Microwave plasma source

A microwave plasma source comprising:

• a tubular magnet portion having a first opening end and a second opening end located on a side opposite to the first opening end, the first opening end having a first polarity and the second opening end having a second polarity opposite to the first polarity;
• a tubular body surrounded by the tubular magnet portion;
• a first magnetic circuit portion being in contact with the first opening end and closing the first opening end;
• a second magnetic circuit portion being in contact with the second opening end, being disposed opposite to the first magnetic circuit portion, and having a first opening part that opens a space surrounded by the tubular body;
• an antenna penetrating the first magnetic circuit portion, being introduced to the space, and being capable of supplying microwave power to the space;
• a nozzle portion being in contact with the second magnetic circuit portion on a side opposite to the first magnetic circuit portion and having a second opening part that has a smaller opening area than the first opening part and communicates with the first opening part;
• a gas port portion penetrating the tubular magnet portion and the tubular body and being capable of supplying a discharge gas to the space;
• and
• an insulating member provided between the antenna and the first magnetic circuit portion,
• wherein, when an inner diameter of the tubular body is represented by a (mm), and a microwave cutoff wavelength of the microwave power being supplied to the space is represented by λ (mm), the microwave plasma source is configured to satisfy a relational expression λ>3.41×(a/2).