Microwave output device and plasma processing device

A plasma processing device comprising:

• a chamber main body;
• and
• a microwave output device that outputs a microwave for exciting a gas to be supplied to the chamber main body, the microwave output device comprising:
• a microwave generation unit configured to generate a microwave having a center frequency, power, and a bandwidth respectively corresponding to a setting frequency, setting power, and a setting bandwidth for which instructions are given from a controller;
• an output portion configured to output the microwave propagating from the microwave generation unit;
• a first directional coupler configured to output parts of travelling waves propagating toward the output portion from the microwave generation unit;
• a second directional coupler configured to output parts of reflected waves returning to the output portion;
• and
• a measurement unit configured to determine first measured values indicating power levels of the travelling waves in the output portion on the basis of the parts of the travelling waves output from the first directional coupler, and determine second measured values indicating power levels of the reflected waves in the output portion on the basis of the parts of the reflected waves output from the second directional coupler,
• wherein the microwave generation unit averages the first measured values and the second measured values at a predetermined movement average time and a predetermined sampling interval, and controls the microwave such that a value obtained by subtracting the averaged second measured value from the averaged first measured value comes close to the setting power, and
• wherein the predetermined movement average time is 60 μs or less, and a relationship of y≥78.178x0.1775 is satisfied when the predetermined sampling interval is indicated by x, and the predetermined movement average time is indicated by y.