PLASMA AND SURFACE DIAGNOSTICS DURING PLASMA-ENHANCED CHEMICAL-VAPOR-DEPOSITION OF SIO2 FROM SIH4 O-2/AR DISCHARGES/

Factors affecting the SiOH incorporation into SiO2 films during plasma -enhanced chemical vapor deposition were studied using in-situ attenua ted total reflection Fourier transform infrared spectroscopy, optical emission actinometry, and Langmuir probe measurements. The silane-to-o xygen ratio, R, in the process gas mixture determines the chemical nat ure of the substrate surface and the incorporation rate of SiOH and Si H into the film. The oxide surface and the him are hydroxyl rich durin g deposition with SiH4-to-O-2 ratio below 0.7. Silicon hydrides are ob served on the surface and in the him when R exceeds 0.7. The SiOH conc entration in the film correlated well with SM concentration above the substrate surface, which is representative of the silane fragment (SiH x) flux arriving at the surface of the growing film. High O flux compa red to SiHx flux results in immediate oxidation of the silane fragment s adsorbed onto the surface which leads to OH rich surface and SiOH in corporation. As the SiHx flux relative to O flux increases, the reacti on of silane fragments with surface SiOH reduces the SiOH coverage on the surface and the SiOH incorporation rate into the film.