Electromigration failure in au and joule heating induced. The microhotplate can be manufactured by a cmos compatible microelectronics process, e. Fast and automated electromigration analysis for cmos rf. Part of theelectrical and electronics commons this dissertation is brought to you for free and open access by the iowa state university capstones, theses and dissertations at iowa state. Latchup, esd, and other phenomena 5 the parasitic thyristor can be triggered by a rapid rise of the supply voltage. As device features reduce in ultralargescale integrated circuits, current densities increase with the metallization layer. The terms metal atoms and metal ions are considered equiv. Us6624499b2 system for programming fuse structure by. Electromigration what ic designers need to know industry. 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. Complementary metaloxidesemiconductor cmosbased integrated circuits use metal interconnect wires, which are made of.
Therefore, a large group of wires should fail immediately after power up. Electromigration test in order to determine their reliability over a period of time. In practice it is equal to the long wire failure time, for a given current density and temperature. One of the major hurdles towards achieving good interconnect performance is electromigration em, a physical wearout mechanism that occurs in metal wires carrying electrical current. Such migration may reduce isolation gaps and ultimately lead to an electrical short circuit. Electromigration is minimized by limiting current densities and by adding metal impurities such as copper or titanium to the aluminum. Electromigration is the transport of material caused by the gradual movement of the ions in a. Black developed an empirical model to estimate the mttf of a wire segment, taking electromigration into consideration 3.
Integrationreliability issues for culowk beol interconnects. Electromigration was not cause of concern until interconnects widths shrunk to. This density depends on the magnitude of forces that tend to hold the ions in place, i. Its generally considered to be a manufacturing problem.
Mar 02, 2015 this is another reason why void free gap fill is important, too. Electromigration mean time to failure mttf of leadfree solder joints subjected. In most of these processes, aluminium, tungsten or copper is optionally used as metallization. Electromigration and its impact on physical design in future. Apr 25, 2007 electromigration in ulsi interconnects article pdf available in materials science and engineering r reports 5812. Fast and automated electromigration analysis for cmos rf pa. Electromigration of flip chip solder joints snpb vs. Electromigration is an effect that occurs when an extremely dense electron flow knocks off atoms within the wire and moves them, leaving a gap at one end and high stress at the other. Ian grout, in digital systems design with fpgas and cplds, 2008. The ions will drift in the direction of the electron flow. European union parliament has a directive to ban the use of pbbased solders in consumer electronic products on july 1st, 2006. Electromigration is the result of the dominant force, that is, the momentum transfer from the electrons that move in the applied electric. Pdf electromigration em is one of the key concerns going forward for interconnect reliability in. Even within the fab, various job functions are segmented enough that variation in one part of the process, such as the photomask shop, doesnt necessarily come to the attention of the people doing deposition and etch or those polishing the wafers.
As the structure size in electronics such as integrated circuits ics. Interface electromigration is dominant for p in average drift velocity for 0. Modeling of electromigration in throughsiliconvia based 3d ic jiwoo pak 1, mohit pathak 2, sung kyu lim and david z. Jan 24, 2019 today, most design engineers dont pay much attention to variation. The book provides a comprehensive overview of electromigration and its effects on the reliability of electronic circuits. Synthesis of hazardfree customized cmos complexgate networks under multipleinput changes prabhakar kudva, ganesh gopalakrishnan, hans jacobson, steven m. Accelerated electromigration lifetest plots lognormal paper of al si2% alloys for different copper concentrations. Electromigration is the gradual displacement of metal atoms in a semiconductor. How to deal with electromigration semiconductor engineering. Electromigration em and thermomigration tm reliability of pbfree solder joints are emerging as critical concerns in advanced packages.
Electromigration inside logic cells modeling, analyzing and. Studies of electromigration behavior reveal that for both technologies, voiding is located above the tsv, in the adjacent metal level. A cmos circuit can fail from spatial or temporal unreliability effects. Cmos onchip temperature sensors for power management. Apr 02, 20 the microhotplate can be manufactured by a cmos compatible microelectronics process, e. Blech, electromigration in thin aluminum films on titanium nitride. Today, most design engineers dont pay much attention to variation. The parameter represents the minimum failure time for a wire under electromigration stress. The discontinuity of cu supply at alcuw interfaces account for most of the reduction in the electromigration resistance of w stud chains. It covers electromigration, methodologies for electromigration aware design for analog and digital circuits, and methods for mitigating electromigration during the physical design, all in depth. In a chip, the formation of such a void will cause an open circuit and result in a failure. The magnitude of the gate voltage may be used to conffol the programming current flowing through the efuse.
This thesis is brought to you for free and open access by lehigh preserve. Electromigration em in onchip metal interconnects is a critical reliability failure mech. Apr 11, 2018 electromigration is the gradual displacement of metal atoms in a semiconductor. Gignac, amc 2007 cu resistivity increases as cu wire area decreases. The efuse may be programmed by either thermal rupture or by electromigration of cosi2 and dopants in the polysilicon. Reason for electromigration is increase in current densities in net, which often occurs when strong cell drives thinner net in ctn clock tree network or in. It introduces the physical process of electromigration, which gives the reader the requisite understanding and knowledge for adopting appropriate counter measures. Cmos maintenance common causes of loosing cmos data are battery run out, dirt, faulty power supply, electrical surges, and chip creeps the cmos settings can be checked by memorizing settings, using optimized defaults, and backing up a copy of the cmos to backup your cmos to a floppy, use a thirdparty program such as cmossave. 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. The most familiar are void failures along the length of the line called internal. In freeelectronlike metals the windforce contribution is expected to be.
The present invention provides a system, apparatus and method of programming via electromigration. Electromigration em and thermomigration tm reliability of pb free solder joints are emerging as critical concerns in advanced packages. Electromigration a phenomenon known as electromigration can occur when a high current level flows in a track. In case of usual thin metallization level, void nucleation and cu diffusion under electromigration occur at the capping layer, leading to expect. Theory of electromigration electromigration is the transport of material in a conductor under the influence of an applied electric field. Electromigration is the mass transport of a metal due to the momentum transfer between conducting electrons and metal atoms. The amg converts human based em modeling into an automated modeling and simulation process with the help of ansys parametric design language apdl program.
Pdf introduction to electromigrationaware physical design. All conductors are susceptible to electromigration, therefore it is important to consider the effects the electrical current resulting from the applied field may have on the conductor. An accelerated test method for electromigration in. This book describes new and effective methodologies for modeling, analyzing and mitigating cellinternal signal electromigration in nanocmos, with significant circuit lifetime improvements and no impact on performance, area and power.
Electromigration em refers to the unwanted movement of materials in a semiconductor. It occurs when the current density is high enough to cause the drift of metal ions in the direction of the electron flow, and is characterized by the ion flux density. Electromigration aware cell design semantic scholar. This effect often was observed in earlier generations of cmos circuits. Electromigration in ulsi interconnects article pdf available in materials science and engineering r reports 5812. Test done at 220c and a current density of 10 6 acm 2.
For automating the neural model training process, trainingdriven adaptive sampling. Electromigration would be faster in the hot region and very slow almost stationary in the cold region since it is a thermally activated process. Pdf electromigration aware cell design semantic scholar. Conventionally, as a standard the electromigration test is carried out in three steps using four commercially available tools. Additionally, the thyristor might be triggered by a high supply voltage far higher than the value given in data sheets. Evans, erik brandon, victor white, emily wesseling, and udo lieneweg jet propulsion laboratory backgroundmotivation electromigration is the. Electromigrationinduced interconnect aging and its. A phenomenon known as electromigration can occur when a high current level flows in a track. Reliability wearout mechanisms in advanced cmos technologies. The lifetime of w stud chains is less than a half of that of alcu flat lines. He is the author of numerous technical papers and tutorials and holds five patents.
All conductors are susceptible to electromigration, therefore it is important to consider the effects the electrical current resulting from the. Rarely, one can find a book with such scope and such practical applications. Electromigration modeling and layout optimization for. Fundamentals of modern vlsi devices learn the basic properties and designs of modern vlsi devices, as well as the factors affectingperformance,withthis thoroughlyupdatedsecondedition.
Electromigration reduction in microhotplates cambridge. Arzt, and nix, 1991 electromigration causes several different kinds of failure in narrow interconnect. Both high current density and joule heating make electromigration em and thermomigration a reliability issue for solder. Oates and lin found that grain boundary diffusion increases with the polycrystalline fraction p of the film. Electromigration in lead free solder joints under high frequency pulse current. If the current density amount of electrical current flowing per crosssectional area, am 2 is high, then electromigration is the gradual movement of the ions in a conductor due to the momentum transfer between conducting electrons. Modern design rules necessarily push the limits for.
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. A semiconductor fuse which includes a cathode and an anode coupled by a fuse link having an electrically conductive component, such as silicide, is coupled to a power supply. Electromigration in submicron interconnect features of integrated. Lifetime is affected by grain size, grain morphology and bend structure in submicron metal lines. 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 and thermomigration reliability of lead. Electromigration em is a critical problem for interconnect reliability in advanced vlsi design.
The damage induced by electromigration appears as the formation of voids and hillocks, resulting in electrical discontinuity. Ieee wmed impact of electron scattering in nanoscale cu wires extracted cu resistivity vs. Design, automation, and test vlsidat, 20 international symposium. The atoms pile up at the anode, voids are generated at the cathode. Electromigration inside logic cells modeling, analyzing. This additional step introduces delays in the final taping out of the chip. When electrons are conducted through a metal, they interact with imperfections in the lattice and scatter. Jan 29, 2017 this paper presents fast and automated electromigration em reliability modeling by using automated modeling generation amg algorithm. Electromigration and its impact on physical design in.
Pdf electromigration is increasingly relevant to the physical design of electronic circuits. Digital circuit wearout due to electromigration in. Cmos onchip temperature sensors for power management chen zhao iowa state university follow this and additional works at. Based on previous electromigration research 15, i have created a tool chain that identifies where electromigration is likely to occur in largescale integrated circuits. Electromigration failure in au and joule heating induced oxidation in cu conductors jose a. Jul 24, 2001 electromigration is an effect that occurs when an extremely dense electron flow knocks off atoms within the wire and moves them, leaving a gap at one end and high stress at the other. Stress mechanics wikipedia, the free encyclopedia, 2014. Pdf electromigration and its impact on physical design in future. Modeling of electromigration in throughsiliconvia based 3d ic. This paper presents fast and automated electromigration em reliability modeling by using automated modeling generation amg algorithm. A potential is applied across the conductive fuse link via the cathode and anode in which the potential is of a magnitude. A statistical model for electromigration failuresy. Electromigration overview for pb free solder systems.
Electromigration is the transport of material caused by the gradual movement of the ions in a conductor due to the momentum transfer between conducting electrons and diffusing metal atoms. Rauch, iii, phd, is currently a senior technical staff member at the ibm srdc in new york, where he specializes in hot carrier and nbti reliability of stateoftheart cmos devices. If the current density amount of electrical current flowing per crosssectional area, am 2 is high, then electromigration is the gradual movement of the ions in a conductor due to the momentum transfer between. Aluminium is by far the cheapest but it is worst in terms of electromigration. Electromigrationinduced interconnect aging and its repercussions on the performance of nanometerscale vlsi circuits.
It causes a net atom transport along the direction of electron flow. Electromigration was discovered more than 100 years ago and it has been a problem ever since. But is this enough to discard the traditional lognormal in favor of the sln. Electromigration is due to the momentum transfer from the electrons moving in a wire. Unique behavior or electromigration in solder joints 3.
Electromigration in leadfree solder joints under high. 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. Electromigration and thermomigration reliability of leadfree. Electromigration and blacks equation electronics world. Complementary metaloxidesemiconductor cmosbased integrated circuits use metal interconnect wires, which are made of aluminium and, more recently, copper, to. For automating the neural model training process, trainingdriven adaptive sampling is applied to.
Study, analysis and modeling of electromigration in srams. Colon california state university at northridge rosa leon, duc t. In the above case, surface scattering is the major factor. Fundamentals of electromigrationaware integrated circuit.
It covers electromigration, methodologies for electromigrationaware design for analog and digital circuits, and methods for mitigating electromigration during the physical design, all indepth. This is another reason why voidfree gap fill is important, too. Pan 1 ece department, the university of texas at austin, austin, tx 78712, u. Electromigration in leadfree solder joints under high frequency pulse current. The effect is important in applications where high direct current densities are used, such as in microelectronics and related structures. Electromigration is a phenomenon, it can lead to opens and shorts due to metal ion displacement caused by the flow of electrons in metal, which can lead to functional failure of ic device. The authors are the first to analyze and propose a solution for. Due to the decrease in device size and increase in current density, electromigration has now become the most serious reliability problem in flip chip solder joints, especially pb free solder joints.
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