Abstract: In order to reduce the scanning transitional time (including scanning time and stepping time) between continuous exposure scans of step-scan lithography tool in a production process, the exposure scan motion of the wafer stage in the scanning direction is divided into two parts：the logical step and the logical scan. The time-overlay algorithms are introduced in trajectories scheming for wafer stage to process the continuous exposure production. According to the algorithms the switching points of the logical scan and the logical step trajectories of continuous scan motions are recalculated under different scanning paths of exposure fields, which will not violate the motion limitations (the requirement of constant velocity during exposure scan and the limitations of acceleration and velocity in logical scan and logical step motions). The theoretical analysis and actual wafer exposure examples calculation show that the time-optimal trajectories of wafer stage for continuous exposure scans are obtained by the time-overlay algorithms. And the inefficiency time between exposures scans schemed by the proposed algorithms is less than that of the conventional exposure scan methods. Consequently the productivity of the wafer production of step-scan lithography tool is improved. It is also fully expected that these research tasks will provide a valuable theoretical foundation for improving the throughput of wafer exposure of step-scan lithography tool in the practical engineering.

Key words: Continuous exposure scans, Polynomial motion trajectories, Step-scan lithography tool, Time-overlap scheme, Wafer stage