Precise positioning system for dual stage switching exposure

A precise positioning system for dual stage switching exposure, comprising:

• a base;
• two wafer stage positioning units disposed on the base, and each including a first X-direction guide bar and a second X-direction guide bar that are individually movable along a Y direction perpendicular to the X direction, the first and second X-direction guide bars of one wafer stage positioning unit being respectively alignable with the first and second X-direction guide bars of the other wafer stage positioning unit;
• a first wafer stage placed on the first X-direction guide bar of one wafer stage positioning unit, and, when the first X-direction guide bars of the two wafer stage positioning units are aligned, being movable to the other wafer stage positioning unit along the aligned first X-direction guide bars;
• and
• a second wafer stage placed on the second X-direction guide bar of the other wafer stage positioning unit, and, when the second X-direction guide bars of the two wafer stage positioning units are aligned, being movable to the one wafer stage positioning unit along the aligned second X-direction guide bars.