Co-W Barrier Layers for Metallization of Copper Interconnects: Thermal Performance Analysis
Abstract
:1. Introduction
2. Materials and Methods
2.1. PVD Film Deposition
2.2. Vacuum Annealing
2.3. Film Characterization
3. Results and Discussion
3.1. Scanning Electron Microscopy
3.2. X-ray Diffraction
3.3. Transmission Electron Microscopy
3.4. Electrical Characterization
4. Conclusions
- From a Cu surface stability perspective, the Co-W system performed worse than the Ta film, with dewetting of the Cu layer in the 300–450 °C range;
- The Ta film revealed superior Cu dewetting resistance, with no discernible agglomeration at the surface after annealing for the studied temperature ranges;
- The Cu/Co-W system exhibited diffusion resistance up to 700 °C, whereas the Cu/Ta system failed in the 600–650 °C range, with Ta diffusion through the Cu layer;
- Co-W displayed structural continuity and integrity throughout the temperature range used;
- The sheet resistance of the Cu/Co-W was minimized after annealing at 450 °C, at 7.07 × 10−6 Ω/sq;
- The Cu/Ta system showed a minimum sheet resistance value of 6.03 × 10−6 Ω/sq after annealing at 450 °C. However, the need for the inclusion of a high resistance diffusion barrier layer such as TaN suggests an overall inferior electrical performance of the Cu/Ta/TaN system in comparison to the Cu/Co-W system.
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
References
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Film | Mean Thickness (nm) | Std. Deviation |
---|---|---|
Co-W (as-deposited) | 26.9 | 1.8 |
Co-W (annealed 600 °C) | 24.0 | 2.4 |
Cu (Co-W, as-deposited) | 42.4 | 2.5 |
Cu (Co-W, 600 °C) | 35.7 | 5.1 |
Ta (as-deposited) | 23.0 | 1.2 |
Ta (annealed 600 °C) | 17.8 | 2.3 |
Cu (Ta, as-deposited) | 39.8 | 2.0 |
Cu (Ta, 600 °C) | 41.0 | 2.6 |
System | Electrical Resistivity (Ω∙cm) | |
---|---|---|
25 °C | 600 °C | |
Cu/Co-W | 1.09 × 10−5 | 5.01 × 10−6 |
Cu/Ta | 4.92 × 10−6 | 3.51 × 10−6 |
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Oliveira, B.M.C.; Santos, R.F.; Piedade, A.P.; Ferreira, P.J.; Vieira, M.F. Co-W Barrier Layers for Metallization of Copper Interconnects: Thermal Performance Analysis. Nanomaterials 2022, 12, 1752. https://doi.org/10.3390/nano12101752
Oliveira BMC, Santos RF, Piedade AP, Ferreira PJ, Vieira MF. Co-W Barrier Layers for Metallization of Copper Interconnects: Thermal Performance Analysis. Nanomaterials. 2022; 12(10):1752. https://doi.org/10.3390/nano12101752
Chicago/Turabian StyleOliveira, Bruno M. C., Ruben F. Santos, Ana P. Piedade, Paulo J. Ferreira, and Manuel F. Vieira. 2022. "Co-W Barrier Layers for Metallization of Copper Interconnects: Thermal Performance Analysis" Nanomaterials 12, no. 10: 1752. https://doi.org/10.3390/nano12101752