Statistical Analysis of Electromigration Lifetimes for Cu Interconnects
- CMOS Platform Device Development, Technology Solutions Organization, Freescale Semiconductor Inc., MDK10, 3501 Ed Bluestein Blvd, Austin, TX 78721 (United States)
- Interconnect and Packaging Group, University of Texas at Austin, PRC/MER, Mail Code R8650, Austin/TX 78712 (United States)
Electromigration (EM) failure statistics and the origin of the lognormal standard deviation ({sigma}) for Cu interconnects have been investigated by analyzing the statistics of lifetime and void size distributions at various stages during EM testing. Experiments were performed on 0.18{mu}m wide, single damascene Cu interconnects with tests terminated after certain amounts of resistance increase, or after a specified test time. Void size distributions of resistance-based and time-based EM tests were obtained. The {sigma} values of lifetime and void size distributions showed a significant decrease with increasing resistance failure criterion. The statistics of resistance-based void size distributions can be explained by considering geometrical variations of the void shape, while the characteristics of time-based void size distributions require consideration of kinetic aspects of the EM process. The {sigma} values of EM lifetime distributions can be adequately simulated by combining the statistics of both types of void size distributions. Thus, using simulation to fit the experimental data, the parameters influencing the EM lifetime statistics were identified as variations in void sizes, geometrical and experimental factors of the EM test and kinetic aspects of the mass transport process, such as differences in interface diffusivity between the lines. The variation in diffusivities at the cathode ends of the lines are a result of varying Cu grain orientations. Furthermore, the analysis of the EM statistics of samples with a reduced line height and dual damascene processing will be presented.
- OSTI ID:
- 20798174
- Journal Information:
- AIP Conference Proceedings, Vol. 817, Issue 1; Conference: 8. international workshop on stress-induced phenomena in metallization, Dresden (Germany), 12-14 Sep 2005; Other Information: DOI: 10.1063/1.2173546; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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