Patent ID: 7438018

Claim:
In a plasma processing apparatus having a process chamber in which substrates are processed with plasma, a confinement ring assembly comprising: a plurality of plungers disposed about the process chamber, and a plurality of confinement rings, each of the plungers including a cylinder, a rod extending vertically through the cylinder and supported so as to be movable up and down in the apparatus, a bushing fixed to a lower end portion of the cylinder and through which the rod extends, and wherein the confinement rings include an upper confinement ring fitted to the bushing of each of the plungers, and a lower confinement ring coupled to a lower end of the rod of each of the plungers so as to move up and down therewith, the upper confinement ring having an inner diameter that is larger than that of the lower confinement ring, and the lower confinement ring having an inner peripheral portion that extends upwardly relative to an outer peripheral portion thereof to form a vertically extending inner wall, the vertically extending inner wall of the lower confinement ring confronting and spaced from an inner side wall surface of the upper confinement ring, whereby the vertically extending inner wall prevents plasma generated while a process is being performed within the process chamber from penetrating into a gap between the upper confinement ring and the lower confinement ring.