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Chlorine-based high density plasmas, commonly used in the etching of elemental and compound semiconductors, are characterized using mass spectrometry, optical emission spectroscopy, and electrostatic probes. Plasma fluxes are characterized by three-dimensional Langmuir probe measurements and optical emission spectroscopy. The flux is further characterized at the substrate platen by mass spectrometry to determine its makeup in terms of charged or neutral species and atomic or molecular species. Langmuir probe investigations show variations in electron temperature (2–6 eV), plasma density (1×1010 to 1×1012 cm−3), and plasma potential (5–25 V) as process conditions (microwave power, total pressure, and fraction of Cl2 in Ar) and measurement location are varied. Concurrent optical emission spectroscopy measurements of ionized species are in general agreement with Langmuir probe results. Further, optical emission spectroscopy of neutral and ionized species provides global insight into the variation of atomic/molecular fractions in the plasma as it is transported to the substrate processing region. At the substrate, mass spectrometric characterizations show Cl+ and Ar+ dominating the flux for low pressure and high powers, while Cl2 and Ar dominate at high pressure and low power. For Cl2 fractions greater than 25% molecular chlorine begins to dominate the flux to the substrate. These observations of processing space are discussed with respect to implications on semiconductor etching and regions most suitable to high rate, anisotropic processing conditions are identified.

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High density plasmas generated using gas mixtures of methane, hydrogen, and argon are characterized using mass spectrometry, optical emission spectroscopy, and three dimensional Langmuir probing. Such plasmas are commonly used to etch compound semiconductors. In this work we examine the chemical and electrical properties of the flux to the region where substrates are placed during processing. The dominant species in the flux are identified as H, H+, CH3, CH3+, Ar, and ArH+. Plasma parameters in the source region include electron temperatures of 4–9 eV, plasma densities of 1–5×1011 cm−3, and plasma potentials of 24–44 V as process conditions are varied. These parameters are considerably reduced in the process region of the plasma to electron temperatures of 2–6 eV, plasma densities of 1×109 to 2.5×1010 cm−3, and plasma potentials of 3–14 V. Mass and optical emission spectral data are correlated to Langmuir probe results and the effects of varying process conditions on plasma properties are presented and discussed.

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The Naval Research Laboratory (NRL) performs basic and applied research on high power railguns as part of the US Navy EM Launcher program. The understanding of damage mechanisms as a function of armature and barrel materials, launch parameters, and bore geometry is of primary interest to the development of a viable high power railgun. Research is performed on a 6m, 1.5 MJ railgun located at NRL. Barrel studies utilize in situ diagnostics coupled with detailed ex situ analysis of rail materials to provide clues to the conditions present during launch. Results are compared with coupled 3-D electromagnetic and mechanical Finite Element Analysis (FEA) models of railgun operation. Results of several experiments on rail wear will be discussed.