Patent ID: 7579137

Claim:
A method for fabricating a dual damascene structure, comprising: providing a photoresist stack comprising a first photoresist layer on top of a second photoresist layer formed on top of a semiconductor substrate, wherein said first photoresist layer is sensitive to a first wavelength of light and said second photoresist layer is sensitive to a second wavelength of light; exposing said photoresist stack to a first predetermined pattern of light comprising said first wavelength; exposing said photoresist stack to a second predetermined pattern of light comprising said second wavelength; developing said photo-resist layers to form a multi-tiered structure in the photo-resist layers, wherein said photo-resist layers are developed after exposing both the first and second photoresist layers; and transferring the multi-tiered structure into an interlayer dielectric layer of the semiconductor substrate, wherein said interlayer dielectric layer is under said second photoresist layer, wherein said first and second predetermined patterns of light form an image which comprises a line-space pattern and a via pattern.