Etch characteristics of CoFeB magnetic thin films using high density plasma of a H2O/CH4/Ar gas mixture

Etch characteristics of CoFeB magnetic thin films patterned with TiN hard masks were investigated using inductively coupled plasma reactive ion etching in H₂O/Ar and H₂O/CH₄ gas mixes. As the H₂O concentration in the H₂O/Ar gas increased, the etch rates of CoFeB and TiN films decreased simultaneously, while the etch selectivity increased and etch profiles improved slightly without any redeposition. The addition of CH₄ to the H₂O gas resulted in an increase in etch selectivity and a higher degree of anisotropy in the etch profile. X-ray photoelectron spectroscopy was performed to understand the etch mechanism in H₂O/CH₄ plasma. A good pattern transfer of CoFeB films masked with TiN films was successfully achieved using the H₂O/CH₄ gas mix.     

Improvement in analysis of O2 in N2 by using Ar drift gas in an ion mobility spectrometer

Ion mobility spectrometry (IMS) is capable of providing real-time analysis of several impurities in inert gases. Because of its poor peak resolution, the IMS is susceptible to peak interferences. Previous study has shown that the detection limit and accuracy of O2 measurement in N2 suffers from peak interference. In many applications, the interference can be avoided by selecting a proper drift gas. For N2 analysis, we have demonstrated that the peak interference of O2 can be eliminated by using Ar as a drift gas. The use of Ar changes the chemical reactions that occur inside the drift region and results in different product ions. The peaks of new product ions are well-separated and do not coincide with the peak representing O2.     

The kinetic model of Al oxidation in heterogeneous aluminum-water plasma. Negative ions

We investigate the mechanisms of formation and death of negative ions in aluminum-water plasma, their role in kinetics of its ionization and recombination, and influence on plasma parameters. Negative ions, in contrast to the positive, do not in fact participate in the heterogeneous processes and require, to enhance their influence on the plasma parameters, first, high electron temperatures (~1.5 eV and higher) and, second, low n _e and [Al] concentrations: in this way, they make a great contribution to the H₂O dissociation at the expense of the electron energy (2–8 electrons per a molecule). We show that, even in the most favorable conditions at low H and O concentrations within the experimental temperature range, T _e = 0.6–1 eV, the negative ions do not, in fact, influence the Al concentration and, in the operation reactor zone, the other parameters, except for the microparticle concentration. We reveal the source, important for the spectral diagnostics of the atomic emission, of recombination populating of the excited Al levels. The main negative ion (OH^–) is established. We have concluded the impossibility of its use in order to optimize the operation of the aluminum-water plasma-chemical reactor.     

Characteristics of transverse volume discharge in Cf2Cl2 and in Ar/Cf2Cl2 mixture

The conditions of ignition and the characteristics are given for a nanosecond transverse volume discharge in Freon-12 (CF₂C1₂) and in an Ar/CF₂C1₂ mixture. It is shown that, in the ultraviolet and visible ultraviolet spectral region, a plasma based on CF₂C1₂ molecules is a source of radiation of excited carbon atoms and Cl₂ molecules. The volumetric stage of the discharge exists atU _charge ≤ 12 kV and [CF₂C1₂] = 0.1–3 kPa, and the current and voltage oscillograms are similar to the respective characteristics of a transverse discharge with prior-to-prebreakdown electron multiplication in He(Ne)/SF6(F2) mixtures. A plasma of an Ar/CF2C12 mixture is a source of radiation of the λ = 258 nm bands for Cl ₂ ^* , 193 nm for ArF, and 175 nm for ArCl. Such sources may be used in short-wave pulse photometry, microelectronics, and photo- and biochemistry.     

Investigation of a glow discharge in a mixture of Ar and OH

A glow discharge in a mixture of argon and hydroxyl (OH) is investigated experimentally. It is shown that under certain discharge conditions a considerable portion of the electrical energy imparted to the discharge is used to generate resonant emission of OH molecules. The results obtained point to a realistic possibility of creating a new, ecologically friendly source of optical radiation, which can replace mercury lamps in the near future. “Applied Chemistry” State Scientific Center Pis’ma Zh. Tekh. Fiz. 25, 62–66 (April 26, 1999)     

Thermal-shock performance of evaporated Al2O3, ZrO2, and laminated cermet coatings in an electric-arc plasma source

Measurements have been made on the thermal stability and performance of protective coatings deposited by plasma-gun techniques on copper with an arc heater.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 31, No. 3, pp. 443–448, September, 1976.     

Effect of N2/Ar gas flow ratios on the nitrided layers by direct current arc discharge

Nitrided layers were prepared on titanium substrates by direct current (DC) arc discharge technique. The effect of nitrogen to argon flow ratios on the microstructures and mechanical properties of the samples was investigated. The X-ray diffraction results show that the surfaces of the layers consist mainly of TiN and a very little TiN_0.3 (101) under the condition of nitrogen/argon gas mixture. A strong TiN (200) preferential orientation in nitrided layers can be seen. With increasing the nitrogen concentration ratio in nitrogen/argon gas mixture, the density and size of TiN dendrites in the nitrided layers, and the hardness and wear resistance of the layers enhanced significantly.     

Synthesis and characterization of nano-crystalline CVD diamond film on pure titanium using Ar/CH4/H2 gas mixture

Titanium and Ti alloys have poor tribological properties and deposition of a well adherent diamond coating is a promising way to solve this problem. But diamond film deposition on pure titanium and Ti alloys is always difficult due to the high diffusion coefficient of carbon in Ti, the large mismatch in their thermal expansion coefficients, the complex nature of the interlayer formed during diamond deposition, and the difficulty of achieving very high nucleation density. A nano-crystalline diamond (NCD) film can resolve Ti and Ti alloys weak tribological performance due to its smooth surface. A well-adhered NCD film was successfully deposited on pure Ti substrate by using a microwave plasma assisted chemical vapor deposition (MWPCVD) system in the environment of Ar, CH₄ and H₂ gases at a moderate temperature. Detailed experimental results on the preparation, characterization and successful deposition of the NCD film on pure Ti are discussed.     

Vacuum plasma spray deposition of YSZ-NiO-Ni coatings at different Ar and H2 gas flow rates

The work presents results of the experimental investigation of vacuum sprayed yttria stabilized zirconia, nickel oxide, nickel (YSZ-NiO-Ni) ceramic composite coatings deposited on Al₂O₃ ceramic and stainless steel substrates produced at different Ar and H₂ gas flow rates. The Ar and H₂ gas flow was varied according to the factorial plan design. It is shown that for the used vacuum plasma spray YSZ and NiO powder mixture the produced coatings were composed of three phases mainly: cubic YSZ (c-YSZ), cubic NiO (c-NiO), and cubic Ni (c-Ni). The quantitative X-ray diffraction (XRD) analysis was used to evaluate each phase amount in the coatings. It was found that the vacuum spray technique enables formation of composite layers with a variable composition and that phase content in the coatings can be controlled choosing the Ar and H₂ gas flow rates. The electrical conductivity measurements revealed that a variation of the phase content in the YSZ-NiO-Ni composites is responsible for the existence of different electrical conduction mechanism and rapid change in the conductivity of coatings with the used powder content. The surface morphology and the cross-section analysis by scanning electron microscope (SEM) have shown porous structures of the deposited coatings.     

Etch characteristics of TiN/Al2O3 thin film by using a Cl2/Ar adaptive coupled plasma

In this study, we carried out an investigation in the etching characteristics of TiN thin films in a C1₂/Ar adaptive coupled plasma. The maximum etch rate of the TiN thin films was 768 nm/min at a gas mixing ratio of C1₂ (75%)/Ar (25%). At the same time, the etch rate was measured as functions of the various etching parameters. The X-ray photoelectron spectroscopy analysis showed the efficient destruction of the oxide bonds by the ion bombardment as well as the accumulation of low volatile reaction products on the etched surface. Field emission Auger electron spectroscopy analysis was used to examine the efficiency of the ion-stimulated desorption of the reaction products.     

Surface,grain-boundary and interfacial energies in Al2O3 and Al2O3-Sn,Al2O3-Co systems

Using the multiphase equilibrium method for the measurement of contact angles, the surface and grain-boundary energies of polycrystalline Al₂O₃ in the temperature range of 1473 to 1923 K were determined. Linear temperature functions were obtained by extrapolation for both quantities between absolute zero and the melting point of Al₂O₃. The temperature dependence of the surface and grain boundary energies can be expressed as $$\gamma _{{\rm A}l_2 O_3 } = 2.559 - 0.784 \times 10^{ - 3} T(J m^{ - 2} )$$ and $$\gamma _{{\rm A}l_2 O_3 - Al_2 O_3 = } 1.913 - 0.611 \times 10^{ - 3} T(J m^{ - 2} )$$ respectively. The interfacial energies of Al₂O₃ in contact with the molten metals tin and cobalt revealed a linear dependence on temperature.     

Spectroscopic study and modelling of a reactive magnetron discharge in Ar/O2 and in air

The Optical Emission Spectroscopy technique was used to monitor a magnetron discharge working in an Ar/O₂ mixture and in air. Hysteresis effects and instability, which are frequently observed when working with reactive gases, were clearly seen in the optical spectra. When the discharge power was increased, the atomic oxygen line intensity increased, saturated and then disappeared whilst, at the transition, sputtered material line intensities suddenly increased. In air, nitrogen lines were found to be less sensitive to this transition. The transition between the two regimes of the discharge is due to a change in the composition of surfaces from oxidised to metallic, as confirmed by the analysis of deposited films. In parallel with the experiment, a plasma model was developed for the magnetised region of the discharge which predicts the variations of the various plasma species in the Ar/O₂ mixture. This model explains the behaviour of line intensities on the two sides of the transition.     

Solid Ar, N2, CO, and O2 in Nanopores

Molecular solids enclosed in pores with diameters in the nm-range are a research field which attracts growing interest. The major questions asked in this context are: what is the structure and the dynamics? How are phase and glass transitions modified by the geometrical constraint? In this contribution we present structural information, by x-ray diffraction measurements, as well as thermodynamic characterization, by vapor pressure and heat capacity measurements, on Ar, which is usually considered the simplest of all condensates, and on the small diatomic molecules N₂, C0, O₂ in porous glasses with average pore diameters from 50 to 130Å.     

Characterization of an Ar/O2 magnetron sputtering plasma using a Langmuir probe and an energy resolved mass spectrometer

An argon plasma with a small amount of oxygen in a radio-frequency magnetron sputtering system has been studied experimentally. A Langmuir probe has been used to measure the ion density, electron temperature and plasma potential in the plasma, whereas an energy-resolved mass spectrometer has been used to investigate the ions flowing towards the growing film. It has been found that the argon ion density decreases when the oxygen gas is added to the plasma above a certain flow. A discussion on which process is responsible for this effect is presented.     

多晶Al2O3薄膜的制备及其红外吸收谱研究

高能氢离子束溅射金属铝靶,沉积在单晶Si基片上的非晶薄膜是Al和Al2O3的混合物.在空气中对其进行900～1200℃的热处理,成功地制备了以不同结晶形式存在的多晶Al2 O3薄膜,讨论了不同退火温度对其结晶性能、表面形貌及红外吸收光谱的影响.为Al2O3薄膜制备与应用提供了良好借鉴.