Coating processes – Electrical product produced – Integrated circuit – printed circuit – or circuit board
Patent
1992-09-14
1994-04-05
Lusignan, Michael
Coating processes
Electrical product produced
Integrated circuit, printed circuit, or circuit board
427123, 4273743, 427379, 4273935, 437198, 20419215, B05D 512
Patent
active
053003071
ABSTRACT:
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.
REFERENCES:
patent: 3848330 (1974-11-01), Hall et al.
patent: 3879840 (1975-04-01), Ames et al.
A. D. Romig, et al., High-Spatial-Resolution X-Ray Microanalysis of Al-2 wt. % Cu Aluminum Thin Films, pp. 216-217; Proceedings of the 47th Annual Meeting of the Electron Microscopy Society of America (1989).
D. R. Frear, et al., The Evolution of Microstructure in Al-2 Pct Cu Thin Film: Precipitation, Dissolution, and Reprecipitation; Metallurgical Transactions A; vol. 21A, Sep. 1990.
D. R. Frear, et al., The Effect of Cu At Al Grain Boundaries on Electromigration Behavior in Al Thin Films (1991).
J. R. Michael, et al., Grainboundary Chemistry in Al-Cu Metallizations as Determined by Analytical Electron Microscopy (no date).
Frear Darrel R.
Michael Joseph R.
Romig, Jr. Alton D.
Libman George H.
Lusignan Michael
Maiorana David M.
Stanley Timothy D.
The United States of America as represented by the United States
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