ELECTROSTATIC CHUCK IN WHICH CORROSIVENESS IS IMPROVED

PROBLEM TO BE SOLVED: To suppress the corrosion of an insulator for supporting an electrode and a substrate having an elevated central part covering the electrode and a lower peripheral part extending over the electrode by forming a step part between the central part and the peripheral part. SOLUTION: An insulator 22 has a central part 25 covering an electrode 24 and supporting a substrate 42, and a peripheral part 26 spreading over the electrode 24. The central part 25 is elevated as compared with the peripheral part 26, thus forming a step part 27. The step part 27 has height of about 10 μm or less, preferably of about 5 μm. This structure suppresses corrosion at the exposed peripheral part of the insulator 22.