Patent ID: 6746966
Filing Date: 2004-06-08
Classification: G03F,H01L

Abstract:
A method of unblinding an alignment mark, comprising the steps of:providing a substrate having a cell area and an alignment mark area; the substrate having an alignment mark within the alignment mark area: forming an STI trench into the substrate within the cell area; forming a silicon oxide layer over the substrate, filling the STI trench and the alignment mark; planarizing the silicon oxide layer to form a planarized STI within the STI trench and leaving silicon oxide within the alignment mark to form a blinded alignment mark; applying a wet chemical etchant within the alignment mark area over the blinded alignment mark to at least partially remove the silicon oxide within the alignment mark; and removing the remaining silicon oxide from within the blinded alignment mark to unblind the alignment mark; wherein the wet chemical etchant is applied to the blinded alignment mark in the form of a drop.