Activation Energy of Electromigration (EM)
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Investigation of the activation energy (Ea) of electromigration (EM) is one of the effective ways to understand the EM diffusion mechanism [1] because each diffusion mechanism has its own value.

For instance, an activation energy (Ea) of ~ 0.9 eV is obtained for the Cu width range of 0.1–6 µm when the dielectric diffusion barrier is SiCxNy. [2] In this case, the interface between Cu and SiCxNy is the dominant diffusion path for the Cu damascene interconnects regardless of the Cu microstructure (either bamboolike or polycrystalline structures). Note that the Ea of grain-boundary diffusion of electroplated Cu is 1.08 eV. [1]

Table 2908. Activation energy of electromigration for various materials.

Activation energy (eV)
Migrating element
Material
Migration path
Reference
0.04   Cu(111) free surfaces    
0.28 - 0.40   Cu(100) free surface    
0.35   Cu(110) for (1-10) direction on a free surface    
0.5   Al-Si alloy    
0.5 - 0.7

Al Pure Al    
0.51 Al Fine-grained Al made by electron-beam evaporation    
0.54   Cu-TiW    
0.66   Cu/W    
0.68 ± 0.09   Electroplated 1.4 µm Au passivated with Si3N4   [11]
0.7   (5%Cu)Al-Si alloy    
0.7 - 0.8 (most); 0.8 - 2.0 (some) Cu Pure Cu    
0.7-0.9   Al-Cu alloy    
0.73 Al Large-grained Al made by electron-beam evaporation    
0.73 ± 0.1   Evaporated 0.26 µm Au   [10]
0.75   Cu    
0.75 ± 0.05   Sputtered 0.8 µm Au passivated with SiO2/Mo   [8]
0.8   Large-grained Al    
0.8 ± 0.2   Evaporated 0.05 µm Au   [7]
0.8 - 1.2   Capped Cu Cu/cap layer interface diffusion  
0.80 ± 0.05   Electroplated 1.0 µm Au passivated with Si3N4   [14]
0.83 - 1.05   Cu Wire/W stud    
0.84   Cu(110) for (001) direction on a free surface    
0.86   Cu (Small grain)    
0.87 Cu Cu/SnPb   [3]
0.8-0.9   Al-Si alloy    
0.8 - 1.0   Cu/SiNx cap/low-e dielectrics    
0.8 - 1.2   Cu/cap layer Cu/cap layer interface  
0.85 - 1.1   Cu capped with SiN    
0.88 ± 0.06   Electroplated 1.3 µm Au   [6]
0.9 Si Al-1%Si    
~0.9 Cu Cu/SiCxNy Cu/SiCxNy interface [2]
0.9-1.0   Al(Cu)    
0.98   Evaporated 0.17 µm Au   [9]
1.00 ± 0.06   Cu with Cl, S, or C impurity    
1.0   Electroplated 1.0 µm Au passivated with SiO2   [12]
1.06 Cu Cu/SnAg   [3]
1.1 Si accumulation mode TiSi2-Si contacts   [4]
1.1 - 1.3   Cu(Sn), Cu(Zr)    
1.2   Al covered with a deposited dielectric film    
1.25   Cu (Large grain)    
1.37   Cu-Zr    
1.4   Bulk Al crystal Lattice electromigration  
1.4   Cu capped with Ta/TaN SiNx Cu/TaN interface [14]
1.5 Si depletion mode

TiSi2-Si contacts

  [4]
2.0   Cu capped with CoWP    
2.1   Cu/Ta Cu/Ta interface [5]
2.3 Cu Bulk Cu crystal Lattice electromigration  
5   Pure W    

 

 

 

 

 

 

[1] D. Gan, P. S. Ho, R. Huang, J. Leu, J. Maiz, and T. Scherban, J. Appl. Phys. 97, 103531 (2005).
[2] T. Usui, H. Nasu, T. Watanabe, H. Shibata, T. Oki, and M. Hatano, Electromigration diffusion mechanism of electroplated copper and cold/hot two-step sputter-deposited aluminum-0.5-wt% copper damascene interconnects, Journal of Applied Physics 98, 063509 (2005).
[3] Hsiao-Yun Chen and Chih Chen, Measurement of electromigration activation energy in eutectic SnPb and SnAg flip-chip solder joints with Cu and Ni under-bump metallization, J. Mater. Res., 25 (9), 1847, 2010.
[4] Milton Ohring and Lucian Kasprzak, Reliability and Failure of Electronic Materials and Devices, 2015.
[5] H. Ceric, S. Selberherr, Electromigration in submicron interconnect features of integrated circuits, Materials Science and Engineering R 71 (2011) 53–86.
[6] A. Gangulee and F. M. d'Heurle, "The activation energy for electromigration and grain-boundary self-diffusion in gold," Scripta Metallurgica, vol. 7, pp. 1027-1030, (1973).
[7] B. J. Klein, "Electromigration in thin gold films," Journal of Physics F: Metal Physics, vol. 3, pp. 691-696, (1973).
[8] B. N. Agarwala, "Electromigration failure in Au thin-film conductors," in Reliability Physics Symposium Proceedings, 13th Annual IEEE International, pp. 107-112, (1975).
[9] R. E. Hummel and H. J. Geier, "Activation energy for electrotransport in thin silver and gold films," Thin Solid Films, vol. 25, pp. 335-342, (1975).
[10] P. F. Tang et al., "Electromigration in thin films of Au on GaAs," in Advanced Electronic Packaging Materials, Materials Research Society Symposium on, vol. 167, Pittsburgh, PA, USA, pp. 341-5, (1990).
[11] K. Croes et al., "High-resolution in-situ of gold electromigration: test time reduction," Microelectronics Reliability, vol. 41, pp. 1439-1442, (2001).
[12] C. S. Whitman, "Prediction of transmission line lifetimes over temperature and current density," Microelectronics Reliability, vol. 49, pp. 488-494, (2009).
[13] Stephen Kilgore, Electromigration in Gold Interconnects, PhD Dissertation, 2013.
[14] Anthony S. Oates, Strategies to Ensure Electromigration Reliability of Cu/Low-k Interconnects at 10 nm, ECS Journal of Solid State Science and Technology, 4 (1) N3168-N3176 (2015).

 

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