Effects of length scaling on electromigration in dual-damascene copper interconnects

M. H. Lin*, M. T. Lin, Ta-Hui Wang

*Corresponding author for this work

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

The electromigration short-length effect in dual-damascene Cu interconnects has been investigated through experiments on lines of various lengths (L), being stressed at a variety of current densities (j), and using a technologically realistic three-level structure. This investigation represents a complete study of the short-length effect after a well-developed dual-damascene Cu process. Lifetime measurement and resistance degradation as a function of time were used to describe this phenomenon. It has been found that the sigma of log-normal distribution increased as the current density-length product decreased. The statistical distribution of the critical volume fits the sigma curve well. Lower jL2 values show large sigma values because of back-stress-induced TTF (time-to-fail) dispersion. A simplified equation is proposed to analyze the experimental data from various combinations of current density and line length at a certain temperature. The resulting threshold-length product (jL)C value appears to be temperature dependent, decreasing with an increase in temperature in a range of 250-300 °C.

Original languageEnglish
Pages (from-to)569-577
Number of pages9
JournalMicroelectronics Reliability
Volume48
Issue number4
DOIs
StatePublished - 1 Apr 2008

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