Electron beam lithography tool image quality evaluating and correcting
including a test pattern with a repeated test pattern cell, an evaluation
method and correction program product are disclosed. The test pattern
cell includes a set of at least three elongated spaces with each
elongated space having a different width than other elongated spaces in
the set such that evaluation of a number of space widths in terms of tool
image quality and calibration can be completed. The evaluation method
implements the test pattern cell in a test pattern in at least thirteen
sub-field test positions across an exposure field, which provides
improved focus and astigmatism corrections for the lithography tool. The
program product implements the use of corrections from the at least
thirteen sub-field test positions to provide improved corrections for any
selected sub-field position.