We have developed a molecular-dynamics technique for investigating migration-induced failures in interconnect films for ULSIs. This technique was used to simulate grain-boundary grooving in Al and Cu films. The simulations showed that the grain-boundary grooves are formed by atomic diffusion at the grain boundary. To clarify what kind of underlay material is effective in suppressing this diffusion, we calculated the dependence of groove depth on the kind of underlay material. The calculation showed that the groove depth of the Al film decreases in the order: Al/Ta, Al/W, and Al/TiN while that of the Cu film decreases in the order: Cu/TiN, Cu/Ta, and Cu/W. The adhesion strength of interface between the interconnect film and the underlay material increases in the same order as the groove depth decreases. It is thus concluded that underlayer materials with strong adhesion to the interconnect films are effective in suppressing diffusion and grain-boundary grooving.
|Number of pages
|CMES - Computer Modeling in Engineering and Sciences
|Published - 2003
- Molecular dynamics