Plasma processes and film deposition using tetraethoxysilane

The fragmentation of tetraethoxysilane, Si(C2H5O)4 (TEOS) has been investigated in a hollow cathode arc discharge plasma. Measurements of the molecular ions were performed with an energy dispersive mass spectrometer having an orifice in the plane of the substrate holder. During the measurements the plasma density and the electron temperature as well as the composition of the background plasma (Ar, Ar+He, Ar+N2, Ar+C2H2, Ar+H2, H2+Ar) were systematically varied. The change of the molecular ion composition which mainly consisted of TEOS fragments was measured as a function of the parametrical changes. The results of these measurements were compared with the chemical composition, the deposition rate and the structure of films deposited under nearly identical conditions. A change in the magnetic field and thus a variation of the electron temperature caused a change of the film composition showing a significant increase in carbon content with an increase in electron temperature. It is assumed that this change in composition is caused by the increased production of lower molecular weight molecule fragments containing carbon with a high sticking coefficient.