An overlay vernier pattern for measuring multi-layer overlay alignment
accuracy and a method for measuring the same is provided. A distance
between a first alignment mark in a first material layer and a second
alignment mark in an underlying second material layer is measured, so as
to provide an alignment offset between the first material layer and the
second material layer. In addition, a distance between the second
alignment mark in the second material layer and a third alignment mark in
a third material layer underlying the second material layer is measured,
so as to provide an alignment offset between the second material layer
and the third material layer. Because the second alignment marks can be
repeatedly used, scribe line areas for forming these alignment marks and
measuring time are saved to increase the production throughput.