| 摘要 |
PROBLEM TO BE SOLVED: To enable a presser ring to evenly descend toward a wafer ring surface with the wafer supporting member expanded. SOLUTION: A magnetic attraction surface 53a is provided on the lower surface of a pressor ring 53, and, beneath the pressor ring 53, an electromagnet 56 is arranged. The electromagnet 56 is excited and its magnetic force is exerted on the magnetic attraction surface 53a for descending the presser ring 53. Since the magnetic force is applied for attraction on the surface of the presser ring 53, the presser ring 53 is prevented from inclining or distorting with the wafer supporting member 31 expanded, and, in this point, the apparatus is different from a structure wherein the force is exerted on some specified spots of the presser ring 53 for pressing down the presser ring 53. COPYRIGHT: (C)2004,JPO&NCIPI |
