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In the etching process, a bias source is usually applied to the bottom electrode in inductively coupled plasmas (ICPs) to achieve independent control of the ion flux and ion energy. In this work, a hybrid model, which consists of a global model combined bi-directionally with a fluid sheath model, is employed to investigate the dual-frequency (DF) bias effect on the inductively coupled Cl2 plasmas under different pressures. The results indicate that the DC self-bias voltage developed on the biased electrode is approximately a linear function of the phase shift between the fundamental frequency and its second harmonic, and the value only varies slightly with pressure. Therefore, the ion energy on the bottom electrode can be modulated efficiently by the bias voltage waveform, i.e. the fluctuation of the ion energy with phase shift is about 40% for all pressures investigated. Besides, the ion energy and angular distribution functions (IEADFs) in DF biased inductive discharges is complicated, i.e. the IEADFs exhibits a four-peak structure under certain phase shift values. Although the species densities and ion fluxes also evolve with phase shift, the fluctuations are less obvious, especially for Cl2+ ions at low pressure. In conclusion, the independent control of the ion energy and ion flux are realized in DF biased ICPs, and the results obtained in this work are of significant importance for improving the etching process. [ABSTRACT FROM AUTHOR]

Stability of advanced functional materials subjected to extreme conditions involving ion bombardment, radiation, or reactive chemicals is crucial for diverse applications. Here we demonstrate the excellent stability of wafer-scale thin films of vertically aligned hexagonal BN nanosheets (hBNNS) exposed to high-energy ions and reactive atomic oxygen representative of extreme conditions in space exploration and other applications. The hBNNS are fabricated catalyst-free on wafer-scale silicon, stainless steel, copper and glass panels at a lower temperature of 400 °C by inductively coupled plasma (ICP) assisted chemical vapor deposition (CVD) and subsequently characterized. The resistance of BNNS to high-energy ions was tested by immersing the samples into the plasma plume at the anode of a 150 W Hall Effect Thruster with BNNS films facing Xenon ions, revealing that the etching rate of BNNS is 20 times less than for a single-crystalline silicon wafer. Additionally, using O2/Ar/H2 plasmas to simulate the low Earth orbit (LEO) environment, it is demonstrated that the simulated plasma had very weak influence on the hBNNS surface structure and thickness. These results validate the strong potential of BNNS films for applications as protective, thermally conductive and insulating layers for spacecrafts, electric plasma satellite thrusters and semiconductor optoelectronic devices. [ABSTRACT FROM AUTHOR]

We investigated the plasma and electrical characteristics depending on the antenna position in an inductively coupled plasma with a passive resonant antenna. When the powered antenna and passive resonant antenna are installed near the top plate and in the middle of the cylindrical reactor (setup A), respectively, the ion density at the resonance is about 2.4 times to 9 times higher than that at non-resonance. This is explained by the reduction in power loss in the powered antenna (including the matching circuits) and the increase in power absorbed by the plasma discharge. However, when the powered antenna and passive resonant antenna are interchanged (setup B), the ion density at the resonance is not significantly different from that at the non-resonance. When RF power is changed from 50 to 200Â W, the ion density at the resonance of setup B is 1.6 times to 5.4 times higher than at the non-resonance of setup A. To analyse this difference, the profile of the z -axis ion density is measured and the electric and magnetic field simulations are investigated. The results are discussed along with the electron kinetics effect and the coupling loss between the antenna and the metal plate. [ABSTRACT FROM AUTHOR]

Silicon dioxide (SiO2) layers using photoresist (PR) masks are etched by inductively coupled plasma in CH4/SF6 under various etching conditions. A thin CHxFy polymer layer which exists on the surface of sample during steady‐state etching is observed. The steady‐state CHxFy layer reduces the physical sputtering of ions, resulting in the etching rate of PR decreases significantly. Although the high‐density plasmas can enhance the physical sputtering to some extent and give SiO2 more opportunities to react with fluorine atoms, it is helpful to improve the etching rate of SiO2. By optimizing process conditions, the thickness of the steady‐state CHxFy layer and the density of ions are regulated, and a reasonable selective etching is obtained. [ABSTRACT FROM AUTHOR]

The International Thermonuclear Experimental Reactor neutral beam injector includes an ion source which can produce D ion beams for 1 h, accelerated at the energy of 1 MeV. An ion source consists of a driver where the plasma is produced by the application of the radio frequency (RF) power to an inductive coil. This paper presents an improved methodology which provides an estimation of the power transfer efficiency to the plasma of the driver. The developed methodology is based on different mechanisms which are responsible for the plasma heating (ohmic and stochastic) and an electrical model describing the power transfer to the plasma. As a first approximation in a previous work, a transformer model was assumed as an electrical model. In this paper, a main improvement is introduced based on the development of a multifilament model which takes into account the mutual coupling between the RF coil, the plasma, and the passive metallic structure. The methodology is applied to the negative ion optimization 1 (NIO1), a flexible negative ion source, currently in operation at Consorzio RFX, Italy. The results from the two models, transformer and multi-filament, are presented and compared in terms of plasma equivalent resistance and power transfer efficiency. It is found that results obtained from both the transformer and the multi-filament model follow the same trend in comparison with the applied frequency and the other plasma parameters like electron density, temperature, and gas pressure. However, lower values of the plasma equivalent resistance and power transfer efficiency are observed with the multi-filament model. The multi-filament model reproduces a more realistic experimental scenario where the power losses due to the generation of the eddy currents in the metallic structure are considered.

Determination of molecular temperatures within inductively coupled plasmas is critical to understanding the reactions that drive the chemistry of these systems and the mechanisms involved in surface processing. To investigate such interactions, a dual, in situ broadband absorption and optical emission spectroscopy system was designed; providing insight into neutral and excited state species energetics, specifically rotational ( TR) and vibrational ( TV) temperatures across a broad spectral range (>800 nm). Nitric oxide plasmas have been investigated, where measured TV values were higher than TR values, indicating rotational degrees of freedom are more easily thermalized. Using the imaging of radicals interacting with surfaces technique, surface scatter coefficients were measured for NO radicals, which are discussed in relation to energy partitioning in these systems. [ABSTRACT FROM AUTHOR]

We present a fully-implicit electromagnetic Particle-In-Cell Monte Carlo collision code, called NINJA, written for the simulation of inductively coupled plasmas. NINJA employs a kinetic enslaved Jacobian-Free Newton Krylov method to solve self-consistently the interaction between the electromagnetic field generated by the radio-frequency coil and the plasma response. The simulated plasma includes a kinetic description of charged and neutral species as well as the collision processes between them. The algorithm allows simulations with cell sizes much larger than the Debye length and time steps in excess of the Courant–Friedrichs–Lewy condition whilst preserving the conservation of the total energy. The code is applied to the simulation of the plasma discharge of the Linac4 H − ion source at CERN. Simulation results of plasma density, temperature and EEDF are discussed and compared with optical emission spectroscopy measurements. A systematic study of the energy conservation as a function of the numerical parameters is presented. [ABSTRACT FROM AUTHOR]

This paper describes the application of a loop type of inductively coupled thermal plasmas (loop-ICTPs) to high-speed oxidation processing. We earlier developed a unique loop-ICTP for large-area thermal plasma materials processing. In this application of the loop-ICTP for oxidation, a part of the Ar/O2 loop-ICTP was formed directly lying in the longitudinal direction on the surface of a Si substrate located downstream of the plasma torch. Oxygen was supplied directly from the sides of the substrate. The uniformity and the stability of the thermal plasma formed on the substrate were measured using a high-speed video camera and spectroscopic observation. In addition, the uniformity of the oxidation processing was estimated from the fabricated oxide layer thickness. Finally, an almost uniform oxide layer could be obtained with 50 mm length and 100 nm depth after only 1 min of irradiation of Ar/O2 ICTP. [ABSTRACT FROM PUBLISHER]

One of the main Interests in science of Nikola Tesla were gas discharges plasmas, their application in lighting and in production of ozone as well as their role in conduction of electricity through the atmosphere. In particular Tesla is well known as the first person to produce rf plasmas. Such plasmas in the present day constitute the main technology required to produce integrated circuits (IC) and have been essential in the revolution that resulted from IC technologies. In addition Tesla participated in studies of arcs especially arcs used as a source of light, corona discharges required to induce plasma chemical reactions and produce ozone and was involved in various aspects of gas breakdown and gaseous dielectrics. His ideas, level of his understanding and current status of these fields are discussed in this review.

Highlights: [•] The etch rate of AST films increase with increasing of Cl2 concentration and bias power. [•] The etch rate firstly increases and then decreases with increasing gas pressure or RF power. [•] High etch rate, anisotropic patterning, smooth surface, and high selectivity of AST to SiO2 is possible using Cl2/BCl3 chemistry. [•] XPS analysis reveals that the accumulation of low volatile SbCl x on the etched surface. [ABSTRACT FROM AUTHOR]

A comparative study of etch characteristics of the InGaZnO4 (IGZO) films has been performed in chlorine- (Cl2 and BCl3) and fluorine-based (CF4 and SF6) inductively coupled plasmas (ICPs). Higher IGZO etch rates were achieved with chlorine-based discharges due to the higher volatility of metal chloride etch products. The IGZO etch rate was significantly affected by ICP source power and rf chuck power, and maximum etch rates of ~1200Å/min and ~1350Å/min were obtained in fluorine-based and Cl2/Ar discharges, respectively. The etched surface morphologies of IGZO in 10BCl3/5Ar mixtures were better than the unetched control sample. Maximum etch selectivities of 1.4:1 for IGZO over HfO2, 3.1:1 for IGZO over Al2O3, and 1.2:1 for IGZO over yttria-stabilized zirconia were obtained. [ABSTRACT FROM AUTHOR]

Abstract: An innovative custom-designed inductively coupled plasma-assisted RF magnetron sputtering deposition system has been developed to synthesize B-doped microcrystalline silicon thin films using a pure boron sputtering target in a reactive silane and argon gas mixture. Films were deposited using different boron target powers ranging from 0 to 350W at a substrate temperature of 250°C. The effect of the boron target power on the structural and electrical properties of the synthesized films was extensively investigated using X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and Hall-effect system. It is shown that, with an initial increase of the boron target power from 0 to 300W, the structural and electrical properties of the B-doped microcrystalline films are improved. However, when the target power is increased too much (e.g. to 350W), these properties become slightly worse. The variation of the structural and electrical properties of the synthesized B-doped microcrystalline thin films is related to the incorporation of boron atoms during the crystallization and doping of silicon in the inductively coupled plasma-based process. This work is particularly relevant to the microcrystalline silicon-based p–i–n junction solar cells. [Copyright &y& Elsevier]

Abstract: A simple, effective and innovative approach based on low-pressure, thermally nonequilibrium, high-density inductively coupled plasmas is proposed to rapidly synthesize Si quantum dots (QDs) embedded in an amorphous SiC (a-SiC) matrix at a low substrate temperature and without any commonly used hydrogen dilution. The experimental results clearly demonstrate that uniform crystalline Si QDs with a size of 3–4nm embedded in the silicon-rich (carbon content up to 10.7at.%) a-SiC matrix can be formed from the reactive mixture of silane and methane gases, with high growth rates of ∼1.27–2.34nms−1 and at a low substrate temperature of 200°C. The achievement of the high-rate growth of Si QDs embedded in the a-SiC without any commonly used hydrogen dilution is discussed based on the unique properties of the inductively coupled plasma-based process. This work is particularly important for the development of the all-Si tandem cell-based third generation photovoltaic solar cells. [Copyright &y& Elsevier]

Abstract: In this work radio frequency inductively-coupled plasmas (ICPs) sustained with a single low-inductance antenna (LIA) have been characterized in an attempt to clarify profiles of plasma parameters in the near-antenna region. The present investigations have been carried out for the purpose of understanding the local discharge features with a single LIA unit, which are regarded as one of the elements for sustaining large-area plasma source with multiple LIA configurations. The ion-saturation current profiles had a peak at a distance of 10–20 mm from the outer surface of the antenna insulator and then decreased with increasing distance from the antenna, while the electron temperature peaked in the vicinity of the outer surface of the antenna insulator. These results suggest that the discharge sustained with a single LIA is mainly excited via the induction electric field, which is inherent in near-field nature of the induction electric fields peaking in the vicinity of the antenna and attenuating with a depth of penetration (skin depth) in the plasma. Distribution of the RF fluctuation of the floating potential was also measured to evaluate the electrostatic coupling of the antenna to the plasma. [Copyright &y& Elsevier]

Abstract: In this paper we apply computer tomography with optical emission spectroscopy (CT-OES) to study the plasma etching of low-k dielectric SiLKTM which may be viewed as representative of the whole class of organic low-k materials in the way it reacts to plasma treatment. We use a two frequency inductively coupled plasma (ICP) with frequencies of 500kHz and 13.56MHz for biasing and for plasma production. The plasma is formed in mixtures of hydrogen and nitrogen. The optical emission is a non-intrusive technique which combined with computer tomography provides ability to control the uniformity of radical production close to the surface and also to observe the beginning and end points of the etching of organic dielectric by observing emission of CN and CH bands. The basic conclusions are that hydrogen is efficient in etching of organic polymer even at low energies while low energy nitrogen radicals form protective layers. As a result, etching in their combination is very anisotropic. If we apply biasing voltages then the etching rates represented by CN emission increase linearly, and without saturation up to 1.4kV. At the same time there is no threshold, so the kinetics of etching is very different from that in Ar–CF4 mixtures applied for silicon etching. [Copyright &y& Elsevier]

Abstract: The characteristics of low-pressure inductively coupled CF4 plasmas have been investigated using a Langmuir probe. The electrons gain energy through the collisionless heating mechanism. In addition, the plasma has two electron populations: low temperature population of electrons with high density, and high temperature population of electrons with low density. With the increase of radio-frequency input power, the former temperature T ce, the latter temperature T he, and mean electron temperature T e decrease, while their densities n ce, n he, n e increase. This phenomenon has been explained by the thermodynamic equilibrium of the collision between the electrons and radicals in the plasma. [Copyright &y& Elsevier]

A compact model for boundary sheaths in inductively coupled plasmas (ICP) is presented. It unifies physical accuracy with computational efficiency. This model takes the fluxes of all incoming species as input parameters. It returns plasma parameters like the particle densities, velocities and the electric field at the cut edge between plasma bulk and sheath. The model can handle inductive sheaths with multiple positive ionic species. The hydrodynamic treatment of plasma sheaths is physically accurate as it takes into account the effects of ion inertia in the sheaths. However, for multi-component plasmas the solution of the full hydrodynamic model consumes an inacceptable amount of time even on today''s computers. This compact model offers the possibility to increase efficiency without loss of accuracy. It is based on the hydrodynamic equations and consists of a small algebraic system, which can be solved very efficiently. [Copyright &y& Elsevier]

In order to extend the operating range of the GEC RF Reference Cell, we developed an inductively coupled plasma source that replaced the standard parallel-plate upper-electrode assembly. Voltage and current probes, Langmuir probes, and an 80 GHz interferometer provided information on plasmas formed in argon, chlorine, and nitrogen at pressures from 0.1 Pa to 3 Pa. For powers deposited in the plasma from 20 W to 300 W, the source produced peak electron densities between 10 10 /cm 3 and 10 12 /cm 3 and electron temperatures near 4 eV. The electron density peaked on axis with typical full-width at half maximum of 7 cm to 9 cm. Discharges in chlorine and nitrogen had bimodal operation that was clearly evident from optical emission intensity. A dim mode occurred at low power and a bright mode at high power. The transition between modes had hysteresis. After many hours of high-power operation, films formed on electrodes and walls of one Cell. These deposits affected the dim-to-bright mode transition, and also apparently caused generation of hot electrons and increased the plasma potential.