When a DC high voltage is applied to the internal electrodes of the electrostatic chuck (ESC) in the electrostatic Coulomb force model, polarized charges are generated on the dielectric surface. These charges create an electrostatic field, which in turn induces polarized charges on the surface of the wafer (in contact with the ESC) on the ESC. Within the range between the wafer surface and the effective electrode area of the ESC, charges of the opposite polarity accumulate. As a result, an attraction between opposite charges occurs, securely adhering the wafer to the ESC surface. The generation of polarized charges or free charges on the wafer surface depends on the conductivity of the wafer or coating. For instance, semiconductor wafers such as silicon wafers produce free charges, while insulating material wafers like sapphire wafers generate polarized charges.