| 摘要 |
PURPOSE: A unit for supporting a substrate is provided to reduce the concentration of an error at the edge of the substrate by arranging an edge ring to surround the side of the substrate and minimize a contact area of the substrate. CONSTITUTION: An insert hole(318) penetrated into the central of a substrate so that it surrounds the circumference of the substrate. An edge ring(310) comprises an edge wing(311) of a disc shape. A cylinder ring(320) supporting the substrate is contacted with the lower surface of the substrate. A rotation ring(330) is combined with the bottom of the cylinder ring and rotates a cylinder ring. The edge wing is separated from the top of the cylinder ring and it is installed or attached to the top of the edge. The cylinder ring comprises a cylindrical body having both openings and a supporting protrusion(326).
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