Patent ID: 8043668

Claim:
A method for depositing a fluorine-doped silicon oxide film on the surface of a substrate made of a material comprising at least 50 mass % of an ethylene/tetrafluoroethylene copolymer, the method comprising flowing a mixed gas into between electrodes, exposing the mixed gas to electric power applied between the electrodes so that the electrical power density between the electrodes becomes from 0.5 to 1.1 W/cm 3 to cause discharge, forming plasma of the mixed gas and depositing the fluorine-doped silicon oxide film on the surface of the substrate, wherein the mixed gas for forming the fluorine-doped silicon oxide film comprises silicon tetrafluoride, oxygen and a hydrocarbon, and wherein the atomic ratio of oxygen atoms to carbon atoms (O/C) is from 1 to 10, and the atomic ratio of oxygen atoms to silicon atoms (O/Si) is from 1.7 to 25 in the mixed gas.