Microprobing mechanical and fracture behavior in complex structures
Abstract/Contents
- Abstract
- As the feature size of device technologies scales to ever-smaller dimensions, they become more susceptible to mechanical damage. This is particularly true in microelectronics, where high temperatures are required for solder reflow during packaging of semiconductor dies. A mismatch in coefficient of thermal expansion between the silicon chip and the package causes mechanical stresses to be exerted on interconnect structures. Such chip-package interactions (CPI) cause damage and delamination of metals and dielectrics found in interconnects and other die structures. This damage occurs at the micron length scale and has been exacerbated by the integration of fragile ultra low-K (ULK) layers, stiffer lead-free solder and elevated reflow temperatures. To explore mechanics at the micron length scale, a microprobe system was designed and built. The system consists of custom-made micron-scale probe tips and a piezoelectric actuator mounted on a high-stiffness steel chassis for the accurate characterization of a range of mechanical properties under compressive, tensile or shear loading. These loading modes can also be performed cyclically, which allows for the study of fatigue phenomena. The system includes integrated heating and active cooling, allowing measurements at temperatures up to 300oC. The microprobe system is used to exert stresses on complex stacked structures consisting of Cu bumps or solder bumps and several layers of passivation and copper/low-K dielectrics. The interconnect architecture, dielectric porosity, loading mode mixity, temperature and the direction of shear loading were found to have a significant effect on damage processes. It was shown that the interconnect stack structures weaken dramatically with temperature and that fracture behavior is sensitive to the presence of high porosity dielectric films with sub-micron thickness. Failure analysis of the test structures was conducted using FIB milling and SEM imaging, revealing that rather than always occurring in the weakest layer, the location of ultimate failure depends on the damage initiation site as well as the overall stack mechanics dictated by both geometry and material properties. This study allows for a quantitative understanding of the mechanics of complex structures, particularly damage initiation and evolution processes. This information is useful for optimizing the manufacturing process of devices with micron-scale features.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2013 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Hsing, Alexander |
|---|---|
| Associated with | Stanford University, Department of Materials Science and Engineering. |
| Primary advisor | Dauskardt, R. H. (Reinhold H.) |
| Thesis advisor | Dauskardt, R. H. (Reinhold H.) |
| Thesis advisor | Nix, William D |
| Thesis advisor | Salleo, Alberto |
| Advisor | Nix, William D |
| Advisor | Salleo, Alberto |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Alexander Hsing. |
|---|---|
| Note | Submitted to the Department of Materials Science and Engineering. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2013. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2013 by Alexander Wei Heng Hsing
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