Chemistry of Plasma-Polymerized Vinyltriethoxysilane Controlled by Deposition Conditions

Plasma-polymerized thin films of vinyltriethoxysilane were deposited on IR-transparent silicon wafers using plasma-enhanced chemical vapor deposition at a wide range of RF pulsed power (0.05-25 W). The deposited films were analyzed by various spectroscopic techniques (RBS, ERDA, XPS, and FTIR) in order to compare their chemical structure and elemental composition, which were correlated with plasma products monitored by mass spectroscopy. Thin polymer films deposited at 0.05 W were SiO-rich (55 at.-%), while those prepared at 25 W were dominated by carbon (66 at.-%). The organic/inorganic character (C/Si ratio) of plasma polymer varied widely, from 2.5 to 7.3 with enhanced power. The chemical structure of the polymer network and side groups was also controlled by the effective power. Chemical analyses enabled us to gain an idea of the chemical structure of the films.