Copper diffusion in Ti–Si–N layers formed by inductively coupled plasma implantation

• Published in: Applied surface science Vol. 253; no. 2; pp. 530 - 534
• Main Authors: Ee, Y.C., Chen, Z., Law, S.B., Xu, S., Yakovlev, N.L., Lai, M.Y.
• Format: Journal Article
• Language: English
• Published: 15.11.2006
• ISSN: 0169-4332
• DOI: 10.1016/j.apsusc.2005.12.152

Ternary Ti-Si-N refractory barrier films of 15 nm thick was prepared by low frequency, high density, inductively coupled plasma implantation of N into TixSiy substrate. This leads to the formation of Ti-N and Si-N compounds in the ternary film. Diffusion of copper in the barrier layer after annealing treatment at various temperatures was investigated using time-of-flight secondary ion mass spectrometer (ToF-SIMS) depth profiling, X-ray diffractometer (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and sheet resistance measurement. The current study found that barrier failure did not occur until 650 deg C annealing for 30 min. The failure occurs by the diffusion of copper into the Ti-Si-N film to form Cu-Ti and Cu-N compounds. FESEM surface morphology and EDX show that copper compounds were formed on the ridge areas of the Ti-Si-N film. The sheet resistance verifies the diffusion of Cu into the Ti-Si-N film; there is a sudden drop in the resistance with Cu compound formation. This finding provides a simple and effective method of monitoring Cu diffusion in TiN-based diffusion barriers.