Two electromigration failure modes in polycrystalline aluminum interconnects

Atakov, E.M.; Clement, J. J.; Miner, B.

doi:10.1109/relphy.1994.307834

Cited by 13 publications

(2 citation statements)

References 28 publications

(25 reference statements)

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“…Several studies have shown that in Al(Cu) technology with near-bamboo grain structure interfacial diffusion, along the edges of the lines, plays a more significant role in the transport of metal ions compared to grain boundaries [for instance : Hu 1993aand 1993b, Atakov 1994]. …”

Section: Influence Of Microstructure On Emmentioning

confidence: 99%

Statistical Analysis of Electromigration Lifetimes and Void Evolution for Cu Interconnects

Hauschildt

Gall²,

Thrasher³

et al. 2004

MRS Proc.

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Electromigration (EM) failure statistics and the origin of the lognormal deviation (σ) for Cu interconnects have been investigated by analyzing the lifetime statistics and void size distributions at various stages during EM testing. Experiments were performed on 0.18 μm wide Cu interconnects with tests terminated after specific amounts of resistance increases, or after a specified test time. Void size distributions of resistance-based, as well as time-based EM tests were obtained using focused ion beam (FIB) microscopy. The lifetime and void size distributions were found to follow lognormal distribution functions. The σ values of EM lifetime and time-based void size distributions decrease with higher percentages of resistance increase, reaching an asymptotic value of σ ∼ 0.14. In contrast, σ values of resistance-based void size distributions are significantly smaller and do not show an obvious dependence on time. The statistics of resistance-based void size distributions can mainly be accounted for by geometrical variations of the void shape, while the statistics of time-based void size distributions requires consideration of kinetic aspects of the EM process. The σ values of EM lifetime distributions at long times can be simulated based on measured void size distributions, taking into account geometrical and experimental factors of EM. In contrast, for short times the statistics of initial void formation and the kinetics of interfacial mass transport have to be considered.

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Section: Influence Of Microstructure On Emmentioning

confidence: 99%

Statistical Analysis of Electromigration Lifetimes and Void Evolution for Cu Interconnects

Hauschildt

Gall²,

Thrasher³

et al. 2004

MRS Proc.

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show abstract

“…In Blech's study, it was found that j th is inversely proportional to the line length l, whereby the threshold length product j th ·l is used to assess EM damage. In addition, from EM tests using Al line-type samples covered with passivation, the relation between j th ·l and temperature was presented, which indicated that j th ·l was lower and there was more EM damage at higher temperature (Blech, 1976 andAtakov, et al, 1994). Many factors are thought to affect the temperature dependence of j th ·l.…”

Section: Introductionmentioning

confidence: 99%

Effect of temperature on preventing electromigration damage based on increasing threshold current density in a thin metal passivated line

Ikadai

Kimura

Saka

2016

Mechanical Engineering Letters

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The influencing factors associated with the temperature dependence of electromigration (EM) damage are discussed. EM is the atomic diffusion in a metal line when the line is stressed with high current density and causes EM damage called voids and hillocks. Voids are the depletion of the metal atoms and lead to breaking of the lines. Hillocks are the accumulation of the metal atoms and cause short circuits. Passivation covering the metal lines has been used as one of the ways to prevent EM damage because it constrains the formation of hillocks and voids at the same time owing to the conservation of mass. The passivation characteristics such as hardness affect the ability to inhibit EM damage. EM damage is significantly affected by temperature, and to reveal the relation of the passivation hardness with temperature contributes to improving EM reliability. In addition, other factors are thought to affect the temperature dependence of EM damage. In the present paper, we investigate the temperature dependence of EM damage measured by means of threshold length product and clarify several factors affecting the temperature dependence of EM damage. A tetraethyl orthosilicate layer is used as passivation on a conventional Al line-type structure sample. Through the experiments, we demonstrate that EM damage can be prevented much more by decreasing temperature and the increase of the passivation hardness with decreasing temperature is assumed to have an influence on the ability of passivation to prevent EM damage. We also discuss the effective bulk modulus and the electrical resistivity of Al as the factors affecting the temperature dependence of EM damage.

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Reliability and early failure in Cu/oxide dual-damascene interconnects

Ogawa

Lee

Matsuhashi

et al. 2002

Journal of Elec Materi

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The drive toward greater device density and higher performance in Si-based microelectronics technology has led to the recent transition to newer backend interconnect materials. However, this transition must be accomplished without sacrificing the reliability requirements necessary for long-term product functionality. 1,2 The recent introduction of Cu metallization to replace Al(Cu) technology is one example, 3 but the transition will also later require the incorporation of new and often exotic low-k interlevel and intralevel dielectrics as well as ultrathin Cu DB materials. The rapid introduction of new materials in advanced integrated circuit technology is in marked contrast to the seemingly less turbulent prior history-at least from a materials perspective-in microelectronics. All this materials change will also be done under a new interconnect integration architecture: the single-damascene (SD) and dual-damascene (DD) processes. The impact of these new materials and integration scheme on interconnect reliability, such as electromigration (EM) and stress-induced voiding, is still presently not well understood, and the literature on Cu/low-k reliability is still rather sparse. Yet, the knowledgebase is growing, and certain aspects of the effect of the damascene architecture on at least EM reliability are becoming clearer. DD Interconnects: Basic ArchitectureThe basic layout of a Cu-based, submicron, twolevel interconnect suitable for study of EM phenomena in DD systems is shown in Fig. 1a. The DD interconnect is placed at the upper metal level (M2), while a SD interconnect is used at the lower level metal (M1). The Cu metal is surrounded by a thin Ta diffusion barrier (DB) around its sides and bottom and by a capping layer (CL, typically SiN x ) on top. A typical barrier thickness may range between 100 and 300 Å, but the thickness on the via sidewall may be thinner by, say, 25-50%. The CL thickness is typically in the range of 1000 Å. The specific thickness dimensions of these films may vary depending on the technology node targeted. An intralevel dielectric material (ILD, for example, CVD-based SiO x glass) lies between the metal lines. Both the ILD and CL are targeted as regions where the introduction of new lower-k materials will be necessary for future device performance improvements. The M1 and M2 interconnects are electrically connected through the via V1, which is processed as a continuous part of the M2 interconnect.In EM studies on DD interconnects, two current flow directions must be considered. The first electron Recent results on up-direction electromigration (EM) studies on Cu dual-damascene (DD) interconnects are presented. The issue of the DD process and its potential effect on EM reliability is described with special focus on the peculiarities of the DD interconnect architecture in comparison to the previous subtractively etched Al-based interconnect technology. Experiments performed on multilink, DD interconnects that highlight EM reliability issues, such as early failure, and the Blech effect a...

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Two electromigration failure modes in polycrystalline aluminum interconnects

Cited by 13 publications

References 28 publications

Statistical Analysis of Electromigration Lifetimes and Void Evolution for Cu Interconnects

Statistical Analysis of Electromigration Lifetimes and Void Evolution for Cu Interconnects

Effect of temperature on preventing electromigration damage based on increasing threshold current density in a thin metal passivated line

Reliability and early failure in Cu/oxide dual-damascene interconnects

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