Patent ID: 8199454

Claim:
An electrostatic chuck comprising: a base body, and an electrostatic electrode embedded in the base body, wherein an adsorption object is placed on the base body, a coulombic force is generated between the adsorption object and the electrostatic electrode by applying a voltage to the electrostatic electrode so as to hold the adsorption object in an adsorption state, the base body includes: an upper surface of the base body opposed to the adsorption object, and a plurality of protrusions extending from the upper surface of the base body at a protrusion portion of the upper surface of the base body, the plurality of protrusions adapted to come into contact with the adsorption object, said plurality of protrusions including a plurality of outermost protrusions disposed along a periphery of the protrusion portion of the upper surface of the base body, each of the plurality of outermost protrusions being spaced from one another, wherein the upper surface of the base body also includes a protrusion-free outer edge portion entirely formed in substantially a same plane as the upper surface of the base body at the protrusion portion, the protrusion-free outer edge portion bounded at an outer end by an outermost edge of the upper surface of the base body, and at an inner end by an outermost point of each of the plurality of outermost protrusions, the protrusion-free outer edge portion surrounding the protrusion portion of the upper surface of the base body and the plurality of protrusions, wherein said protrusion-free outer edge portion is configured such that, upon generation of the coulombic force between the adsorption object and the electrostatic electrode, a peripheral portion of the adsorption object bends toward a perimeter of the protrusion-free outer edge portion and an outer edge portion of a lower surface of the adsorption object contacts the protrusion-free outer edge portion so as to define a substantially enclosed space between the base body and the adsorption object.