REGISTRATION MARK WITHIN AN OVERLAP OF DOPANT REGIONS

摘要

A registration mark, in integrated circuit technology, is formed by a first etching of a first mask layer (205) on top of an ONO stack (120, 125, 130) . After a first region (210) is doped, a second etching occurs at first etching sites (305) in the uppermost oxide layer (130) of the ONO stack forming a first alignment artifact (510b) . A second mask layer (405) is applied after removing the first mask layer. A second doping (515) occurs at second mask layer etching sites (510a) to maintain clearance between the two doped regions (210, 515) within active areas and provide an overlap (520) of the two doped regions in a frame area. At the overlap of the two wells, further etchings remove remaining layers of the ONO stack and remove silicon (605) from the upper most layer of the semiconductor forming a second registration mark (710) , which may be covered by a protective layer (720) .