Reservoir effect and the role of low current density regions on electromigration lifetimes in copper interconnects
Mhaisalkar, Subodh Gautam
Li, Hong Yu
Tu, K. N.
Gusak, A. M.
Date of Issue2006
School of Materials Science and Engineering
Electromigration (EM) in copper dual-damascene interconnects with extensions(also described as overhang regions or reservoirs) in the upper metal (M2) were investigated. It was found that as the extension length increases from 0 to 60 nm, the median-time-to-failure increased from 50 to 140 h, representing a ∼200% improvement in lifetimes. However, further increment of the extension length from 60 to 120 nm did not result in any significant improvement in EM lifetimes. Based on calculations of current densities in the reservoir regions and recently reported nucleation, void movement, and agglomeration-based EM phenomena, it is proposed that there is a critical extension length beyond which increasing extension lengths will not lead to longer EM lifetimes.
Journal of materials research
© 2006 Materials Research Society. This paper was published in Journal of Materials Research and is made available as an electronic reprint (preprint) with permission of Materials Research Society. The paper can be found at the following DOI: [http://dx.doi.org/10.1557/JMR.2006.0270]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.