| The purpose of this investigation is to apply the principles of multicomponent diffusion to tailor alloys for interconnect applications. One of the many novel effects arising out of multicomponent diffusion interactions in alloys containing three or more components is the appearance of zero-flux planes (ZFPs). ZFPs are locations in the interdiffusion zone where the flux of a component vanishes. The occurrence of ZFPs in an interconnect alloy would inhibit or even eliminate diffusion for some components, thereby improving the alloy's resistance to electromigration and stress-induced voiding.;Indium and lanthanum were chosen as solute elements for the ternary Al alloys studied in this thesis because they possess negligible solid solubility in Al and have the same valency as Al. Consequently, these elements were expected to improve the reliability of the alloy by blocking diffusion through the grain boundaries without increasing the electrical resistivity of the alloy significantly.;Initially, binary films of Al-In and Al-La were investigated as there exists little information about these alloys. The resistivity of the annealed binary alloys was comparable to that of Al-Cu alloys used at present provided that the solute concentration was ∼1at.%. Solute segregation, crystallographic texture, evolution of second phase, and grain size, were some of the microstructural details that were studied. The lattice and grain boundary diffusivity of the two solute species in Al was also evaluated. A novel procedure was developed to determine the diffusivity matrix for a ternary alloys from a single interdiffusion experiment. Finally, efforts were undertaken to model ZFPs in Al-In-La alloys.;Although the annealed resistivities of the two alloys are comparable, Al-La is a better interconnect material than Al-In. Al-In films suffer from poor adhesion in the as-deposited condition, exhibit hillock formation upon annealing, and are subject to rapid diffusion in Al. Non-uniform segregation after annealing adversely impacts the application of simple ternary interdiffusion models. It was found that the requirements for solute elements with almost negligible solubilities prove to be restrictive in conducting straightforward single-phase multicomponent interdiffusion experiments. Thus, the diffusivity for the Al-In-La system could not be determined, thereby precluding the prediction of ZFPs for Al. |
