[Problem] To provide a microwave plasma treatment apparatus that is not provided with complicated, long gas flow paths inside a dielectric substrate, to stabilize generation and retention of a plasma, and can generate a highly uniform, high-density, stable low-temperature plasma not only at low atmospheric pressures but also at middle atmospheric pressures and high atmospheric pressures.

[Solution] In a micro plasma treatment apparatus including a dielectric substrate, a microwave introducing section, a microstrip line, an earth conductor, a gas inlet, a plasma generating section, and a nozzle for blowing out a plasma, the gas inlet is provided at the earth conductor or the microstrip line, and the gas inlet is provided with a diameter preferably smaller than a cut-off wavelength determined depending on a cross-section of the gas inlet, to prevent leakage of a microwave.

The invention comprises a method and apparatus for generating a plasma, comprising: (1) receiving a microwave from a co-axial cable, with a first impedance, into an electron cyclotron resonance source, the electron cyclotron resonance source comprising: a housing containing a first transform material and a transmission section; (2) passing the microwave through the first transform material with a second impedance; (3) coupling the microwave into the transmission section of the electron cyclotron resonance source, the transmission section comprising a third impedance, the transmission section comprising a first dielectric gap positioned between an inner conductor and an outer conductor; (4) generating a magnetic field with a set of magnets; and (5) accelerating cyclotron resonant electrons circulating about the magnet field with the microwave, such as where the first transform material has a thickness of one-quarter of a wavelength of the microwave.