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Schematic diagram of an unbalanced DC magnetron sputtering system
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The measurements of plasma parameters from inside a plasma boundary give more accurate results. Current-voltage (I-V) characteristics were obtained from plasma measurements in an unbalanced magnetron sputtering system using a Langmuir probing technique which collects the measured data from a biased probe inserted inside the plasma. These I-V charac...
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... schematic diagram of an unbalanced DC magnetron sputtering system is shown in Fig. 1. The reactor chamber was made of stainless steel in a cylindrical form 31 cm in diameter. A 99.97% purity Ti target with 7.6 cm diameter was attached to the cathode which was connected to a high-power DC generator. 99.999% purity Ar gas was used as the sputtering gas. The vacuum system consisted of a diffusion pump backed by a rotary ...
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Knowledge of the real EEDF is of great importance in understanding the underlying physics of processes occurring at the magnetized plasma, such as the formation of transport barriers, cross-field diffusion coefficients and plasma–substrate interactions. In the present experiment, the application of Langmuir probe to evaluate EEPF in presence of mag...
In this study, an experimental investigation of a DC cylindrical magnetron discharge for argon gas in post-cathode (i.e. direct) and hollow-cathode (i.e. inverted) configurations was carried out. The discharge properties at different externally applied magnetic fields and operating pressures were measured and compared for both the configurations. T...
The ion, electron density and electron temperature during formation of TiN films in reactive magnetron sputtering system have been investigated for various settings of radio frequency (RF) power and working pressure by using Langmuir probe measurements. The RF power and working pressure able to affect the densities and plasma properties during the...
Citations
... Among the contact methods for plasma diagnostics, electrical probes are the least expensive, yet the fastest and most reliable diagnostic tools, providing values for plasma parameters such as plasma potential (Vp), electron temperature (Te), electron (Ne), and ion (Ni) densities, as well as the distribution functions (EEDF) of the charged particles (electrons and ions) [30][31][32]. A complete fixed probe system consists of an interface unit (EPIU-ESPION Probe Interface Unit), a gas-cooled, radio-frequency electrostatically compensated probe, and connection cables. ...
In the current study, bulk tungsten material surfaces are exposed to hydrogen, deuterium, and helium plasmas in the radiofrequency domain (13.56 MHz) at an input power of 250 W using the hollow-cathode configuration. The ejected material is collected on titanium substrates at various distances (from 6 mm up to 40 mm). Therefore, the exposed tungsten materials are investigated for surface changes (blister occurrence, dust formation, or nano-structuration), along with the crystallinity, depending on the plasma’s exposure times (from 30 min up to 120 min for each plasma type). Also, the collected materials are analyzed (morphological, structural, and statistical investigations) for dust and dust film-like appearance. Plasma discharges are analyzed using two methods: optical emission spectroscopy, and single Langmuir probes, to emphasize the nature of the used plasmas (cold discharges, ~2 eV), along with the presence of tungsten emission (e.g., WI 406.31 nm, WI 421.31 nm) during the plasma lifetime. By using a dedicated protocol, a method was established for obtaining fusion-relevant tungsten surfaces in the hydrogen and deuterium plasma discharges. By using the implemented method, the current paper introduces the possibility of obtaining a new tungsten morphology, i.e., the dandelion-like shape, by using helium plasma, in which the W18O49 compound can be found.
... Electrical probes are essential diagnostic instruments in plasma research, particularly in cold plasma and at low gas pressure. These probes have the advantage of being able to perform local plasma parameter measurements [8,9]. The perturbation of the plasma across the position of the probe caused by the space charge sheath in front of the surface of the probe and the extraction of charged particles is detected by the immersed electrical probe. ...
... By controlling the external parameters of the plasma system one can control the plasma parameters and consequently improve the film properties [8]. Over the last few years, extensive research has been conducted on thin film growth and characterisation. ...
... By excluding the inner and outer parts of magnetic core and at the same time preserving the hollow-cathode structure of the substrate, it is possible to expand the plasma discharge over the entire surface of the cathode, as demonstrated in Fig. 9(l). [84][85][86] Corresponding probe measurements presented in Fig. 9(m) provide further confirmation of the expansion of the plasma discharge with the elimination of the magnetic core. These measurements also demonstrate a drastic change in the distribution of the ion current density, where the initial Gaussian distribution transforms into abroad plateau with a high degree of uniformity. ...
... II B 1 and II C 1), the key features of the dielectric breakdown within the system was explored experimentally and numerically, with the details of this study reported elsewhere. 84 The electrical breakdown can be described using: ...
Given the vast number of strategies used to control the behavior of laboratory and industrially relevant plasmas for material processing and other state-of-the-art applications, a potential user may find themselves overwhelmed with the diversity of physical configurations used to generate and control plasmas. Apparently, a need for clearly defined, physics-based classification of the presently available spectrum of plasma technologies is pressing, and the critically summary of the individual advantages, unique benefits, and challenges against key application criteria is a vital prerequisite for the further progress. To facilitate selection of the technological solutions that provide the best match to the needs of the end user, this work systematically explores plasma setups, focusing on the most significant family of the processes - control of plasma fluxes - which determine the distribution and delivery of mass and energy to the surfaces of materials being processed and synthesized. A novel classification based on the incorporation of substrates into plasma-generating circuitry is also proposed and illustrated by its application to a wide variety of plasma reactors, where the effect of substrate incorporation on the plasma fluxes is emphasized. With the key process and material parameters, such as growth and modification rates, phase transitions, crystallinity, density of lattice defects, and others being linked to plasma and energy fluxes, this review offers direction to physicists, engineers, and materials scientists engaged in the design and development of instrumentation for plasma processing and diagnostics, where the selection of the correct tools is critical for the advancement of emerging and high-performance applications.
... Understanding of particles behavior due to magnetron in the plasma is important [6]- [13]. In recent years, studying the magnetic field distribution and its effect on plasma parameters have been gained importance to improve the quality of thin films [14]- [17]. Field distribution at axial and radial positions causes variations in plasma parameters such as electron temperature and densities [18]- [22]. ...
Magnetic field (B) distribution of the magnetron was measured and discussed its effect on plasma parameters and deposition rate. Plasma parameters such as electron temperature (Te), electron number density (ne) were estimated using electron flux (EF) and electron energy distribution function (EEDF) methods as function of axial, radial distances from the cathode. Te and ne decreased with increasing of axial, radial distances from the cathode. Dr was obtained for the same positions where the above plasma parameters were measured, and found that similar profile with Te and ne. Magnetron configuration was simulated using COMSOL Multiphysics software and compared with the experimentally measured profile. Further, density distribution was simulated using measured B through particle in cell - Monte Carlo collision and found simulation results are well supported to the experimental results.
... For instance, Olaya et al. 27 found electron density of 4.7 Â 10 10 cm À3 at 5 cm, 0.9 Pa and 200 W (2.5 W/cm 2 ), whereas Spolaore et al. 28 reported 4 Â 10 10 cm À3 for 15 cm, 1 Pa, and 100 W (1.2 W/cm 2 ). Wiemer et al. 29 give 1.5 Â 10 11 cm À3 at 11 cm, 2.5 Pa, 300 W (3.8 W/cm 2 ) and Honglertkongsakul et al. 30 9.5 Â 10 11 cm À3 at 8 cm and 0.5 Pa. The electron temperature is typically of the order of 2-3 eV although Spatenka et al. 6 have highlighted the presence of hot electrons whose energy was in the range of 5-6 eV, 80 mm away from the target. ...
... For instance, Olaya et al. 27 found electron density of 4.7 Â 10 10 cm À3 at 5 cm, 0.9 Pa and 200 W (2.5 W/cm 2 ), whereas Spolaore et al. 28 reported 4 Â 10 10 cm À3 for 15 cm, 1 Pa, and 100 W (1.2 W/cm 2 ). Wiemer et al. 29 give 1.5 Â 10 11 cm À3 at 11 cm, 2.5 Pa, 300 W (3.8 W/cm 2 ) and Honglertkongsakul et al. 30 9.5 Â 10 11 cm À3 at 8 cm and 0.5 Pa. The electron temperature is typically of the order of 2-3 eV although Spatenka et al. 6 have highlighted the presence of hot electrons whose energy was in the range of 5-6 eV, 80 mm away from the target. ...
In this work, the energetic conditions at the substrate were investigated in dc magnetron sputtering (DCMS), pulsed dc magnetron sputtering (pDCMS), and high power impulse magnetron sputtering (HiPIMS) discharges by means of an energy flux diagnostic based on a thermopile sensor, the probe being set at the substrate position. Measurements were performed in front of a titanium target for a highly unbalanced magnetic field configuration. The average power was always kept to 400 W and the probe was at the floating potential. Variation of the energy flux against the pulse peak power in HiPIMS was first investigated. It was demonstrated that the energy per deposited titanium atom is the highest for short pulses (5 {mu}s) high pulse peak power (39 kW), as in this case, the ion production is efficient and the deposition rate is reduced by self-sputtering. As the argon pressure is increased, the energy deposition is reduced as the probability of scattering in the gas phase is increased. In the case of the HiPIMS discharge run at moderate peak power density (10 kW), the energy per deposited atom was found to be lower than the one measured for DCMS and pDCMS discharges. In these conditions, the HiPIMS discharge could be characterized as soft and close to a pulsed DCMS discharge run at very low duty cycle. For the sake of comparison, measurements were also carried out in DCMS mode with a balanced magnetron cathode, in the same working conditions of pressure and power. The energy flux at the substrate is significantly increased as the discharge is generated in an unbalanced field.
This work reports a systematic review of the studies of magnetron sputtering (MS) discharges and their utilities for the deposition of transparent coating oxide thin films like indium tin oxides (ITOs). It collates the overall information of plasma science, diagnostics, and chemistry and their usefulness in controlling the plasma process, film growth, and properties. It discusses studies on various MS systems and their capabilities and reports scientific aspects like the formation of instability and plasma flares to understand the various discharge phenomena. The study also discusses various issues, progress, and challenges in ITO films for industrial applications. In addition, this work highlights the importance of plasma parameters and energy flux on thin film growth and film properties.
This chapter describes several important technological approaches and schematic solutions for efficient control of plasma parameters in the technological setups. Incorporating and externalsubstrate technological architectures are introduced and discussed, including magnetically enhanced RF discharges, arrays of ferromagnetic enhanced inductive plasma sources, arrays of helicon plasma sources, and other important systems.
Vanadium dioxide (VO2) is a promising material for electronics and optics due to abrupt change in conductivity of VO2 that occurs at ∼68 °C, which is the metal-insulator transition temperature. The abruptness and magnitude of this transition is governed by the crystal structure of VO2. The growth of thin VO2 films therefore requires substrate heating during deposition and, as well as the occasional need for additional post-deposition annealing. The processes that occur during annealing depend upon the deposition technique. However, the published reports related to these studies are rarely systematic and lack consistency. The annealing of thin nanocrystalline VO2+x films at temperatures above the melting point is reported here. Thin films were deposited onto a polycrystalline corundum substrate by means of radio-frequency reactive magnetron sputtering, with the thin film composition fine-tuned by applying negative substrate bias during deposition and proceeding with ex-situ control of the vanadium oxidation state. Post-deposition annealing causes recrystallization, which is in accordance with the V–O phase diagram. No epitaxial or other substrate-induced processes were detected. However, the sharpest transition was attributed to the film possessing the most uniform grain size, as opposed to the film with the largest VO2 crystallites. The temperature dependency of the microwave radiation transmittance was investigated over the 8–18 GHz range, with the samples measured in free-space conditions. This was intended to reveal any frequency-dependent features, which can possibly appear as benefits or obstacles during the development of designs in the microwave range that are based on the VO2 films being studied.
