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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 114 (1992), S. 8717-8719 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    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 64 (1988), S. 4384-4397 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using space-time-resolved laser-induced fluorescence and plasma-induced emission spectroscopy, we find metastable and dissociation product densities to vary nonlinearly as Ar is diluted with SF6, Cl2, and BCl3. Because rare gases are relatively inert in the ground state, it is often assumed that rare gases change discharge chemistry through metastable interactions. Surprisingly, the measured changes cannot be accounted for by considering only direct metastable energy transfer. A model is proposed in which Ar metastable states indirectly enhance molecular dissociation by enhancing the ion density via Penning reactions; the increase in ion density in turn causes an increase in the dissociative recombination rate. This rate varies nonlinearly with concentration because both ion-producing metastable states and recombining electrons are quenched by addition of the attaching, molecular gases. The model satisfactorily explains discharge changes when small concentrations of molecular gases are added to an Ar discharge. Less well understood are changes over a broader concentration range, where dissociation and excitation rates decrease with decreasing Ar concentration because of electron attachment and cooling.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 598-606 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Although rate coefficients are essential ingredients in modeling chemical processes such as chemical vapor deposition and plasma etching, the values measured as a function of temperature under well-defined equilibrium conditions may be inappropriate for use in models of nonequilibrium systems. For this reason, it is important to have measurements of in situ rates that can be used as input parameters or can provide stringent tests for reactor simulations. Using time-resolved plasma-induced emission and laser-induced fluorescence spectroscopy, we measured quenching rates for Ar metastable states in radio-frequency discharges through mixtures of Ar and the molecular gases SF6, Cl2, BCl3, and N2. After verifying the validity of modulation spectroscopy to measure in situ rates, the effects of discharge power, pressure, and flowrate are investigated. The most important effect occurs when the discharge power is increased; the decline in quenching rates with increased power is attributed to increased molecular dissociation that produces products with lower collision cross sections.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 492-500 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In many radio frequency plasma applications, use of unequal area electrodes leads to a dc self-bias voltage that is correlated with sputtering, etching, deposition, and surface damage rates. Using the techniques of laser-induced fluorescence (LIF) and Stark-mixed LIF, we measure (1) ion densities in N2 discharges and (2) electric fields in BCl3 and 5% BCl3/Ar discharges as a function of electrode area ratio (from 1:1 to 7.4:1). We find that the discharge current density is constricted and nonuniform. As a consequence, the dependence of sheath field strengths on electrode area ratio is weaker than expected, ion bombardment of the larger electrode is nonuniform, and large radial electric fields periodically pull ions into the small electrode sheath. These observations are consistent with ballistic (or beam) electron models for low-frequency glow discharges.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 983-985 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: By cooling substrates to low temperatures (−40 °C), plasma etching of AlGaAs/AlAs/GaAs structures is performed in an ion-activated, surface reaction limited regime. As a result, microscopic and macroscopic uniformity are vastly improved and etching is independent of gas flow patterns, plasma geometry, and reactor loading. Because the reactant is concentrated on the surface, etching rates remain large.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 821-823 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Monitoring wafer changes in situ during plasma treatment provides real-time feedback for developing and controlling device processing. In this letter we report the use of photoluminescence spectroscopy to monitor epitaxial films of Al0.3Ga0.7As and semi-insulating GaAs substrates during BCl3 plasma etching and H2 plasma passivation. Photoluminescence monitoring is used for etching endpoint detection, surface damage quantification, and wafer temperature measurement.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1572-8986
    Keywords: Reactive ion etching ; loading ; uniformity ; anisotropy ; triode pattern transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Dry etching of compound semiconductors is becoming increasingly important as design ruler shrink for electronic devices. For photonic device applications, dry or plasma etching is used fin- device isolation, fine-line pattern transfer, and fabrication of optical quality interfaces. As has been well established for Si and W. plasma etching at reduced temperatures can provide superior critical dimension control and obviate the need for operating at high bias voltages that produce excessively energetic ion bombardment t. In this work, we explore low-temperature (−60 C to +60 C) etching of the compound semiconductors GaAs, AlGaAs, and AlAs, In addition to improving etch anisotropy, which provides critical dimension control, rye find thut processing at lower temperatures improves microuniformity and reduces loading effects. At high lemperaturcs, where larger samples are observed to etch more slowly than smaller pieces (loading effect), etching rates appear limited bv reactant transport to the wafer. In this regime, both microuniformity and macrouniformity arc poor. As the temperature is reduced, the etching rate becomes limited by surfitce processes us a residue containing the semiconductor elements, etchant gases, and residual background gases forms on the surface. hi this regime, the etch rare becomes independent of surface area and uniformity is improved.
    Type of Medium: Electronic Resource
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