Optical emission spectra of TEOS and HMDSO derived plasmas used for thin film deposition

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 UV-visible 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 O2/TEOS(HMDSO) plasmas. The OES of O2/TEOS and O2/HMDSO plasmas are very close and are dominated by CO, OH, H2 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+, CO2+ 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.