Plasma processing apparatus and plasma processing method

A method of carrying out plasma processing using a plasma processing apparatus, the plasma processing apparatus includes:

• a chamber having a depressurizable internal space, the chamber being configured to carry out a plasma processing with respect to a target object in the internal space;
• an upper lid configured to be provided on an upper surface of the chamber, the upper lid being formed of a dielectric plate;
• a flat plate-shaped inner electrode disposed inside the chamber, the inner electrode being configured to receive the target object to be mounted thereon;
• a spiral-shaped outer electrode disposed outside the chamber, the outer electrode being disposed so as to face the inner electrode with the upper lid interposed therebetween;
• a plasma generating power source configured to apply alternating-current power having a predetermined frequency to the outer electrode;
• and
• a gas introduction part configured to introduce a processing gas into the internal space of the chamber, wherein
• the outer electrode is separated in a radial direction of the outer electrode,
• the outer electrode includes a spiral-shaped first electrode, a spiral-shaped second electrode, and a spiral-shaped third electrode,
• the first electrode is disposed at a medial portion in the radial direction,
• the second electrode is disposed at an outer-peripheral portion in the radial direction,
• the third electrode is sandwiched between the first electrode and the second electrode in the radial direction,
• the plasma generating power source includes a first high-frequency power source, a second high-frequency power source, and a power splitter,
• the first high-frequency power source is configured to apply alternating-current power having a first frequency λ1 to the first electrode and the second electrode,
• the second high-frequency power source is configured to apply alternating-current power having a second frequency λ2 to the third electrode,
• a relationship between the first frequency λ1 and the second frequency λ2 satisfies a relationship of λ1>λ2,
• the power splitter is configured to split the alternating-current power to be applied to the first electrode and the second electrode, into the first electrode and the second electrode, with a predetermined split ratio, and
• the power splitter is configured to apply the split alternating-current power to each of the first electrode and the second electrode;
• wherein
• the method of carrying out plasma processing comprising:
• generating plasma in the internal space by applying the alternating-current power having the first frequency λ1 to the first electrode and the second electrode by use of the first high-frequency power source;
• controlling a space distribution of the plasma generated in the internal space by splitting the alternating-current power having the first frequency λ1 into the first electrode and the second electrode with a predetermined split ratio by use of the power splitter;
• and
• increasing an electron density of the plasma by applying the alternating-current power having the second frequency λ2 to the third electrode by use of the second high-frequency power source.