Microwave cvd method for deposition of robust barrier coatings

A composite material including a microwave-plasma-enhanced-chemical-vapor-deposited silicon oxide barrier coating deposited atop a temperature sensitive substrate obtained by a method including : providing the substrate within a deposition region in an evacuable deposition chamber; evacuating said chamber to a sub-atmospheric pressure; performing a plasma pretreatment of the substrate; introducing a precursor gaseous mixture including at least a silicon-hydrogen containing gas and an oxygen containing gas into said deposition region; directing microwave energy from a source of microwave energy to the deposition region, thereby creating a plasma by interaction of said microwave energy and said precursor gaseous mixture; depositing from said plasma, onto said substrate, the coating, thus providing the coated substrate with oxygen and water vapor barrier properties greater than the non-coated substrate; and introducing a sufficient flow rate of oxygen-containing gas into said precursor gaseous mixture to substantially eliminate the inclusion of silicon-hydrogen bonds into the deposited coating.