A puncture resistant electrostatic chuck (20) is described. The chuck (20) comprises at least one electrode (25); and a composite insulator (30) covering the electrode. The composite insulator comprises a matrix material having a conformal holding surface (50) capable of conforming to the substrate (35) under application of an electrostatic force generated by the electrode to reduce leakage of heat transfer fluid held between the substrate and the holding surface. A hard puncture resistant layer, such a layer of fibers or an aromatic polyamide layer, is positioned below the holding surface (50) and is sufficiently hard to increase the puncture resistance of the composite insulator.