Patent ID: 7811924

Claim:
A method for patterning a film, comprising: forming an amorphous carbon mask over a substrate, wherein the substrate comprises a damascene layer including alternating inter-metal dielectric (IMD) and metal interconnect and a cap layer over the damascene layer; depositing a spacer layer over the amorphous carbon mask; etching the spacer layer to form a spacer and to expose the amorphous carbon mask; removing the amorphous carbon mask selectively to the spacer to expose the substrate layer; depositing a gap fill layer around the spacer to cover the substrate layer but expose the spacer; removing the spacer to form a gap fill mask over the substrate; and transferring the pattern of the gap fill mask into the substrate, wherein transferring further comprises: patterning the cap layer by etching a portion of the cap layer unprotected by the gap fill mask; and etching at least a portion of the IMD from the damascene layer.