Plasma processing apparatus

A plasma processing apparatus, comprising:

• a chamber main body;
• and
• a microwave output device configured to output a microwave for exciting a gas supplied into the chamber main body,
• wherein the microwave output device comprises:
• a microwave generator configured to generate a microwave a power of which is pulse-modulated such that the power of the microwave has a pulse frequency, a duty ratio, a High level and a Low level according to a set pulse frequency, a set duty ratio, a set power of High level and a set power of Low level instructed from a controller;
• an output unit configured to output the microwave propagated from the microwave generator;
• a first directional coupler configured to output a part of a progressive wave propagated to the output unit from the microwave generator;
• and
• a measurement device configured to determine, based on the part of the progressive wave outputted from the first directional coupler, a first High measurement value and a first Low measurement value respectively indicating a High level and a Low level of a power of the progressive wave in the output unit,
• wherein the microwave generator is configured to alternately generate a microwave of a first waveform and a microwave of a second waveform in synchronization with switching of the High level and the Low level of the power, the microwave of the first waveform having a median frequency, a bandwidth and a carrier pitch according to a set frequency, a set bandwidth and a set carrier pitch instructed from the controller, respectively, and the microwave of the second waveform having a single frequency peak at a median frequency according to the set frequency instructed from the controller,
• the measurement device averages, between the first High measurement value and the first Low measurement value, the measurement value corresponding to the microwave of the first waveform with a moving average time equal to or larger than a reciprocal of the set carrier pitch and a preset sampling number,
• the measurement device averages, between the first High measurement value and the first Low measurement value, the measurement value corresponding to the microwave of the second waveform with a moving average time less than the reciprocal of the set carrier pitch and a preset sampling number,
• the microwave generator controls the power of High level of the pulse-modulated microwave based on the averaged first High measurement value and the set power of High level, and
• the microwave generator controls the power of Low level of the pulse-modulated microwave based on the averaged first Low measurement value and the set power of Low level.