Ion current to a substrate in the pulsed dc hollow cathode plasma jet deposition system (original) (raw)
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Measurements of positive ion flux to the substrate during deposition of thin films by hollow cathode plasma jet are presented. Different methods of obtaining negative bias of substrate and measuring the resulting ion flux are compared and discussed-pulsed DC bias, RF bias, and pulse-modulated RF bias of substrate. For determination of current and voltage waveforms on the substrate when the RF bias is applied, an electric circuit model of power feed line to the substrate is presented.
Plasma properties of a DC hollow cathode discharge
2006
We have investigated the plasma properties of a Hollow Cathode Discharge (HCD) using different dimensions of hollow cathode aperture (1 to 8 mm) in argon operating medium. The diagnostic used to investigate the plasma properties is a tiny Langmuir probe. The diameter and length of the Langmuir probe was chosen such that it draws a measurable current from the plasma causing a minimal perturbation to the surrounding plasma and remains rigid within the plasma as well as the cylindrical probe theories are applicable while calculating the electron temperature and plasma density. The probe was placed perpendicular to the axis of the hollow cathode at a distance of 20 mm from the hollow cathode side. The HCD was operated in the voltage range of 600 to 1000 V and pressures range of 70 to 100 mtorr. We observed that electron temperature and density varies with the operational condition. The estimated electron temperature is less than 10 eV and the temperature is maximum in the range of 3 to 5 mm diameter of the hollow cathode and a pressure range of 75 to 85 mTorr. The calculated maximum density is of the order of 10 10 cm -3 .
Plasma Properties of a Low-Pressure Hollow Cathode DC Discharge
Iraqi Journal of Science
The current study involves an experimental investigation of plasma main parameters of a DC discharge with a hollow cathode (HCD) geometry in air using apertures of different diameters from the hollow cathode (1, 1.5, 2, and 2.5 cm). A tiny Langmuir probe is used to investigate the plasma properties. The HCD was operated at constant power of 12.4 W and gas pressures ranging between 0.1 to 0.8 torr. It was observed that the operational conditions strongly affect the electron temperature and density, while the hollow cathode diameter has not much influence. The main important observation was that at relatively high air pressure (>0.4 torr) two electron temperatures were obtained, while at relatively low pressure (<0.4 torr), a single electron temperature was found. The results showed that the measured electron temperature decreased nearly linearly with increasing gas pressure.
Japanese Journal of Applied Physics, 2011
The channel spark discharge was used as a high-current density (up to 30 kA/cm 2 ) relatively low-energy (<20 keV) electron beam source in a pulsed plasma deposition (PPD) gun. The PPD gun was used for the deposition of thin films by pulsed ablation of different target materials, at a background gas pressure in the 10 À3 -10 À5 Torr range. The parameters of the electron beam generated in the modified PPD gun were studied using electrical, optical, and X-ray diagnostics. It was found that a higher background pressure stimulates a denser plasma formation between the gun output and the target, that restricts the energy delivery to the beam electrons. Namely, the efficient (up to $74%) transfer of the initially stored energy to the electron beam is realized at the background gas pressure of 10 À4 Torr. Conversely, at a pressure of 10 À3 Torr, only 10% of the stored energy is acquired by the energetic electrons. It was shown that the modified PPD gun, owing to the extremely high energy density delivered by the electrons to the target, may be applied for the deposition of a wide variety of different insulators, semiconductors, and metals. A selection of materials such as diamond-like carbon (DLC), cadmium telluride (CdTe), cadmium sulphide (CdS), zinc oxide (ZnO), tungsten, and tungsten carbide (WC) have been deposited as thin films and the properties and deposition rates of the deposited thin films are discussed.
Contributions to Plasma Physics, 2006
Low temperature low pressure hollow cathode plasma jet system working in static magnetic field was investigated by means of time resolved Langmuir probe technique. The hollow cathode discharge was excited in a cylindrical nozzle fabricated from Ti by continuous DC, pulsed DC, continuous wave radio-frequency (RF) and pulse-modulated RF power. Pure Ar was used as working gas. Electron distribution, electron density, and effective electron temperature were measured and compared between the different plasma jet excitation modes. Time evolution of plasma parameters was studied and compared with time evolution of power absorbed in the discharge in pulsed DC and pulse-modulated RF discharge excitation modes.
Contributions to Plasma Physics, 2008
Electric probe diagnostics were used to determine plasma parameters of the low pressure low temperature hollow cathode plasma jet system used for TiO x thin films depositions. The Langmuir probe technique together with measurements of positive ion current to the substrate was employed. High-density hollow cathode discharge was generated in titanium nozzle with argon and a mixture of argon and oxygen as working gases. Lagmuir probe measurements provided electron energy probability function, electron density, and effective electron temperature in the plasma jet for different working conditions. They were compared with measurements of the positive ion current to the negatively biased substrate. The substrate was biased with pulsed DC or RF voltage. Determination of plasma parameters contributes to better understanding of the deposition processes as well as to the reproducibility of the deposition.
Physics of Plasmas, 2020
The theoretical derivation of the relation between moving charges in the plasma and external circuit current was first established on a firm basis by Sato 1 for the case of a discharge with constant applied voltage between bare electrodes. The generalization to time varying applied voltages was established by Morrow and Sato 2 , still considering bare electrodes. In the present work we extend the latter derivation to include general devices with arbitrarily arranged linear dielectric media, and multiple electrodes with time dependent voltages, of interest, for instance, for a Dielectric Barrier Discharge (DBD). In particular, the present derivation determines a general, practical expression for the reactive term present in Morrow and Sato formula. Using the expression derived we show how in simple DBD geometries usual circuit approximations of the plasma discharge can be obtained and its validity justified. Also, we consider the determination of the internal plasma current from the measurement of the external circuit current for a cylindrical DBD operated with helium at atmospheric pressure. Finally, we apply the theory to a three-electrode device in order to relate electric measurements to volume integrals on the plasma that were shown to be useful in order to quantify species production by electron impact.
Contributions to Plasma Physics, 2002
In the recent decade an RF driven, low-pressure plasma reactor with supersonic plasma jet was developed (RPJ). This reactor was successfully used for deposition of thin films of various materials. The deposition of thin films indicates that the properties of the deposited films are dependent on the sputtering or reactive sputtering processes appearing inside the nozzle (hollow cathode). The nozzle (hollow cathode) fabricated of different kinds of materials and alloys works both as a cathode of the radio frequency (RF) hollow cathode discharge and as a nozzle for plasma jet channel generation as well. The RF hollow cathode discharge is a secondary discharge, which is induced by the primary RF plasma generated in the reactor chamber. The present paper deals with the experimental study of this RF hollow cathode discharge. The stress is laid on the investigation of the axial distribution of discharge parameters and sputtering processes inside the nozzle. On the base of experiments, the simple model of the axial distribution of the investigated RF hollow cathode discharge has been developed.
Laser-triggered hollow-cathode plasma process for film growth
Journal of Vacuum Science & Technology A Vacuum Surfaces and Films
A method of generating a pulsed plasma plume of metallic species using a hollow-cathode arc discharge arrangement is presented. Electrical energy from a pulse-forming network (PFN) generates the transient plasma that evaporates material from the anode that is placed inside a hollow cathode. The discharge is triggered by thermionic electrons produced by a CO 2 laser pulse that impinges on one of the electrodes. This plasma process has been used to deposit carbon films in a low-pressure argon or nitrogen ambient. Current pulses of 4 -10 ms in duration with peak currents of 350 A have been produced by the PFN. Characteristics of the produced plasma have been studied by optical emission spectroscopy. The amount of energy imparted to the argon plasma is more than that for a nitrogen plasma. Comparison of on-axis intensity for the 426.9 nm line of C + for the two plasmas shows that the density of carbon ions generated in the nitrogen plasma is higher than that in the argon plasma. Films deposited by this method have fairly uniform thickness profiles that are of the form cos 0.4 for the argon plasma and cos 2.2 for the nitrogen plasma. This indicates that the nitrogen plasma is more forward directed than the argon plasma. Deposition rates of about 10-16 Å / pulse have been obtained for carbon films.