Effect of post-pattern annealing on the grain structure and reliability of Al-based interconnects
- Center for Advanced Materials, Lawrence Berkeley National Laboratory
- Chemistry and Materials Science, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)
The possibility is addressed of improving the electromigration resistance of Al and Al{endash}Cu thin-film conductors with {open_quote}{open_quote}quasi-bamboo{close_quote}{close_quote} structures by post-pattern anneals that decrease the maximum polygranular segment length. Pure Al, Al{endash}2Cu, and Al{endash}2Cu{endash}1Si lines were patterned and annealed at temperatures high enough to stimulate grain growth. Appropriate anneals led to predominantly bamboo structures with short polygranular segments. These grain structures had a high median time to failure with a relatively low deviation of the time to failure. Metallographic analyses showed that polygranular segment length was a dominant factor in determining the failure site. Post-pattern annealing promotes a preferential shortening of the relatively long polygranular segments that cause early failures. However, even after annealing, failure occurred at the longest residual polygranular segments, even when these were significantly shorter than the {open_quote}{open_quote}Blech length{close_quote}{close_quote} under the test conditions. Statistical analysis of the failure of alloy lines revealed a simple exponential relation between the failure time and the longest polygranular segment length within a line, which is functionally identical to that previously found for lines tested in the as-patterned condition.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- DOE Contract Number:
- AC03-76SF00098; W-7405-ENG-48
- OSTI ID:
- 284254
- Journal Information:
- Journal of Applied Physics, Vol. 79, Issue 11; Other Information: PBD: Jun 1996
- Country of Publication:
- United States
- Language:
- English
Similar Records
The mechanism of electromigration failure of narrow Al-2Cu-1Si thin-film interconnects
Microstructural evolution of Al-Cu thin-film conducting lines during post-pattern annealing