No abstract

This paper is devoted to the optical emission spectra (OES) of low pressure (1 mTorr-1 Torr) plasmas created in tetraethoxysilane (TEOS) and hexamethyldisiloxane (HMDSO) used pure or mixed with oxygen. The UVvisible emission spectra are recorded at low resolution (0.3 nm) using a 46 cm focal length monochromator and at high resolution (0.3 cm −1 ) using a Fourier transform spectrometer. Since almost all the atomic and molecular emissions have been identified, the spectra displayed here can be used as reference emission spectra for TEOS, HMDSO and O 2 /TEOS(HMDSO) plasmas. The OES of O 2 /TEOS and O 2 /HMDSO plasmas are very close and are dominated by CO, OH, H 2 and H emissions. In contrast, the OES of TEOS and HMDSO plasmas are quite different: the emissions of excited Si, SiO and SiH are characteristics of HMDSO plasma, while those of OH, CO, CO + ,CO + are characteristics of TEOS plasmas. On the basis of these spectra and the data reported in the literature, it is finally concluded that the CO and OH molecules detected in TEOS plasmas are very likely created at the reactor walls by desorption from the growing film.

Oxygen/tetraethoxysilane (O 2 /TEOS) plasmas created in a low-pressure (2 mTorr) rf helicon reactor have been studied by optical emission spectroscopy and mass spectrometry as a function of the rf (13.56 MHz) power injected into the plasma, which is varied from 25 to 300 W. Complementary measurements for the interpretation of the mass spectrometric data have also been carried out using the threshold ionization mass spectrometry technique. It is shown that valuable information on the parent molecules is obtained by both optical emission spectroscopy and threshold ionization mass spectrometry techniques. At low rf power TEOS molecules and organic compounds like hydrocarbons (CH 4 , C 2 H 2 ) and alcohols (CH 3 CH 2 OH) as well as H 2 , H 2 O, CO, O 2 , CO 2 are observed. At high rf power TEOS and O 2 molecules are totally or mostly depleted, the share of hydrocarbons decreases and carbon monoxide, carbon dioxide, water and hydrogen become the essential parts of the gas phase.