Microwave output device and plasma processing apparatus

A microwave output device, comprising:

• a microwave generator configured to generate a microwave having a median frequency, a bandwidth and a carrier pitch respectively corresponding to a set frequency, a set bandwidth and a set carrier pitch instructed from a control device, a power of the microwave being pulse-modulated such that a pulse frequency, a duty ratio, a High level and a Low level become a set pulse frequency, a set duty ratio, a set power of High level and a set power of Low level instructed from the control device;
• 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 from the microwave generator to the output unit;
• and
• a measurer configured to determine 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, based on the part of the progressive wave outputted from the first directional coupler,
• wherein a reciprocal of the set carrier pitch becomes a longest cycle among power variation cycles of the microwave having the bandwidth, and the set carrier pitch is set to satisfy a preset condition,
• the preset condition includes a condition that a value obtained by dividing the set pulse frequency by the set carrier pitch or a value obtained by dividing the set carrier pitch by the set pulse frequency is not an integer and a condition that an ON-time of the High level with respect to a set cycle in the set duty ratio is equal to or larger than 50%,
• the microwave generator averages the first High measurement value and the first Low measurement value in a preset moving average time at a preset sampling interval, the preset moving average time being longer than a sum of the ON-time of the High level,
• the microwave generator controls the power of the 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 the Low level of the pulse-modulated microwave based on the averaged first Low measurement value and the set power of Low level.