Patent ID: 6858377

Claim:
A dual damascene process using a single photo mask, comprising the steps of: (a) providing a substrate; (b) forming a dielectric layer on the substrate; (c) forming a mask layer on the dielectric layer; (d) forming a photoresist layer on the mask layer; (e) executing photolithography with a photo mask to define a photoresist pattern having a first dual layer opening comprising a first opening and a second opening which expose the surface of the mask layer; (f) removing the mask layer not covered by the photoresist pattern to form a mask pattern having a second dual layer opening comprising a third opening and a fourth opening which expose the surface of the dielectric layer; (g) removing the surface of the dielectric layer exposed in the fourth opening not covered by the mask pattern to form a contact window in the dielectric layer which exposing the surface of the substrate; (h) removing part of the mask pattern to form a residue mask pattern exposing part of the dielectric layer; (i) removing part of the dielectric layer not covered by the residue mask pattern to form a trench which constitutes a dual opening together with the contact window; (j) removing the mask layer; and (k) forming a conductive layer in the opening.