OES and FTIR diagnostics of HMDSO/O2 gas mixtures for SiOx deposition assisted by RF plasma

A capacitively coupled radiofrequency PACVD process for SiOx deposition using oxygen-hexamethyldisiloxane (HMDSO) gas mixtures is characterised under a pressure of 1 Torr. Optical emission spectroscopy and FTIR absorption spectroscopy analyses are performed for different values of the dilution ratio X-hm of HMDSO in oxygen. The power delivered to the plasma is set high enough (5 W/cm(2)) to have a strong fragmentation of the monomer by electron impact. Two different regimes are then observed depending whether X-hm exceeds or not 20 vol.%. Below this critical value, the monomer fragments are strongly oxidised. Above, densities of CO and CH4 molecules strongly decrease. Trends observed in the evolution of the species concentrations as a function of X-hm better agree the results by Aumaille et al. [K. Aumaille, C. Vallee, A. Granier, A. Goullet, F. Gaboriau, G. Turban, Thin Solid Films 359 (2000) 188] than those by Lamendola et al. [R. Lamendola, R. d'Agostino, F. Fracassi, Plasmas Polym. 2 (1997) 147] despite the pressure set in this work is closer to that used by the latter. (C) 2004 Elsevier B.V. All rights reserved.