Microstructure Evolution and Dielectric Properties of Plasma Sprayed BaTiO3 Coatings

BaTiO3 coatings are very promising for a wide range application in microelectronics because of their high dielectric constant and low leakage current. In this study, atmospheric plasma spraying has been employed to produce a thick BaTiO3 coating, and microstructural features and dielectric properties of BaTiO3 coatings have been investigated.  As-sprayed BaTiO3 coating was mainly composed of amorphous phase from splat quenching of fully molten droplets.  Small amounts of crystalline phase also remained due to incorporation of partially-molten droplets.  The as-spayed amorphous coating was crystallized to BaTiO3 at low temperatures and a mixture of BaTiO3 and BaTi2O5 at high temperatures.  At 1200^oC, the coating was formed an equiaxed grain structure due to sintering effects.  Dielectric constant of BaTiO3 coatings was rapidly increased from 85 for as-sprayed to 270 for heat-treated at 1200^oC.  The plasma-sprayed BaTiO3 coatings were discussed for the application of electrostatic chuck.