Exposing the pattern multiple times improves line-edge roughness , CD uniformity, resolution and results in a more uniform dose distribution. Shifting the fields and/or subfields between the exposures additionally reduces field / subfield stitching issues. In standard multi-pass (2, 4, or 9 passes) , the price to pay for the improved lithographic quality is exposure time and a more complex data preparation.
BEAMER makes multi-pass simple by automating the data preparation part (the user just needs to select the number of passes, and set the desired field shift / subfield shift). BEAMER then generates a single machine file for the overlaying field positions.
To further mitigate the throughput impact, it is possible to apply multi-pass to selected parts of the layout (layer specific multi-pass) or apply different number of passes to different doses (dose dependent multi-pass). This helps to maintain throughput and still get the advantage of multi-pass for critical features.