REACTION-MECHANISM OF CHEMICAL VAPOR-DEPOSITION USING TETRAETHYLORTHOSILICATE AND OZONE AT ATMOSPHERIC-PRESSURE

The decomposition process of tetraethylorthosilicate (TEOS) and ozone at atmospheric pressure was measured in a closed vessel by in-situ Fourier-transform infrared absorption (FT-IR) analysis, and the changes of the deposition rate and the overall sticking probability beta of the film precursor were obtained along the flow direction in a flow-type reactor. It has been found that the film precursors are formed by TEOS decomposition with O-atoms and/or ozone in the gas phase, and that CH3CHO may be the first product, followed by the oxidation to CO2 and H2O via HCHO. It is also shown that the film quality changes along the flow direction, that is, O-H bonds in the film decrease and the beta-value increases as the reaction proceeds. These results may show that there are several kinds of precursors, and the sticky (unstable) precursors become dominant in the later stages.