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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 56 (1993), S. 479-492 
    ISSN: 1432-0630
    Keywords: 57.70.−m ; 81.15.Gh ; 81.60.−j
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A survey is given of in-situ diagnostics of plasma and surface for application in plasma etching and deposition. Especially those diagnostics that increase the fundamental understanding of the elementary processes occurring both within the plasma and at the surface are highlighted. In general, diagnostics are performed to determine the value of a physical parameter. This value is fed into models of plasma or surface, and in that way the understanding of the process is enhanced. In the paper first the most interesting physical parameters are defined. Subsequently the diagnostic techniques currently available to determine those parameters are reviewed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 3720-3725 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electron density and the electron temperature in a low-pressure neon mercury positive column are determined using Thomson scattering. Special attention has been given to the stray light reduction in the Thomson scattering setup. The results are obtained in a discharge tube with a 26 mm diam, 10 mbar of neon, a mercury pressure inbetween 0.14 and 0.85 Pa, and an electric current ranging from 100 to 400 mA. The systematic error in the electron density is 15%–45%, the statistical error is 25%–35%. The total error in the electron temperature is 15%–35%. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 2007-2014 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: One of the biggest problems in performing Thomson scattering experiments in low-density plasmas is the very high stray light intensity in comparison with the Thomson scattering intensity. This problem is especially present in fluorescent lamps because of the proximity of the glass tube. We propose an atomic notch filter in combination with a dye laser and an amplified spontaneous emission (ASE) filter as a way of reducing this stray light level. The dye laser produces 589 nm radiation which is guided through the ASE filter that increases the spectral purity. The beam is then guided in the fluorescent lamp, where the Thomson scattering process takes place. The scattered light is collected and guided through a sodium vapor absorption cell, where the stray light is absorbed because it is resonant to the D2 transition of sodium. The spectral width of the Thomson scattering light is large enough to be transmitted through the absorption cell. In this way we only measure the Thomson scattering light. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 2597-2599 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Experiments to study negative ion densities have been carried out using the photodetachment effect in a rf plasma in CF4. Electrons are detached from the negative ions under the influence of the pulse of a Nd:YAG laser. The induced increase of the electron density is measured as a function of time using the shift of the resonance frequency of a microwave cavity containing the plasma. The negative ion density [F−] is found to be about (4±1)×1015 m−3, a factor 4±1 higher than the electron density.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2959-2961 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Nd:YAG-laser-induced evaporation of particulates formed in an Ar-CCl2F2 rf plasma and the subsequent discharge in the vapor have been investigated in situ by means of optical emission spectroscopy. The estimated threshold for discharge formation is 5×106 W/cm2. The maximum laser-induced emission intensity is observed when the laser is operated in the long-pulse mode (about 200 μs pulse duration) at the fundamental frequency. The wavelength integrated intensity of this continuum emission has been compared with light scattering intensity at the same laser energy. It has been found that the laser-induced emission intensity can be more than ten times higher than the scattering intensity, especially for particulates with a diameter much smaller than the wavelength of the laser. Therefore, this effect provides a sensitive particulate detection method.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 8017-8026 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The complex refractive index of SiGe alloys at 632.8 nm has been measured as a function of the Ge concentration using in situ ellipsometry while the material is slowly removed from a silicon substrate using reactive-ion etching (RIE). Homogeneous, strained epitaxial SiGe films on silicon substrates were used. The Ge concentration was obtained by Rutherford backscattering. If an unknown SiGe structure is etched with RIE, in situ ellipsometry yields combinations of the ellipsometric angles Ψ and Δ with time. Starting at the Si substrate, these points are, on a point-to-point basis, converted into combinations of complex refractive index and depth in a numerical procedure. For this inversion of the ellipsometry equations, the known relation between the real and the imaginary part of the refractive index of SiGe is used. Finally the refractive indices are converted into Ge concentrations. Thus the depth profile of the Ge concentration in an unknown epitaxial SiGe structure can be inferred from an in situ ellipsometric measurement during RIE of the unknown structure. The obtained resolutions in depth and Ge concentration are 0.3 nm and 0.3%, respectively.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 8982-8992 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The ion energy distributions (IEDs) at the electrodes in a capacitively coupled 13.56 MHz plasma in CF4 have been measured mass resolved with a Balzers quadrupole in combination with a home-built energy analyzer. Mass-resolved determination offers the possibility to compare the IED of different ions achieved in the same sheath. The IEDs have been determined at both the largest and the smallest electrode. Apart from the IEDs of the CF4 species, the IEDs of ionic species in plasmas in argon and nitrogen also were determined. Apart from the CF4 ionic species CF+3, CF+2, CF+, and F+, CHF+2 ions also are present in the CF4 plasma due to residual water in the reactor. Because the CHF+2 ions are not produced in the sheath and because we do not detect elastically scattered ions, the IEDs of these ions show the typical bimodal distribution for rf plasmas which corresponds to an IED of ions which have not collided in the sheath. From these IEDs we can obtain the sheath characteristics, such as the averaged sheath potential. From the IEDs of CF+n ions one can conclude that, in the sheath of the CF4 plasma, a large number of chemical reactions takes place between the CF+n ions and the neutrals. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 4867-4872 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The average electron density and electron density fluctuations in a dusty Ar/SiH4 rf discharge have been studied using a microwave resonance technique. The average electron density increases with rf input power and it has a maximum as a function of pressure at about 30 mTorr. Within the first second of plasma operation the electron density decreases with a factor of ten. This is caused by submicroscopic particles, formed in the discharge, which rapidly absorb electrons. When the particles reach a critical size they are expelled from the plasma. This process is governed by a balance between the Coulomb force, trapping the particles in the positive plasma glow and the neutral drag force, flushing them out. The periodic growth and expulsion of particles, monitored by light scattering, results in an oscillatory behavior of the electron density. From the measured oscillation period (τ), which is in the order of seconds to minutes, and its dependence on the gas flow rate (F) and on the fraction α of SiH4 in the plasma (τ[s]≈4.5×102α−1F−2 [sccm], at 10 W rf power input), the trapping force (FC) on particles can be calculated: FC[N]≈4×10−18r [nm], where r is the radius of a particle. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The high-power density of a frequency quadrupled pulsed Nd-YAG laser has been used to photodetach electrons from negative ions in rf plasmas generated within a microwave cavity. Negative ion densities have been determined by measuring the frequency shift of the resonance transmission, the shift being caused by the photoelectrons created by irradiating the plasma with the laser pulse. By measurement of the shape of the resonance curve as a function of time and of microwave frequency, and consecutive fitting of a parabola to the top of the resonance curve, the negative ion density has been determined as a function of gas pressure, rf power, and position in the plasma. Measurements were performed in plasmas of CF4, C2F6, CHF3, and C3F8. The results indicate that the negative ion densities are about one order of magnitude larger than the electron density, which is in good agreement with a fluid model calculation. The pressure and power dependence of the electron density and of the negative ion density gives insight in the relation between the electron temperature and the macroscopic plasma parameters. Measurements as a function of the laser wavelength, using a pulsed dye laser, show that in CF4 the negative ions mainly consist of F−, whereas in C2F6 significant densities of other negative ions may occur.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 2939-2946 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Electron and negative ion densities in the afterglow and in the plasma initiation phase of a 13.56-MHz rf discharge in CF4 were measured by using a microwave cavity method and a laser photodetachment technique. Measurements were carried out at low rf powers ((approximately-less-than)10 W) and in the pressure range from 100 to 300 mTorr. The electron density in the afterglow showed an enhanced decay rate due to the presence of negative ions. Electrons originating from negative ions through associative collisional detachment with neutral radicals were also detected in the afterglow. Decay curve analysis of the negative ion density gave an ion–ion (presumably CF+3−F−) recombination rate constant of (5±2)×10−13 m3 s−1, and showed that, in the active plasma, the negative ion loss rates by associative detachment and ion–ion recombination are of the same order of magnitude. The behavior of the electron and negative ion densities in the plasma initiation phase indicates that molecules and radicals that slowly accumulate in the plasma do not play a significant role in the production of negative ions.
    Type of Medium: Electronic Resource
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