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Measurements of ion flux-energy distribution functions at the high sheath potential of the driven electrode in a classical low-pressure asymmetric capacitively coupled plasma are technically difficult as the diagnostic device needs to float with the applied radio frequency voltage. Otherwise, the ion sampling is disturbed by the varying electric field between the grounded device and the driven electrode. To circumvent such distortions, a low-pressure plasma chamber with inverted electrode geometry, where the larger electrode is driven and the smaller electrode is grounded, has been constructed and characterized. Measurements of the ion flux-energy distribution functions with an energy-selective mass spectrometer at the high sheath potential of the grounded electrode are presented for a variety of conditions and ions. The potential for suppressing low-energy ions from resonant charge transfer collisions in the sheath by the dilution of the working gas is demonstrated. Additionally, the setup is supplemented by an inductively coupled plasma that controls the plasma density and consequently the ion flux to the substrate while the radio frequency bias controls the ion energy. At high ion energies, metal ions are detected as a consequence of the ionization of sputtered electrode material. The proposed setup opens a way to study precisely the effects of ion treatment for a variety of substrates such as catalysts, polymers, or thin films.

A novel direct current (DC) magnetron sputtering system via radio frequency (RF) bias with hexamethyldisiloxane (HMDSO) plasma polymerization was developed for the deposition of SiOx-doped diamond-like carbon (DLC) films on a glass substrate. As the RF bias increased, the ratio of intensity of D peak and G peak (I(D)/I(G)) decreased and the G peak shifted to a low position, leading to high hardness and a large portion of sp3 bonds. Additionally, weak sp2 graphite bonds were broken and sp3 diamond bonds formed because the RF bias attracted hydrogen ion bombarding the DLC films. Increasing DC power was helpful to improve the hardness of the DLC films because the proportion of sp3 bonds and the I(D)/I(G) ration was increased. HMDSO was introduced into this process to form SiOx:DLC films with enhanced optical performance. The average transmittance in the visible region of these very thin SiOx:DLC films with a thickness of 37.5 nm was 80.3% and the hardness of the SiOx:DLC films was increased to 7.4 GPa, which was 23.3% higher than that of B270 substrates.

One challenge for microcrystalline silicon (mu c-Si:H) deposition is to achieve high deposition rates while maintaining high quality films. In this work, an inductively-coupled plasma (ICP) is used to deposit mu c-Si:H on glass substrates by means of a novel planar resonant antenna at 13.56 MHz. No particle formation occurs in the low pressure (5 Pa) plasma, but the films suffer post-oxidation. By embedding a 5 MHz RF-biased substrate, films deposited simultaneously with and without RF bias are compared. It is shown that large area, low pressure (5 Pa), particle-free ICP deposition at 1 nm/s of mu c-Si:H films can be obtained without post-oxidation by means of a planar resonant antenna, provided that RF substrate bias is included for independent control of the ion energy. (C) 2017 Elsevier Ltd. All rights reserved.