Plasma Sprayed Coatings of High Purity Ceramics for Semiconductor and Flat-Panel Display Production Equipment

High purity oxide ceramic powders of alumina (Al₂O₃) and yttria (Y₂O₃) for plasma spraying have been developed to apply to semiconductor and flat-panel-display (FPD) production equipments. The ceramic coatings onto inside chamber wall of the equipments are required to have highly erosion resistance against CF containing plasma, widely used in dry etching process for micro-fabrications of the devices. Yttria is increasingly used in this application due to the high resistance compared to alumina. It is found that the yttria coating formed from agglomerated-and- sintered powder consisting of large primary particle has smoother eroded surface. Considering that particle deposition onto the devices, this coating will be effective to decrease generation of large sized particle, which is easily deposit onto the devices. Electric insulating properties of the coatings are also investigated to apply to electrostatic chuck. Electric breakdown voltage of yttria coatings is almost comparable to that of alumina coatings. However, yttria is difficult to apply due to its lower mechanical strength. Using smaller powder as feedstock is effective to improve the electric properties and influence of coating purity is lower than the powder size.