Bulletin of the American Physical Society
63rd Annual Gaseous Electronics Conference and 7th International Conference on Reactive Plasmas
Volume 55, Number 7
Monday–Friday, October 4–8, 2010; Paris, France
Session TF4: Plasma Diagnostics III: Reactive Plasmas |
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Chair: Gilles Cunge, LTM-CNRS, Grenoble, France Room: 151 |
Friday, October 8, 2010 10:30AM - 11:00AM |
TF4.00001: Increasing understanding of the plasma-surface boundary layer and surface chemistry using optical sum frequency generation diagnostic tools Invited Speaker: Understanding and controlling the properties of materials at the plasma surface boundary is fundamental to applications such as microelectronic feature definition, surface cleaning, and surface treatment. While traditional surface science diagnostic tools have been used to increase fundamental understanding of this critical boundary layer, their interpretation is sometimes clouded by the need to remove the sample from the plasma environment to analyze it. Infrared-visible sum frequency (IVSF) spectroscopy is a molecularly specific diagnostic that can be used to follow molecular interactions and plasma initiated chemistry at the plasma-surface boundary layer in quasi real-time. This talk will first provide an overview of surface sum-frequency generation spectroscopy and its applications to plasma-surface interactions. We then present an in-situ characterization of octadecyltrimethoxysilane monolayers and other common industrial polymers on quartz in the presence of a high pressure oxygen plasma. These test systems will be used to demonstrate the unique advantages and limitations of IVSF as an in-situ surface diagnostic in plasma systems. This work was supported by the Department of Energy Office of Science, Division of Materials Science, and Sandia National Laboratories, a multiprogram laboratory operated by Sandia Corporation a Lockheed Martin company for the United States Department of Energy's national nuclear security administration under contract DE-AC04-94AL85000. [Preview Abstract] |
Friday, October 8, 2010 11:00AM - 11:15AM |
TF4.00002: Non-contact monitoring of Si substrate temperature during plasma etching using optical low-coherence interferometry Takayuki Ohta, Chishio Koshimizu, Shigeki Tuchitani, Masufumi Ito One of the critical parameters in many semiconductor-processing steps such as plasma etching, chemical vapor deposition, and so on, is the substrate temperature. In order to control the processing precisely, the temperature of Si substrate was monitored with non-contact by optical low coherence interferometry. The low coherence interferometry is based on Michelson interferometry, and a super-luminescent diode (SLD) was used as a low-coherence light source. We demonstrated the real-time monitoring of the temperatures of a Si wafer and a Si focus ring in a dual-frequency capacitively coupled Ar/C$_{4}$F$_{8}$/O$_{2}$ plasmas. The temperature of Si wafer was successfully monitored with the accuracy of 0.34 degree C in the range from room temperature to 400 degree C. The response of the the low-coherence interferometry was faster than that of a fluorescence temperature sensor, and the low-coherence interferometry enabled the monitoring of the actual temperature during plasma processing. [Preview Abstract] |
Friday, October 8, 2010 11:15AM - 11:30AM |
TF4.00003: Wafer-level plasma parameters measurements in a multi-frequency capacitively coupled plasma discharge L. Dorf, S. Rauf, J. Kenney, K. Bera, N. Misra, K. Collins Two complications with wafer-level measurements in a CCP discharge are very high DC ($\sim $ -1kV) and RF ($\sim $2kV peak-to-peak) voltages of the substrate, and the lack of theoretical basis for interpretation of volt-ampere characteristics (VACs) of the probes inside the RF sheath. In this work, we present the diagnostic apparatus that measures ion current to the wafer, along with near-sheath plasma density (ne) and electron temperature (Te). Particle-in-cell (PIC) and fluid plasma simulations are used to help interpret collected VACs. Measurements are performed using a set of radially distributed planar double probes (DP). The external circuitry provides: (1) DC isolation and RF filtering, (2) bias to the probes, (3) switching between the probes, and (4) probe current measurements. Results of wafer-based measurements at a variety of rf-frequencies (2, 13, 162 MHz), rf power levels (300 -- 1000 W), neutral pressures (30 -- 100 mT), chemistries (Ar, O2, Ar/CF4), and magnetic field configurations are presented. At low frequency, pressure was found to have stronger effect on ion current and plasma density than that at intermediate and high frequencies; in all chemistries. Magnetic field was confirmed to be a powerful knob for controlling radial uniformity of the discharge at all frequencies; namely, edge current and density tend to increase with application of the magnetic field. [Preview Abstract] |
Friday, October 8, 2010 11:30AM - 11:45AM |
TF4.00004: Improvements of modulated beam mass spectrometry: application to pulsed plasma Fran\c{c}ois Boulard, Gilles Cunge, Thierry Chevolleau, Nader Sadeghi, Olivier Joubert Mass Spectrometry (MS) measurements accuracy is of major interest for fundamental plasma studies as well as process development. In this sense, complex hand made system have been developed to address the beam to background issue [1-2]. In addition, radical kinetics was investigated by the analysis of the temporal decay of radicals' density in time resolved pulsed discharges [3]. In this work, we introduce a novel method to subtract the MS background signal, based on a tuning fork resonant chopper. With examples in Ar, O$_{2}$ and Cl$_{2}$ inductively coupled plasmas, we show a strong impact of species reactivity and beam component intensity on the background level estimation. Thanks to improvements in the counting system, we present time resolved measurements of the beam components in pulsed discharges. \\[4pt] [1] H. Singh, \textit{et. al}., J. Vac. Sci. Technol. A 17 (5), (1999) 2447. \\[0pt] [2] J. Benedikt, \textit{et. al}., Rev. Sci. Instrum. 80, 055107 (2009). \\[0pt] [3] J. Perrin, \textit{et. al}., J. Vac. Sci. Technol. A 16 (1), (1998) 278. [Preview Abstract] |
Friday, October 8, 2010 11:45AM - 12:00PM |
TF4.00005: Time-resolved electron density and OES measurements for studying the surface loss rates of H and Cl atoms in a Cl$_2$-H$_2$ ICP plasma Garrett Curley, Lina Gatilova, Stephane Guilet, Sophie Bouchoule, Gurusharan Gogna, Nishant Sirse, Shantanu Karkari, Jean-Paul Booth The recombination coefficients of H and Cl atoms were determined under etching conditions in an inductively coupled plasma using a time-resolved emission spectroscopy technique referred to as pulsed induced fluorescence. We used a 100~\% modulation of the RF power with the plasma off-time and duty cycle varied. The measurements were performed at 10~mTorr in H$_2$ and Cl$_2$ plasmas with a small addition (10~\%) of argon. The validity of the technique was examined through correlation with simultaneous time-resolved electron density measurements. The study of Cl atoms required the use of an actinometer, but care was needed to choose emission lines that are not influenced by the presence of metastables. We believe this condition to be of greater importance than choosing emission lines with similar excitation thresholds. We show that a time-resolved actinometry procedure using argon can be valid if appropriate argon lines are chosen. [Preview Abstract] |
Friday, October 8, 2010 12:00PM - 12:15PM |
TF4.00006: Time-Resolved Emission and Electrical Diagnosis of High Pressure H$_{2}$ and SiH$_{4}$/H$_{2}$ RF Discharges Eleftherios Amanatides, Dimitrios Mataras In the present work, we apply ultra-fast spatially and temporally resolved emission spectroscopy together with electrical measurements in order to investigate elementary collision processes in SiH$_{4}$/H$_{2}$ RF discharges. Such plasmas operating above 1 Torr can deposit device grade $\mu $c-Si:H films at high deposition rates even at the conventional frequency of 13.56 MHz. Short and long living excited species were monitored in order to study the variation of species production during the RF period for a pressure range of 1 to 10 Torr. These measurements were also correlated with the peaks of power deposition during the RF cycle. The results have shown that above 2.5 Torr plasma oscillates at double the excitation frequency and this was also identified by the significant enhancement of the current second harmonic. The production of excited species and their variation during the RF cycle were then related to the production of silicon hydrides radical and H atoms after taking into account differences in the collision frequencies of these processes. Finally, the spatial and temporal variations of species generation with pressure were correlated with the film deposition rate and structure and the changes on the growth mechanism are discussed. [Preview Abstract] |
Friday, October 8, 2010 12:15PM - 12:30PM |
TF4.00007: A comprehensive GD-OES and GD-MS study to elucidate the effect of trace molecular gases (O$_{2}$, H$_{2}$, and N$_{2}$) on argon-based glow discharge plasmas S. Mushtaq, J.C. Pickering, E.B.M. Steers, P. Horvath, J.A. Whitby Rapid spectrochemical analysis obtained from ``Grimm-type'' glow discharge (GD) sources, which mainly depend on the carrier gas (usually Ar), vary if traces of molecular gases -- such as O$_{2}$, H$_{2}$, and N$_{2}$ -- are present. Use of clean instruments can remove external sources of trace molecular gases, but problems remain when traces are present as constituents of the sample material itself. There is hence a need to investigate, in detail, how traces of molecular gases can affect the plasma species, and cause possible errors in spectrochemical analysis. Here, we present an extensive study into the effects of trace molecular gases in an argon carrier gas. Emission spectra were generated in pure Ar plasma with a pure Fe, Ti and Cu samples, and relative line intensities measured using the Imperial College high resolution vacuum UV Fourier Transform spectrometer. These line intensities are then compared to line intensities obtained from emission spectra of Ar/O$_{2}$ and Ar/H$_{2}$ plasmas. In order to get further relevant information, glow discharge mass spectrometry (GD-MS) experiments were also taken with the pure Ar, Ar/O$_{2}$ and Ar/H$_{2}$ plasmas. Comparison of results by GD-OES and GD-MS will be presented and discussed [Preview Abstract] |
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