Electromigration em refers to the unwanted movement of materials in a semiconductor. Black developed an empirical model to estimate the mttf mean time to failure of a wire, taking electromigration into consideration. Black 1 established the relationship between the mean time to failure. Methodology for electromigration signoff in the presence. Tin, tiw barriers, glue layers, anti reflection coatings and short local. Since then, the formula has gained popularity in the semiconductor industry. Theory of electromigration electromigration is the transport of material in a conductor under the influence of an applied electric field. Black s law revisited nucleation and growth in electromigration failure. Black developed an empirical model to estimate the mttf of a wire segment, taking electromigration into consideration 3. Electromigration is generally considered to be the result of momentum transfer from the electrons, which move in the applied electric field, to the ions which make up the lattice of the interconnect material. Effects of texture and grain structure on electromigration. At this point, research was focused into electromigration. Electromigration em is a critical problem for interconnect reliability in advanced vlsi design. In this model, electromigration lifetimes are predicted without resort to adjustable parameters.
Black s equation for dependence of em lifetime on current density and temperature 3 leads to the relation which must be satisfied by the current density to maintain equal em reliability lifetimes 4. Electromigration modeling and layout optimization for. Electromigration refers to the gradual displacement of the metal atoms of a conductor as a result of the current flowing through that conductor. Because em is a strong function of current density, a smaller crosssectional area of interconnects can degrade the emrelated lifetime of ic, which is expected to become more severe in future technology nodes. Electromigration analysis of solder joints under ac load.
The parameter for temperature is the activation energy for the electromigration failure process. This model does not represent latchup failures and the actual. Pecht1,2 1center for advanced life cycle engineering calce university of maryland college park, md 20742 usa. Pan, and sung kyu lim 1 department of ece, georgia institute of technology, atlanta, ga 30332, u. Electromigration a brief survey and some recent results james r. Modeling of electromigration phenomena sciencedirect.
We project the via array electromigration em lifetime based on random via failure sequences, and demonstrate that the computed via array em lifetime distribution model correlates well with experimental results. Copper is both a better and more stable conductor than aluminum. Therefore, the need for reliability within ics drives research to make further development in avoiding electromigration failure. Study, analysis and modeling of electromigration in srams student name. With the advance of vary large scale integrated vlsi circuits and insatiate demand for miniaturization in the industry, electromigration reliability is studied widely. Failure mechanisms, such as electromigration, create reliability problems. Analyzing the electromigration effects on different metal. Electromigration overview for pb free solder systems. The most familiar are void failures along the length of the line called internal. Difficult though the transition was, it helped extend device scaling for another eighteen. Electromigration modeling and fullchip reliability analysis for beol interconnect in tsvbased 3d ics mohit pathak 1, jiwoo pak 2, david z.
Electromigration was not cause of concern until interconnects widths shrunk to the micrometer scale. Electromigration failure modes in aluminum metallization 1589 fig. Study, analysis and modeling of electromigration in srams. Electromigrationa brief survey and some recent results. Electromigration modeling and fullchip reliability. Although the electromigration phenomenon has been intensively studied on silicon level interconnect lines since the late 1960s, it. One famous result is the black s equation, which relates the electromigration mean time to failure to the inverse square of the current density. Its mechanisms are quite different compared to solidstate electromigration.
The process of electromigration is analogous to the movement of small pebbles in a stream from one point to another as a result of the water gushing through the pebbles. Electromigration failure modes in aluminum metallization. Investigation of electromigration reliability of solder. Abstractin this paper, we propose a model and an algorithm for calculating currents in multivia structures. Mediantimetofailure for aluminum film conductors as a function of current density, temperature, and cross sectional dimensions. The electro migration modeling the proposed electro migration flow application of the em flow to a leon3based case study system experimental results and discussion conclusion and hints for future work reduction of interconnect width and thickness with. The electromigration phenomenon is also challenging to model because it involves several driving forces and coupled equations as well as several diffusion paths. In addition to the solidstate electromigration process, socalled electrolytic electromigration can occur in electronic circuits, often on printed circuit boards pcbs. All conductors are susceptible to electromigration, therefore it is important to consider the effects the electrical current resulting from the. Electromigration electromigration is an electrochemical process where metal on an insulating material, in a humid environment and under an applied electric field, leaves its initial location in ionic form and redeposits somewhere else. Analyzing the electromigration effects on different metal layers and different wire lengths gracieli posser, vivek mishra y, ricardo reis, sachin s.
Najm integrated circuits business division ece department agilent technologies university of toronto fort collins, colorado 80525, usa toronto, ontario m5s 3g4, canada abstract the lognormal has been traditionally used to model. Black s equation is a mathematical model for the mean time to failure mttf of a semiconductor circuit due to electromigration. It has been shown that it is not possible to model electromigration induced early resistance changes completely based on the dynamics of vacancies only oneparticle model 20. Both modes involve mass transport by momentum exchange between. If the current density is high enough, there can be a momentum transfer from moving electrons to the metal ions that make up the lattice of the interconnect material. Failure mechanisms of insulated gate bipolar transistors. Electromigration induced material transport equations. The electromigration modeling the proposed electro. Very beautiful little girls from usa, canada, europe, asia and russia. The model parameter for current density is the exponent n to which the current density is raised in black s equation. Effects of solder mask on electrochemical migration of tinlead and leadfree boards xiaofei he1, michael h.
Electromigration of flip chip solder joints snpb vs. Starting from the early derivation of black s equation, we present the development of the models in. We then present various physical design constraints that affect electromigration. Electromigration failure models in aluminium metallization for semiconductor devices proc. Electromigration related damage in solder bumps is one of the emerging issues resulting from the fast scalingdown of features in semiconductor packages. Electromigration in gold interconnects by stephen kilgore. Since then, the formula has been getting popularity in. Thermomigration versus electromigration in microelectronics solder joints mohd f. Blacks equation for electromigration accelerated life testing. Ionic migration on printedcircuit boards espec corp. In this talk, we give an introduction to the electromigration problem and its relationship to current density. From black s equation to modern tcad models electromigration failure is a major reliability concern for integrated circuits. Ee143 f2010 lecture 16 17 electron flow moment transferred from electrons thermally excited metal atom out of lattice site metal lattice atomic potential position x electromigration motion metal atom at lattice site equilibrium electromigrated metal atoms move along the same direction of electrons.
Request pdf physically based models of electromigration. View all the girls in our interracial sex videos here. Black s equation for electromigration accelerated life testing. Black, member, ieee abstractrecently, electromigration has been identified as a potential wearout failure mode for semiconductor devices employ ing metal film conductors of inadequate crosssectional area. Electromigration and its impact on physical design in. Insulation resistance test copper and silver migration 5. Here is a constant based on the crosssectional area of the interconnect, is the current density, is the activation energy e. Black s equation for estimating the time to failure due to electro migration is a classic. Unique behavior or electromigration in solder joints 3. A statistical model for electromigration failuresy gilbert yoh and farid n. Methodology for electromigration signoff in the presence of adaptive voltage scaling weiting jonas chant, andrew b. Effects of solder mask on electrochemical migration of tin. The ultimate goal is then to use the model and the insights gained for failure prediction.
It causes a net atom transport along the direction of electron flow. Electromigration electromigration is the transport of material caused by the gradual movement of the atoms in a conductor due to momentum transfer driven by conducting electrons. The model was based on the suhirs interface stress equation coupled with the coffin manson equation. Stephen krause arizona state university december 20. Arzt, and nix, 1991 electromigration causes several different kinds of failure in narrow interconnect. Black s equation is an empirical model to estimate the mttf mean time to failure of a wire, taking electromigration into consideration. Electromigration failure modes in aluminum metallization for semiconductor devices abstracttwo wearout type failure modes involving aluminum metallization for semiconductor devices are described. Migration occurring on electronics components copper migration. James black explored and wrote about electromigration in aluminum metallization within semiconductors since 1969. Although black s equation provides useful insight into electromigration failure, it does not allow a thorough understanding of the underlying physics related to the electromigration behavior for which more sophisticated physically based models are required. Empirical onedimensional models are now not sufficient to optimize the design of advanced technologies and the use of numerical software to model electromigration has become mandatory.
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