TREATMENT DEVICE

PROBLEM TO BE SOLVED: To provide a treatment device with an electrostatic chuck where deposit hardly projects on the upside of a suction surface. SOLUTION: An electrostatic chuck 112 for sucking and retaining a wafer W is provided on a lower electrode 110 which is arranged in the treatment room of an etching device. There electrostatic chuck 112 is constituted by placing a conductive thin film 130 connected to a high-voltage DC power supply between insulating members 132 which consist of ceramics. An almost recessed shape stage part 134 is formed downward by a height (α) of 30 μm-50 μm at the peripheral part of a chuck surface 112a of the electrostatic chuck 112. A width (β) of the stage part 134 is set to 2 mm or less. The radius of the electrostatic chuck 112 is constituted, being set within a range that is smaller than that for the wafer W by 2 mm or less. An angled part which is formed at the peripheral part of a bottom surface of the stage part 134 is subjected to beveling for the action of a slanting surface 134c.