Activation Energy for Electromigration Failure in Aluminum Films Containing Copper

d’Heurle, F. M.; Ainslie, N. G.; Gangulee, A.; Shine, M. C.

doi:10.1116/1.1316583

Cited by 69 publications

(10 citation statements)

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“…If a material were fully covered by rigid walls, the lattice expansion of the material under current stressing is suppressed; therefore, the rigid cap-layers can either postpone the time to reach the yield point or increase the threshold current density for yielding. (3) Stronger materials, e.g ., (111)-textured 31 – 34 , precipitation hardened 33 , 35 , 36 , and nanotwin-modified 37 materials, showed larger resistances to EM-induced failure. It can be rationalized based on the proposed mechanism that the stiffer materials have stronger resistances to electron flow-induced expansion, so they are more prone to being retained in the elastic region shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

The electromigration effect revisited: non-uniform local tensile stress-driven diffusion

Lin

Liu

Chiu

et al. 2017

Sci Rep

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The electromigration (EM) effect involves atomic diffusion of metals under current stressing. Recent theories of EM are based on the unbalanced electrostatic and electron-wind forces exerted on metal ions. However, none of these models have coupled the EM effect and lattice stability. Here, we performed in situ current-stressing experiments for pure Cu strips using synchrotron X-ray diffractometry and scanning electron microscopy and ab initio calculations based on density functional theory. An intrinsic and non-uniform lattice expansion – larger at the cathode and smaller at the anode, is identified induced by the flow of electrons. If this electron flow-induced strain is small, it causes an elastic deformation; while if it is larger than the yield point, diffusion as local stress relaxation will cause the formation of hillocks and voids as well as EM-induced failure. The fundamental driving force for the electromigration effect is elucidated and validated with experiments.

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Section: Resultsmentioning

confidence: 99%

The electromigration effect revisited: non-uniform local tensile stress-driven diffusion

Lin

Liu

Chiu

et al. 2017

Sci Rep

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“…This correlation, however, does not inply causalrecipitation and increased activation energy may both be by products of the same phenomena. and the absorption energy of Cu onto Al grain boundaries, with dn additional contribution due to the differenice between the activation eriergies for Cu and Al diffusion dlong Al grain boundaries [14]. Unfortunately, even a tentative interpretdtion of the mechanism responsible for an ircrease in the activation energy in Al-Si-Ti conductors cannot be made.…”

Section: Resultsmentioning

confidence: 99%

Electromigration in Titanium Doped Aluminum Alloys

Towner

Dirks

Tien

1986

24th International Reliability Physics Symposium

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Homogeneous f iLms of titanium-doped aluminum and aluminum-l%siLicon were evaluated for possible application as interconnects in integrated circuits.Titanium concentration was systemnatically varied in the range of 0 to 1.2 wt.%. Electromigration behavior was studied for each film composition as a function of temperature. Significant differences were found between the binary and ternary alloys, corresponding to differences in the film microstructure.

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“…Aluminum-copper (A1-Cu) alloys are the most widely used materials for interconnects in microelectronic circuits because a small amount of Cu added to an AI thin film can dramatically increase the electromigration resistance of conductor lines made from that film [1]. During the fabrication process of integrated circuits, A1-Cu interconnects are exposed to temperature cycling required for the various process steps and are subjected to very high stresses due to the differential thermal expansion between the metal and the silicon substrate.…”

Section: Introductionmentioning

confidence: 99%

Mechanical properties and microstructures of Al-Cu Thin films with various heat treatments

Joo¹

1998

Metals and Materials

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The relationship between microstructure and mechanical properties has been investigated in AI-Cu thin films. The Cu content in AI-Cu samples used in this study ranges from 0 to 2 wt.% and substrate curvature measurement was used to measure film stress. In thin films, the constraints on the film by the substrate influence the rnicrostructure and mechanical properties. AI-Cu thin films cooled from high temperatures have a large density of dislocations due to the plastic deformation caused by the thermal mismatch between the film and substrate. The high density of dislocations in the thin film enables precipitates to form inside the grain even during a very rapid quenching. The presence of a large density of dislocations and precipitates will in turn cause precipitation hardening of the AI-Cu films. The precipitation hardening is dominant at lower temperatures, and solid solution hardening is observed at higher temperatures in the tensile regime. Pure AI films showed the same values of tensile and compressive yield stresses at a given temperature during stress-temperature cycling.

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Activation Energy for Electromigration Failure in Aluminum Films Containing Copper

Cited by 69 publications

References 0 publications

The electromigration effect revisited: non-uniform local tensile stress-driven diffusion

The electromigration effect revisited: non-uniform local tensile stress-driven diffusion

Electromigration in Titanium Doped Aluminum Alloys

Mechanical properties and microstructures of Al-Cu Thin films with various heat treatments

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