The role of lower hybrid resonance and helicon waves excitations in a magnetized plasma for coating production of complex crystalline structures as hydroxyapatite. (December 2017)

• Record Type: Journal Article
• Authors: López, Elvis O.; Borges, Fábio O.; Rossi, Alexandre M.; Galvão, Ricardo M.O.; Mello, Alexandre
• Is Part Of: Vacuum. Volume 146(2017)
• Page Start: 233
• Page End: 245
• Publication Date: 2017-12
• Subjects: Plasma processes -- Radio-frequency magnetron sputtering -- Resonance for plasma heating -- HydroxyApatite films -- Biomedical applications; Vacuum -- Periodicals; 621.55
• DOI: 10.1016/j.vacuum.2017.10.002
• Languages: English
• ISSNs: 0042-207X

Abstract

Abstract: The non-equilibrium electro-thermodynamic properties of magnetized plasma produced by a modified radio-frequency magnetron sputtering system were investigated in detail. The plasma was analyzed using Hall, Langmuir, and Faraday probes and optical emission spectroscopy, and numerical simulations were conducted to determine the electric and magnetic field profiles. It is found that the occurrence of lower hybrid resonance and excitation of helicon waves are satisfied locally along the plasma profile ( Z ). This unusual effect in magnetron sputtering systems plays an important role in the increase of the electrons and ions temperature improving the quality of the films produced. Films of complex structure as hydroxyapatite that have biomedical applications were produced along the Z to confirm our plasma results. The films were characterized by performing grazing incidence X-ray diffraction using synchrotron radiation, X-ray photoelectron spectroscopy and atomic force microscopy. The microstructure analysis of hydroxyapatite films produced at different Z revealed that films with high crystallinities and with ideal stoichiometries (Ca/P = 1.67 ± 0.05) were produced within a magnetic cusp region (26 mm < Z < 32 mm). Based upon the results from plasma diagnostics and films characterization, we proposed a model of plasma of this system. The delivered energy by ions bombardment for films formation was determined and reached values around 8 eVs −1 Å −2 and plasma temperature of T ≈ 10 eV inside the magnetic cusp region. Finally, this work opens the possibility to produce coatings of other complex compounds by the fine-tuning of resonant waves and their high delivered energies in vacuum magnetized plasmas. Highlights: Locally increase of plasma temperature from resonance waves of a radio-frequency right-angle magnetron sputtering system (RAMS). Dependence of the microstructure of hydroxyapatite films with the plasma delivered energy. Control of the stoichiometry of crystalline hydroxyapatite thin films produced at room temperature for biomedical applications. Proposal of plasma model of this RAMS system geometry.