CPC H01J 37/32642 (2013.01) [H01J 2237/334 (2013.01)] | 11 Claims |
1. A focus ring comprising:
a first ring contacting a substrate;
a second ring coupled to the first ring;
a third ring coupled to the second ring; and
a stepped structure provided between the second ring and the third ring, wherein the stepped structure is downwardly disposed towards the substrate and includes a plurality of stepped portions including a first stepped portion, a second stepped portion, a third stepped portion and a fourth stepped portion, which are downwardly disposed toward the substrate, and wherein the first to the fourth stepped portions have depths increased toward the substrate and widths decreased toward the substrate, respectively.
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