Experimental data and statistical models for bimodal EM failures

Fischer, A.; Abel, Andreas; Lepper, Markus; Zitzelsberger, A.E.; Glasow, A. von

doi:10.1109/relphy.2000.843940

Cited by 24 publications

(10 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…If we only consider the single crystal test structure the failure happens at the same location at a fixed lifetime for a given stress condition. However, in reality there will be a spread in failure lifetimes for integrated circuit chips even from the same wafer and bimodal and multimodal failure is commonly observed (Ogawa et al Fischer et al 2000;Fischer et al 2001;Baklanov et al 2012). This can be explained by considering the randomness involved in the grain distribution.…”

Section: Resultsmentioning

confidence: 99%

Modeling the copper microstructure and elastic anisotropy and studying its impact on reliability in nanoscale interconnects

Basavalingappa

Shen

Lloyd

2017

Mech Adv Mater Mod Process

View full text Add to dashboard Cite

Background: Copper is the primary metal used in integrated circuit manufacturing of today. Even though copper is face centered cubic it has significant mechanical anisotropy depending on the crystallographic orientations. Copper metal lines in integrated circuits are polycrystalline and typically have lognormal grain size distribution. The polycrystalline microstructure is known to impact the reliability and must be considered in modeling for better understanding of the failure mechanisms. Methods: In this work, we used Voronoi tessellation to model the polycrystalline microstructure with lognormal grainsize distribution for the copper metal lines in test structures. Each of the grains is then assigned an orientation with distinct probabilistic texture and corresponding anisotropic elastic constants based on the assigned orientation. The test structure is then subjected to a thermal stress.

show abstract

Section: Resultsmentioning

confidence: 99%

Modeling the copper microstructure and elastic anisotropy and studying its impact on reliability in nanoscale interconnects

Basavalingappa

Shen

Lloyd

2017

Mech Adv Mater Mod Process

View full text Add to dashboard Cite

show abstract

“…A AR/R=20% criterion was used to defme the time to failure. The medium time to failure was determined separately for each mode by fitting the bimodal distribution underlying a weighted supelposition of two lognormal distributions [2]. No significant difference in the activation energy between the two mechanisms was found (Ea=0.83 ... 0.86eV, Fig.3).…”

Section: Methodsmentioning

confidence: 99%

Electromigration failure mechanism studies on copper interconnects

Fischer

Glasow

Penka

et al.

Proceedings of the IEEE 2002 International Interconnect Technology Conference (Cat. No.02EX519)

Self Cite

View full text Add to dashboard Cite

Electromigration (EM) studies revealed a strong correlation between observed failure scenario and local microstructural properties at the via-to-line-transition, in particular that of the liner. "Early" failure modes were found to have not only smaller failure times but also a lower current density exponent. The influence of specific processes on the occurrence ofcertain failure modes will he discussed. IntroductionThe EM resistivity of bulk copper is known to be larger compared to AI(Cu) [I]. However, failure times measured on integrated Cu interconnects strongly depend on the used integration scheme and the degree of process control. The presence of "early" failure modes can result in a reduction of EM lifetimes to a level similar to AI(Cu) or even below. Ofien, two or more different physical failure mechanisms act in parallel within a test sample or a single interconnect.

show abstract

“…For some via/line EM structures, failure time distributions have been found to severely deviate from ideal linear behavior. Introduction of two bimodal lognormal distributions was needed to obtain a satisfactory fit [5]. These models were 1) the superposition model, where the overall distribution is the sum of two 2-parameter lognormal distributions, (4) and 2) the weakest link (or competing risks) model , (5) where F is the overall CDF, F1 and F2 are the CDF for early mode and late mode, respectively, and p1 is the fraction of the early mode.…”

Section: -Vs 3-parameter Lognormal Distributionsmentioning

confidence: 99%

Minimum Void Size and 3-Parameter Lognormal Distribution for EM Failures in Cu Interconnects

Li¹,

Christiansen²,

Gill³

et al. 2006

2006 IEEE International Reliability Physics Symposium Proceedings

View full text Add to dashboard Cite

z = HLog@tD − Log@t 50 DL ê σ F@tD= p1 * F1@t;t 501 ,σ1D +H1−p1L * F2@t;t 502 , σ2D F@tD=F1@t;t 501 ,σ1D+F2@t;t 502 ,σ2D−F1@t;t 50 1 ,σ1D * F2@t;t 502 ,σ2D f@t;t 50 , σD = 1 t è!!!!!!!!!! 2 πσ 2 e −JLogB t t 50 FN 2 í2 σ 2F@t; t 50 , σD = ‡ 0 t f@x; t 50 , σD x ABSTRACT Broad failure time distributions were observed for line depletion electromigration in Cu interconnects for various structures without sufficient liner contact and via redundancy. The root cause for this behavior was identified as the sensitivity of failure times to the void size, shape and location. Application of the traditional 2-parameter lognormal distribution model to corresponding stress data often results in very pessimistic EM lifetime projections. A 3-parameter lognormal distribution was found not only to fit the experimental data better, especially for the early portion of the failure time distributions, but also to generate more accurate lifetime projections for void-size-limited EM. Given the nature of EM wear-out, deeper consideration indicates that a 3-parameter lognormal distribution has a sounder physical basis than a 2-parameter lognormal distribution. The new parameter introduced in the model, the minimum failure time (X 0 ), scales with via size over several technology generations, further validating the minimum void size explanation. [KEY

show abstract

Experimental data and statistical models for bimodal EM failures

Cited by 24 publications

References 6 publications

Modeling the copper microstructure and elastic anisotropy and studying its impact on reliability in nanoscale interconnects

Modeling the copper microstructure and elastic anisotropy and studying its impact on reliability in nanoscale interconnects

Electromigration failure mechanism studies on copper interconnects

Minimum Void Size and 3-Parameter Lognormal Distribution for EM Failures in Cu Interconnects

Contact Info

Product

Resources

About