Methods and systems for forming an alignment mark with optically mismatched alignment mark stack materials
View Patent ↗Methods for fabricating an alignment mark are disclosed. A method includes forming a base layer that includes a first material and forming an alignment mark layer above the base layer that includes a second material that is optically mismatched with the first material. The alignment mark is formed using both first and second layers.
1. An alignment mark, comprising:
a base layer comprising a first material;
an alignment mark layer above said base layer and comprising a second material that is optically mismatched with said first material; and
a variable thickness optically transparent Al 2 O 3 spacer between said first material and said second material.
2. The alignment mark of claim 1 wherein said first material is selected from the group consisting of NiFe, Ta, Cu, Rh, CoFe, W and Au and said second material is selected from the group consisting of NiFe, Ta, Cu, Rh, Ir, Ru, CoFe and W.