Chiaki Nakayama

Electrostatic Force and Absorption Current of Alumina Electrostatic Chuck

Electrostatic chucks composed of alumina ceramics doped with 1.3 wt% TiO2 and 3.5 wt% Cr2O3 were fabricated. Evaluations of electrostatic force and absorption charge in various atmospheres were carried out. The electrostatic force in various atmospheres clarified that the electrostatic force is affected not only by the bulk resistance, but also by the surface resistance of the ceramics. Absorption charge measurements revealed that the surface resistance affects the charge distribution of the dielectric layer, and it is deduced that the large electrostatic force of the alumina electrostatic chuck in the vacuum atmosphere is explained by the space charge which concentrates on the dielectric layer and intensity contact potential difference.

Relationship between Electrical Resistivity and Electrostatic Force of Alumina Electrostatic Chuck

Alumina electrostatic chucks having various electrical resistivities were fabricated by changing the amount of TiO2 and heat treatment conditions. Experimental data on electrostatic force and its response time were obtained for the fabricated electrostatic chucks. The experimental results are compared with the theoretically predicted results utilizing the equivalent circuit model, and the relationship between electrical resistivity and electrostatic force characteristics is discussed.

H2S-sensitive thin film fabricated from hydrothermally synthesized SnO2 sol

A porous thin film of SnO2 prepared on an alumina substrate by using hydrothermally synthesized SnO2 sol shows excellent sensitivity to dilute H2S in air together with good response transient characteristics when calcined at 700 °C. The pore size of the film increases uniformly with calcination temperature, and this well developed porous structure appears to be responsible for the excellent H2S sensing characteristics.

Ozone Generation of Bipolar-Type Ceramic Ozonizer Module with Semiconductor Ceramic Discharge Electrode

A bipolar type ozonizer of small size and long life is developed for use in the living environment. The ozonizer is composed of an alumina substrate with tungsten inner electrodes, and a discharge electrode made of TiO2- or Cr2O3-added alumina ceramics. Effects of resistivity of the ceramic discharge electrode on ozone generation and discharge voltage are evaluated. Based on the differences in the dependency of the resistivity on discharge ignition voltage between monopolar-type and bipolar-type ozonizers, advantages of bipolar ozonizers over monopolar type in practical applications are discussed.