Method of processing a wafer by using and reusing photolithographic masks

摘要

A method of processing a wafer includes establishing a fine of symmetry defining left and right die areas on a front side of the wafer and left and right die areas on a back side. A first mask is used to form a first interconnection layer on the left and right die areas comprising a first portion on the left die area and second portion different than the first portion on the right die area. A second mask is used to form a second interconnection layer on the left and right die areas comprising a third portion on the left die area and fourth portion different than the third portion on the right die area. The first mask is reused to form a third interconnection layer on the left and right die areas on a back side, and the second mask to form a fourth interconnection layer on the left and right die areas on a back side.