OPTICAL-EMISSIONS FROM ELECTRON-IMPACT-EXCITED TETRA-ETHOXYSILANE

The optical emission spectrum in the spectral region 200-800 nm produced by electron impact on tetra-ethoxysilane (TEOS) under controlled single-collision conditions is analyzed. Absolute emission cross sections (at an impact energy of 100 eV) of 0.7 +/- 0.2 X 10(-20) cm2 for the Si (3p4s 1P0-->3p2 1S) line at 390.6 nm, 2.4 +/- 0.5 X 10(-20) cm2 for the CH(A 2DELTA-->X 2PI) band centered around 430 nm, and cross sections below 0. 5 X 10(-20) cm2 for the hydrogen Balmer-alpha, -beta, and -gamma lines at, respectively, 656.4, 486.1, and 434.0 nm are measured. Comparatively high onset energies of 56.2 +/- 2.0 eV (Si) and 30.7 +/- 2.0 eV (CH) were found which when combined with the small cross sections indicate that the single-step dissociative excitation of TEOS by electron impact cannot be expected to play a major role in the collision processes that dominate the plasma chemistry of TEOS-containing processing plasmas.