Vladimir V. Serikov

Particle-in-cell plus direct simulation Monte Carlo (PIC-DSMC) approach for self-consistent plasma-gas simulations

The particle-in-cell (PIC) and direct simulation Monte Carlo (DSMC) approaches have been combined into a PIC-DSMC model for self-consistent simulations of low-temperature collisional plasmas and the background gas. This novel approach is based on the weighting collision simulation scheme allowing for disparate number densities and time scales of different species. The applicability of the developed algorithm is illustrated by simulations of one-dimensional direct current and two-dimensional magnetron sputtering discharges in argon. An appreciable effect of the energetic discharge species on the density, temperature, and flow field of the background gas shows the importance of the coupled plasma-gas simulation for such technologies as sputtering, dry etching, plasma enhanced vapor deposition, etc.

MONTE CARLO NUMERICAL ANALYSIS OF TARGET EROSION AND FILM GROWTH IN A THREE-DIMENSIONAL SPUTTERING CHAMBER

A combination of two mathematical models for three‐dimensional Monte Carlo particle simulation of a low pressure sputtering environment is proposed. One is intended for the simulation of a discharge gas flow, and the other for the sputtered atom transport. The combination is used to characterize target erosion and film growth. The models are refined with recourse to experimental measurements made in a practical sputtering apparatus (SPF‐210 AS, ANELVA Ltd.) over the range of operating pressures and flow rates of 0.3–10 Pa and 0.5–5 sccm, respectively. A considerable number of numerical analyses are done to find possible reasons for the measured nonuniformity of target erosion and film growth rate distributions. Simulation results show that under the operating and design conditions treated here the nonuniformity of gas flow field appears to be too weak to explain the experimental data. Film growth rates simulated for measured erosion rates show a good agreement with the experimental data for the various op...

The analysis of background gas heating in direct current sputtering discharges via particle simulation

A particle-in-cell/Monte Carlo numerical model has been developed to simulate a direct current discharge self-consistently with the motion and thermalization of both energetic charge-exchange neutrals and sputtered cathode atoms. In the model the charged particle motions are considered in a self-consistent electric field. A one-dimensional glow discharge in Ar has been simulated for the cases of Al and Cu cathode. The background argon gas heating has been predicted, with the temperature rise being larger for the case of Cu cathode which is characterized by a higher sputtering yield than Al. The balance of power input into the gas due to the energetic neutrals, sputtered atoms, and ions is analyzed. The dominant contribution is from energetic neutrals. Comparison of the calculated fluxes of these three species at the cathode surface shows a great contribution of the energetic neutrals into sputtering of the cathode material. The effect of applied voltage has been also investigated. Lastly, the influence of...

Limits of DWDM with gratings and Fabry-Perots and alternate solutions

High resolution DWDM devices based on the principles of gratings (planar, Bragg, AWG, etc.) and Fabry-Perots (etalon, Lummer-Gehrke plate, etc.) suffer from inherent limitations due to (i) temporal pulse stretching of data, and (ii) broadening of time integrated spectral (demuxed) fringes. While the relation, dνFdt >1, can account for these limitations, our analysis imply that dnF does not represent real, physical frequencies. We explain the broader implications of this interpretation in designing DWDM devices based on gratings and Fabry-Perots and illustrate how to use prisms, photonic crystals and non-linear devices for very high data rate per channel.

Spatio-temporal variations in a three-dimensional DC glow discharge via particle-in-cell simulation

A particle-in-cell Monte Carlo collision algorithm has been developed to numerically investigate the three-dimensional structure of a parallel-plate direct current glow discharge. The discharge in argon under a low pressure of 42 mtorr has been simulated as taking place between two circular electrodes in a grounded rectangular chamber. The motion of ions and electrons was calculated in a self-consistent electric field, which was obtained from Poissons equation by a fast Fourier transform algorithm at each electron time step. Spatial distributions and temporal behavior of the electric field and discharge macroparameters were analyzed. The oscillations and wavy structure of the discharge characteristics have been revealed.

Numerical experiments in Monte Carlo modeling of polarization, diffraction, and interference phenomena

We present the numerical tests for a Monte Carlo ray-tracing model. The model has been extended to simulate not only geometrical but also physical optics phenomena, including polarization, diffraction, and interference of light. Light beams are represented by a flux of simulated particles (photons) carrying a complex vector characteristic that contains information about amplitude and phase of electromagnetic field oscillations. The model allows simulations of polarization phenomena in global coordinates. It has been verified by predicting the results that perfectly match those derived from the Fresnel formulae for unpolarized light reflection/refraction at the interface of two media. The capability of handling diffraction and interference has been tested on the problems of Fraunhofer diffraction at an infinite slit and circular aperture, and Fresnel diffraction at a semi-infinite knife-edge plane. The results obtained for the former compare fairly well with the analytical solutions from the wave theory, whereas, for the latter, there is only a qualitative agreement with the fringe pattern deduced from the Cornu spiral.

Particle-in-Cell Simulation of Expansions of Dense Plasma Sources for X-Ray Laser Systems

A numerical model based on the particle-in-cell (PIC) simulation method is applied to C5+ high density plasma expansions. Spherical, cylindrical, and planar expansions are simulated and compared for two cases of initial conditions. In the first, a compact plasma cloud of 22 nm in diameter (width) with the ion density n i0 = 1029 m-3 and the ion and electron temperatures kT i0=kT e0= 10 keV is modeled, while in the second an inflated cloud of 20 µm diameter (width) with n i0 = 1025 m-3 and kT i0=kT e0= 100 eV is considered. The expansion wave-front is shown to have a double layer structure which rapidly decays with time. The electrons that are diffused beyond the plasma core, are divided into two groups; runaway electrons and captured ones. The split of temperatures which are based on different components of the particle velocity, demonstrate nonequilibrium nature of expansion. The density and temperatures drop rapidly all over the cloud volume during the compact plasma expansion. In the inflated cloud, there exists a core where the plasma density remains unchanged, while the temperature is gradually decreasing. The geometry dependence of the expanding plasma characteristics is also discussed.

Polarizers designed by FEM for electromagnetic simulation

FEM for electromagnetic simulation with absorbing boundary condition is applied to the design of polarizers, and the characteristics of metal sheet polarizers has been studied numerically. The dimensions of Au and Al metal sheet polarizers, which give enough performance as practical polarizers with much thinner structure than conventional polarizers, are presented. An Al metal sheet polarizer with comparable performance to Au metal sheet polarizer can be achieved by applying thinner Al metal sheets than the thickness of Au metal sheets. However, the performance given by Al metal sheet polarizer should be taken care, because the relative permittivity of Al film varies largely according to the film condition. Though Au and Al metal sheet polarizers exhibit high performance, the reflectance of TE polarization is higher than that of conventional polarizers. Therefore, the stray light should be paid attention more than conventional ones. The metal sheet polarizer exhibits enough high polarization performance for wide range of wavelength over 5 times as large as the distance between the metal sheets. The characteristics of metal fiber polarizers are also simulated. The metal fiber polarizers need much finer and thicker structure than metal sheet polarizers to exhibit enough performance.