Photomask structures providing improved photolithographic process windows and methods of manufacturing same

摘要

Photolithographic methods for semiconductor manufacturing are provided wherein photomask structures are designed to provide increased lithographic process windows for printing sub-wavelength features. In one aspect, a photomask includes a mask substrate transparent to exposure light of a given wavelength, and a mask pattern formed on a surface of the substrate. The mask pattern comprises a printable element defined by a first and second critical edge, wherein the printable element includes an inner, non-printing feature formed between the first and second critical edges. The inner, non-printing feature is adapted to enhance image contrast at the first and second critical edges of the printable element for the given wavelength of exposure light during a photolithographic process. The non-printing feature comprises a space feature that exposes a region of the mask substrate aligned to the printable element between the first and second critical edges, and a trench feature that is formed in the mask substrate and aligned to the space feature.