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The H− ion dynamics in the positive column of H2 DC glow discharge was studied by the laser photodetachment technique in a wide range of pressure, 0.1–3 Torr, and current, 1–30 mA, which cover a range of E/N from ∼40 Td up to ∼170 Td. Using a partial modulation of the discharge current, it is shown that the H−concentration follows H atom dynamics due to a fast detachment reaction with the atoms; the higher the H density, the lower the H–/ n e ratio. The dynamics of H atom density during discharge modulation was measured by time-resolved actinometry on Ar atoms, while H2 vibrational temperature was estimated by comparing measured and simulated H2 VUV absorption spectra. The analysis of the experimental dependencies of H− and H/H2 on the discharge parameters allowed estimating the effective rate constant of H− production in the discharge as a function of the reduced electric field. For this discharge model, self-consistent state-to-state vibrational kinetics as well as H2 highly excited electronic states were developed. The main processes that contribute to H− production and loss are discussed in detail. Dissociative attachment to vibrationally excited H2(v) molecules is the main channel of H – production but occurs via the excitation of the well-known low-energy (ϵ th ≈ 3 eV) shape resonance of H2−(X2Σu+) only at low E/N. At high E/N, the H– production mostly occurs via the excitation of high-energy H2− states, such as H2–(B2Σg+, A2Σg+, C2Πu) and Feshbach resonances similar to H2−(2Σg+) Rydberg state. [ABSTRACT FROM AUTHOR]

This work presents the results of developing a set of electronic and chemical reactions for a plasma discharge in octafluoropropane (C3F8). Electronic reactions were obtained using the most relevant set of cross sections at the moment, taking into account experimentally known dissociation and ionization channels. Based on the dissociation products obtained during electronic reactions, a set of chemical reactions was adapted by analogy with the C4F8 reaction scheme from the literature. Next, the resulting complete set of reactions was tested against published experimental data on the concentration of electrons, negative ions, and electronegativity in a capacitive plasma discharge at different gas pressures and discharge input powers. For this purpose, a one-dimensional hydrodynamic drift-diffusion model was used. Reasonable agreement was obtained between the model and experimental data on electronegativity. Eventually, the resulting set of reactions was adapted for a two-dimensional hydrodynamic drift-diffusion model of an ICP discharge. The results of the calculations are two-dimensional distributions of radicals and ions, radical and ion composition of fluxes onto the substrate under conditions typical for industrial reactors. [ABSTRACT FROM AUTHOR]

The developed kinetics of the vibrationally excited states of ozone (with excitation of up to five vibrational quanta), built into the chemical kinetics of O/N/Ar mixtures, was used to model the series of photolysis experiments of V.N. Azyazov et al. The experimental and calculated dynamics of O3 and O2(a1∆) in various O3/O2/Ar mixtures were compared. The dynamics of chemiluminescent radiation of in the titration technique and the applicability of this technique to measuring the dynamics of O atoms in an O3/O2/N2O/Ar mixture were considered. The dynamics of various states of O3(v1,v2,v3) after ozone photolysis was analyzed in detail. The role of these states in the acceleration of the chemical conversion of oxygen components and nitrogen oxides, occurring with competition with ozone vibrational relaxation, was considered. [ABSTRACT FROM AUTHOR]

The effect of low-pressure He plasma on properties of nanoporous organosilicate glasses low-k films with 24% and 33% open porosity is studied. The influence of ions, VUV radiation, and metastable atoms are extracted separately using a special experimental system designed for this purpose. The low-k films treated in He plasma were exposed to O or H atoms in the downstream of high-pressure O2 or H2 rf discharge. The changes in chemical composition and structure occurring in low-k films were measured before and after all treatments. The loss probabilities of oxygen and hydrogen atoms on the low-k film surface were measured for both treated and pristine films. It is shown that the film pretreatment in He plasma leads to the noticeable densification of the top surface layer up to complete sealing all the films studied. The sealing layer prevents O atoms from deep penetration to the film bulk and carbon extraction. The sealing mechanism related to the joint impact of low-energy ions and VUV photons with metastable atoms in He plasma is discussed in detail. [ABSTRACT FROM AUTHOR]

Modification of ultra-low-k films by extreme ultraviolet (EUV) and vacuum ultraviolet (VUV) emission with 13.5, 58.4, 106, 147 and 193 nm wavelengths and fluences up to 6 × 1018 photons cm−2 is studied experimentally and theoretically to reveal the damage mechanism and the most ‘damaging’ spectral region. Organosilicate glass (OSG) and organic low-k films with k-values of 1.8–2.5 and porosity of 24–51% are used in these experiments. The Si–CH3 bonds depletion is used as a criterion of VUV damage of OSG low-k films. It is shown that the low-k damage is described by two fundamental parameters: photoabsorption (PA) cross-section σPA and effective quantum yield φ of Si–CH3 photodissociation. The obtained σPA and φ values demonstrate that the effect of wavelength is defined by light absorption spectra, which in OSG materials is similar to fused silica. This is the reason why VUV light in the range of ∼58–106 nm having the highest PA cross-sections causes strong Si–CH3 depletion only in the top part of the films (∼50–100 nm). The deepest damage is observed after exposure to 147 nm VUV light since this emission is located at the edge of Si–O absorption, has the smallest PA cross-section and provides extensive Si–CH3 depletion over the whole film thickness. The effective quantum yield slowly increases with the increasing porosity but starts to grow quickly when the porosity exceeds the critical threshold located close to a porosity of ∼50%. The high degree of pore interconnectivity of these films allows easy movement of the detached methyl radicals. The obtained results have a fundamental character and can be used for prediction of ULK material damage under VUV light with different wavelengths. [ABSTRACT FROM AUTHOR]