CHARACTERIZATION OF FLUORINATED TETRA ETHYL ORTHO SILICATE OXIDE-FILMS DEPOSITED IN A LOW-PRESSURE PLASMA-ENHANCED CHEMICAL-VAPOR-DEPOSITION REACTOR

Fluorinated silicon dioxide films were deposited in a commercial plasm a enhanced chemical vapor deposition reactor using tetra ethyl ortho s ilicate (TEOS), oxygen, and C2F6. The depositions were carried out usi ng dual rf frequency power at low pressure, 500-750 mTorr. Film proper ties were investigated as a function of rf power, pressure, gas flows, and wafer temperature. Fluorine content, refractive index, stress, an d deposition rate are among the film properties studied. Special atten tion was paid to the stability of these properties in air, in boiling water, and after subsequent annealing. The base line TEOS process is u nusual in that high compressive stress values can be achieved, up to a bout 300 MPa. It was thought that this high initial stress would lead to improved stability at higher fluorine concentration. Film stress wa s found to be quite compressive, even at high fluorine concentration. Good film stability was observed for fluorine concentrations up to 10% (Si-F/Si-O peak ratio). Refractive indices as low as 1.40 were measur ed. This work demonstrates that a stable, production-quality, fluorina ted oxide film can be deposited in this reactor. (C) 1997 American Vac uum Society.