B. Bora

Theoretical approach for plasma series resonance effect in geometrically symmetric dual radio frequency plasma

Plasma series resonance (PSR) effect is well known in geometrically asymmetric capacitively couple radio frequency plasma. However, plasma series resonance effect in geometrically symmetric plasma has not been properly investigated. In this work, a theoretical approach is made to investigate the plasma series resonance effect and its influence on Ohmic and stochastic heating in geometrically symmetric discharge. Electrical asymmetry effect by means of dual frequency voltage waveform is applied to excite the plasma series resonance. The results show considerable variation in heating with phase difference between the voltage waveforms, which may be applicable in controlling the plasma parameters in such plasma.

Measurements of time average series resonance effect in capacitively coupled radio frequency discharge plasma

Self-excited plasma series resonance is observed in low pressure capacitvely coupled radio frequency discharges as high-frequency oscillations superimposed on the normal radio frequency current. This high-frequency contribution to the radio frequency current is generated by a series resonance between the capacitive sheath and the inductive and resistive bulk plasma. In this report, we present an experimental method to measure the plasma series resonance in a capacitively coupled radio frequency argon plasma by modifying the homogeneous discharge model. The homogeneous discharge model is modified by introducing a correction factor to the plasma resistance. Plasma parameters are also calculated by considering the plasma series resonances effect. Experimental measurements show that the self-excitation of the plasma series resonance, which arises in capacitive discharge due to the nonlinear interaction of plasma bulk and sheath, significantly enhances both the Ohmic and stochastic heating. The experimentally ...

Dual radio frequency plasma source: Understanding via electrical asymmetry effect

On the basis of the global model, the influences of driving voltage and frequency on electron heating in geometrically symmetrical dual capacitively coupled radio frequency plasma have been investigated. Consistent with the experimental and simulation results, non-monotonic behavior of dc self bias and plasma heating with increasing high frequency is observed. In addition to the local maxima of plasma parameters for the integer values of the ratio between the frequencies (ξ), ourstudies also predict local maxima for odd integer values of 2ξ as a consequence of the electrical asymmetry effect produced by dual frequency voltage sources.

Investigation on plasma parameters and step ionization from discharge characteristics of an atmospheric pressure Ar microplasma jet

In this communication, we report a technique to estimate the plasma parameters from the discharge characteristics of a microplasma device, operated in atmospheric pressure on the basis of homogeneous discharge model. By this technique, we investigate the plasma parameters of a microplasma jet produced by microplasma device consisting of coaxial capillary electrodes surrounded by dielectric tube. Our results suggest that the complex dependence of electrical discharge characteristics observed for microplasma device operated with Ar or it admixtures probably signify the existence of step ionization, which is well known in inductively coupled plasma.

Nitridation of steel 460LI-21Cr by plasma immersion ion implantation in capacitively couple radio frequency plasma

Summary form only given. Results on nitriding of newly developed superferritic steel 460LI-21Cr in a low power 13.56 MHz capacitively coupled radio frequency plasma are reported. Nitrogen ions are implanted by plasma immersion ion implantation method for different process temperature, process time and gas mixture. Preliminary results of energy dispersive X-ray spectroscopy show presence of up to 15 % of nitrogen. The measured Vickers Hardness is found to increase up to 5 times. Detailed characterizations, including plasma parameters, will be presented.

Nitriding of Ti substrate using energetic ions from plasma focus device

Plasma Focus (PF) discharge is a pulsed plasma producing discharge that generates high temperature and high density plasma for a short duration. PF devices are known to emit intense ion beams pulses of characteristic energy in the keV to a few MeV range, in a time scale of tens of nanoseconds. We have previously investigated the ion flux and energy spectrum of ion beams emitted from a low energy PF, operating at 20 kV, with 1.8 kJ stored energy. It was observed that the ion beams have wide range of energy and intensity spectra with a clear angular anisotropy. Due to the wide range of ion energy and intensity spectra PF has become a subject of current interest for its applications in material sciences including surface modification and thin film deposition. The purpose of this study is the formation of titanium nitride (TiN) thin film and to investigate the structural properties of the TiN thin films in terms of PF angular positions. Substrates like Ti and Ti/Si were nitrided in a 1.8 kJ PF device at different angular positions with respect to the PF axis in order to correlate their surface properties with ion beam parameters. Preliminary characterizations of the ion implanted substrates have been conducted, using SEM, EDX and XRD. Our results indicate the formation of nanocrystalline TiN thin film only in certain angular positions. Angular dependency of the surface morphology was observed, which shows that the surface features strongly depends on ion beam energy and flux. With increasing angular positions, a reduction in the deposition rate and the sputter rate is observed. A pronounced nanostructured surface is only observed at the axis of the pinched plasma column, indicating the dominant role of sputtering and perhaps melting and fast re-crystallization of the surface in creating the nanostructures.

Characterization of Capacitively Coupled Radio-Frequency Argon Plasma by Electrical Circuit Simulation

Low temperature radio frequency plasma is widely used in low temperature plasma processing medium for material processing in many fields including microelectronics, aerospace, and the biology. For proper utilization of the process, it is very much important to know the plasma parameters. In this paper a novel technique is used to determine the plasma parameters from the electrical discharge characteristic and the power balance method. The homogeneous discharge model is used to evaluate the relation between the plasma parameters with the discharge characteristics. The electron density and temperature is found to be well agree with the Langmuir probe data in the range of 0.5x1016 to 45x1016 cm-3 and 1.4 to 1.6 ev for wide range of rf power.