Bulletin of the American Physical Society
2006 59th Annual Gaseous Electronics Conference
Tuesday–Friday, October 10–13, 2006; Columbus, Ohio
Session GW1: Diagnostics I: Electrical |
Hide Abstracts |
Chair: Mark Sobolewski, National Institute of Standards and Technology Room: Holiday Inn Salon CD |
Wednesday, October 11, 2006 8:00AM - 8:15AM |
GW1.00001: Detailed Time-resolved Plasma Diagnostics in a Pulsed DC Magnetron Discharge Ian Swindells, Peter Kelly, James Bradley Mid-frequency (5 - 350 kHz) pulsed DC magnetron plasmas provide a stable, arc free sputtering process for deposition of metal oxide films. A combination of Langmuir probe and optical emission spectroscopy plasma diagnostics provide detailed time-resolved measurements of plasma density, $n_e $, electron temperature, $T_e $, plasma potential, $V_p $, and plasma excitation. The bi-polar waveform of the power supply, in particular the fast transient periods, drives the evolution and energetics of the plasma. Using electrical probes we observe a short lived increase in $n_e $ and $T_e $ during the on to off and off to on phases. This is accompanied by a burst of light in the optical emission. The large overshoot in voltage during the target reversal on to off drives the plasma potential to values of over +150 V relative to ground. Sheath dynamics at the boundaries between the plasma and the target, for the switch to the `on-phase', and between the plasma and the substrate or walls, during the overshoot period, provide an explanation for the observed peaks. The effect different boundary conditions have on the bursts during the overshoot period is investigated. [Preview Abstract] |
Wednesday, October 11, 2006 8:15AM - 8:30AM |
GW1.00002: Investigation of total energy flux density at a floating substrate in pulsed DC unbalanced magnetron. Martin Cada, Greg Clarke, James Bradley The total energy flux density (TEFD) at a floating substrate in an asymmetric bipolar pulsed DC unbalanced magnetron system with titanium target has been investigated using a thermal probe (in substrate) and a time-resolved Langmuir probe. It was found that for various pulsing parameters: 1) the TEFD is approximately 70{\%} higher in a pulsing plasma than for DC operation and 2) the total energy flux density increases linearly with pulse frequency and decreases with duty cycle (with maximal value at 60{\%} duty). The EFD for the charged particles (electrons and ions) and neutrals were calculated. The neutral particle flux was determined from the deposition rate. The charged particle energy flux at the floating substrate was calculated from the measured electron mean energy, charged particle concentration, plasma and floating potentials. Finally, the total energy balance was calculated and compared to the TEFD measured by the thermal probe. Good agreement between the measured and calculated TEFD was found for DC and low pulse frequencies. For higher frequencies, the calculated TEFD was observed to be several times lower than measured. We attribute this to the inability of the Langmuir probe technique to measure the high energy electrons and ions generated during the pulse transients. [Preview Abstract] |
Wednesday, October 11, 2006 8:30AM - 8:45AM |
GW1.00003: RF Impedance of a Spherical Probe at High and Low Gas Pressure R.F. Fernsler, D.N. Walker, D.D. Blackwell, W.E. Amatucci, S.J. Messer The plasma electron density n$_{eo}$ is most often determined using a Langmuir probe to measure the dc current as a function of the applied dc voltage V$_{dc}$. The dc impedance Z$_{dc}$ varies strongly with V$_{dc}$, and models are needed to relate Z$_{dc}$ to n$_{eo}$. Secondary electron emission, ion collisions, and other effects further complicate the analysis. Alternatively, a variable rf voltage can be applied while holding V$_{dc}$ fixed. As long as the rf voltage is small, the rf impedance Z$_{rf}$ varies with the frequency f but not the amplitude of the voltage, and for a fixed frequency, Z$_{rf}$ depends only on n$_{e}$(r) and the neutral gas density N. In this talk theoretical and experimental results for Z$_{rf}$ are related to n$_{eo}$ for a small spherical probe. At low N, Z$_{rf}$ becomes resistive whenever f equals the local plasma frequency, and both the real and imaginary parts of Z$_{rf}$ peak when f equals the bulk plasma frequency. The peaks make n$_{eo}$ easy to determine, and the resistance at lower frequencies can be used to determine n$_{e}$(r) within the sheath and presheath. At high N, the resistance depends mainly on n$_{eo}$/N, so n$_{eo}$ is again easy to determine. Theoretical and experimental results for several spheres will be compared with Langmuir-probe data at high and low gas pressure. [Preview Abstract] |
Wednesday, October 11, 2006 8:45AM - 9:00AM |
GW1.00004: Extended plasma parameter extraction using in-line RF metrology for multi-frequency plasma reactors Steven Shannon, Daniel Hoffman, Matthew Miller In-line RF metrology combined with plasma discharge models is a convenient, non-intrusive means for obtaining plasma parameters in industrial processing discharges. [1] Typically, this analysis is performed at the fundamental RF drive frequency used to sustain the discharge, and provides two equations (real and imaginary discharge impedance) from which at least two plasma parameters can be independently determined. This necessitates approximation of other plasma parameters such as discharge asymmetry and electron -- neutral collision frequency to obtain accurate outputs. Currently, many state-of-the-art plasma reactors used for semiconductor manufacturing use multiple frequencies for independent control of multiple plasma parameters. [2] The purpose of this work is to demonstrate the extended capabilities of this in-line RF diagnostic when multiple frequencies are used to drive a CCP discharge, with particular focus on the replacement of approximated plasma parameters with calculated plasma parameters using this multi-frequency approach, and the extension of real time parameter tracking in plasma processing that it can provide. \newline [1] Bull. Am. Phys. Soc. \textbf{48 }(5) \newline [2] IEEE Conf. Rec. 05CH37537 - 2005 Int. Conf. Plasma Sci., Talk 10498 [Preview Abstract] |
Wednesday, October 11, 2006 9:00AM - 9:15AM |
GW1.00005: Response of an Isolated Dust Particulate in a DC Glow Discharge Subjected to External Excitations J. McFerran, J. West, V. Subramaniam, A. Kahraman Isolated spheres of borosilicate glass are suspended in a DC glow discharge in neon. The response of spheres 16 to 42 times heavier than in previous work is observed under heavily damped conditions when displaced laterally by applying a transient voltage. It is shown that lateral excitation of the isolated particulate cannot drive the motion to classical resonance as observed in previous work involving axial displacements in RF plasmas. The base excitation (BE) model, rather than the classical forced damped oscillator model, is found to exhibit good agreement with the present results. A new means of estimating charge from the frequency response of the particulate motion using the BE model is described. Sheath polarization and ion drag effects neglected in previous work are included here. Ion drag is found to be the dominant drag mechanism for the heavier particulates. Finally, the trajectory of an isolated sphere displaced by radiation pressure while under heavily damped conditions is observed and analyzed. [Preview Abstract] |
Wednesday, October 11, 2006 9:15AM - 9:30AM |
GW1.00006: Collisionless nonlinear damping of dust acoustic waves due to dust charge fluctuations Jyotirmoy Pramanik A novel technique to calculate the damping effects on dust acoustic waves due to dust charge fluctuations in a dusty (complex) plasma is reported. The perturbed distribution function of the dust charge has been obtained by solving the linearized Vlasov equation introducing charge fluctuation effects in the source term. To get the damping coefficient, we followed the Dawson's model for longitudinal plasma oscillations. The present calculations show that dust charge fluctuations and the so called charging frequency ($\eta )$ enhance the damping of the dust acoustic waves and also modifying the electrostatic energy density decay rate of dust acoustic wave. The breakdown of the linear theory is also discussed. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700