An electron-cyclotron resonance plasma source that generates 500 mm wide plasma has been developed. The plasma is generated by a 2.45 GHz traveling microwave which is supplied through a long slot antenna prepared in the waveguide in a divergent magnetic field generated by permanent magnets and a solenoid coil. Diamondlike carbon (DLC) films were deposited in a wide zone 320 mm in width. The breakdown field was 8.4 X 10(6) V/cm and permittivity, 3.89. The prepared Al/DLC/Si metal/insulator/semiconductor diode revealed fairly good field effect in its capacitance-voltage curve.