Experimental measurement of the effect of copper through-silicon via diameter on stress buildup using synchrotron-based X-ray source

In this work, the effect of copper through-silicon via (TSV) interconnect diameter on stress buildup in Cu TSVs was experimentally determined using a synchrotron-based X-ray microdiffraction technique. A single chip with different Cu TSV diameters (3, 5, and 8 µm), all having the same depth and proc...

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Bibliographic Details
Published in:Journal of materials science 2015-09, Vol.50 (18), p.6236-6244
Main Authors: Okoro, Chukwudi, Levine, Lyle E, Xu, Ruqing, Obeng, Yaw
Format: Article
Language:English
Subjects:
Analysis
Characterization and Evaluation of Materials
Chemistry and Materials Science
Classical Mechanics
Copper
Crystallography and Scattering Methods
Deformation mechanisms
Diffraction
Dislocations
finite element analysis
Finite element method
Grain boundaries
Grain boundary sliding
Integrated circuits
Interconnections
Materials Science
Measurement
Mechanical properties
Original Paper
Particle accelerators
Plastic deformation
Polymer Sciences
Silicon
Solid Mechanics
Stress relaxation
Thermomechanical properties
X ray sources
X-radiation
X-rays
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Summary:In this work, the effect of copper through-silicon via (TSV) interconnect diameter on stress buildup in Cu TSVs was experimentally determined using a synchrotron-based X-ray microdiffraction technique. A single chip with different Cu TSV diameters (3, 5, and 8 µm), all having the same depth and processing conditions was studied. Prior to the measurements, the chip was annealed at 420 °C (30 min), leading to microstructurally stable Cu TSVs. The mean measured hydrostatic stresses were (190 ± 25) MPa (3 µm diameter), (138 ± 19) MPa (5 µm diameter), and (209 ± 26) MPa (8 µm diameter), respectively. No clear relationship between the measured stress and Cu TSV diameter was observed. This trend is attributed to the operation of stress relaxation mechanisms in the polycrystalline Cu TSVs, which includes plastic deformation, grain boundary sliding, void formation/growth, and rate-controlled dislocation motion, which are often neglected in reported finite element analysis studies. Additionally, this study highlights that the thermo-mechanical behavior of Cu TSVs is significantly influenced by their thermal history.
ISSN:0022-2461
1573-4803
DOI:10.1007/s10853-015-9184-9