An electrostatic chuck has an electrode capable of being electrically charged to electrostatically hold a substrate. A composite layer covers the electrode. The composite layer comprises (1) a first dielectric material covering a central portion of the electrode, and (2) a second dielectric material covering a peripheral portion of the electrode, the second dielectric material having a different composition than the composition of the first dielectric material. The chuck is useful in a plasma process chamber to process substrates, such as semiconductor wafers.