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Microstructure control of Al-Cu films for improved electromigration resistance

Patent ·
OSTI ID:869221
 [1];  [1]
  1. Albuquerque, NM
+ Show Author Affiliations

A process for the forming of Al-Cu conductive thin films with reduced electromigration failures is useful, for example, in the metallization of integrated circuits. An improved formation process includes the heat treatment or annealing of the thin film conductor at a temperature within the range of from 200.degree. C. to 300.degree. C. for a time period between 10 minutes and 24 hours under a reducing atmosphere such as 15% H.sub.2 in N.sub.2 by volume. Al-Cu thin films annealed in the single phase region of a phase diagram, to temperatures between 200.degree. C. and 300.degree. C. have .theta.-phase Al.sub.2 Cu precipitates at the grain boundaries continuously become enriched in copper, due, it is theorized, to the formation of a thin coating of .theta.-phase precipitate at the grain boundary. Electromigration behavior of the aluminum is, thus, improved because the .theta.-phase precipitates with copper hinder aluminum diffusion along the grain boundaries. Electromigration, then, occurs mainly within the aluminum grains, a much slower process.

Research Organization:
AT & T CORP
DOE Contract Number:
AC04-76DP00789
Assignee:
United States of America as represented by United States (Washington, DC)
Patent Number(s):
US 5300307
OSTI ID:
869221
Country of Publication:
United States
Language:
English

References (4)

Grain Boundary Chemistry in Al-Cu Metallizations as Determined by Analytical Electron Microscopy journal January 1991
Effect of Cu at Al grain boundaries on electromigration behavior in Al thin films
  • Frear, Darrel R.; Michael, Joseph R.; Kim, C.
  • Metallization: Performance and Reliability Issues for VLSI and ULSI, SPIE Proceedings https://doi.org/10.1117/12.51013
conference December 1991
High-spatial-resolution x-ray microanalysis of Al-2wt.% Cu aluminum thin films journal August 1989
The evolution of microstructure in Al-2 Pct Cu thin films: Precipitation, dissolution, and reprecipitation journal September 1990

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