Theoretical Evaluation of Reliability and Via Resistance of Liner-Less Co Interconnect Using Co-Ti Binary Alloy

초록

The structural and transport properties of CoTi binary alloys were investigated using density functional theory (DFT) calculations to evaluate the potential as a single-layer liner/barrier in liner-less Co interconnects. Cohesive energies of CoTi binary phases were calculated to identify thermodynamically stable compositions, with CoTi, Co2Ti, and Co3Ti exhibiting the lowest values. Interface binding energies were then evaluated for multiple Co/CoxTiy configurations and compared with conventional Cu/TaN interfaces. We identified several Co/CoxTiy interfaces with binding energies lower than similar to-5 J/m(2) such as fcc-Co(100)/CoTi(110), which exceeds that of the conventional Cu(111)/TaN(0001) interface. Finally, electron transport across the via stack was analyzed. Co/CoxTiy/Co via structures showed consistently higher specific conductance compared to Cu/TaN/Ta/Cu, with the highest value of 4.40 x 10(-4) S/nm(2) observed for fcc-Co(110)/Co2Ti(110)/ fcc-Co(110). These results support the use of CoTi alloys as reliable, high-performance alternatives to conventional liner/diffusion barrier stacks in future interconnect technologies.

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