New Insight On Electromigration Failure Mechanism And Its Impact On Design Guidelines

Jawarani,; Gall, Harald C.; Hernández,; Capasso,; Kawasaki,

doi:10.1109/vlsit.1997.623684

Cited by 5 publications

(3 citation statements)

References 4 publications

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“…Due to the tight distributions for the latter devices, the error bars ͑using 90% confidence͒ decrease and a determination of activation energies to the second decimal can be performed. The activation energies obtained here are in excellent agreement with values found in earlier experiments, using nearbamboo or bamboo interconnects, 10,14 and in good agreement with generally reported values ranging from 0.87 to 1.0 eV for Cu diffusion in Al͑Cu͒ metallization. 15 We surmise that interface diffusion of Cu along the Al͑Cu͒ sidewalls and along the top and bottom refractory layers, coupled with grain boundary diffusion within the interconnects, constitutes the Cu incubation mechanism.…”

Section: Activation Energy Characterizationsupporting

confidence: 91%

“…Due to the high activation energy of Cu depletion mechanisms and due to the high current exponent of nϭ2, this first stage of the EM damage process will be masked completely. 9,10 The EM failure times will then become very dependent on the local microstructure of the Al͑Cu͒ interconnect close to the via, e.g., a grain boundary triple point right on top of the via would lead to very fast diffusion and manifest itself in an early failure datapoint. However, the preceding Cu incubation time at low temperatures and current densities would have rendered this datapoint irrelevant.…”

Section: Discussionmentioning

confidence: 99%

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Statistical analysis of early failures in electromigration

Gall

Capasso

Jawarani

et al. 2001

Journal of Applied Physics

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The detection of early failures in electromigration (EM) and the complicated statistical nature of this important reliability phenomenon have been difficult issues to treat in the past. A satisfactory experimental approach for the detection and the statistical analysis of early failures has not yet been established. This is mainly due to the rare occurrence of early failures and difficulties in testing of large sample populations. Furthermore, experimental data on the EM behavior as a function of varying number of failure links are scarce. In this study, a technique utilizing large interconnect arrays in conjunction with the well-known Wheatstone Bridge is presented. Three types of structures with a varying number of Ti/TiN/Al(Cu)/TiN-based interconnects were used, starting from a small unit of five lines in parallel. A serial arrangement of this unit enabled testing of interconnect arrays encompassing 480 possible failure links. In addition, a Wheatstone Bridge-type wiring using four large arrays in each device enabled simultaneous testing of 1920 interconnects. In conjunction with a statistical deconvolution to the single interconnect level, the results indicate that the electromigration failure mechanism studied here follows perfect lognormal behavior down to the four sigma level. The statistical deconvolution procedure is described in detail. Over a temperature range from 155 to 200 °C, a total of more than 75 000 interconnects were tested. None of the samples have shown an indication of early, or alternate, failure mechanisms. The activation energy of the EM mechanism studied here, namely the Cu incubation time, was determined to be Q=1.08±0.05 eV. We surmise that interface diffusion of Cu along the Al(Cu) sidewalls and along the top and bottom refractory layers, coupled with grain boundary diffusion within the interconnects, constitutes the Cu incubation mechanism.

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Section: Activation Energy Characterizationsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Statistical analysis of early failures in electromigration

Gall

Capasso

Jawarani

et al. 2001

Journal of Applied Physics

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show abstract

“…The choice of this criterion reflects the fact that the incubation time during which Cu diffuses past the critical length is the dominating failure mechanism at operating conditions. 6,7 The onset of Al drift, concurrent with void formation and resistance/voltage changes, signals the end of the incubation time. A detailed view of the voltage imbalance in a Wheatstone Bridge device as a function of time, ⌬V(t), is depicted in Fig.…”

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confidence: 99%

Detection and analysis of early failures in electromigration

Gall

Capasso

Jawarani

et al. 2000

Applied Physics Letters

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The early failure issue in electromigration (EM) has been an unresolved subject of study over the last several decades. A satisfying experimental approach for the detection and analysis of early failures has not been established yet. In this study, a technique utilizing large interconnect arrays in conjunction with the well-known Wheatstone Bridge is presented. A total of more than 20 000 interconnects were tested. The results indicate that the EM failure mechanism studied here follows lognormal behavior down to the four sigma level.

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Massive-Scale Statistical Studies for Electromigration

2022

Electromigration in Metals

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New Insight On Electromigration Failure Mechanism And Its Impact On Design Guidelines

Cited by 5 publications

References 4 publications

Statistical analysis of early failures in electromigration

Statistical analysis of early failures in electromigration

Detection and analysis of early failures in electromigration

Massive-Scale Statistical Studies for Electromigration

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