Why split field microscopy is used in mask aligner?

I. As dimension of the alignment marks on wafer as well as masks are in micron range, microscopes are required to observe those while aligning
II. Split-field microscopy enables the user to view the output from both the microscopes at time that helps to align faster
III. Split field microscopy gives better depth of focus
IV. Split field microscopy system is easier to install and does not require any optimization
I, II, III, IV
I, II, III
I, II
I, II, IV

2 answers

I, II, III

1,2,3