Diagnostics and analyses of a laser produced organic vapor plasma

2000 
Summary form only given. A fast Langmuir probe technique is developed for diagnosing a plasma produced by a 193 nm laser ionizing an organic vapor, tetrakis(dimethyl-amino)ethylene (TMAE). The plasma is characterized as high electron density (10/sup 13/-10/sup 12/ cm/sup -3/), low electron temperature (/spl sim/0.1 eV). A probe theory on correction of sheath motion effects on ion saturation currents in Langmuir probe measurements is developed, and validity conditions are also presented. Correction factors for sheath motion effect are calculated for wide ranges of electron-ion recombination coefficients, electron densities, electron temperature changes, plasma potentials and bias voltages. The calculation results can be directly applied for the correction of the sheath motion on Langmuir probe measurements. Langmuir probe electron saturation current method provides a direct electron density measurement, which is independent of ion species. The ratio of electron and ion saturation current from Langmuir probe and optical emission experiment can confirm that the major species in the experiments has not been changed. The optical emission is also carried out for diagnosing can enhance the delayed emission spectra from TMAE plasma. The plasma decay mechanisms are studied, and a delayed ionization process is found to be important. A model is developed to calculate the lifetime of the delayed ionization which is dependent of TMAE pressure and electron density.
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