AVS 53rd International Symposium
    Plasma Science and Technology Thursday Sessions
       Session PS2-ThM

Paper PS2-ThM5
Low Temperature PECVD of Silicon Oxynitride Thin Films from Dimethylaminosilanes: Role of Oxygen Addition

Thursday, November 16, 2006, 9:20 am, Room 2011

Session: Plasmas and Polymers
Presenter: R. d'Agostino, University of Bari, Italy
Authors: R. Di Mundo, University of Bari, Italy
F. Fracassi, University of Bari, Italy
R. d'Agostino, University of Bari, Italy
F. Palumbo, IMIP-CNR
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Silicon oxynitride (SiON) coatings are important materials as dielectrics and optical components. So far attempts to replace hazardous silane in SiON PECVD processes with organosilicon precursors have led to organic SiC@sub x@N@sub y@O@sub w@H@sub z@ films. However, considering the good features of SiN coatings deposited at low temperature from inductively coupled discharges fed by bis(dimethylamino)dimethylsilane (BDMADMS) and argon,@footnote 1@ we tested the addition of O@sub 2@ to this novel system for SiON films deposition. The O@sub 2@-to-monomer ratio was varied at low and high input power until transition to oxide was observed. The chemical composition of the coatings was characterized by means of FT-IR and XPS analyses while a deep investigation on the plasma phase was carried out by Optical Emission Spectroscopy (OES) in order to gain insight into the role of oxygen atoms in the deposition mechanism. Results indicate that at high input power and low O@sub 2@-to-BDMADMS ratio highly inorganic SiON films can be obtained. The sharp increase of the O/Si ratio in the coating, as the O@sub 2@ concentration in the feed rises, is accompanied by a significant reduction of the N/Si ratio, which is even faster than the decrease of the C/Si ratio. This particular chemical evolution can be correlated with the trends of relative density in plasma phase of N-containing species (NH, CN) as well as of oxidation products (CO, OH) detected with OES, suggesting some favourite reaction paths within the process.@FootnoteText@@footnote 1@R. Di Mundo, R. d'Agostino, F. Fracassi, F. Palumbo, Plasma Process. Polym., 2, 612-617 (2005).