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In the first litography+etching step I guess aligning the wafer perfectly isn’t as important. In subsequent litography steps, how do they align the wafer with nanometer precision?
There are tricks like using wafer alignment marks and some algorithms for doing this. Here's one reference that discusses: https://sites.engineering.ucsb.edu/~sumita/courses/Courses/ME141B/Alignment.pdf
In the first litography+etching step I guess aligning the wafer perfectly isn’t as important. In subsequent litography steps, how do they align the wafer with nanometer precision?
There are tricks like using wafer alignment marks and some algorithms for doing this. Here's one reference that discusses: https://sites.engineering.ucsb.edu/~sumita/courses/Courses/ME141B/Alignment.pdf