lee, Ki Seok Kim, Geun Young Yeom, Keun Heo, Jin-Hong Park
Summary: Multi-valued logic (MVL) technology has been reconsidered due to the need for greater power saving in current binary logic systems. This study reports a reconfigurable m-NDR device with electric-field-induced tunability of multiple threshold voltages. The m-NDR phenomenon is achieved by modulating the resistance of the ReS2 layer using electrical pulses. The reconfigurability of the device is demonstrated in MVL circuits composed of the m-NDR device and a load transistor.
ADVANCED MATERIALS
(2022)
Article
Chemistry, Physical
Hee Ju Kim, Long Wen, Doo San Kim, Ki Hyun Kim, Jong Woo Hong, Won Jun Chang, Soo Namgoong, Dong Woo Kim, Geun Young Yeom
Summary: The etch characteristics of silicon trenches masked with various SiO2/Si3N4 pattern distances were investigated using different pulse modes in Ar/Cl-2 inductively coupled plasmas. The results showed that using synchronously and asynchronously pulse modes instead of continuous wave (CW) mode increased the selectivity between Si and the mask layer and reduced the etch rate differences between wide and narrow pattern distance patterns (ARDE). The improvements in etch selectivity and reduction of ARDE were attributed to the increased conduction of Cl radicals/byproducts and time separated etch cycle composed of Cl chemical adsorption and removal of chemisorbed species.
APPLIED SURFACE SCIENCE
(2022)
Article
Chemistry, Physical
Hyun Woo Tak, Hye Joo Lee, Long Wen, Byung Jin Kang, Dain Sung, Jeong Woon Bae, Dong Woo Kim, Wonseok Lee, Seung Bae Lee, Keunsuk Kim, Byeong Ok Cho, Young Lea Kim, Han Dock Song, Geun Young Yeom
Summary: In this study, the effects of chemical branch structure on plasma characteristics and etch characteristics of high aspect ratio ACL patterned SiO2 were investigated using three isomers with the same chemical composition. The results showed that the chemical branch structure significantly influenced the plasma properties and etch characteristics, even with the same chemical composition.
APPLIED SURFACE SCIENCE
(2022)
Article
Nanoscience & Nanotechnology
Doo San Kim, Yun Jong Jang, Ye Eun Kim, Hong Seong Gil, Byeong Hwa Jeong, Geun Young Yeom
Summary: In this study, atomic layer etching (ALE) process was used to precisely etch Sn for the fabrication of next generation extreme ultraviolet (EUV) mask. Optimized ALE conditions were identified to control the etch thickness of Sn and achieve high etch selectivity over the capping layer Ru, with minimal physical and chemical damage.
Article
Chemistry, Physical
You Jin Ji, Hae In Kim, Ki Hyun Kim, Ji Eun Kang, Doo San Kim, Ki Seok Kim, A. R. Ellingboe, Dong Woo Kim, Geun Young Yeom
Summary: In this study, the characteristics of PEALD SiNx films deposited at low temperatures were investigated. The use of a floating multi-tile electrode resulted in films with higher growth rate, higher N/Si ratio, lower surface roughness, and higher conformality. The electrical properties of the SiNx films deposited with the floating multi-tile electrode also showed improvement.
SURFACES AND INTERFACES
(2022)
Article
Materials Science, Coatings & Films
Ye Eun Kim, Doo San Kim, Yun Jong Jang, Hong Seong Gil, Ho Seop Jeon, Jong Woo Hong, In Ho Kim, Cheol Kim, Jeong-Heon Park, Geun Young Yeom
Summary: Rf-biased reactive ion beam etching (RIBE) with a H-2:NH3 gas mixture was used to etch CoFeB and MgO in the magnetic tunnel junction (MTJ) layer of magnetic random access memory. The etch selectivity of MTJ materials was increased with H-2 percentage in the gas mixture, and the etch rates were highest between 2:1 and 1:1 ratio of H-2:NH3 due to the synergy effect of H-2 and NH3. High rf-biasing during RIBE increased etch rates but decreased etch selectivities, while small rf-biasing improved etch characteristics such as higher selectivity, improved anisotropy, and thinner sidewall residue. The addition of small rf-biasing increased chemical etching effect without increasing physical sputtering effect, and also eliminated substrate charging.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2023)
Article
Engineering, Electrical & Electronic
Jong Woo Hong, Hyun Min Cho, Yu Gwang Jeong, Da Woon Jung, Yun Jong Yeo, Ji Eun Kang, Hee Ju Kim, Hyun Woo Tak, Geun Young Yeom, Dong Woo Kim
Summary: A study was conducted on the dry etching of indium tin oxide (ITO) using novel hydrocarbon gases mixed with Ar, such as ethane and propane. The results showed that these gases increased the etch rate and selectivity of ITO, and reduced dimensional loss. The etch residues formed during the process could be successfully removed using H2/Ar plasma.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2023)
Article
Nanoscience & Nanotechnology
Hyunseok Kim, Yunpeng Liu, Kuangye Lu, Celesta S. Chang, Dongchul Sung, Marx Akl, Kuan Qiao, Ki Seok Kim, Bo-In Park, Menglin Zhu, Jun Min Suh, Jekyung Kim, Junseok Jeong, Yongmin Baek, You Jin Ji, Sungsu Kang, Sangho Lee, Ne Myo Han, Chansoo Kim, Chanyeol Choi, Xinyuan Zhang, Hyeong-Kyu Choi, Yanming Zhang, Haozhe Wang, Lingping Kong, Nordin Noor Afeefah, Mohamed Nainar Mohamed Ansari, Jungwon Park, Kyusang Lee, Geun Young Yeom, Sungkyu Kim, Jinwoo Hwang, Jing Kong, Sang-Hoon Bae, Yunfeng Shi, Suklyun Hong, Wei Kong, Jeehwan Kim
Summary: Multiple compound semiconductor membranes can be produced from a single wafer by directly growing two-dimensional materials on III-N and III-V substrates and then harvesting each epilayer through layer-by-layer mechanical exfoliation. This high-throughput layer transfer technique eliminates time-consuming processes and has the potential to greatly reduce manufacturing costs. The atomic-precision exfoliation at the 2D interface allows for the recycling of wafers for subsequent membrane production.
NATURE NANOTECHNOLOGY
(2023)
Article
Materials Science, Multidisciplinary
Jong Woo Hong, Yeon Hee Kim, Hee Ju Kim, Hyun Woo Tak, Ki Deok Bae, Jeong Yub Lee, Hae Soo Bae, Yong Su Kim, Geun Young Yeom
Summary: TiO2 meta materials with high aspect ratio pillars of different widths were etched using various plasma techniques. The results showed that the etch rates decreased in the order of continuous wave, bias pulsing, synchronous pulsing, and asynchronous pulsing conditions. However, the etch selectivities over ACL and SiO2 and the aspect ratio dependent etching (ARDE) effect improved in that same order. The improvement in ARDE effect was attributed to the decreased compositional differences between wide and narrow TiO2 pattern areas, especially under the asynchronous pulse condition.
Article
Nanoscience & Nanotechnology
Jong Woo Hong, Hyun Woo Tak, Young Hun Choi, Hee Jung Kim, Dong Woo Kim, Geun Young Yeom
Summary: Adding 50% CF3I into C4F8/Ar/O-2 gas mixtures resulted in both high etch selectivity over mask materials and potentially reduced etch damage.
SCIENCE OF ADVANCED MATERIALS
(2022)