Incorporating Process Variations Into SRAM Electromigration Reliability Assessment Using Atomic Flux Divergence

2015 ◽  
pp. 1-13 ◽  
Author(s):  
Zhong Guan ◽  
Malgorzata Marek-Sadowska
Keyword(s):  
Reliability Assessment ◽  
Process Variations ◽  
Flux Divergence ◽  
Atomic Flux

Modeling Electromigration-Induced Stress Buildup Due to Nonuniform Temperature

1994 ◽  
Vol 338 ◽  
Author(s):  
J. J. Clement ◽  
C. V. Thompson ◽  
A. Enver
Keyword(s):  
Integrated Circuits ◽  
Driving Force ◽  
Stress Evolution ◽  
Nonuniform Temperature ◽  
Flux Divergence ◽  
Atomic Transport ◽  
Atomic Flux ◽  
Induced Stress ◽  
Interconnect Lines ◽  
Stress Buildup

ABSTRACTAtomic transport due to electromigration in interconnect lines in integrated circuits depends strongly on temperature. Therefore temperature nonuniformities can create sites of atomic flux divergence resulting in material accumulation or depletion leading to failure. The mechanical stress which will evolve at the sites of material flux divergence will oppose the electromigration driving force. A model is developed to describe the stress evolution during electromigration in the presence of temperature nonuniformnities. Solutions of the differential equations describing the electromigration-induced stress buildup are calculated numerically. The solutions are compared to experimental data in the literature.

Electromigration Simulation for Metal Lines

2010 ◽  
Vol 132 (1) ◽  
Author(s):  
JianPing Jing ◽  
Lihua Liang ◽  
Guang Meng
Keyword(s):  
Concentration Gradient ◽  
High Performance ◽  
Simulation Method ◽  
Flux Divergence ◽  
Atomic Concentration ◽  
Atomic Flux ◽  
Fortran Code ◽  
Current Densities ◽  
Void Propagation ◽  
Electron Wind

As the electronics industry continues to push for high performance and miniaturization, the demand for higher current densities, which may cause electromigration failures in an IC, interconnects. Electromigration is a phenomenon that metallic atoms constructing the line are transported by electron wind. The damage induced by electromigration appears as the formation of voids and hillocks. A numerical simulation method for electromigration void incubation, and afterwards, void propagation, based on commercial software ANSYS Multiphysics and FORTRAN code, is presented in this paper. The electronic migration formulation considering the effects of the electron wind force, stress gradients, temperature gradients, and the atomic concentration gradient has been developed for the electromigration failure mechanisms. Due to introducing the atomic concentration gradient driving force in atomic flux formulations, the conventional atomic flux divergence method is no longer valid in electromigration (EM) simulation. Therefore, the corresponding EM atomic concentration redistribution algorithm is proposed using FORTRAN code. Finally, the comparison of voids generation through the numerical example of a standard wafer electromigration accelerated test (SWEAT) structure with the measurement result is discussed.

122 Testing of the Electromigration Resistance of High Purities Al Based on Atomic Flux Divergence Method

2009 ◽  
Vol 2009.44 (0) ◽  
pp. 42-43
Author(s):  
Xu ZHAO ◽  
Masumi SAKA ◽  
Mitsuo YAMASHITA ◽  
Fumiaki TOGOH
Keyword(s):  
Flux Divergence ◽  
Atomic Flux

Analysis of Geometrical and Microstructural Effects on Void Formation in Metallization: Observation and Modelling

1996 ◽  
Vol 428 ◽  
Author(s):  
W. C. Shih ◽  
A. Ghiti ◽  
K. S. Low ◽  
A. L. Greer ◽  
A. G. O'Neill ◽  
...  
Keyword(s):  
Focused Ion Beam ◽  
Ion Beam ◽  
Void Formation ◽  
Grain Structure ◽  
Flux Divergence ◽  
Damage Development ◽  
Temperature Variations ◽  
Atomic Flux ◽  
Grain Structures ◽  
Microstructural Effects

AbstractThis paper reports the analysis of geometrical and microstructural effects on void formation in interconnects. Ion-beam machining is used to define segments for study at the cathode end of test lines. Scanning electron microscopy is used to observe damage development, focused ion beam microscopy to observe the corresponding grain structure. Finite-element calculations of self-consistent current density and temperature distributions in the conductor are used to predict damage locations both for a continuum material and for simulated grain structures. Cross-section changes in the line give temperature variations leading to divergences in atomic flux. Regions of high flux divergence are favoured for electromigration damage, but the precise sites of damage are determined by the grain structure, as shown both in the experiment and in the modelling.

The Effects of Width Transitions on the Reliability of Interconnects

2000 ◽  
Vol 612 ◽  
Author(s):  
C. S. Hau-Riege ◽  
C.V. Thompson ◽  
T.N. Marieb
Keyword(s):  
Line Width ◽  
Failure Rate ◽  
Critical Stress ◽  
Void Nucleation ◽  
Electron Source ◽  
Stress Range ◽  
Flux Divergence ◽  
Atomic Flux ◽  
A Site

AbstractExperimental and modeling studies of Al-based interconnects with narrow-to-wide transitions show that the width transition is a site of atomic flux divergence due to the discontinuity in diffusivities between the narrow and wide segments, which have different microstructures. Lifetimes have been experimentally determined for populations of lines with width transitions, which have varying line-width ratios and varying locations of the width transitions with respect to the line end. The electromigration failure rate is increased as the width-transition is moved closer to the electron-source via. Correlation of the effects width transitions on lifetimes allows determination of the critical stress range for void -nucleation failure, which was found to be 600 ± 108 MPa.

Effects of Preexisting Stress Voids on Electromigration Stress Buildup and Flux Divergence

1999 ◽  
Vol 563 ◽  
Author(s):  
Y. -L. Shen ◽  
C. A. Minor ◽  
Y. L. Guo
Keyword(s):  
Stress Field ◽  
Stress Profile ◽  
Flux Divergence ◽  
Element Analysis ◽  
One Dimensional ◽  
Atomic Flux ◽  
The Finite Element Analysis ◽  
The One ◽  
Aluminum Interconnects ◽  
Stress Buildup

AbstractNumerical modeling of electromigration stress buildup and flux divergence was undertaken. The objective is to provide a mechanistic understanding of the question: Do preexisting stress voids grow during later electromigration, to become potentially fatal? Conflicting experimental results have been reported. In this work the stress field in aluminum interconnects containing voids was first quantified using the finite element analysis. The averaged stress field then served as the initial condition in the one-dimensional partial differential equation of electromigration stress buildup. The finite difference method was employed to solve the evolving stress profile and the associated atomic flux and flux divergence along the conducting line. It was found that a large preexisting void suffers greater flux divergence and is therefore more prone to growth during electromigration. A single large stress void is more detrimental than populous small voids. Published experimental observations seem to support these findings.

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