A target system for determining positioning error between lithographically
produced integrated circuit fields on at least one lithographic level.
The target system includes a first target pattern on a lithographic field
containing an integrated circuit pattern, with the first target pattern
comprising a plurality of sub-patterns symmetric about a first target
pattern center and at a same first distance from the first target pattern
center. The target system also includes a second target pattern on a
different lithographic field, with the second target pattern comprising a
plurality of sub-patterns symmetric about a second target pattern center
and at a same second distance from the second target pattern center. The
second target pattern center is intended to be at the same location as
the first target pattern center. The centers of the first and second
target patterns may be determined and compared to determine positioning
error between the lithographic fields.