A method of fabrication of alignment marks for a non-STI CMOS image sensor is introduced. In some embodiments, zero layer alignment marks and active are alignment marks may be simultaneously formed on a wafer. A substrate of the wafer may be patterned to form one or more recesses in the substrate. The recesses may be filled with a dielectric material using, for example, a field oxidation method and/or suitable deposition methods. Structures formed by the above process may correspond to elements of the zero layer alignment marks and/or to elements the active area alignment marks.