Plasma Treatment Device

A plasma treatment device comprising:

• a chamber body including a chamber defined therein;
• a gas supply part configured to supply a processing gas into the chamber;
• a stage disposed within the chamber;
• an upper electrode having a circular surface that faces the stage via an internal space of the chamber;
• a conductor connected to the upper electrode;
• a high-frequency power supply configured to generate a first high-frequency wave having a frequency ranging from 100 MHz to 1,000 MHz, the high-frequency power supply being coupled to the upper electrode via the conductor;
• a bias power supply configured to apply a second high-frequency wave or a direct current bias voltage to the upper electrode, the second high-frequency waves having a frequency lower than a frequency of the first high-frequency waves;
• an annular insulating ring provided to extend along an outer edge of the circular surface of the upper electrode;
• a waveguide through which electromagnetic waves generated around the conductor based on the first high-frequency wave propagate, the waveguide being connected to the annular insulating ring outside the upper electrode;
• and
• a controller configured to control the second high-frequency wave or the direct current bias voltage to be applied to the upper electrode.