Electromigration copper activation energy

Electromigration copper activation energy

Therefore, the overall electromigration resistance is lower Failure due to electromigration of a single wire is usually expressed by Blacks equation [1]: (1) 2 where A is a material constant, J is the current density, Ea is the activation energy, k is the Boltzmann constant, and T is the temperature. In general, dislocations drift velocity estimation with line sections in SEM (so-called BLECH-experiments) to determine the EM activation energy; thermal cycling under EBSD observation or with similar layer stress measurements (wafer curvature method) study of alloying effects on electromigration characteristics of CuX lines (X = Ag, Al) The results indicated that although the failure time of Ni-silicide migration mode is lower than that of Cu-line depletion mode for a shorter Cu line at a higher stress temperature, Ni-silicide migration with a higher activation energy (similar to 1. Activation Energy and the Arrhenius Equation. Boltzmann constant. Electromigration (EM) is a mass transport phenomenon resulting from the We show that this methodology allows the calculation of activation energies, early Due to the continuous downscaling of interconnect linewidths, copper is starting  Cross-section-area- dependent constant. 2 eV for Cu lines, indicating grain boundary paths for electromigration. E e-. 7 eV) results in a longer EM lifetime at a lower operation temperature. 9um cubes separated by 0. I. 1 eV was measured in PVD-Cu layers leading to significant improvement over AlCu technology: lifetime Despite the various advantages of copper, the electromigration lifetime of a copper film depends strongly on the processes used to form the copper film. The surface diffusion  F. Then a conclusion on how Black’s equation could use with nanoscale technologies to predict the time during the occurrence of electromigration. Ea is the activation energy of metal ions, T is the temperature of the interconnect, and k is Boltzmann constant. May 05, 2011 · Whereas on LTCC substrates the activation energy of E a~ 0. [9] This is mainly due to the higher electromigration activation energy levels of copper, caused by its superior electrical and thermal conductivity as well as its higher melting point. It is usually used in the context of chemical reactions, i. (usually set to   Electromigration life tests on Al. The incorporation of calculated electromigration force into the interatomic forces in molecular dynamics enabled the simulation of the diffusion process under the effect of culated activation energy upon alloying is very similar to the electromigration. 9 to 1. 94 ± 0. In general, the activation energy of copper and brass are not a function of any cold work done to the material. The effect is important in applications where high direct current densities are used, such as in microelectronics and related structures. The apparent activation energy of the overall reaction was found to be 51. Electromigration experiments were performed on passivated damascene copper interconnects with 1 μm linewidth. Rudack and A. Brian Joseph Setlik, University of Rhode Island. 4 Laboratory stressed samples The energy needs to initiate the reaction is known as Activation energy. The minimum energy necessary to form a product during a collision between reactants is called the activation energy (E a). Diebold Journal of Micro/ Nanolithography, MEMS, and MOEMS (2013) The use of silicide interconnects in VLSI circuits is becoming common. The electromigration (EM) effect describes atomic diffusion in conductors driven by electric currents, which may lead to the formation of voids and hillocks at the cathode and the anode, respectively. References 9 and 10 provide thoughtful discussions of different types of voids in copper, both with cross-sectional images. Finite element modeling on electromigration of solder joints in wafer level packages P. 0 eV, for this interface [13,34]. Since it appears that copper will also be used at 7 nm, the benefits and challenges of copper must be taken into consideration for the foreseeable future. Introduction and Background (Blech effect) [7]. The activation energies of Cu/SiLK and Cu/oxide were found to be 0. The apparent effective valence (Z*) characterizing electromigration was measured to be −5. 16 energy. e. 9 eV for the. For crystallization of copper, the Kissinger activation energy obtained from the DSC data corrected for thermal inertia is 34% larger than the value estimated from uncorrected data. S. The areas discussed include: electromigration; failure models; annealing; current density; activation energy; copper consumption and current stressing. Activation energy for electromigration. Once voids nucleate, copper can migrate through them. Electromigration is actually not a function of current, but a function of current density. Pan 1 ECE department, The University of Texas at Austin, Austin, TX 78712, U. 1. Moreover, if In this work, a cold wall, single wafer, CVD tungsten reactor was used for the deposition of copper with Cu(I)(hfac)(tmvs). Diaoc a Department of Mechanical Engineering, Lamar University, PO Box 10028, Beaumont, TX 77710, USA The activation energy E a of electromigration of Ta/Cu/Ta multilayer interconnects is 0. 81 eV, respectively. In contrast, PSD analysis can determine the new material's activation energy fairly quickly. g. II. 87 Effective charge number Z* - –4 Pure copper wires can withstand approximately five times more current density than aluminum wires while maintaining similar reliability requirements. If the resulting force in the direction of the electron wind (which also corre-sponds to the energy transmitted to the ions) exceeds a given trigger known as the activation energy E a, a directed diffusion process starts. 9 eV and the threshold product of current density and line length was found as 2500-3000 A/cm. 1um-thick grain boundaries, both The factor, e -E a RT, in the Arrhenius equation is the proportion of molecules with energy equal to or greater than the activation energy. C. edu Abstract-Electromigration (EM) is a growing reliability concern in sub-22nm technology. The copper damascene process is widely established and has brought higher performance to semiconductor devices. Can anyone help me understand where they may have got these figures e. The activation energy of EM for Cu multilayer on polyimide is smaller than that reported in literature for Cu multilayer on SiO 2. NOTE The activation energy is used in the Arrhenius equation for the thermal acceleration of physical reactions. 7 to 1. 61 Sep 21, 2016 · Finally, as copper replaces aluminum, new and different EM challenges are emerging at advanced nodes. 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. The activation energy for the GB diffusion is 1. 2. pathways gets smaller, the activation energy threshold needed to stimulate electromigration also decreases, and becomes significantly lower when the width falls below 30nm. As is obvious from Equation (1), the MTTF due to electromigration depends on two factors that can be structures for electromigration testing and the packages were assembled on test cards. Although copper is expected to be much more electromigration resistant than aluminum owing to its smaller bulk diffusivity, the different metallization scheme between the two interconnect material Dec 13, 2000 · The addition of copper to aluminum thin films has previously been shown to reduce the rate of electromigration failure considerably. Substitute for D, for T, and for R. M. soluble and requires a low activation energy to initiate the migration process. 4±1. The diffusion coefficient D depends negative exponentially on the activation energy EA and the reciprocal of the temperature T. 0 eV suggests a similar mass transport mechanism that can be attributed to interfacial diffusion. The activation energy over the range of 83–174 °C is The activation energy for EM in Cu and the EM lifetime of the Cu interconnect decreases with an increased degree of plasma treatment. Cu) have lower activation energy MTF ∝ 1 J2 exp E A kT ⎛ ⎝ ⎜ ⎞ ⎠ ⎟ J =current density E A = activation energy MTF =mean time to failure Electromigration activation energy is measured by a built-in sensor that detects the real temperature during current stressing. (continued on J. Two activation energies are obtained suggesting a surface electromigration mechanism at low temperature (140–190 °C) and a combined migration mechanism at high temperature (190–230 °C). Thus, high density of Joule heating and high-speed diffusion of copper atoms along low crystallinity grain boundaries accelerated the EM degradation of the interconnection. 5~0. Now if one uses the last equation in the antepenultimate equation, it can be seen that the ion flux is of T -dependent. Publication: Sep 03, 2019 · Since Ruthenium is resistant to electromigration, conventional testing would take a very long time and require significantly higher temperatures and current densities. 9eV, and seems to be based on empirical data. . This can be activation energy for the velocity of surface scratch motion on bulk materials \. 8 to 1. ” Activation Energy Formula Where. It is observed that resistance of a solder joint is not just a function of the temperature but also a function of the current density. A. R. Hence, the activation energy for copper in silicon is. Time to opens failure by resistance increase follows Black's equation with current exponent n=1. 55 Electromigration in Submicron Wide Copper Lines p. It is shown that activation energy in the Cu/BCB architecture is quite low, and copper migration might preferentially occur at Cu/barrier and/or Cu/BCB interfaces. In our TSV model, we construct a simplified regular grain structure on the TSV and wires. Cu/Ta and TaN/Cu/TaN structures report a 2-fold higher activation energy and a 10-fold longer lifetime for the former, thus confirming an important role of the interface between Cu and the cap and/or barrier. T = absolute temperature. Thus, electromigration is easily observed in Al metal lines that are subjected to high current densities at high temperature over time. This has the effect of passivating the surface, so surface diffusion is very low. For n=1, the time-average current Cu into polyimide and retards the degradation of the polymer dielectric. 2 eV for Cu lines, indicating grain boundary paths for electromigrationo The surface diffusion   Investigation of the activation energy (Ea) of electromigration (EM) is one of the For instance, an activation energy (Ea) of ~ 0. The rate The activation energy for dislocation nucleation at a crack 335 energy (ARGON, 1987). 8 eV for both (111) and (200) CVD Cu films. MTTF-Activation energy dependency Interconnect material is the dominant factor that determines the value of E a. Biderman et. The testing is being done using five (5) stress conditions (combination of current and temperature) to estimate the current density exponent, n, and the activation energy, Ea, parameters for Black’s equation. 0+0. The activation energy for diffusion was found to be 0. Jan 14, 2000 · Read "Microstructure and electromigration in copper damascene lines, Microelectronics Reliability" on DeepDyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Copper films with a Ta diffusion barrier show clearly different behaviors. Film growth rates were between 100 to 800 A/min depending on processing conditions, and an Arrhenius type activation energy of 16. 29 Mar 2009 formation by electromigration. 2 at 350 °C. The drift experiment led Blech (1976) himself to discover a quantitative mechanical effect on electromigration. Abstract: - This paper summarizes the electromigration properties of thick copper lines embedded in BCB in BICMOS technologies. An activation energy of 1. Activation energy of electromigration damage was determined as 1. The activation energy of electromigration is about 0. The current exponent n determines whether the shape of a current waveform affects EM lifetime [4]. Influence of Temperature Gradient on the Electromigration - Failures in 3D activation energy, eV. Temperature. The small thermal conductivity of polyimide causes a tempera-ture gradient and accelerates the electromigration process. 9 eV is obtained for the Cu width  Activation energy for electromigration in Cu films. EM can increase wire resistance, which can cause voltage drop resulting in device slowdown; it can also cause permanent failures in circuits due to shorts or opens. In Eq. 327 x 10-18 J/atom (or 2. a is the activation energy, k is Boltzmann constant, T is the absolute temperature in K. aEM is the activation energy, and n is a constant. W. For copper and brass (which is mostly copper), the activation energy E is, E = 0. Detailed EMA using standard and novel SEM Electromigration is the transport of material caused by the gradual movement of the ions in a is the effective activation energy of the thermal diffusion of metal atoms. Failure analysis showed that both copper-silicon nitride cap layer interface and the copper grain boundary were active diffusion paths. Using the proper seed layers, either (111) or (200) textured CVD Cu films with similar grain size distributions have been obtained. (1) below, where A is constant, j is current density, n is a model parameter for current density, Q is the activation energy, k is Boltzmann™s constant, and T is the average bump temperature. Fana,*, Y. Nowadays copper/low-K dielectric material has been rapidly replacing aluminum alloy/SiO2-based interconnect. and electromigration (EM) [14] [30] [31]. 8 Nov 2016 The preliminary electromigration studies on the TaN/Cu/Ta and twofold higher activation energy and a tenfold longer lifetime for the former,  CA. electromigration-robust than aluminum. From your measurements of weight gain determine the rate constant at each temperature together with n the rate exponent. 94 eV. Small electromigra - tion voids in copper will be located along a surface. Electromigration characterization of aluminum -copper alloy interconnects. Scaling factor. Sapatnekar ECE Department, University of Minnesota, Minneapolis, MN Abstract—Electromigration (EM), a growing problem in on-chip in-terconnects, can cause wire resistances in a circuit to increase under activation energy obtained for Cu electromigration in this study and other studies [8,12,16–20] suggests that lattice and grain boundaries are not the major paths for electromigration in Cu. Previous work on Al single-crystals without Al3Ti overlayers resulted in an acti-vation energy of 0. This is mainly due to the higher electromigration activation energy levels of copper, caused by its superior electrical and thermal conductivity as well as its higher melting point. Since the Ta/Cu/Ta specimen has enhanced crystallographic texture and larger grain size, it has both higher electromigration endurance and thermal stress resistance than Cu. 75 eV is similar to other face centered cubic metals such as silver, the higher activation energies of about E a~ 1 eV on glass and alumina indicate a suppression of back diffusion especially at enhanced temperature levels. Migration occurring on electronics components Ea = Activation energy ( Glass Epoxy PCB = 1eV) The paper reports on electrical resistance measurements of the activation energy for EMD (electromigration damage) in Cu films as determined by an isothermal annealing method carried out under high vacuum conditions. 39-46 11 Electromigration and Current Density Black‘s Equation [1]: Mean time to failure of a single wire due to electromigration ⋅ = ⋅ k T E J A MTTF a n exp Cross-section-area-dependent constant Activation energy for electromigration Temperature The electromigration (EM) activation energy ( $\text {E}_{\text {A}}$ ) of alternative metals, such as Ru and Co, was obtained using low-frequency noise (LFN) measurements. The intermetallics form and segregate to grain boundaries during an annealing process to reduce copper atom mobility. A model is presented which attributes the increase in activation energy (about 0. For example, the activation energy required to create failures, due to electromigration of a copper film, typically ranges from 0. Dandua, X. 6 eV. the effective vation energy for electromigration-induced failure was determined to be 0. Pure copper wires can withstand approximately five times more current density than aluminum wires while maintaining similar reliability requirements. APPLIED PHYSICS REVIEWS—FOCUSED REVIEW Recent advances on electromigration in very-large-scale-integration of interconnects K. PECVD Si Nitride) Multilevel Metallization Components EE143 – Ali Javey Interconnect Resistance RI =R/L = / (WAlTAl) Interconnect-Substrate Capacitance CV C/L = WAl ox / Tox Interconnect electromigration, and (b) the flow-rate was ~10 4 times larger than observed in solid state. With this limitation in mind, various crystals were classified as ductile or brittle based on the outcome of this calculation. 94 eV, suggest that the electromigration in copper proceeds via an interfacial diffusion path. In addition, the Ni layer changes the electromigration failure mode. 0 eV. edu. Activation Energy, usually denoted by its symbol Ea, is defined as the minimum amount of energy required to initiate a particular process. The activation energy for Cu diffusion in CNT–Cu composite was estimated, from slope of Fig. These were attributed to (i) the larger scattering cross-section of atoms in liquid state, and (ii) the higher mobility of liquid atoms due to the low activation energy of self diffusion. The activation energies for eutectic SnAg and SnPb solder bumps are electromigration (grain boundary diffusion has a lower activation energy than bulk diffusion so electromigration occurs at lower temperatures) Al forms a very tough oxide (Al2O3), which is almost lattice-matched to the parent metal (Al). 98 ± 0. EE143 F2010 Lecture 16 12 ðœ ðœ ðß ðø ðŒ ðŒ ðº ðØ ð÷ ð÷ ðł ðö ðç ðç ðŁ ðæ ð= s B c h N m ðeðf ðr 2 * exp Approaches to lowering of contact resistance: 1) Use highly doped Si as contact semicodnuctor 2) Choose metal with lower Schottky barrier height ðfB is the Schottky barrier height N = surface doping activation energy (E a): The excess free energy over the ground state that must be acquired by an atomic or molecular system in order that a particular process can occur. E. 65eV). There are several reasons for the increase in electromigration resistance: As most mass transport in Al occurs along grain boundaries, the addition of Si and Cu reduced the grain boundary diffusion rate, by increasing the activation energy of grain-boundary diffusion. d'Heurle. where t 50 is the mean time to failure, A is a constant, j is the current density, n is a current density exponent, E a is the activation energy of the failure mechanism, k is Boltzmann’s constant, and T is the temperature. 77eV, which is higher than that of Cu monolayer interconnects (0. Usually the first term can be assumed to be negligible [4]. The electromigration lifetime is measured for a large number of copper Carl Thompson is profiled on MIT News. Keywords: activation energy, current density, electromigration, interconnects, integrated circuits, electromigration in aluminum, copper, and solder joints. Suo# *Intel Corporation, 5200 NE Elam Young Parkway, Hillsboro, Oregon 97124 #Division of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138 Abstract. 1). 2. The activation energy is the energy required to start a reaction. Aluminum was the typical material used for interconnects before copper was first introduced in 1997 [6]. Migration via interfacial diffu-sion paths, such as surface diffusion, may play an important role in Cu electromigration. (1), the second term is the most dominant one that is affected by the current density ~j, while other two factors are of secondary importance. Chapter 1. where Q is the activation energy for the process, R the gas constant and T the absolute temperature. Therefore, the lower an activation energy is to reach the transition state, the higher the rate constant will be. Electromigration depletes the cathode and accumulates atoms near the anode, inducing a net volume contraction and expansion, respectively. The article consists of a Powerpoint presentation on current density dependence of electromigration induced flip-chip Cu pad consumption. In the present work, we report on electrical resistance measurements of the activation energy for EMD in Cu films as determined by an isothermal annealing Copper is a possible substitute for Al in very large scale integration interconnects because of its higher resistance to electromigration damage (EMD) and its lower electrical resistivity. Because the reaction time is longer, the rate constant is lower. Copper, zinc, and lead will also migrate, although only under much more severe conditions. Carl Thompson, the Stavros Salapatas Professor of Materials Science and Engineering, is the co-director of the newly organized Materials Research Laboratory at MIT. In the Cu/Ta sample, Ta starts to diffuse up to the surface via fast-diffusing grain boundaries (GBs) after annealing at 500 °C. 7eV and 1. strings of text saved by a browser on the user's device. Jul 02, 2013 · Therefore, according to Black's equation, increasing the activation energy allows for a higher tolerance for current density, and thus, a greater resistance to electromigration. Temperature-dependent electromigration measurements have been performed and a model incorporating Joule heating is used to describe those. 15,16 In those studies, the surface reaction was assumed to be the rate-limiting Activation Energy for Electromigration Failure in Aluminum Films Containing Copper D'Heurle, F. 1 eV has been reported . Fig. 8±0. Activation Energy for Electromigration in Aluminum Films Alloyed with Copper. KahngH and Siddhartha Nath+ TECE and +CSE Departments, UC San Diego, La Jolla, CA 92093 {wechan, abk, sinath} @ucsd. \-as determined by the Rens- selaer group to be identical to the activation energy for the lattice self-diffusion of the metals. aluminum and copper. 2 eV for Cu lines, indicating grain boundary paths for electromigrationo The surface diffusion was found to play a role during At temperatures in the range from 100 to 200°C the activation energy for electromigration has been found to have the same value for both the pure and the copper-alloyed samples, namely, 0. Where does “0. t. As a result, the gradient in atomic density will drive atoms back to the cathode. Electromigration • Copper added to aluminum to improve lifetime (Al, 4% Cu, 1% Si) • Heavier metals (e. “Activation Energy is the minimum amount of energy that is needed to start a chemical reaction. An activation energy for diffusion between 100 and 180meV is found. 0 eV/atom). 7eV to extrapolate High T Operating Life test data to use conditions for every kind of electronic component (from complex ICs to simple passives). 1eV [9]. In this same study, it was also observed that the mass transport during electromigration occurred preferentially through the grain boundaries and the surface of the conductor and could be measured through their activation energies: 2 PUBLICATIONS IN REFEREED SCIENTIFIC JOURNALS I. Tu Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, cal resistivity, vacancy diffusivity, vacancy diffusion activation energy, and effective valence. BTl degrades chip performance by slowing down device switching speeds in critical paths. anodically very soluble and requires a low activation energy to initiate the migration process. 2 Calculation of Drift Velocity Thermal Activation Energy. 2 New Electromigration Behaviors in Cu Interconnects . 97 copper sample would move towards the cathode when high current densities were. Black’s equation for estimating the time to failure due to electro migration is a classic. is it the migration susceptibility of say copper or tin ? Pure copper wires can withstand approximately five times more current density than aluminum wires while maintaining similar reliability requirements. Using all the rate constants, k, determined by the class plot a graph that will enable the activation energy to be determined. such as solder capped copper A Black-type electromigration time to failure equation is developed to describe the time to failure versus current density and temperature. 76 eV to 0. This is mainly due to the higher electromigration activation energy levels of copper caused by its superior electrical and The electromigration (EM) reliability of porous methylsilsesquioxane (MSQ)/ copper low dielectric interconnects was investigated. By comparison, the activation energy for metal organic chemical vapor deposition (MOCVD) using copper(II) hexafluoroacetylacetone, Cu(hfac)2, has been reported to be ˘75-80 kJ/mol. Kong, J. They tend to use a figure between 0. The grains are 1. Lifetime measurements demonstrate that the drift velocity and the activation energy for mass transport along an interface correlate with the measured Sep 24, 2007 · Physics Based Modeling of Electromigration-Induced Degradation Phenomena in Copper Interconnects. Electromigration and Stressmigration Failure Mechanism Studies in Copper Interconnects Armin H. To meet performance requirements, design teams overcome The present invention provides an alloy seed layer and laminated impurities to incorporate indium, tin, titanium, their compounds with oxygen, and their complexes with oxygen, carbon, and sulfur into other films. Park and R. electromigration is the use of alloys, which tend to increase the activation energy and reduce the mobility of the grain boundaries [7], [9]. 7eV” come from? Most manufacturers are still using an Arrhenius law (shouldn’t we rather call it “Erroneous law” ? ;-) with an activation energy of 0. 8 pm (4 ) Activation energy of 0. The activation energy of 0. 7 were obtained. R = gas constant. Carbon atoms are selectively deposited onto a copper layer of the interconnect structure by a deposition process to form a graphene cap. E technology such as replacing aluminum with copper,. This method allows to model the EM behavior for realistic three-dimensional nanoscaled interconnect Cu lines. electromigration despite the fact that these wires are very narrow [3]. The graphene cap increases the activation energy of the copper, thus allowing for higher current density and improved resistance to electromigration of the copper. 164 Electron current flowing in the tungsten (W) via into the aluminum-copper (Al-Cu). Vook. 5eV and 0. This is mainly due to the higher electromigration activation energy levels of copper, caused by its superior electrical and thermal conductivity as well as its  Activation energy of electromigration damage was determined as 1. Copper wires can withstand approximately five times more current density than aluminum wires while assuming similar reliability requirements. For example, no Cu diffusion has been seen in silicon nitride at 450–500 Cafter1h[18]. Lienig: An Introduction to Electromigration-Aware Physical Design, ISPD 2006, pp. The proposed talk will discuss a current status of our physics-based numerical simulations regarding the stress evolution during EM in dual-inlaid copper interconnect, and the capability to predict the sites for void nucleation and to describe a void movement and growth. However, the rate of migration is much smaller, by a factor as large as 100, in the copper-bearing samples. nctu. Low-K dieletric) (e. If we know the rate constant The activation energy Q in narrow (<1µ) Copper lines is dominated by surface transport [18] and is ˘0:5 eV [19], k B is the Boltzmann’s constant, and T m is the metal temperature. E a = activation energy. A good adhesion has been observed between copper and tantalum, so that a high activation energy, about 2. This difference drops to 8% and becomes statistically insignificant when the fastest heating rate used is decreased to 10 K min −1 . We report life test results for two geometries of Al-Si-Cu to TaSi2 contact windows. It was concluded (Copper and silver migration) 5. 43 Activation Energy of Electromigration in Copper Thin Film Conductor Lines p. Mar 02, 2015 · The polycrystalline structure of very narrow copper lines also introduces another electromigration pathway. Rather, they are intrinsic properties of the metal. ) Figure: Activation energy Qe of the electromigration in various metals as a function of the melting point of the metals. Electromigration occurs only at Feb 17, 2005 · One of the figure used in the Arrhenius equation is the activation energy. The activation energy in the range of 0. 25 In Situ UHV Electromigration in Cu Films p. A failure criterion of 2% change in initial resistance was used for EM rather than the traditional 20% used for aluminum interconnect. 31 Electromigration and Diffusion in Pure Cu and Cu(Sn) Alloys p. , as the minimum amount of energy that chemical reactants must possess before they can undergo a chemical reaction. Keywords: Metallization, Copper, Silver, Tantalum, High tempreture, Diffussion, Electromigration, Stability For other alloy systems, the plots lie in the shaded area. Black’s equation indicates that larger current density results in shorter EM lifetime. 9 kJ/mol. The Impact of Electromigration in Copper Interconnects on Power Grid Integrity Vivek Mishra and Sachin S. 9 × 10-14. CiteSeerX - Document Details (Isaac Councill, Lee Giles, Pradeep Teregowda): We have studied the effect of texture on the electromigration lifetime of CVD Cu. 3 eV) caused by copper to the dissolution of Al2Cu Electromigration in Gold Interconnects by Stephen Kilgore A Dissertation Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy Approved November 2013 by the Graduate Supervisory Committee: James Adams, Co-chair Dieter Schroder, Co-chair Craig Gaw Stephen Krause ARIZONA STATE UNIVERSITY December 2013 Copper electromigration occurs more predomi-nantly between the copper and the barrier liner, not at triple points as for aluminum. This is mainly due to its higher electromigration activation energy levels caused by its superior electrical and thermal conductivity as t 50 is the time for 50% of the lines to fail, j is current density, k is Boltzman’s constant, Ea is activation energy (in eV), and T is the temperature in degrees Kelvin) Requires determination of both Ea (the activation energy for electromigration) and the exponent on the current density term (n), which is dependent on current density. Not Available . 1/f noise can serve as a very sensitive indicator for electromigration damage: The 1/f noise level is increased by up to two orders of magnitude whereas the resistance of the damaged interconnects is enhanced by less than a factor of two only. 1 kcal/mole was obtained in the temperature region of 150-180 °C. C. In our work, which focuses on (AC) signal EM, we use the root mean square (RMS) current density. However, little has been published on the aluminum to tantalum silicide contact window reliability. The activation energy for void formation is lower at grain boundaries than in the bulk. The addition of Cu to the Al alloy, Dec 04, 2018 · The more activation energy that is required to reach the transition state, the longer it takes to create a chemical reaction. COPPER RESISTIVITY When considering the resistivity of a metal line, three main components must be included: Activation Energy . Un-capped Cu is electrically stable up to 800 °C. 2–0. Abstract. It is also accelerated by elevated temperature. For copper, n has been reported with values between 1 and 2 [1] and E aEM varies between 0. 6 eV and the current density exponent of 2. The effective “activation energy” for failure time has been found to be a function of the concentration of copper. A wide range of activation energy values were obtained depending upon barrier layer (Ti or TiN), Cu deposition technique (PVD or CVD process) and grain size. Since the activation energy for the uncatalysed decomposition of hydrogen peroxide is 75 kJ mol-1, 5 the proportion at 25°C is equal to e-75000/(8. 8 Feb 2006 Copper interconnect electromigration (EM) was examined in various structures and The activation energies of failure modes were calculated. The diffusion coefficient and the activation energy are dependent on the nature of the   31 May 2016 Silver-tin solders have a higher activation energy for electromigration than lead- tin solders, as silver helps to stabilize the tin microstructure. 03 eV. Due to its generally higher activation energy, copper has a significantly better electromigration resistance than Jul 23, 2013 · The Cu diffusion coefficient (D*, related the ease of electromigration) was calculated from the activation energy by: where D 0 is the diffusion coefficient at infinity 17 . The simulation and experimental results illustrate that the addition 3-µm-Ni layer is able to reduce the maximum current density and hot-spot temperature in solder, resulting in a longer electromigration lifetime. Electromigration and Reliability of Thin Film Metallizations for Microelectronic Devices 1. and J. tw Resistance saturation was observed with exponential time constant corresponding to vacancy diffusivity. silicon nitride exhibits good barrier properties against copper diffusion [18]. 24 Sep 2007 10:15 - 10:50, Void Dynamics in Cu Interconnects the current exponent, n, the activation energy, ΔH and a constant A. Dislocation diffusion has a similar activation energy to grain boundary and. Most other common electronic materials are not susceptible to migration: iron, nickel, and tin because of their low solubility in Activation energy of electromigration damage was determined as 1. INTRODUCTION The CdS/Cu2 _ a S solar cell is a candidate for large scale solar energy conversion. tanford University 10 EE311 / Al Interconnects araswat Materials Composition Electromigration: Material and Composition Adding Cu to Al decreases its self diffusivity and thus increases resistance to electromigration Materials with higher activation energy have higher resistance to electromigration E a (e V) Temperature (K) Cumulative failure Standards & Documents Search. 6 Mar 2019 Lastly, ϕ is the activation energy of diffusion and D0 is a factor that of void formation in copper during electromigration stress for (A) and (B)  Electromigration in the BEOL of chips occurs in the metal (copper) pathways. Since the activation energy value for diffusion at material interfaces in copper-based interconnects is the lowest value measured (table 1. Besides the long-standing issue of DC electromigration, which interconnects and how electromigration happens differently are also discussing in this paper. INTRODUCTION. (In our earlier analogy, a leaf has been blown off the tree by the Electromigration has remained a reliability issue today even though the industry started to adopt copper as an interconnect material in early 2000. Possible electromigration activation energies for silicides are pointed out [original curve from Magro-Campero] and is the primary cause of electromigration (Fig. The parameter for temperature is the activation energy for the electromigration failure process. 314 × 298) = 6. 2 eV, and lifetimes of similar magnitude. Measuring Electromigration. The kinetic energy of reactant molecules plays an important role in a reaction because the energy necessary to form a product is provided by a collision of a reactant molecule with another reactant molecule. This interconnection type allows increasing the density of interconnects but the occurrence of defects, especially intermetallic compounds (IMC) and Kirkendall voids, may reduce the lifetime at elevated operating conditions. activation energy for  ISOTHERMAL ELECTROMIGRATION TEST PROCEDURE: The parameter for temperature is the activation energy for the electromigration failure process. where Ea is activation energy and Do is initial diffusivity. Section 8: Metallization Jaeger Chapter 7 EE143 – Ali Javey EE143 – Ali Javey Multilevel Metallization EE143 – Ali Javey FOX Si substrate ( InteMetal Oxide e. N. Electromigration is the mass transport of atoms in a material due to elevated temperatures and an applied electric field. Hummel Effect of via arrangement on electromigration performance. 45 eV. The activation energy for EM failure was found as 0. It has been used to study alloying effects in copper lines. 7 eV determined for M-S AI+Cu (2 wt % Cu) is equal to. 3. Activation energy can be accurately determined by calibrating the temperature using the temperature coefficient of resistivity of an Al trace. June 28, 2018. 1 Black™s study involved aluminum Methodology for Electromigration Signoff in the Presence of Adaptive Voltage Scaling Wei-Ting Jonas Chant, Andrew B. Oxidation Resistance of Copper Alloy Thin Films Formed by Chemical Vapor Deposition p. Electromigration in bismuth is studied as a way to create bismuth(111) bilayers. 1), it is evident that diffusion of atoms in this metallization lines is interface dominated and has an early effect on electromigration failure. EM is measured by determining current density passing through Black’s Equation for Electromigration Accelerated Life Testing. In their studies with copper interconnects, researchers learned that this is due in large part to the growing percentage of Electromigration lifetime and failure mechanism have been investigated for Cu/SiLK™ interconnects. BPSG. This landmark discovery has since become a guiding light in the interconnect structure design and electromigration research. May 09, 2003 · Electromigration in sub-micron conductors of Cu and CuAl was studied by 1/f noise measurements for the first time. Laboratory for Solid State Science and Technology, Physics Department, Syracuse  to more and more electromigration problems, let us now investigate in detail the Copper, by contrast, has the lowest activation energy at 0. AI+Cu and Al+Cu+Si film conductors(0. 05 eV. The use of 1/f noise measurements is explored for the purpose of finding faster techniques for electromigration (EM) characterization in advanced microelectronic interconnects, which also enable a better understanding of its underlying physical mechanisms. One of the recent innovations has been the substitution of copper for the standard aluminum-copper metal wiring in order to decrease resistance and tailor RC Copper Interconnect Technology for the 32 nm node – Electromigration Activation energy for diffusion Modeling of Electromigration in Through-Silicon-Via Based 3D IC Jiwoo Pak 1, Mohit Pathak 2, Sung Kyu Lim and David Z. The change of Joule heating density and activation energy for the EM damage were evaluated by using the interconnection annealed at 400 °C for 3 h. Abstract The present uncertainty in the ability of Cu to substitute for Al as the conductor material in very large scale integration arises from the perplexing electromigration behavior of Cu interconnects: the electromigration activation energy in multigrained lines is often about two times lower than for grain-boundary diffusion, while the pre-exponential factor in the electromigration rate where j is the current density, E a is the activation energy, k is the Boltzmann constant, T is the mean temperature of the test structure, n is the current-density exponent and A is the pre-exponential factor. The adhesion of copper to barrier Copper wires can withstand approximately five times more current density than aluminum wires while assuming similar reliability requirements. A = frequency factor. Three different applications of 1/f noise Abstract: Die-to-wafer interconnections such as copper pillars play a vital role in order to enable 3-D integration. James Black explored and wrote about electromigration in aluminum metallization within semiconductors since 1969. activation energy (E a): The excess free energy over the ground state that must be acquired by an atomic or molecular system in order that a particular process can occur. In more complex metals the effect of the “hole wind” on electromigration is poorly understood. In the present work, we report on electrical resistance measurements of the activation energy for EMD in Cu films as determined by an isothermal annealing method carried out under high vacuum conditions The electromigration performance of copper-based conductors is reviewed critically. The effective “activation energy” for failure time has been foun Dec 13, 2000 · The addition of copper to aluminum thin films has previously been shown to reduce the rate of electromigration failure considerably. A first observation is that the activation energy for electromigration decreases  know the reasons for changing from Al-based to Cu-based metallization. voids (solid) copper diffusion barriers electromigration integrated circuit interconnections copper drift velocity resistance-evolution dynamics activation energy interconnects progressive linear increase resistance-step amplitude resistance-increase rate interconnect diffusion barrier drift velocity Fig. The electromigration behavior of furnace annealed films is compared to rapid thermal annealed films and the activation energy is found to be in the range of 0. Keywords: activation energy, current density, electromigration, interconnects, integrated circuits, temperature, and electromigration activation energy. al. k = rate constant. Temperature measurement and control were accomplished by means of a Cu thin-film thermistor. Lloyd, A. Regarding the barrier layer, tantalum is the most commonly used material. ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ = − kT Q MTTF Aj n exp Eq. An Advanced Method to Study Electrotransport in Thin Films by Resistance Measurements, R. × Close The Infona portal uses cookies, i. It is known that pure copper used for Cu-metallization offers a much better resistance against electromigration than aluminum. Current density. Theoretically, this can . electromigration utilizes Black™s Equation, shown in Eq. If the activation energy is great enough, electromigration within the interconnect can be significantly reduced—if not eliminated. The electromigration damage (EMD) of Cu with a TiW barrier is investigated utilizing an empirical formula. In their studies with copper interconnects, researchers learned that this is due in large part to the growing percentage of activation energy for the velocity of surface scratch motion on bulk materials \. Liub, C. W. Step 1 of 5 (a) Obtain the diffusion constant for copper in silicon from the figure 5. Solder alloy migration . The electromigration lifetime of (111) CVD Cu is about four times longer than that of (200) CVD Cu. Furthermore, in-situ activation energy; k b Boltzmann constant and T the film temperature. Forces acting on a thermally activated ion at its saddle point in a conductor. 90 and activation energy Ea=0. EA is the activation energy in electron volts. The electromigration (EM) performance of the Cu lines was evaluated by the accelerated isothermal test. Fischer and Alexander von Glasow Reliability Methodology, Infineon Technologies AG, Munich Abstract Electromigration (EM) and stressmigration (SM) are serious wear-out mechanisms, limiting the lifetime of ULSI copper interconnect systems. The increasingly rapid transition of the electronics industry to high-density, high-performance multifunctional microprocessor Si technology has precipitated migration to new materials alternatives that can satisfy stringent requirements. chemical diffusion coefficient of copper in coper sulfide depends on the stoichiometry of the material and exhibit Arrhenius-type activated temperature dependence with the activation energy Ea = 0. Abstract: The rate of electromigration in thin films of aluminum and  X-ray microbeam analysis of electromigration in copper interconnects current density exponent, Ea is the thermal activation energy to electromigration failure. Thermal gradients due to high current stress were characterized and accounted-for in acceleration models. 3b to be 2. (This is another reason why void-free gap fill is important, too. On the right side of Eqn. The effect of atomic density gradient in electromigration 41 Table 2 EM parameters of Al (1%Si) Parameters Symbol Unit Value Activation energy Ea eV 0. The activation energies obtained, ranging from 0. From the available literature it appears that electromigration in copper proceeds via an interfacial diffusion path with an activation energy significantly less than that of grain boundary diffusion. 12 “logarithm of versus ” in the textbook. Both E aEM and n depend on the interconnect metal. Investigation of the activation energy (E a) of electromigration (EM) is one of the effective ways to understand the EM diffusion mechanism [1] because each diffusion mechanism has its own value. 98 eV and 0. L. higher performance to semiconductor devices. Enzymes are proteins that bind to a molecule, or substrate, to modify it and lower the energy required to make it react. Copper has replaced aluminum because of its lower resistivity and higher reliability, which was expected to be better because of its higher activation energy for diffusion. The median lifetime (t50) is approximated as the MTTF of the interconnect. g. 3 eV. Activation energy Table 1 shows the experimental results for electromigration measurements of the tested Cu nanowires with widths of 90 and 141 nm. The straight line has been extrapolated to higher temperatures. Nevertheless, some works have found relatively low activation energies, approximately 1. Barrier layer effect of titanium-tungsten on the electromigration in sputtered copper films on polyimide HSUEH-WEN WANG, BI-SHIOU CHIOU* Institute of Electro-Physics and *Department of Electronics Engineering and Institute of Electronics, National Chiao-Tung University, Hsinchu, Taiwan E-mail: bschiou@cc. Here, is the activation energy, is the gas constant, and is the temperature. Electromigration in a metal depends strongly on its grain structure, which in turn depends on the fabrication process and subsequent thermal and electrical history [8]. Copper is a possible substitute for Al in very large scale integration interconnects because of its higher resistance to electromigration damage (EMD) and its lower electrical resistivity. As a candidate of future interconnect material,  Comparison of activation energies for Au electromigration . J. High activation energies, moderate sigmas and large current density exponents are observed. Most other common electronic materials are not susceptible to migration: iron, nickel, and tin because of their low solubility Statistics of Electromigration Lifetime Analyzed Using a Deterministic Transient Model Jun He* and Z. Lloyd 2013 IEEE 39th Photovoltaic Specialists Conference (PVSC) Diffusion activation energy of cadmium in thin film CuInGaSe. 2 eV in the temperature range 320–400 °C, which suggests that the path for diffusion of Cu is along the Al/AlOx/SiOy interface for these single crystals. the reliability of aluminum-copper, refractory metal barrier interconnect systems. 4 Sep 2018 ing Electromigration in Cu-CNT Composite Interconnects: A Multiscale Cu's activation energy thanks to the presence of C atoms. A main concern at this point A relationship between the adhesion of a Cu conductor to its surrounding medium, the electromigration drift velocity, and lifetime in a conventional electromigration test has been demonstrated. However, copper still suffers from electromigration (EM) and stress The electromigration behavior of furnace annealed films is compared to rapid thermal annealed films and the activation energy is found to be in the range of 0. electromigration copper activation energy



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