To allow reuse of photomasks in the vertical structure, hiding alignment marks and repeated overlay marks is repeated

摘要

It is possible In the preparation of a monolithic three dimensional memory array, using multiple photomasks. The reuse of the photo mask, a second, reference mark following examples or third is formed. Stepper measuring alignment achieved directly above the previous examples with the same reference marks and to achieve (alignment marks) aligned with the reference mark these examples (registration marks). Sometimes preceding examples of the same fiducials, cause interference with the current example of a reference mark, there is a case where alignment and measurement is complicated, but using the method of the present invention, the light shielding structure on the same basis interposed vertically between the subsequent example of the mark, the interference is prevented.