Plasma processing apparatus and plasma processing method

A plasma processing apparatus for performing plasma processing on a substrate in a processing container, the plasma processing apparatus comprising:

• an upper electrode disposed in an upper side in the processing container;
• a power feeding rod configured to supply high-frequency power from a plasma source to a center of the upper electrode via a matcher;
• a gas diffusion plate having a plurality of ejection holes and disposed below the upper electrode;
• a gas introduction member configured to introduce a processing gas into the processing container, the gas introduction member including an annular portion that is disposed above the upper electrode and has a shape surrounding the power feeding rod, a gas flow path being formed in the annular portion;
• an insulation introduction member having a cylindrical shape and provided below the annular portion;
• a plurality of gas supply paths formed inside the insulation introduction member in a vertical direction to communicate with the gas flow path;
• and
• a confluence provided directly below a connection between the upper electrode and the power feeding rod, and configured to cause the processing gas from the gas supply paths to merge,
• wherein the processing gas after merging in the confluence flows in a space that is formed above the gas diffusion plate and communicating with the ejection holes.