Effect of Different Ni Contents on Thermal Stability of Cu(Ni) Alloy Film

• Published in: Journal of electronic materials 2020-10, Vol.49 (10), p.5674-5680
• Main Authors: Li, Xu, Cheng, Bin, Asempah, Isaac, Shi, Quan, Long, An-Qiong, Zhu, Yi-Lin, Wang, Qi, Li, Yuan-Liang, Wang, Lei, Jin, Lei
• Format: Article
• Language: English
• Subjects: Annealing; Barrier layers; Characterization and Evaluation of Materials; Chemistry and Materials Science; Copper; Diffusion barriers; Doping; Electronics and Microelectronics; Grain refinement; Instrumentation; Intermetallic compounds; Magnetron sputtering; Materials Science; Nickel; Optical and Electronic Materials; Silicides; Silicon dioxide; Silicon substrates; Solid State Physics; Thermal stability
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-020-08340-2

The effect of doping different contents of Ni on the thermal stability of Cu(Ni) alloy films has been investigated. Cu(Ni) films with different Ni contents were deposited on SiO 2 /Si substrates by magnetron sputtering, then annealed in vacuum at 350°C to 650°C for 0.5 h. X-ray diffraction analysis and resistance measurements revealed that high-resistance copper silicide was formed after annealing at 450°C for the Cu(Ni, 1.66 at.%) and Cu(Ni, 9.16 at.%) samples. However, no copper silicide was observed for Cu(Ni, 3.59 at.%) even after annealing at 650°C. Transmission electron microscopy provided evidence for a ∼ 25-nm self-formed barrier layer at the Cu/SiO 2 interface with Cu(Ni, 3.59 at.%). The failure to form a diffusion barrier for the Cu(Ni, 1.66 at.%) sample resulted from its low Ni doping concentration, which was insufficient to produce such a self-formed layer during annealing. The barrier failure was caused by grain refinement due to the increased Ni content, providing diffusion channels for atom diffusion. The results clearly suggest that addition of an appropriate amount of Ni can improve the thermal stability of Cu(Ni)/SiO 2 /Si interconnect structure materials.