Elasticity study of very thin Cu films
โ Scribed by K. Fujiwara; H. Tanimoto; H. Mizubayashi
- Book ID
- 103841231
- Publisher
- Elsevier Science
- Year
- 2006
- Tongue
- English
- Weight
- 646 KB
- Volume
- 442
- Category
- Article
- ISSN
- 0921-5093
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โฆ Synopsis
The elastic properties and the surface morphology of Cu/Ta films and Ta/Cu/Ta films sputter-deposited on Si reed substrates were studied for the Cu film thickness, t Cu , between 7 and 1000 nm. A monotonic increase in the internal friction, Q -1 f , in the constituent Cu film above 200 K was commonly observed. For Cu/Ta films, Young's modulus of a Cu film, E f , showed good agreement with the theoretical value for t Cu > โผ80 nm and a decrease with decreasing t Cu below โผ80 nm. A decrease in Q -1 f after 400 K annealing, Q -1 f,400 K and the surface roughness showed a local minimum and a local maximum near 80 nm, respectively, indicating that the properties of the Cu film were modified by subsequent deposition of a Cu layer (the self capping effect). For Ta/Cu/Ta films, Ta capping brought about an increase in the grain size parallel to the film surface, a decrease in the internal stress and a decrease in E f but no changes in the grain size normal to the film surface, Q -1 f , Q -1 f,400 K and the t Cu -dependence of the surface roughness. These results are discussed in the light of the anelastic responses of grain boundaries and interface in nano-scale Cu films which may be important for down-sizing of electric devices.
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