AVS 46th International Symposium
    Plasma Science and Technology Division Tuesday Sessions
       Session PS-TuA

Paper PS-TuA4
Determination of Electron Temperatures and Species Concentrations During Aluminum Etching

Tuesday, October 26, 1999, 3:00 pm, Room 609

Session: Plasma Diagnostics II
Presenter: V.M. Donnelly, Bell Laboratories, Lucent Technologies
Authors: V.M. Donnelly, Bell Laboratories, Lucent Technologies
M.V. Malyshev, Bell Laboratories, Lucent Technologies
S.W. Downey, Bell Laboratories, Lucent Technologies
J.I. Colonell, Bell Laboratories, Lucent Technologies
N. Layadi, Bell Laboratories, Lucent Technologies
Correspondent: Click to Email
Electron temperatures (T@sub e@) and species concentrations were obtained in chlorine-containing, high-density, inductively coupled plasmas (Applied Materials decoupled plasma source (DPS) metal etcher), using trace rare gases optical emission spectroscopy (TRG-OES). Measurements were carried out as a function of total pressure, source power, fraction of BCl@sub 3@ added to Cl@sub 2@ and substrate material (SiO@sub 2@, Al, and photoresist). A small amount (1.7% each) of all five rare gases was added to the plasma and emission spectra were recorded. TRG-OES T@sub e@ s corresponding to the high energy tail of the electron energy distribution function were derived from the best match between the observed and computed rare gas emission intensities. At source and bias powers of 1000 and 100 W, TRG-OES T@sub e@ s in Cl@sub 2@/BCl@sub 3@/N@sub 2@/rare gas plasmas increased from 1.5 eV at 40 mTorr to 3.0 eV at 3 mTorr, in good agreement with values computed from a global model and somewhat lower (at higher pressures) than those measured with a Langmuir probe. Surprisingly little dependence of T@sub e@ on substrate material was found. Reduced plasma induced damage at higher pressures correlated with a drop in both T@sub e@ and plasma density, but appears to be due mostly to the lower T@sub e@. Cl@sub 2@, Cl, BCl@sub 2@, BCl, B, AlCl@sub 2@, AlCl, Al, N@sub 2@ and BN emissions were identified. Qualitative, and in some cases quantitative absolute number densities were obtained by dividing these emission intensities by that from Ar, or Xe, corrected for electron impact excitation from Xe metastables.