Effect of TiO2 addition on the microstructure and electrical properties of Al2O3 ceramics

摘要

The resistivity of the dielectric layer material of a Johnsen-Rahbek (J-R) electrostatic chuck is generally between E8 and E12 omega & sdot;cm, while that of pure alumina ceramic is more than E15 omega & sdot;cm. Therefore, it is necessary to regulate the resistivity of the alumina ceramic for use as a dielectric layer material for a J-R-type electrostatic chuck. An electrostatic chuck requires a uniform and controllable surface temperature on the silicon wafer. Therefore, there is a certain requirement for the thermal conductivity of the dielectric layer.In this experiment, Al2O3 ceramics with different TiO2 contents (ranging from 0.08 to 3.6 wt%) were used as the research system and sintered at 1550 degrees C in a reducing sintering atmosphere. The obtained samples showed electrical resistivity from E9 to E14 omega & sdot;cm and thermal conductivity from 26 to 37 W/m & sdot;K. The effects of Al2O3 ceramics with TiO2 on the phase composition, microstructure, relative density, electrical conductivity, and thermal conductivity were systematically studied, along with the relationship between the temperature and electrostatic adsorption force J-R and the resistivity of the sample. The addition of 1.2 wt% TiO2 gave the Al2O3 sample better overall performance; its relative density was up to 97.88 %, resistivity was reduced to 7.09 x 109 omega cm, thermal conductivity was 27.211 W/m & sdot;K, and the electrostatic adsorption forces at 300 and 500 V/mm were up to 119 and 331 gf/cm2, respectively. The samples were primarily used as dielectric layers of the elec-trostatic chuck. By simulating the electrostatic adsorption between the dielectric layer and silicon wafer under an external voltage, the J-R force of stable adsorption between the electrostatic chuck and the silicon wafer was realised.

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