Patent ID: 7686917

Claim:
A plasma processing apparatus which processes a sample located in a process chamber inside of a vacuum vessel, using a plasma generated therein, the apparatus comprising: a sample stage disposed at a lower position inside of the process chamber and having a sample mounting surface on which the sample is located; an upper portion member of the process chamber including a housing which constitutes a part of the vacuum vessel and a disk shaped conductor having electric power from a power source supplied thereto for generating a plasma in the process chamber; a plate held by the upper portion member and disposed on a plasma facing side of the disk shaped conductor, the plate constituting a ceiling of the process chamber and extending from a center of the sample to at least a periphery thereof inside of the vacuum vessel, wherein the plate has a substantially uniform thickness and has the electric power supplied thereto via the disk shaped conductor and a radio frequency power as a bias supplied thereto, the plate being disposed opposite to and substantially parallel with the sample stage, and the plate being made of a material including at least silicon and having a through-hole disposed therein above the sample mounting surface; and an optical transmitter disposed inside of the vacuum vessel and detachably held with respect to the upper portion member of the vacuum vessel at a position above and spaced from a back surface of the plate so that a portion of the optical transmitter is exposed to a process gas passage in the disk shaped conductor, the optical transmitter having a cylindrical shape and having a diameter of an end face thereof which is larger than a diameter of the through-hole of the plate, the optical transmitter receiving light at an end face of the optical transmitter from the process chamber via the through-hole, wherein the end face of the optical transmitter is opposite to and spaced from the back surface of the plate, and the optical transmitter being constituted so as to be independently detachable with respect to the upper portion member.