Sebastian Okrasa

Novel GIMS technique for deposition of colored Ti/TiO₂ coatings on industrial scale

Abstract The aim of the present paper has been to verify the effectiveness and usefulness of a novel deposition process named GIMS (Gas Injection Magnetron Sputtering) used for the flrst time for deposition of Ti/TiO₂ coatings on large area glass Substrates covered in the condition of industrial scale production. The Ti/TiO₂ coatings were deposited in an industrial System utilizing a set of linear magnetrons with the length of 2400 mm each for covering the 2000 × 3000 mm glasses. Taking into account the speciflc course of the GIMS (multipoint gas injection along the magnetron length) and the scale of the industrial facility, the optical coating uniformity was the most important goal to check. The experiments on Ti/TiO₂ coatings deposited by the use of GIMS were conducted on Substrates in the form of glass plates located at the key points along the magnetrons and intentionally non-heated during any stage of the process. Measurements of the coatings properties showed that the thickness and optical uniformity of the 150 nm thick coatings deposited by GIMS in the industrial facility (the thickness differences on the large plates with 2000 mm width did not exceed 20 nm) is fully acceptable form the point of view of expected applications e.g. for architectural glazing.

Optimization of gas injection conditions during deposition of AlN layers by novel reactive GIMS method

In 2011, we proposed a novel magnetron sputtering method. It involved the use of pulsed injection of working gas for the initiation and control of gas discharge during reactive sputtering of an AlN layer (Gas Injection Magnetron Sputtering — GIMS). Unfortunately, the presence of Al-Al bonds was found in XPS spectra of the AlN layers deposited by GIMS onto Si substrate. Our studies reported in this paper proved that the synchronization of time duration of the pulses of both gas injection and applied voltage, resulted in the elimination of Al-Al bonds in the AlN layer material, which was confirmed by the XPS studies. In our opinion the most probable reason of Al-Al bonds in the AlN layers deposited by the GIMS was the self-sputtering of the Al target in the final stage of the pulsed discharge.

Impulse Plasma In Surface Engineering - a review

The article describes the view of the plasma surface engineering, assuming the role of non-thermal energy effects in the synthesis of materials and coatings deposition. In the following study it was underlined that the vapor excitation through the application of an electric field during coatings deposition gives new possibilities for coatings formation. As an example the IPD method was chosen. During the IPD (Impulse Plasma Deposition) the impulse plasma is generated in the coaxial accelerator by strong periodic electrical pulses. The impulse plasma is distributed in the form of energetic plasma pockets. Due to the almost completely ionization of gas, the nucleation of new phases takes place on ions directly in the plasma itself. As a result the coatings of metastable materials with nano-amorphous structure and excellent adhesion to the non-heated intentionally substrates could be deposited. Recently the novel way of impulse plasma generation during the coatings deposition was proposed and developed by our group. An efficient tool for plasma process control, the plasma forming gas injection to the interelectrode space was used. Periodic changing the gas pressure results in increasing both the degree of dispersion and the dynamics of the plasma pulses. The advantage of the new technique in deposition of coatings with exceptionally good properties has been demonstrated in the industrial scale not only in the case of the IPD method but also in the case of very well known magnetron sputtering method.

On coating adhesion during impulse plasma deposition

The impulse plasma deposition (IPD) technique is the only method of plasma surface engineering (among plasma-based technologies) that allows a synthesis of layers upon a cold unheated substrate and which ensures a good adhesion. This paper presents a study of plasma impacts upon a copper substrate surface during the IPD process. The substrate was exposed to pulsed N2/Al plasma streams during the synthesis of AlN layers. For plasma–material interaction diagnostics, the optical emission spectroscopy method was used. Our results show that interactions of plasma lead to sputtering of the substrate material. It seems that the obtained adhesion of the layers is the result of a complex surface mechanism combined with the effects of pulsed plasma energy impacts upon the unheated substrate. An example of such a result is the value of the critical load for the Al2O3 layer, which was measured by the scratch-test method to be above 40 N.

The role of magnetic energy on plasma localization during the glow discharge under reduced pressure

Abstract In this work, we present the first results of our research on the synergy of fields, electric and magnetic, in the initiation and development of glow discharge under reduced pressure. In the two-electrode system under reduced pressure, the breakdown voltage characterizes a minimum energy input of the electric field to initiate and sustain the glow discharge. The glow discharge enhanced by the magnetic field applied just above the surface of the cathode influences the breakdown voltage decreasing its value. The idea of the experiment was to verify whether the contribution of potential energy of the magnetic field applied around the cathode is sufficiently effective to locate the plasma of glow discharge to the grounded cathode, which, in fact, is the part of a vacuum chamber wall (the anode is positively biased in this case). In our studies, we used the grounded magnetron unit with positively biased anode in order to achieve favorable conditions for the deposition of thin films on fibrous substrates such as fabrics for metallization, assuming that locally applied magnetic field can effectively locate plasma. The results of our studies (Paschen curve with the participation of the magnetic field) seem to confirm the validity of the research assumption. What is the most spectacular - the glow discharge was initiated between introduced into the chamber anode and the grounded cathode of magnetron ‘assisted’ by the magnetic field (discharge did not include the area of the anode, which is a part of the magnetron construction).

Characterization of sp 3 bond content of carbon films deposited by high power gas injection magnetron sputtering method by UV and VIS Raman spectroscopy

This paper presents the results of investigations of carbon films deposited by a modified version of the magnetron sputtering method - HiPGIMS (High Power Gas Injection Magnetron Sputtering). In this experiment, the magnetron system with inversely polarized electrodes (sputtered cathode at ground potential and positively biased, spatially separated anode) was used. This arrangement allowed us to conduct the experiment using voltages ranging from 1 to 2kV and a power supply system equipped with 25/50μF capacitor battery. Carbon films were investigated by VIS/UV Raman spectroscopy. Sp3/sp2 bonding ratio was evaluated basing the elementary components of registered spectra. Our investigation showed that sp3 bond content increases with discharge power but up to specific value only. In extreme conditions of generating plasma impulses, we detected a reversed relation of the sp3/sp2 ratio. In our opinion, a energy of plasma pulse favors nucleation of a sp3 phase because of a relatively higher ionization state but in extreme cases the influence of energy is reversed.

Multi-sided metallization of textile fibres by using magnetron system with grounded cathode

Abstract The synthesis of coatings on textiles fibers enables functionalization of their properties e.g.: changing the reaction on IR radiation. In our experiment, a magnetron with a grounded cathode and positively biased anode was used as a source of plasma. A ring anode was positioned at 8 cm distance from the cathode. Samples of glass and cotton textile were placed at the plane of the anode. Ti and TiN coatings were deposited by sputtering of titanium target in Ar or Ar+ N2 atmosphere. SEM studies showed that, using the magnetron system described above, the textile fibers were covered by the 2 μm to 3 μm thick coatings. Unexpectedly, the coatings were deposited at both sides of the samples: the front side was exposed to glow discharge plasma and the backside was completely shaded from the plasma. IR optical investigation exhibited significant change in reflectance and transmittance of the coated textiles. The using of standard magnetron system (grounded anode and cathode at negative potential) resulted in a coating deposition at the textile side exposed to the plasma action only. We believe that the multi-sided deposition of coatings observed during the process run with magnetron with grounded cathode is a result of an ambipolar diffusion mechanism in the anodic potential drop region.

The application of magnetic self-filter to optimization of AIN film growth process during the impulse plasma deposition synthesis

Abstract This work presents the very first results of the application of plasma magnetic filtering achieved by a coil coupled with an electrical circuit of a coaxial accelerator during the synthesis of A1N thin films by use of Impulse Plasma Deposition method (IPD). The uniqueness of this technical solution lies in the fact that the filter is not supplied, controlled and synchronized from any external device. Our solution uses the energy from the electrical circuit of plasma accelerator. The plasma state was described on the basis of OES studies. Estimation of the effects of plasma filtering on the film quality was carried out on the basis of characterization of structure morphology (SEM), phase and chemical composition (vibrational spectroscopy). Our work has shown that the use of the developed magnetic self-filter improved the structure of the AlN coatings synthesized under the condition of impulse plasma, especially by the minimization of the tendency to deposit metallic aluminum droplets and columnar growth.