Multiple targets on substrate layers for layer alignment
Embodiments described herein may be related to apparatuses, processes, and techniques related to using full stack overlay cell (FSOL) targets within lithography masks and on fabricated layers of a substrate in order to align or to assess the alignment of fabricated layers of the substrate during the substrate manufacturing process. Other embodiments may be described and/or claimed.
1 . A substrate comprising:
a plurality of layers;
a plurality of targets on each of the plurality of layers; wherein individual ones of the plurality of the targets on a first layer of the plurality of the layers overlap, respectively, with a corresponding one of the plurality of the targets on a second layer of the plurality of layers in a top-down view;
wherein the plurality of targets on the first layer include a first pattern with a metal feature having a longest dimension along a first direction;
wherein the plurality of targets on the second layer include a second pattern with a metal feature overlapping the metal feature of the first pattern in the top-down view, the metal feature of the second pattern having a longest dimension along a second direction, the second direction orthogonal to the first direction in the top-down view; and
wherein the first pattern is different than the second pattern.
2 . The substrate of claim 1 , wherein the metal feature of the first pattern is symmetric around an axis.
3 . The substrate of claim 2 , wherein the axis is a first axis; and wherein a second metal feature of the first pattern is symmetric around a second axis that is orthogonal to the first axis.
4 . The substrate of claim 1 , wherein a comparison of the plurality of targets on the first layer with the plurality of targets on the second layer determines a degree of alignment between the first layer and the second layer.
5 . The substrate of claim 1 , wherein the metal features of the first pattern and the second pattern are not electrically coupled with other metal features in the substrate.
6 . The substrate of claim 1 , wherein the plurality of targets on the first layer and the plurality of targets on the second layer are arranged in a grid.
7 . The substrate of claim 6 , wherein a horizontal distance or a vertical distance between a subset of the plurality of target regions in the first layer is less than 1 mm.
8 . The substrate of claim 1 , wherein a width of the target region or a height of the target region is 2 μm or less.