Methods for electrostatically chucking an object to an electrostatic chuck that reduce uncorrectable placement error of the object

摘要

Methods are disclosed for electrostatically chucking an object (e.g., reticle or lithographic substrate used in charged-particle-beam microlithography) to an electrostatic chuck, in a manner resulting in reduction of uncorrectable placement errors that otherwise arise at time of chucking. The electrostatic chuck has multiple electrodes. After energizing the electrodes with respective voltages to cause the object to adhere electrostatically with a chucking force to the mounting surface, a voltage applied to at least one selected electrode is changed momentarily so as to reduce the chucking force momentarily in a corresponding region of the reticle sufficiently to reduce chucking stress in the object. Stress reduction typically is achieved by allowing the object to experience side-slip relative to the chuck. After a prescribed time period of stress reduction, the electrodes are energized sufficiently to hold the object to the chuck with a full chucking force. This sequence can be repeated multiple times as required to achieve a desired reduction of chucking stress in the object.