Pore-sealing by etch-byproduct followed by ALD-Ta adhesion layer for Cu/porous low-k interconnects

Abstract

Increase of process steps by pore-sealing and low via yield by low adhesion between Cu and barrier metal are cost issues when atomic layer deposited (ALD) barrier metal process is integrated into Cu/porous low-k interconnects. In order to solve these issues, etch-byproduct in-situ deposited on the sidewall and ALD-Ta is proposed. The etch-byproduct successfully prevented Ta penetration into the porous low-k film without increase process steps. ALD-Ta film of 0.8 nm, deposited by exposures of pentakisdimethylaminotantalium (PDMAT) and He/H/sub 2/ plasma to the substrate in turn, demonstrated strong adhesion layer as same as the conventional PVD barrier. Via yield of single-damascene Cu/porous low-k interconnects with the etch-byproduct was improved by substituting ALD-Ta for ALD-TaN.