Abstract
The structure and mechanical behavior of organosilicate glass (OSG) coatings have been analyzed as a function of composition and UV irradiation time. A decrease in the OSG carbon content results in more networking bonds and increased connectivity; UV irradiation increases the connectivity by severing weak terminal bonds and stabilizes the network through local bond rearrangements. These structure modifications lead to a significant improvement in the stiffness, hardness, and fracture energy of these coatings. The networking bond density and mean connectivity number correlate well with the mechanical behavior of the OSG films, although network bond density weighted by bond energy is a more appropriate measure. The adhesion energy of silicon nitride to OSG is significantly higher than the cohesive energy of the OSG as a result of interface densification and crack-tip shielding. Subcritical fracture measurements in aqueous environments show that the detrimental effect of water on adhesion surpasses the effect of network connectivity.
| Original language | English |
|---|---|
| Pages (from-to) | 4932-4943 |
| Number of pages | 12 |
| Journal | Acta Materialia |
| Volume | 56 |
| Issue number | 17 |
| Early online date | 3 Jul 2008 |
| DOIs | |
| Publication status | Published - Oct 2008 |
| Externally published | Yes |
Funding
The authors acknowledge funding from the Semiconductor Research Corporation (2005-KC-1292.011, 2005-KJ-1339.001) and the School of Engineering and Applied Sciences at Harvard University. The OSG film stacks were provided by Texas Instruments Incorporated. The authors thank Dr. Nancy Ota for help with the nanoindentation measurements
Keywords
- Fracture
- Low-permittivity
- Mechanical properties
- Organosilicate glass
- Thin film