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i l St. Petersburg Polytechnic University Journal. Physics and Mathematics. 2022 Vol. 15, No. 3.3 Научно-технические ведомости СПбГПУ. Физико-математические науки. 15 (3.3) 2022
ATOM PHYSICS AND PHYSICS OF CLUSTERS AND NANOSTRUCTURES
Conference materials UDC 29.19.22
DOI: https://doi.org/10.18721/JPM.153.318
Growth of nanostructured cobalt thin film at oblique angle deposition
I. S. Fattakhov 1 2e, O. S.Trushin \ A. A. Popov \ L. A. Mazaletsky 2
1 Valiev Institute of Physics and Technology of Russian Academy of Sciences, Yaroslavl Branch, Yaroslavl, Russia; 2 P. G. Demidov Yaroslavl State University, Yaroslavl, Russia H 33ychenikan@mail.ru
Abstract. Nanocolumnar Co thin films growth by oblique angle deposition on Si substrate is experimentally studied. Formation of regular arrays of vertical Co nanocolumns has been observed at incidence angles more than 80 degrees with rotation of substrate. Such films might be perspective material for applications as a magnetic recording media for next generations of hard disks.
Keywords: Co thin films, nanocolumns, oblique angle deposition
Funding: Reported study was carried out under State Programs No. FFNN-2022-0018 of the Ministry of Science and Higher Education of Russia on the equipment of the center for collective use of the scientific equipment "Diagnostics of micro- and nanostructures".
Citation: Fattakhov I. S., Trushin O. S., Popov A. A., Mazaletsky L. A., Growth of na-nostructured cobalt thin film at oblique angle deposition, St. Petersburg State Polytechnical University Journal. Physics and Mathematics, 15 (3.3) (2022) 97-100. DOI: https://doi. org/10.18721/JPM.153.318
This is an open access article under the CC BY-NC 4.0 license (https://creativecommons. org/licenses/by-nc/4.0/)
Материалы конференции УДК 29.19.22
DOI: https://doi.org/10.18721/JPM.153.318
Рост наноструктурированной плёнки кобальта при наклонном напылении
И. С. Фаттахов 1 2Н, О. С. Трушин А. А. Попов Л. А. Мазалецкий 2
1 Ярославский филиал Физико-технологического института имени К. А. Валиева Российской академии наук, Ярославль, Россия; 2 Ярославский государственный университет им. П. Г. Демидова, Ярославль, Россия
н 33ychenikan@mail.ru
Аннотация. Экспериментально исследован рост тонких пленок Co при наклонном напылении на подложку Si. Образование массивов наноколонн Co наблюдалось при углах падения более 80 градусов при вращении подложки. Такие плёнки могут быть перспективным материалом для применения в качестве носителей магнитной записи для следующих поколений жестких дисков.
Ключевые слова: тонкие плёнки из кобальта, наноколонны, напыление под углом
Финансирование: Работа выполнена в рамках Государственной программы № ФФНН-2022-0018 Министерства науки и высшего образования России на оборудовании центра коллективного пользования научным оборудованием «Диагностика микро- и наноструктур».
Ссылка при цитировании: Фаттахов И. С., Трушин О. С., Попов А. А., Мазалецкий Л. А., Рост наноструктурированной плёнки кобальта при наклонном напылении //
© Fattakhov I. S., Trushin O. S., Popov A. A., Mazaletsky L. A., 2022. Published by Peter the Great St.Petersburg Polytechnic University.
Научно-технические ведомости СПбГПУ. Физико-математические науки. 2022. Т. 15. № 3.3. С. 97-100. DOI: https://doi.org/10.18721/JPM.153.318
Статья открытого доступа, распространяемая по лицензии CC BY-NC 4.0 (https:// creativecommons.org/licenses/by-nc/4.0/)
Introduction
Magnetic thin films with easy axis normal to the substrate surface are of considerable interest as a promising material for ultrahigh density magnetic recording. However thin film growth at standard conditions leads to magnetization vector oriented in the plane of the surface. By controlling the texture parameters of the films during their growth, one can change their properties in a targeted manner, thereby achieving the required functional characteristics [1]. A promising method for the formation of films with special properties is their nanostructuring during growth. The formation of homogeneous and well-ordered arrays of nanostructures on the surface makes it possible to change significantly the electrophysical, magnetic, and optical properties of the films. One of the well-known technological methods allowing to ensure the growth of nanostructures is oblique angle deposition. It is a relatively inexpensive technology that can be easily implemented in conditions of mass production. This method of producing films has attracted considerable interest in recent years, and many works are devoted to it [2, 3]. It is known that this method can be used to obtain nanostructures of various shapes and sizes, from inclined nanowires and nanospirals to vertical nanocolumns [2]. It has been found that by varying the angle of incidence one can change the direction of magnetic anisotropy [4]. Besides that chiral nanostructured thin films can be produced through precise control of the angle of incidence of a vapor flux concurrent with substrate rotation [5]. It was found that the reason for nanostructuring of films under oblique deposition is the shading effect, which consists in the fact that crystallites, which received a random advantage in growth at the initial stages, further suppress the growth of neighbors, intercepting the flux of atoms incident on the surface and, thereby, forming pores. Main goal of this work was finding optimal conditions for the formation of perpendicular magnetic anisotropy
Experiment
Electron beam evaporation is a suitable technology for oblique angle deposition experiments. This method combines a sufficiently high working vacuum and a homogeneous flow of the evaporated material. Experiments on the deposition of Co films on an inclined substrate were carried out on an Oratoria-9 electron beam evaporation unit. The deposition conditions were as follows: base vacuum 4 10-6 Torr, electron beam voltage 8 kV, current 0.5 A. A standard single-crystal silicon wafer with a thermal oxide layer 300 nm thick was used as a substrate. During deposition substrate inclination angle was fixed to be equal to 85°. The distance from the evaporator to the substrate was about 1 m. This significant distance from the source of the evaporated material provided a high level of flow Fig. 1. Schematic of the experiment uniformity. Besides that the substrate was rotating around for the oblique angle deposition its vertical axis with variable rate. All experiments were
done at room temperature. The growth rate of the film at these conditions was equal to 1 nm/s. The schematic of the experiment is shown in Figure 1. We used a collector motor to rotate the substrate at a controlled speed. The static sample was located as close as possible to the rotating one and is needed to compare with the results obtained on the rotating sample. The surface morphology of the obtained films was investigated by scanning electron microscopy (SEM) (Supra 40).
© Фаттахов И. С., Трушин О. С., Попов А. А., Мазалецкий Л. А., 2022. Издатель: Санкт-Петербургский политехнический университет Петра Великого.
in Co films using this method.
holder
Target
Atom physics and physics of clusters and nanostructures
Results and Discussion
Cross-section of the film deposited at incidence angle ^ = 85° and rotation rate of 30 rpm is shown at fig, 2, a. One can see that fibrous nanostructure is formed at these conditions. A rotation of the substrate during growth leads to vertical alignment of nanocolumns. More complete information about the morphology of the film is obtained from the analysis of top view on its surface shown at fig. 2, b. One can see that separate Co fibers have shape of nanocolumns extending upwards with the width less than 70 nm.
Fig.2: Cross-section of the Co film (a) and top view on its surface (b). The images were obtained using
electron scanning microscopy (SUPRA-40)
The next experiment was carried out at the speed of rotation of 0.6 rpm and at incidence angle ^ = 85°. Cross-section of the film is shown at fig. 3, a. One can see that vertical spiral nanocolumns are formed at these conditions. The analysis of the top view from fig. 3, b shows that separate Co fibers have shape of nanocolumns extending upwards with the width less than 100 nm. The fig. 3, c. and fig. 3, d. show the cross-section and top view of the static sample. These images confirm that spiral form of nanocolumns is the result of substrate rotation.
Fig. 3: Cross-section of the Co film (a) and top view on its surface (b). The images were obtained using
electron scanning microscopy (SUPRA-40)
Conclusion
In summary, as the results of experimental studies of the growth of Co thin films by oblique angle deposition with rotation of substrate it was found that optimal conditions for regular arrays formation of nanocolumns and nanospirals, are achieved at the angle of 85°. By varying substrate rotation rate it is possible to change shape of nanocolumns from spiral to rod. Studies of magnetic properties of the films are currently in progress. Such films might be perspective for application in ultrahigh density magnetic recording.
1. Amirov I. I., Selyukov R. V., Naumov V. V., Gorlachev E. S., Russian Microelectronics, 50 (1) (2021) 1.
2. Barranco A., Borras A., Gonzalez-Elipe A., Palmero A., Perspectives on oblique angle deposition of thin films: From fundamentals to devices, Progress in Materials Science, 76 (2016) 59—153.
3. Hawkeye M., Taschuk M., Brett M., Glancing Angle Deposition of Thin Films, UK: John Wiley &Sons Ltd, 2014. Pp. 1-299.
4. AkulovA. A., Trushin O. S., Popov A. A., Pestova A. N., Mazaletsky L. A., Nanostructuring at oblique incidence deposition of cobalt, J. Phys. Conf. Ser., 2086 (2021) 012001.
5. Liu F., Umlor M. T., Shen L., Weston J., Eads W., Barnard J. A., Mankey G. J., The growth of nanoscale structured iron films by glancing angle deposition, Journal of Applied Physics, 85 (1999) 5486.
REFERENCES
THE AUTHORS
FATTAKHOV Ilya S.
33ychenikan@mail.ru ORCID: 0000-0002-6671-9179
aapopov@mail.ru
POPOV Aleksandr A.
MAZALETSKY Leonid А.
TRUSHIN Oleg S.
otrushin@gmail.com
boolvinkl@ya.ru
Received 20.07.2022. Approved after reviewing 22.07.2022. Accepted 22.07.2022.
© Peter the Great St. Petersburg Polytechnic University, 2022
