Graduation Semester and Year
Fall 2024
Language
English
Document Type
Dissertation
Degree Name
Doctor of Philosophy in Materials Science and Engineering
Department
Materials Science and Engineering
First Advisor
Choong-Un Kim
Abstract
The relentless miniaturization of semiconductor devices has intensified reliability challenges in electronic packaging, particularly for solder interconnects and thin metal lines. This dissertation investigates two critical failure mechanisms—electromigration (EM) and thermomechanical fatigue (TMF)—and explores strategies to mitigate these effects. Electromigration, driven by high-density current-induced atomic migration, significantly impacts solder interconnects. This study examines the role of Under-Bump Metallization (UBM) and solder microstructure in improving EM reliability. Findings reveal that thicker UBMs delay void nucleation and enhance EM resistance, while the absence of UBM leads to failure through vertical void propagation. Additionally, grain orientation, particularly the c-axis alignment in Sn grains, is shown to affect EM susceptibility. Techniques like substrate texturing and optimized reflow processes are proposed to refine solder microstructure, improving durability. For thermomechanical fatigue, thin metal lines subjected to surge current conditions were analyzed. These high-density pulses generate localized stress and Joule heating, leading to fatigue-induced failure through extrusion, cracking, or void formation. Experimental data and simulations highlight the influence of interconnect dimensions and ambient temperature on failure behavior. This work advances the understanding of EM and TMF in electronic packaging, offering insights to enhance reliability for next-generation semiconductor technologies through UBM optimization, microstructure control, and innovative testing methodologies.
Keywords
Electromigration reliability, Thermomechanical fatigue, Solder interconnects, Under-Bump Metallization (UBM), Surge current conditions, Thin metal lines, Joule heating effects, Grain orientation control, Alternating current electromigration (AC EM), Failure mechanisms in microelectronics
Disciplines
Electronic Devices and Semiconductor Manufacturing | Semiconductor and Optical Materials
License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Recommended Citation
Mohanram, Hariram, "Enhancing Electromigration Reliability in Solder Interconnects through Microstructure Control and Thermomechanical Failure Mechanisms in Thin Metal Lines under Surge Current Conditions" (2024). Material Science and Engineering Dissertations. 127.
https://mavmatrix.uta.edu/materialscieng_dissertations/127
Included in
Electronic Devices and Semiconductor Manufacturing Commons, Semiconductor and Optical Materials Commons