Abstract: A substrate support includes a disk having a disk shape to support at least one substrate, at least one pocket groove which is formed to be concave from an upper surface of the disk in a shape corresponding to the substrate such that at least an edge portion of the substrate is seated therein, a free space forming portion which is spaced inwardly at a predetermined distance from an edge of the pocket groove and formed to be concave from at least a part of a bottom surface of the pocket groove so as to define a stepped portion that supports at least the edge portion of the substrate and forms a free space below the substrate when the substrate is seated on the stepped portion, and an exhaust passage which connects an outer circumferential surface of the disk to at least a part of the free space forming portion.