ASML Stepper 3 - Substrates smaller than 100mm/4-inch

Work In Progress This article is still under construction. It may contain factual errors. Content is subject to change.

Multi-Layer - Alignment to previous layers

Alignment Mark Locations

The optical prealigner requires prealignment marks to be ≥ 32.5mm radius from the wafer center.

This allows wafers of 3-inch (75mm) and greater to have the marks located directly on the mounted substrate, greatly simplifying re/mounting.

For smaller substrates (eg. 2-inch/50mm) the PreAlignment marks must be located separately on the 4-inch carrier, while the global alignment marks must be located on the mounted substrate. The complication is whether the relative position of the Carrier and Mounted parts' alignment marks change between lithographies.