Microwave plasma processing apparatus using a hybrid microwave having two different modes of oscillation or branched microwaves forming a concentric electric field

An apparatus for processing a target object by using a plasma, comprising:

• an airtight processing chamber;
• a work table for supporting the target object disposed in said processing chamber;
• an exhaust for exhausting said processing chamber and setting said processing chamber at a vacuum;
• a process gas supply for supplying a process gas into said processing chamber;
• and
• a microwave supply for supplying into said processing chamber a microwave for exciting the process gas to convert the process gas into a plasma, said microwave supply having a main waveguide connected to a microwave generator, a flat antenna disposed to oppose said processing chamber and having a plurality of openings disposed concentrically, and a plurality of branched waveguides for connecting said main waveguide and said openings of said flat antenna to each other, and said microwave being transmitted from said main waveguide to the openings of said flat antenna while being branched through said branched waveguides, and introduced into said processing chamber from the openings such that respective portions of branched microwaves are synthesized, thereby forming a concentric electric field,
• wherein said branched waveguides are set to have substantially a same length, and said branched waveguides and a portion of said main waveguide connected thereto are made of coaxial waveguides.

An apparatus for processing a target object by using a plasma, comprising:

• an airtight processing chamber;
• a work table for supporting the target object disposed in said processing chamber;
• an exhaust for exhausting said processing chamber and setting said processing chamber at a vacuum;
• a process gas supply for supplying a process gas into said processing chamber;
• and
• a microwave supply for supplying into said processing chamber a microwave for exciting the process gas to convert the process gas into a plasma, said microwave supply having a first waveguide connected to a microwave generator, a second waveguide open to face said processing chamber, and a mode converter for connecting said first and second waveguides so as to change an oscillation mode and transmitting direction of the microwave, and said mode converter converting the microwave such that the microwave transmitted through said second waveguide becomes a hybrid wave having two mode waves of oscillation modes that are different from each other,
• wherein said first waveguide and said second waveguide are a rectangular waveguide and a circular waveguide, respectively,
• wherein said two mode waves are a TM.sub.01 -mode wave and a TE.sub.11 -mode wave, respectively,
• wherein said mode converter has a recessed portion defined by a conductive wall, and being concentric with said second waveguide and open to face said second waveguide through an extension line at a center of said first waveguide, and a distance Ld from the extension line at the center of said first waveguide to an inner end face of said recessed portion is set to satisfy a relation .lambda.a/4<Ld<.lambda.b/4 with respect to respective wavelengths .lambda.a and .lambda.b of said two mode waves, and
• wherein said apparatus further comprises a polarizing member disposed in said mode converter or said second waveguide in order to circularly polarize the TE.sub.11 -mode wave.