Methods and systems for determining drift in a position of a light beam with respect to a chuck

摘要

Methods and systems for determining drift in a position of a light beam with respect to a chuck are provided. One method includes illuminating a surface with the light beam. The surface has a predetermined position with respect to the chuck during illumination. The method also includes generating signals responsive to the illumination of the surface and determining the drift in the position of the light beam with respect to the chuck using the signals. One system includes an illumination subsystem configured to illuminate a fiduciary with the light beam. The fiduciary has a predetermined position with respect to the chuck during illumination. This system also includes a detector configured to generate signals responsive to the illumination of the fiduciary and a processor configured to use the signals to determine the drift in the position of the light beam with respect to the chuck.