Embodiments include an electrostatic chuck assembly having an electrostatic chuck mounted on an insulator. The electrostatic chuck and insulator may be within a chamber volume of a process chamber. In an embodiment, a ground shield surrounds the electrostatic chuck and the insulator, and a gap between the ground shield and the electrostatic chuck provides an environment at risk for electric field emission. A dielectric filler can be placed within the gap to reduce a likelihood of electric field emission. The dielectric filler can have a flexible outer surface that covers or attaches to the electrostatic chuck, or an interface between the electrostatic chuck and the insulator Other embodiments are also described and claimed.