US Patent 7907383 Electrostatic chuck

The present invention provides 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 and easy to manufacture by low-temperature firing. The electrostatic chuck includes a dielectric material in which alumina is 99.4 wt % or more, and titanium oxide is more than 0.2 wt % and equal to or less than 0.6 wt %, wherein the electrostatic chuck's volume resistivity is 108-1011 Ωcm in room temperature, and wherein the titanium oxide segregates in boundaries of particles of the alumina.