Microwave plasma film deposition system

A microwave plasma film deposition system, comprising:

• a coaxial waveguide for feeding microwaves by way of a microwave feeding window provided at an end thereof, the difference between the inside radius of a cylindrical external conductor and the radius of an inner conductor of said coaxial waveguide being arranged to be shorter than the mean free path of an electron of the gas in said coaxial waveguide;
• a plasma cavity in communication with another end of said waveguide and further having a discharge gas inlet which is not in communication with said waveguide;
• a specimen chamber in communication with said plasma cavity and having a substrate setting rest therein and a material gas inlet;
• and
• magnetic field applying means provided near said plasma cavity for generating plasma in said plasma cavity, the strength B (Tesla) of the magnetic field near said microwave feeding window satisfying the following conditions:
• ##EQU6## where 2r' designates the difference between the inside radius of the cylindrical external conductor and the radius of the inner conductor of said coaxial waveguide;
• m (kg) represents the mass of the electron;
• e (C) depicts the electric charge of the electron;
• and T (eV) is the energy sufficient to ionize the gas.