| 摘要 |
<p>A step-and-repeat exposure system incorporates a method for achieving die-by-die alignment at high speed in order to increase the throughput of the system. In order to align circuit patterns which are to be exposed onto a semiconductor wafer (10) in an overlapping fashion, the wafer (10) is initiallly moved to a target position in order to view an alignment target (24) previously formed on the wafer (10), and is subsequently moved to an exposure position. The movement to the exposure position is controlled as a function of the calculated position of the alignment target (24). The method involves initiating the video scan to view the alignment target (24) prior to the stage (12) coming to a complete rest at the target position. The characteristics of the stage (12) motion are determined and the acquisition of the video data is initiated as soon as the oscillation of the stage (12) has subsided by an acceptable amount. By initiating the video scan at an early point, a significant decrease in the alignment time at each die site is achieved. </p> |
