Chamber apparatus for chemical etching of dielectric materials

Implementations of the disclosure generally provide an improved pedestal heater for a processing chamber. The pedestal heater includes a temperature-controlled plate having a first surface and a second surface opposing the first surface. The temperature-controlled plate includes an inner zone comprising a first set of heating elements, an outer zone comprising a second set of heating elements, the outer zone surrounding the inner zone, and a continuous thermal choke disposed between the inner zone and the outer zone, and a substrate receiving plate having a first surface and a second surface opposing the first surface, the second surface of the substrate receiving plate is coupled to the first surface of the temperature-controlled plate. The continuous thermal choke enables a very small temperature gradient to be created and manipulated between the inner zone and the outer zone, allowing center-fast or edge-fast etching profile to achieve on a surface of the substrate.