Intra-level voltage ramping-up to dielectric breakdown failure on Cu/porous low-k interconnections in 45 nm ULSI generation

The degradation of reliability for intra-level voltage-breakdown in the 45 nm generation node has become an increasingly important issue with the introduction of porous low-k dielectrics. The dominant failure mechanism for lower voltage ramping-up to dielectric breakdown and higher leakage current was that more electrons easily transported through the percolation path in intra-level porous low-k interconnections damaged from HF corrosion. An optimal ultraviolet curing process and a less NH₃ plasma pre-treatment on porous low-k dielectrics before the SiCN capping layer are developed to improve performance in both of these cases. The stiff configuration of the reconstruction of Si-O network structures and less HF corrosion is expected to have high tolerance to electrical failure. As a result, the proposed model of this failure facilitates the understanding of the reliability issue for Cu/porous low-k interconnections in back-end of line (BEOL) beyond 45 nm nodes.