Abstract
This chapter investigates in detail the actual low-level migration processes. A solid grounding in the physics of electromigration (EM) and its specific effects on the interconnect will give us the knowledge to establish effective mitigation methods during the design of integrated circuits. We first explain the physical causes of EM (Sect. 2.1) and then present options to quantify the EM process (Sect. 2.2), which enable us to effectively characterize key aspects of the process and its effects. In Sect. 2.3, we introduce EM-influencing factors arising from the specific circuit technology, the environment, and the design. We then investigate detailed EM mechanisms with regard to circuit materials, frequencies, and mechanical stresses (Sect. 2.4). Since EM is closely related to thermal and stress migration that also occur in the conductors of electronic circuits, we examine their interdependencies (Sect. 2.5). Finally, Sect. 2.6 outlines the principles of a migration analysis through simulation. This honors the importance of finite element modeling (using the finite element method, FEM) in electromigration analysis and enables the reader to develop and apply similar modeling and simulation techniques.
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Notes
- 1.
The crystal lattice of metals is built up of ordered metal ions with an “electron fog” in-between, consisting of shared free electrons. The terms metal atoms and metal ions are considered equivalent in this context.
- 2.
The Boltzmann constant, which is named after Ludwig Boltzmann (1844–1906), is a physical constant relating the average kinetic energy of particles with the temperature.
- 3.
Long-range order in a crystal means that atoms are organized in a periodic order across many atoms, such as in a periodic lattice.
- 4.
The heat equation is a differential equation that describes the distribution of heat (or variation in temperature) in a given region over time.
- 5.
A duty factor is the fraction of one period in which a signal or system is active, i.e., it expresses the ratio of the positive pulse duration to the period. The duty factor is commonly scaled to the maximum of one. A duty cycle expresses the same notion; however, it is labeled as a percentage.
- 6.
The skin effect is due to opposing eddy currents induced by the changing magnetic field resulting from the alternating current. This effect leads to a reduction in current from the outside to the inside of a metallic conductor as a function of the frequency and the electrical material constants of the conductor (permeability and conductivity).
- 7.
Entropy is a measure of the “disorder” of a system. Hence, the more “ordered” or “organized” a system is, the lower its entropy. For example, building blocks that have been used to construct a wall are “highly organized” (i.e., they are arranged in a complex structure) and are thus in a low-entropy state. This state is achieved only by the input of energy. If this structure is left unattended, it will decay after a number of years, and the disorganized, high-entropy state will return (i.e., an unorganized heap of blocks).
- 8.
Electron mobility is a measure of how quickly an electron can move through a material such as a metal or semiconductor, when pulled by an electric field.
- 9.
The Korhonen model combines vacancy dynamics with stress development. It assumes that the recombination and generation of vacancies alter the concentration of the available lattice sites, which influences the hydrostatic stress distribution. Specifically, the loss of the available lattice sites increases the hydrostatic stress.
References
E. Arzt, W.D. Nix, A model for the effect of line width and mechanical strength on electromigration failure of interconnects with ‘near-bamboo’ grain structures. J. Mater. Res. 6(4), 731–736 (1991). https://doi.org/10.1557/JMR.1991.0731
M.J. Attardo, R. Rosenberg, Electromigration damage in aluminum film conductors. J. Appl. Phys. 41(6), 2381–2386 (1970). https://doi.org/10.1063/1.1659233
J.R. Black, Electromigration—a brief survey and some recent results. IEEE Trans. Electron Devices 16(4), 338–347 (1969). https://doi.org/10.1109/T-ED.1969.16754
J.R. Black, Electromigration failure modes in aluminum metallization for semiconductor devices. Proc. of the IEEE 57(9), 1587–1594 (1969). https://doi.org/10.1109/PROC.1969.7340
I.A. Blech, Electromigration in thin aluminum films on titanium nitride. J. Appl. Phys. 47(4), 1203–1208 (1976). https://doi.org/10.1063/1.322842
W.G. Breiland, S.R. Lee, D.D. Koleske, Effect of diffraction and film-thickness gradients on wafer-curvature measurements of thin-film stress. J. Appl. Phys. 95(7), 3453–3465 (2004). https://doi.org/10.1063/1.1650882
A.F. Bower, S. Shankar, A finite element model of electromigration induced void nucleation, growth and evolution in interconnects. Modell. Simul. Mat Sci. Eng. 15(8), 923–940 (2007)
H. Chang, Y.-C. Lu, S.-M. Jang, Self-aligned dielectric cap. U.S. Patent App. 11/747,105, 2008
H. Ceric, R. de Orio, S. Selberherr, Integration of atomistic and continuum-level electromigration models, in 18th IEEE International Symposium on the Physical and Failure Analysis of Integrated Circuits (IPFA) (2011), pp. 1–4
H. Ceric, S. Selberherr, Electromigration in submicron interconnect features of integrated circuits. Mater. Sci. Eng.: R: Rep. 71(5–6), 53–86 (2011). https://doi.org/10.1016/j.mser.2010.09.001
L. Doyen, X. Federspiel, D. Ney, Improved bipolar electromigration model, in 44th Annual., IEEE International Reliability Physics Symposium Proceeding (2006), pp. 683–684. https://doi.org/10.1109/relphy.2006.251323
R.G. Filippi, P.C. Wang, A. Brendler, et al., The effect of a threshold failure time and bimodal behavior on the electromigration lifetime of copper interconnects, in 2009 IEEE International Reliability Physics Symposium (2009), pp. 444–451. https://doi.org/10.1109/irps.2009.5173295
T. Gupta, Copper Interconnect Technology. Springer (2009). https://doi.org/10.1007/978-1-4419-0076-0
C.S. Hau-Riege, An introduction to Cu electromigration, Microel. Reliab. 44, 195–205. https://doi.org/10.1016/j.microrel.2003.10.020 (5, 2004)
A. Heryanto, K.L. Pey, Y. Lim, et al., Study of stress migration and electromigration interaction in copper/low-k interconnects, in IEEE International Reliability Physics Symposium (IRPS) (2010), pp. 586–590
International Technology Roadmap for Semiconductors (ITRS), 2013 edn. (2014), http://www.itrs2.net/itrs-reports.html. Last retrieved on 1 Jan 2018
International Technology Roadmap for Semiconductors 2.0 (ITRS 2.0), 2015 edn (2016), http://www.itrs2.net/itrs-reports.html. Last retrieved on 1 Jan 2018
G. Jerke, J. Lienig, Early-stage determination of current-density criticality in interconnects, in Proceeding of International Symposium on Quality in Electronic Design (ISQED) (2010), pp. 667–774. https://doi.org/10.1109/isqed.2010.5450505
P. Jain, A. Jain, Accurate estimation of signal currents for reliability analysis considering advanced waveform-shape effects, in 24th International Conference on VLSI Design (VLSI Design) (2011), pp. 118–123. https://doi.org/10.1109/vlsid.2011.61
Y.-C. Joo, C.V. Thompson, Electromigration-induced transgranular failure mechanisms in single-crystal aluminum interconnects. J. Appl. Phys. 81(9), 6062–6072 (1997). https://doi.org/10.1063/1.364454
K. Küpfmüller, W. Mathis, A. Reibiger, Theoretische Elektrotechnik/Eine Einführung, 19. aktual. Aufl. (Springer Vieweg, 2013). ISBN 978-3-642-37940-6
J. Knechtel, I.L. Markov, J. Lienig, Assembling 2-D blocks into 3-D chips, IEEE Transaction on Computer-Aided Design of Integrated Circuits and Systems, vol. 31, no. 2 (2012), pp. 228–241. https://doi.org/10.1109/tcad.2011.2174640
J. Knechtel, E.F.Y. Young, J. Lienig, Planning massive interconnects in 3D chips, IEEE Transaction on Computer-Aided Design of Integrated Circuits and Systems, vol. 34, no. 11 (2015), pp. 1808–1821. https://doi.org/10.1109/tcad.2015.2432141
A.R. Lavoie, F. Gstrein, Self-aligned cap and barrier. U.S. Patent App. 12/165,016, 2009
J. Lienig, Interconnect and current density stress—an introduction to electromigration-aware design, in Proceeding of 2005 Interconnect Workshop on System Level Interconnect Prediction (SLIP) (2005), pp. 81–88. https://doi.org/10.1145/1053355.1053374
J. Lienig, Introduction to electromigration-aware physical design, in Proceeding of International Symposium on Physical Design (ISPD) (ACM, 2006), pp. 39–46. https://doi.org/10.1145/1123008.1123017
W. Li, C.M. Tan, Black’s equation for today’s ULSI interconnect electromigration reliability—A revisit, in International Conference of Electron Devices and Solid-State Circuits (EDSSC) (2011), pp. 1–2. https://doi.org/10.1109/edssc.2011.6117717
T.O. Ogurtani, E.E. Oren, Computer simulation of void growth dynamics under the action of electromigration and capillary forces in narrow thin interconnects. J. Appl. Phys. 90(3), 1564–1572 (2001). https://doi.org/10.1063/1.1382835
K. Shono, T. Kuroki, H. Sekiya, et al. Mechanism of AC electromigration, in Proceeding Seventh International IEEE VLSI Multilevel Interconnection Conference (1990), pp. 99–105. https://doi.org/10.1109/vmic.1990.127851
Y. Sohn, Phase-field modeling and experimentation of constituents redistribution in metallic alloys, Slides of NIST Diffusion Workshop (2009), https://www.nist.gov/sites/default/files/documents/mml/msed/thermodynamics_kinetics/NIST-09-Workshop-fsrd.pdf. Last retrieved on 1 Jan 2018
W. Schatt, H. Worch (ed.), Werkstoffwissenschaft, 8. neu bearb. Aufl. (Dt. Verl. für Grundstoffindustrie, Stuttgart, 1996). ISBN 3-342-00675-7
J. Tao, J.F. Chen, N.W. Cheung, et al., Modeling and characterization of electromigration failures under bidirectional current stress. IEEE Trans. Electron Devices 43(5), 800–808 (1996). https://doi.org/10.1109/16.491258
J. Tao, N.W. Cheung, C. Hu, Metal electromigration damage healing under bidirectional current stress. IEEE Electron Device Lett. 14(12), 554–556 (1993). https://doi.org/10.1109/55.260787
C.M. Tan, Y. Hou, W. Li, Revisit to the finite element modeling of electromigration for narrow interconnects, J. Appl. Phys. 102(3), 033705-1–033705-7 (2007)
M. Thiele, S. Bigalke, J. Lienig, Exploring the use of the finite element method for electromigration analysis in future physical design, in Proceeding of the 25th IFIP/IEEE International Conference on Very Large Scale Integration (VLSI-SoC) (2017), pp. 1–6. https://doi.org/10.1109/VLSI-SoC.2017.8203466
C.V. Thompson, Using line-length effects to optimize circuit-level reliability, in 15th International Symposium on the Physical and Failure Analysis of Integrated Circuits (IPFA) (2008), pp. 1–48. https://doi.org/10.1109/ipfa.2008.4588155
K.-N. Tu, Solder Joint Technology--Materials, Properties, and Reliability. Springer (2007). https://doi.org/10.1007/978-0-387-38892-2
M. Uekubo, T. Oku, K. Nii, et al., Wnx diffusion barriers between Si and Cu. Thin Solid Films 286(1–2), 170–175 (1996). https://doi.org/10.1016/S0040-6090(96)08553-7
S. Van Nguyen, A. Grill, T.J. Haigh, Jr., et al., Self-aligned composite M-MOx/dielectric cap for Cu interconnect structures. U.S. Patent 8,299,365, 2012
W. Wu, J.S. Yuan, Skin effect of on-chip copper interconnects on electromigration. Solid-State Electron. 46(12), 2269–2272 (2002). https://doi.org/10.1016/S0038-1101(02)00232-0
K. Weide-Zaage, D. Dalleau, X. Yu, Static and dynamic analysis of failure locations and void formation in interconnects due to various migration mechanisms. Mater. Sci. Semicond. Process. 6(1–3), 85–92 (2003). https://doi.org/10.1016/S1369-8001(03)00075-1
X. Xu, A. Karmarkar, 3D TCAD modeling for stress management in through silicon via (TSV) stacks. AIP Conf. Proc. 1378(53), 53–66 (2011). https://doi.org/10.1063/1.3615695
H. Ye, C. Basaran, D.C. Hopkins, Numerical simulation of stress evolution during electromigration in IC interconnect lines. IEEE Trans. Compon. Packag. Technol. 26(3), 673–681 (2003). https://doi.org/10.1109/TCAPT.2003.817877
C.S. Yoo, Semiconductor Manufacturing Technology, World Sci. (2008). ISBN 978-981-256-823-6
X. Yu, K. Weide, A study of the thermal-electrical- and mechanical influence on degradation in an aluminum-pad structure. Microelectron. Reliab. 37(10–11), 1545–1548 (1997). https://doi.org/10.1016/S0026-2714(97)00105-4
A. Ziabari, J.-H. Park, E.K. Ardestani, et al., Power blurring: fast static and transient thermal analysis method for packaged integrated circuits and power devices, in IEEE Transactions on VLSI Systems, vol. 22, no. 11 (2014), pp. 2366–2379. https://doi.org/10.1109/tvlsi.2013.2293422
C.J. Zhai, H.W. Yao, P.R. Besser, et al., Stress modeling of Cu/low-k BEoL—Application to stress migration, in Proceeding 42nd Annual IEEE International Reliability Physics Symposium (2004), pp. 234–239. https://doi.org/10.1109/relphy.2004.1315329
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Lienig, J., Thiele, M. (2018). Fundamentals of Electromigration. In: Fundamentals of Electromigration-Aware Integrated Circuit Design. Springer, Cham. https://doi.org/10.1007/978-3-319-73558-0_2
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