Etch-Byproduct Pore Sealing for Atomic-Layer-Deposited-TaN Deposition on Porous Low-k Film

摘要

Porous low-k and ultrathin atomic-layer-deposited (ALD)-TaN are expected to be useful materials for Cu interconnects in ULSI devices of the 45-nm technology node and beyond. One problem with integrating these into the Cu interconnect is the Ta penetration which occurs during ALD-TaN deposition. In this work, we propose a novel pore-sealing technique using an etch-byproduct that is deposited on a sidewall of the pattern during reactive-ion-etching of the stopper under the porous low-k. It was found that the Ta penetration is completely prevented by the etch-byproduct if the cap insulator for the porous low-k is a SiC/SiO_2 multilayer. Two levels of single-damascene Cu interconnects with ALD-TaN and porous low-k were successfully fabricated without the penetration, and good electrical characteristics were obtained for the interconnects.