Tailoring structural and optical properties of Si-doped HfO2 thin films via target composition and plasma environment.

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Bibliographic Details
Title:	Tailoring structural and optical properties of Si-doped HfO2 thin films via target composition and plasma environment.
Alternate Title:	Вплив хімічного складу мішені та газової плазми на оптичні та структурні характеристики плівок HfO2, легованих кремнієм.
Authors:	Khomenkov, D. V.¹ dmkhomen@gmail.com, Ponomaryov, S. S.² s.s.ponomaryov@gmail.com, Portier, X.³ xavier.portier@ensicaen.fr, Melnichuk, L. Yu.¹ lyu.melnichuk@gmail.com, Khomenkova, L. Yu.^2,4 khomen@ukr.net, Gourbilleau, F.³ fabrice.gourbilleau@ensicaen.fr, Melnichuk, O. V.¹ mov310310@gmail.com
Source:	Semiconductor Physics, Quantum Electronics & Optoelectronics. 2025, Vol. 28 Issue 4, p441-448. 8p.
Subjects:	Refractive index, Reactive sputtering, Magnetron sputtering, Thin films, Glass coatings, Optical properties, Plasma deposition, Microstructure
Abstract:	Optical and structural properties of as-deposited Si-doped HfO2 thin films were investigated as a function of target composition, substrate temperature (100...500 °C), and plasma environment. The films were deposited on Si (100) substrates by RF magnetron sputtering from composite Si:HfO2 targets in either pure argon or argon-hydrogen plasma. The Si content in the films was varied by adjusting the target composition, the hydrogen fraction in the plasma, and the total pressure. TEM, FTIR, ellipsometry, and Auger electron spectroscopy revealed that the Si-doped films maintained chemical uniformity and dense amorphous structure. For deposition in pure Ar plasma at a total pressure of 0.04 mbar, increasing Si incorporation led to formation of homogeneous amorphous films with a refractive index higher than that of pure HfO2 (2.42 vs. 1.98 at 1.95 eV). Deposition in Ar-H2 plasma enabled further raise of the refractive index up to 2.75 through variation of the hydrogen flow rate. An even higher refractive index up to 3.4 was achieved by lowering the total pressure to 0.02 mbar and/or by increasing the substrate temperature. However, the latter resulted in a reduced film growth rate. The extended structure-zone model provided a consistent framework to interpret the observed film morphologies, linking adatom mobility, ion bombardment, and film densification to the deposition parameters. The novelty of this work is in demonstrating that hydrogen-assisted reactive sputtering enables in situ control of the Si content during deposition without need to modify the target composition. These findings show that the microstructure and optical response of Si-doped HfO2 films can be systematically tailored, offering a route for designing high-index amorphous coatings suitable for optical and microelectronic applications. [ABSTRACT FROM AUTHOR]
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Database:	Engineering Source

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Abstract:	Optical and structural properties of as-deposited Si-doped HfO2 thin films were investigated as a function of target composition, substrate temperature (100...500 °C), and plasma environment. The films were deposited on Si (100) substrates by RF magnetron sputtering from composite Si:HfO2 targets in either pure argon or argon-hydrogen plasma. The Si content in the films was varied by adjusting the target composition, the hydrogen fraction in the plasma, and the total pressure. TEM, FTIR, ellipsometry, and Auger electron spectroscopy revealed that the Si-doped films maintained chemical uniformity and dense amorphous structure. For deposition in pure Ar plasma at a total pressure of 0.04 mbar, increasing Si incorporation led to formation of homogeneous amorphous films with a refractive index higher than that of pure HfO2 (2.42 vs. 1.98 at 1.95 eV). Deposition in Ar-H2 plasma enabled further raise of the refractive index up to 2.75 through variation of the hydrogen flow rate. An even higher refractive index up to 3.4 was achieved by lowering the total pressure to 0.02 mbar and/or by increasing the substrate temperature. However, the latter resulted in a reduced film growth rate. The extended structure-zone model provided a consistent framework to interpret the observed film morphologies, linking adatom mobility, ion bombardment, and film densification to the deposition parameters. The novelty of this work is in demonstrating that hydrogen-assisted reactive sputtering enables in situ control of the Si content during deposition without need to modify the target composition. These findings show that the microstructure and optical response of Si-doped HfO2 films can be systematically tailored, offering a route for designing high-index amorphous coatings suitable for optical and microelectronic applications. [ABSTRACT FROM AUTHOR]
ISSN:	15608034
DOI:	10.15407/spqeo28.04.441