Plasma processing apparatus

A plasma processing apparatus configured to supply a gas into a chamber, generate a plasma from the gas using a power of an electromagnetic wave, and perform a predetermined plasma process on a substrate that is held by a mounting table, the plasma processing apparatus comprising:

• a chamber in which plasma is generated;
• a dielectric window through which the electromagnetic wave that is output from an electromagnetic wave generator is propagated and transmitted into the chamber;
• a support that supports the dielectric window;
• a partition arranged below the dielectric window, the partition separating a space where the support is arranged from a plasma generation space in the chamber, and including a protrusion abutting against the dielectric window;
• and
• a conductive ring formed of silicon that is arranged between the partition and the dielectric window, and an inner diameter side of the conductive ring is covered by the protrusion to protect the conductive ring from being exposed to the plasma generation space, wherein a gap between the protrusion and the conductive plate is arranged to have a distance of less than 0.68 mm.