Plasma Enhanced Chemical- and Physical- Vapor Depositions Using Hollow Cathodes

Abstract: Development of coating deposition technologies, in terms of performance and costs, is an ongoing process. A promising class of deposition technologies are based on hollow cathode discharges.This thesis investigates performance of selected hollow cathode plasma sources developed at the Plasma group, at Uppsala University for coating deposition at moderate pressures. Amorphous carbon film deposition was investigated by Radio frequency (RF) Hollow Cathode Plasma Jet (RHCPJ) and Magnets-in-Motion (M-M) linear hollow cathode plasma sources. Titanium nitride (TiN) films were deposited by a magnetized Hollow Cathode Enhanced magnetron Target (HoCET). Aluminium nitride (AlN) deposition by RHCPJ was compared with High Power Impulse Magnetron Sputtering (HiPIMS).Amorphous carbon films were prepared on glass substrates without an interlayer. The AlN and TiN films were deposited on Si substrates. Optical emission spectroscopy was used to analyze plasma composition. The coating structure was analyzed by X-ray diffraction and Raman spectroscopy. The thickness of films was measured by scanning electron microscopy and profilometry. The TiN hardness was analyzed by microhardness test method and confirmed by nanoindentation analysis.Adherent amorphous carbon coating deposition process was transferred from RHCPJ to the M-M linear hollow cathode. Utilizing the latter plasma source, it was found that thick and adherent amorphous carbon coatings can be deposited in a range of 0.25% to 0.5% of C2H2 in Ar at constant a deposition pressure of 0.3 Torr and 1200 W of RF power. Deposition rates of 0.2 μm/min and 0.375 μm/min respectively were reached. Self-delaminating, thick (50 μm) amorphous carbon films can be deposited at a deposition rate of 2.5 μm/min at 2% C2H2. A non-linear relation was observed between the deposition rate and the C2H2 content.Utilizing the HoCET arrangement, high deposition rates of stoichiometric, polycrystalline TiN films are obtained. A maximum of 0.125 μm/min is obtained at 2.4% N2 in Ar, 1200 W RF power, 14 mTorr deposition pressure. TiN films deposited at 4 - 20% nitrogen contents displayed hardness values above 28 GPa reaching a maximum of 31.4 GPa at 5% N2.For a (002) oriented AlN film deposition the RHCPJ offers deposition rates of up to 150 nm/min. Using the HiPIMS at comparable deposition conditions the AlN films were achieved at a rate of 24 nm/min.