Non-equilibrium molecular dynamics of electromigration in aluminum and its alloys

Şen, Fatih Gürçağ
With constant miniaturization of integrated circuits, the current densities experienced in interconnects in electronic circuits has been multiplied. Aluminum, which is widely used as an interconnect material, has fast diffusion kinetics under low temperatures. Unfortunately, the combination of high current density and fast diffusion at low temperatures causes the circuit to fail by electromigration (EM), which is the mass transport of atoms due to the momentum transfer between conducting electrons and diffusing atoms. In the present study, the effect of alloying elements in aluminum on the diffusion behavior is investigated using a non equilibrium molecular dynamics method (NEMD) under the effect of electromigration wind force. The electromigration force was computed by the use of a pseudopotential method in which the force depends on the imperfections on the lattice. 1.125 at% of various elements, namely Cu, Mg, Mn, Sn and Ti were added into aluminum. The electromigration force was then calculated on the alloying elements and the surrounding aluminum atoms and these forces incorporated into molecular dynamics using the non-equilibrium formalism. The jump frequencies of aluminum in these systems were then computed. Cu, Mn and Sn impurities were found to be very effective in lowering the kinetics of the diffusion under electromigration conditions. Cu was known experimentally to have such an effect on aluminum for several years, but the Mn and Sn elements are shown here for the first time that they can have a similar effect.


Microstructural characterization of hypoeutectoid steels quenched from the Ae1 - Ae3 intercritical temperature range by magnetic barkhausen noise technique
Boyacıoğlu, Beril; Gür, Cemil Hakan; Department of Metallurgical and Materials Engineering (2006)
This thesis aims to examine the possibility of using Magnetic Barkhausen Noise technique in characterizing the ferritic-martensitic microstructure of hypoeutectoid steels quenched from the intercritical temperature range. For this purpose, rectangular specimens were prepared from SAE 1020, 1040 and 1060 steels. The specimens were heated at different temperatures within the intercritical temperature range and then quenched into water. Microstructures of the specimens were characterized by metallographic exam...
Theoretical and experimental investigation of bulk glass forming ability in bulk amorphous alloy systems
Ayas, Can; Mekrabov, Amdulla O.; Department of Metallurgical and Materials Engineering (2005)
In this study molecular dynamics simulation program in NVT ensemble using Velocity Verlet integration was written in order to investigate the glass forming ability of two metallic systems. The Zn-Mg system, one of the frontiers of simple metal-metal metallic glasses and Fe-B, inquiring attention due to presence of many bulk glass forming alloy systems evolved from this binary with different alloying element additions. In addition to this, atomistic calculations on the basis of ordering were carried out for ...
Development of lead alloys for valve-regulated lead-acid (VRLA) batteries
Halıcı, Şafak; Aydınol, Mehmet Kadri; Department of Metallurgical and Materials Engineering (2010)
In this study, Mg, Sn, Cd, Bi and Sb containing, five binary, three ternary and two quaternary different alloys to be used in a Valve-Regulated Lead-Acid (VRLA) batteries have been studied in terms of their mechanical and electrochemical properties. The investigated properties are hardness, passivity, corrosion rate, hydrogen gassing and the conductivity of the passive film. All electrochemical tests were carried out in 3.75 M H2SO4 solution by using open-circuit potential, anodic polarization, polarization...
Characterization of dual phase steels by using magnetic barkhausen noise analysis
Kaplan, Mücahit; Gür, Cemil Hakan; Department of Metallurgical and Materials Engineering (2006)
The aim of this work is to nondestructively characterize the industrial dual phase (ferritic-martensitic) steels (DPS) by the Magnetic Barkhausen Noise (MBN) method. By quenching of AISI 8620 steel specimens having two different starting microstructures, from various intercritical annealing temperatures (ICAT) in the ferrite-austenite region, the microstructures consisting of different volume fractions of martensite and morphology have been obtained. The microstructures, strength properties and hardness val...
Finite element modeling of stress evolution in quenching process
Doğu, Doruk; Gür, Cemil Hakan; Department of Metallurgical and Materials Engineering (2005)
In this thesis the finite element computer code QUEANA simulating the quenching of axisymetric parts and determining the residual stress state was improved by adding pre- and post-processors. The code was further verified by additional numerical experiments and comparison of the results with commercial software أMARCؤ. The possible applications of this code are optimization of industrial quenching processes by controlling the evolution of internal stresses and dimensional changes.
Citation Formats
F. G. Şen, “Non-equilibrium molecular dynamics of electromigration in aluminum and its alloys,” M.S. - Master of Science, Middle East Technical University, 2006.