US Patent 7248457 Electrostatic chuck

The object of the present invention is to provide an electrostatic chuck in which the surface can be kept smooth after being exposed to plasma, so as to protect a material to be clamped such as a silicon wafer from being contaminated with particles, and which is excellent in clamping and releasing a material to be clamped. According to the present invention, there is provided an electrostatic chuck comprising a dielectric material in which alumina is 99.4 wt % or more, titanium oxide is more than 0.2 wt % and equal to or less than 0.6 wt %, whose average particle diameter is 2 μm or less, and whose volume resistivity is 108-1011 Ωcm in room temperature, wherein the electrostatic chuck is used in a low temperature of 100° C. or less.