High-throughput computational screening of Ti-based binary alloys as diffusion barrier layers for copper interconnects

This study utilized first-principles high-throughput computations to scrutinize the viability of Ti-W and Ti-Ru binary alloys as diffusion barrier layers for copper interconnects. By computing the formation energy, as well as constructing a convex hull phase diagram, we discerned the stability ranges for these alloys: specifically for Ti1-xWx at 0.45 < x < 0.82, and for Ti1-xRux at 0.12 < x < 0.31 and 0.87 < x < 1. It became evident that regions rich in Ti and Ru needed exclusion due to their inherent instability and diminished mechanical properties. Detailed analyses regarding structural stability, electronic structure, and mechanical properties helped confirm that Ti1-xWx at 0.45 < x < 0.82 and Ti1-xRux at 0.12 < x < 0.31 alloys offer optimal choices for efficient diffusion barriers. Moreover, the materials' mixing energy and formation energy were substantively less than 0 kJ/mol, with the alloys' convex hull energy poised within the range of 0-4 kJ/mol, thus explaining the observed superior stability of the solid solubility. Advanced screening also shed light on the previously well-studied Ti-W alloy, with Ti content between 70 % and 90 %. Interestingly, TiRu in the Ti-Ru alloys emerged as a potential area warranting further exploration. The Ti0.25W0.75 solid solution and TiRu intermetallic compound, among other alternatives probed, boasted integrative properties and thus appear as the most promising materials for diffusion barrier layers. This study delivers meaningful insights for the design and execution of high-performance diffusion barrier materials.

Automated summary

This study used first-principles high-throughput computations to investigate the feasibility of Ti-W and Ti-Ru binary alloys as diffusion barrier layers for copper interconnects. The stability ranges and optimal choices of these alloys were determined by calculating the formation energy, constructing a convex hull phase diagram, and analyzing structural stability, electronic structure, and mechanical properties. The study also explored TiRu in Ti-Ru alloys as a potential area for further exploration. Ti0.25W0.75 solid solution and TiRu intermetallic compound were identified as the most promising materials for diffusion barrier layers. This research provides meaningful insights for the design and implementation of high-performance diffusion barrier materials.