Film forming apparatus having electrically insulated element that introduces power of 20-450MHz

A deposited film-forming apparatus comprising a reaction chamber capable of being evacuated and a high frequency power introduction means for transmitting a high frequency power with a frequency of 20 MHz to 450 MHz, said reaction chamber having a glow discharge region in which glow discharge is caused by supplying said high frequency power with said frequency of 20 MHz to 450 MHz introduced through said high frequency power introduction means forming a deposited film on a substrate positioned in said reaction chamber, wherein said high frequency power introduction means has an electrode for transmitting said high frequency power, said electrode comprising an electrically conductive metallic material, and said electrode being patterned with a configuration which is branched into plural portions so that a region where impedance is discontinuous is provided so as to generate a uniform supply of said high frequency power to said reaction chamber, said high frequency power introduction means has (i) a first insulating surface in contact with said electrode such that there is no clearance between said metallic material and said first insulating surface, and (ii) a second insulating surface for isolating said metallic material from said glow discharge region.