Patent ID: 7348280

Claim:
A method for fabricating a back-end-of-line (BEOL) interconnect structure comprising the steps of: providing a first inter-level dielectric (ILD) layer; said first ILD layer underlying a dielectric hard mask (HM) layer, and an interconnect conductor extending through said dielectric hard mask (HM) layer into said first ILD layer; providing selective cap formation to create a metallic cap surface on said interconnect conductor and a dielectric HM surface; depositing a two-phase photoresist material over said dielectric HM surface and said metallic cap surface; wherein a phase separation of said two-phase photoresist material is formed by an interaction of said two-phase photoresist and said dielectric hard mask (HM) layer and said two-phase photoresist and said metallic cap layer; depositing a two-phase separated photoresist material pattern to the first ILD layer to create a columnar air gap structure; and depositing an insulator material for forming a second ILD layer.