In low temperature plasmas, the interaction of electrons with electric field is an important current research topic that relevant for many applications. Particularly, in pressure regime (≤10 Pa), can traverse a distance may be comparable to reactor dimensions without any collisions. This causes “nonlocal,” dynamics which results complicated space- and time-dependence strong anisotropy distribution function. Capacitively coupled radio frequency (CCRF) discharges, operate this regime, exhibit...

The effect of changing the driving frequency on plasma density and electron dynamics in a capacitive radio-frequency argon operated at low pressures few Pa is investigated by particle-in-cell/Monte-Carlo collision simulations analytical modeling. In contrast to previous assumptions, does not follow quadratic dependence this non-local collisionless regime. Instead, step-like increase distinct observed. Based an power balance model, combination with detailed analysis kinetics, jump found be...

Power absorption by electrons from the space- and time-dependent electric field represents basic sustaining mechanism of all radio-frequency driven plasmas. This complex phenomenon has attracted significant attention. However, most theories models are, so far, only able to account for part relevant mechanisms. The aim this work is present an in-depth analysis power electrons, via use a moment Boltzmann equation without any ad-hoc assumptions. analysis, which input quantities are taken...

Abstract Particle based simulations are indispensable tools for numerical studies of charged particle swarms and low-temperature plasma sources. The main advantage such approaches is that they do not require any assumptions regarding the shape velocity/energy distribution function (VDF/EDF), but provide these basic quantities kinetic theory as a result computations. Additionally, can provide, e.g. transport coefficients, under arbitrary time space dependence electric/magnetic fields. For...

Low pressure capacitive radio frequency (RF) plasmas are often described by equivalent circuit models based on fluid approaches that predict the self-excitation of resonances, e.g., high oscillations total current in asymmetric discharges, but do not provide a kinetic interpretation these effects. In fact, they leave important questions open: How is continuity ensured presence energetic electron beams generated expanding sheaths lead to local enhancement conduction propagating through bulk?...

In particle-in-cell/Monte Carlo collisions (PIC/MCC) simulations of capacitively coupled plasmas (CCPs), the plasma-surface interaction is generally described by a simple model in which constant secondary electron emission coefficient (SEEC) assumed for ions bombarding electrodes. most PIC/MCC studies CCPs, this set to γ = 0.1, independent energy incident particle, electrode material, and surface conditions. Here, effects implementing energy-dependent yields ions, fast neutrals, taking...

Abstract The etching of sub micrometer high-aspect-ratio (HAR) features into dielectric materials in low pressure radio frequency technological plasmas is limited by the accumulation positive surface charges inside etch trenches. These are, at least partially, caused highly energetic ions that are accelerated sheath electric field to high velocities perpendicular wafer. In contrast these anisotropic ions, thermal electrons typically reach electrode only during collapse and cannot penetrate...

In high aspect ratio (HAR) dielectric plasma etching, dual-frequency capacitively coupled radio-frequency plasmas operated at low pressures of 1 Pa or less are used. Such sources often driven by a voltage waveform that includes low-frequency component in the range hundreds kHz with amplitude 10 kV and more to generate highly energetic vertical ion bombardment wafer. such discharges, positive ions can overcome repelling potential created wall charges inside etch features, which allows ratios...

In simulation as well analytical modeling studies of low-pressure capacitively coupled radio frequency (CCRF) discharges, the assumption both a driving voltage source or current is commonly used. It unclear, however, how and to what extent choice mode driving, that prescribes either sinusoidal discharge current, itself defines dynamics results from these studies. To address this issue, 1d3v cylindrical particle-in-cell/Monte Carlo collisions simulations asymmetric CCRF discharges are...

Abstract We present a spatio-temporally resolved analysis of electron power absorption in capacitively coupled argon plasmas at low pressures (1–10 Pa), based on the 1D momentum balance equation embedded into 1d3v particle-in-cell/Monte Carlo collisions simulations. In contrast to predictions theoretical models we find ‘Ohmic heating’ be dominant mechanism time average lowest pressures, and not ‘stochastic’ or ‘Pressure heating’. The cause for this is identified attenuation due acceleration...

Abstract Low pressure single- or dual-frequency capacitively coupled radio frequency (RF) plasmas are frequently used for high-aspect ratio (HAR) dielectric etching due to their capability generate vertical ion bombardment of the wafer at high energies. Electrons typically reach low energies and with a wide angular distribution during local sheath collapse. Thus, in contrast positive ions, electrons cannot propagate deeply into HAR etch features bottom as well sidewalls such trenches can...

The electron dynamics and the mechanisms of power absorption in radio-frequency (RF) driven, magnetically enhanced capacitively coupled plasmas (MECCPs) at low pressure are investigated. device focus is a geometrically asymmetric cylindrical magnetron with radially nonuniform magnetic field axial direction an electric radial direction. studied analytically using cold plasma model single-particle formalism, numerically inhouse energy charge conserving particle-in-cell/Monte Carlo collisions...

This paper investigates the electron dynamics in three distinct discharge modes of a cross-field atmospheric pressure plasma jet, COST-Jet. Thereby, are non-neutral, quasi-neutral, and constricted mode. Using hybrid Particle-In-Cell/Monte-Carlo Collisions (PIC/MCC) simulation, study systematically varies applied voltage driving frequency to explore operation their relations. The results reveal that at low input power, COST-Jet operates non-neutral mode, characterized by close extinction,...

Abstract This study investigates electron dynamics in three distinct discharge modes of a cross-field atmospheric pressure plasma jet: the non-neutral, quasi-neutral, and constricted modes. Using hybrid Particle-In-Cell/Monte Carlo Collisions (PIC/MCC) simulation, we systematically vary applied voltage driving frequency to explore these their transitions. At low power, operates non-neutral mode, characterized by near-extinction behavior, analogous chaotic mode other devices. As power...

A thorough understanding of the energy transfer mechanism from electric field to electrons is utmost importance for optimization and control different plasma sources processes. This mechanism, called electron power absorption, involves complex dynamics in electronegative capacitively coupled plasmas (CCPs) at low pressures, that are still not fully understood. Therefore, we present a spatio-temporally resolved analysis absorption pressure oxygen CCPs based on momentum balance equation...

Abstract An atmospheric pressure surface dielectric barrier discharge in helium–nitrogen mixtures is investigated experimentally using phase-resolved optical emission spectroscopy and computationally employing a two-dimensional simulation framework. A good qualitative agreement between experiments simulations found. It shown that by applying microsecond or nanosecond driving voltage waveform pulses, the exhibits filamentary homogeneous structures. The time evolution/propagation of ionization...

Abstract This study investigates the flow field induced by a surface dielectric barrier discharge (SDBD) system, known for its efficient pollution remediation of volatile organic compounds (VOCs). We aim to understand dynamics that contribute high conversion observed in similar systems using this specific SDBD design. Examining how affects gas mixing chemical processes is important both understanding fundamentals and potential industrial applications. Experimental techniques, including...

Abstract Radio-frequency-driven atmospheric pressure plasma jets (RF APPJs) play an essential role in many technological applications. This work studies the characteristics of these discharges so-called non-neutral regime where conventional structure a quasi-neutral bulk and electron depleted sheath does not develop, electrons are instead organized drift-soliton-like that never reaches quasi-neutrality. A hybrid particle-in-cell/Monte Carlo collisions (PIC/MCC) simulation is set up, which...

Three-dimensional (3D) etching of materials by plasmas is an ultimate challenge in microstructuring applications. A method proposed to reach a controllable 3D structure using masks front the surface plasma etch reactor combination with local magnetic fields steer incident ions sheath region toward directionality during and deposition. This effect has potential be controlled modifying field and/or properties adjust relationship between thickness mask feature size. However, because guiding...

Abstract Based on experiments and simulations, various plasma parameters are found to undergo a hysteresis as function of the driving voltage amplitude in capacitively coupled CF 4 discharges. Phase Resolved Optical Emission Spectroscopy reveals that discharge operates hybrid combination drift-ambipolar α -mode at low voltage. In this mode, electric field mean electron energy high electronegative bulk region. As cross section for attachment is appreciable only energies, mode results strong...

In atmospheric pressure capacitively coupled microplasma jets, Voltage Waveform Tailoring (VWT) was demonstrated to provide ultimate control of the Electron Energy Distribution Function (EEDF), which allows enhance and adjust generation selected neutral species by controlling electron power absorption dynamics. However, at fundamental level, physical origin these effects VWT remained unclear. Therefore, in this work, dynamics is investigated a He/N$_2$ jet with nitrogen concentration 0.05\%...

Abstract The electron momentum loss obtained from kinetic simulations, as well the classical approximation based on electron–neutral collision frequency, are calculated and compared in low pressure capacitively coupled plasmas argon, helium oxygen gases. (which is commonly used theoretical or numerical fluid models) exaggerates role of low-energy electrons can lead to a significantly lower exact depending gas used, even if distribution function known. This leads an underestimation Ohmic...

Abstract The physical characteristics of an argon discharge excited by a single-frequency harmonic waveform in the low-intermediate pressure regime (5–250 Pa) are investigated using particle-in-cell/Monte Carlo collisions simulations. It is found that, when increased, non-negligible bulk electric field develops due to presence ‘passive bulk’, where plateau constant electron density forms. As ionization region decreases (due shrinking energy relaxation length electrons accelerated within...

Abstract Electron power absorption dynamics is investigated in radio-frequency (RF) argon capacitively coupled plasmas (CCPs) at low pressure (4–70 Pa) excited by a dual-frequency waveform with frequencies of 27.12 MHz and 1.937 MHz. Based on the spatio-temporal ambipolar electric field novel interpretation mechanism frequency coupling given, which not based hard wall model, as previous explanations. Within this framework, arises due to decreased size region outside sheath when low-frequency...

An argon-xenon (Ar/Xe) plasma is used as a model system for complex plasmas. Based on this system, symmetric low-pressure capacitively coupled radio-frequency discharges are examined utilizing Particle-In-Cell/Monte Carlo Collisions (PIC/MCC) simulations. In addition to the simulation, an analytical energy balance fed with simulation data applied analyze findings further. This work focuses investigating ion dynamics in two species and gas mixture background. By varying composition driving...