Electrostatic chucks (ESCs) for reactor or plasma processing chambers, and methods of fabricating ESCs, are described. In an example, a substrate support assembly includes a ceramic bottom plate having heater elements therein, the ceramic bottom plate composed of alumina having a first purity. The substrate support assembly also includes a ceramic top plate having an electrode therein, the ceramic top plate composed of alumina having a second purity higher than the first purity. A bond layer is between the ceramic top plate and the ceramic bottom plate. The ceramic top plate is in direct contact with the bond layer, and the bond layer is in direct contact with the ceramic bottom plate.