STUDYING THE SURFACE OF METAL / SILICON STRUCTURES, OBTAINED BY ION-ASSISTED DEPOSITION METAL-CONTAINING COATINGS IN VACUUM

UDC 539.1.06:539.23.234

 

Tul’ev Valentin Valentinovich − PhD (Physics and Mathematics), Associate Professor, Assistant Professor, the Department of Physics. Belarusian State Technological University (13a, Sverdlova str., 220006, Minsk, Republic of Belarus). E-mail: tvv69@mail.ru

DOI: https://doi.org/ 10.52065/2520-6141-2024-284-5.

Key words: ion-assisted deposition, silicon, titanium, zirconium, molybdenum, hydrogen, Rutherford backscattering, resonance nuclear reaction method, nanohardness.

For citation: Tul’ev V. V. Studying the surface of metal / silicon structures obtained by ion-assisted deposition metal-coating in vacuum. Proceedings of BSTU, issue 3, Physics and Mathematics. Informatics, 2024, no. 2 (284), pp. 31–37 (In Russian). DOI: 10.52065/2520-6141-2024-284-5.

Abstract

The paper discusses experimental results on studying the distribution of elements in the near-surface layers of Me/Si structures (Me = Ti, Zr, Mo) formed by ion-assisted deposition in a vacuum. This method consists of depositing a coating onto a substrate, during which the surface of the structure being formed is irradiated with a beam of accelerated ions. The coating deposition time was (1–6) hours at an accelerating voltage U = 5–0 kV and an ion current density of ~4–10 μA/cm2. During the deposition of coatings, a vacuum was maintained in the working chamber at a pressure of ~10−2 Pa. The average coating deposition speed was in the range of 0,2–0,4 nm/min. The ratio Ji/Jа of the flux density Ji of assisting ions to the flux density Ja of neutral atoms was 0,2–0,5, which corresponds to the condition for growth of the coating on the substrate. The composition and depth distribution of elements in the formed coatings were studied using the Rutherford backscattering method of helium ions in combination with RUMP computer modeling and the method of resonance nuclear reactions. The mechanical properties of the surface of the formed structures were studied using nanoindentation, and the topography of the surface of the samples was studied using a scanning atomic force microscope. Studies of Me/Si structures carried out using the Rutherford backscattering method and the method of resonant nuclear reactions showed that the formed structures contain atoms of the deposited metal (~5 at. %), silicon atoms from the substrate (10‒15 at. %), atoms technological impurities of carbon (20‒25 at.%), oxygen (10‒15 at. %) and hydrogen (30‒40 at. %). The source of process impurities is the volatile hydrocarbon fraction of the vacuum oil of a diffusion steam-oil pump. It has been established that the nanohardness of the surface of Me/Si structures at a depth of ∼50 nm exceeds the nanohardness of pure silicon by 5 times, and at a depth of ∼100 nm by 3 times. An increase in the surface hardness of the resulting structures leads to a decrease in its Young’s modulus by 5–10 times. With a further increase in the indentation depth, the hardness of the modified surface and Young's modulus approaches the characteristics of the surface of unmodified silicon. A study of the surface topography of the samples showed that the surface roughness of unmodified silicon is very insignificant and amounts to ∼0,2 nm. The roughness of the formed Me/Si structures increases to 0,3–0,7 nm depending on the base metal of the coating, and the total surface area of the sample is practically no different from its projective area.

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18.04.2024