Self-Formed Ti-Rich Barrier Layers in Cu(Ti)∕Low-k Samples

Abstract

Thin Ti‐rich diffusion barrier layers were found to be formed at the interface between Cu(Ti) films and SiO2/Si substrates after annealing at elevated temperatures. This technique was called “self‐formation of the diffusion barrier,” which is attractive for fabrication of ultra‐large scale integrated (ULSI) interconnects. In the present study, we investigated the applicability of this technique to Cu(Ti) alloy films deposited on low dielectric constant (Low‐k) materials (SiOxCy). In addition, SiCO and SiCN were also used as dielectric layers, which are potential dielectric layers for future ULSI‐Si devices. The microstructures were analyzed by transmission electron microscopy (TEM), Rutherford backscattering spectrometry (RBS) and secondary ion mass spectrometry (SIMS), and correlated with the electrical properties of the Cu(Ti) films. The resistivity of the Cu(1 at.%Ti)/dielectric‐layer samples was reduced to about 2.5 μΩcm after annealing in Ar at 400° C for 2 h. It was concluded that the Ti‐rich interf...