Exemplary semiconductor processing chambers may include a chamber body. The chambers may include a showerhead. The chambers may include a substrate support. The substrate support may include a platen characterized by a first surface facing the showerhead. The substrate support may include a shaft coupled with the platen along a second surface of the platen opposite the first surface of the platen. The shaft may extend at least partially through the chamber body. A coating may extend conformally about the first surface of the platen, the second surface of the platen, and about the shaft.