CPC G03F 7/70725 (2013.01) | 10 Claims |
1. A vertical motion protection method based on a dual-stage motion system of a photolithography machine, wherein the dual-stage motion system comprises a macro-motion stage and a micro-motion stage located above the macro-motion stage, the macro-motion stage and the micro-motion stage have flat square shapes, and the vertical motion protection method comprises:
establishing a space rectangular coordinate system O-XYZ by taking a point on an upper surface of the micro-motion stage at an initial position as an original point O, wherein an X-axis and a Y-axis are in horizontal directions, and a Z-axis is upward in a vertical direction, the micro-motion stage has three degrees of freedom in directions of the X-axis, the Y-axis and the Z-axis, wherein vertical displacement sensors are respectively disposed at four corners of a lower surface of the macro-motion stage, and the vertical displacement sensors are configured to measure vertical distances between a lower surface of the micro-motion stage and the macro-motion stage respectively, wherein a horizontal displacement measuring device is further provided for measuring displacements of the micro-motion stage in the directions of the X-axis and the Y-axis;
obtaining coordinates of measured points respectively according to data of the vertical displacement sensor and the horizontal displacement measuring device;
obtaining a point normal form equation f(X, Y, Z)=0 of the lower surface of the micro-motion stage in the space rectangular coordinate system O-XYZ by using the coordinates of the measured points;
taking a nearest corner point of a measured point corresponding to a maximum value hmax among measured values of the measured points as a highest point on the lower surface of the micro-motion stage, and obtaining a Z-axis coordinate hb of the highest point on the lower surface of the micro-motion stage at the current time by using the point normal form equation f(X, Y, Z)=0; and
obtaining a Z-axis coordinate hu of a highest point on the upper surface of the micro-motion stage according to the Z-axis coordinate hb of the highest point on the lower surface of the micro-motion stage, and comparing the hu with a height threshold, if the hu exceeds the height threshold, shutting down for protection, if the hu does not exceed the height threshold, continuing to operate the dual-stage motion system.
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