Abstract: Provided is a bush insert coupled to a plasma electrode plate. The bush insert is configured to provide an insert inner hole that passes through the bush insert in a first direction, an inner surface of the bush insert that defines the insert inner hole is configured to provide a female screw structure, and an outer surface of the bush insert has a non-circular shape in a plan view.

Abstract: A focus ring and a method for manufacturing the same. The focus ring include a first ring made of a first material, a second ring covered by the first ring, wherein the second ring is made of a second material different from the first material, and a fastening member configured to couple the first ring to the second ring. The fastening member includes a through-part configured to pass through the second ring and a buried part buried in a lower portion of the first ring. The through-part has a first diameter, and the buried part has a second diameter greater than or equal to the first diameter.