Failure mechanism of a multilayer (TiN/Al/TiN) diffusion barrier between copper and silicon
2002
The improvement of the diffusion barrier performance for Cu metallization, by inserting a thin Al layer between two TiN layers, has been clearly demonstrated and reported by us. The key idea behind our scheme is “stuffing” of grain boundaries of columnar TiN films by Al2O3. It has been also found that the barrier property is at its best when the Al thickness is 1 nm, but above this value, the barrier performance degrades drastically when the upper TiN film is not preannealed. In this study, why the barrier breaks down at above 1 nm of Al interlayer thickness is investigated. High-resolution transmission electron microscopy, scanning transmission electron microscopy, and energy dispersive spectroscopy analyses revealed that the fast diffusion of Cu in the presence of the free Al is the main reason for the failure of the present diffusion barrier scheme. These results are discussed on the basis of the differences between the movements of Al and Cu through TiN film, and the differences between the solid solu...
Keywords:
- Scanning electron microscope
- Thin film
- High-resolution transmission electron microscopy
- Energy-dispersive X-ray spectroscopy
- Scanning transmission electron microscopy
- Nuclear magnetic resonance
- Diffusion barrier
- Tin
- Grain boundary
- Inorganic chemistry
- Physics
- Analytical chemistry
- Condensed matter physics
- Metallizing
- Transmission electron microscopy
- Composite material
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