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Title: Microstructure control of Al-Cu films for improved electromigration resistance

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.

Inventors:
 [1];  [1];  [2]
  1. Albuquerque, NM
  2. (Albuquerque, NM)
Issue Date:
Research Org.:
AT&T
OSTI Identifier:
869221
Patent Number(s):
5300307
Assignee:
United States of America as represented by United States (Washington, DC)
Patent Classifications (CPCs):
C - CHEMISTRY C23 - COATING METALLIC MATERIAL C23C - COATING METALLIC MATERIAL
Y - NEW / CROSS SECTIONAL TECHNOLOGIES Y10 - TECHNICAL SUBJECTS COVERED BY FORMER USPC Y10S - TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
DOE Contract Number:  
AC04-76DP00789
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
microstructure; control; al-cu; films; improved; electromigration; resistance; process; forming; conductive; reduced; failures; useful; example; metallization; integrated; circuits; formation; heat; treatment; annealing; film; conductor; temperature; range; 200; degree; 300; time; period; 10; minutes; 24; hours; reducing; atmosphere; 15; volume; annealed; single; phase; region; diagram; temperatures; theta; -phase; cu; precipitates; grain; boundaries; continuously; enriched; copper; due; theorized; coating; precipitate; boundary; behavior; aluminum; hinder; diffusion; occurs; mainly; grains; slower; reducing atmosphere; grain boundaries; time period; integrated circuits; integrated circuit; heat treatment; single phase; grain boundary; phase diagram; film conductor; formation process; phase precipitate; /427/148/204/438/

Citation Formats

Frear, Darrel R, Michael, Joseph R, and Romig, Jr., Alton D.. Microstructure control of Al-Cu films for improved electromigration resistance. United States: N. p., 1994. Web.
Frear, Darrel R, Michael, Joseph R, & Romig, Jr., Alton D.. Microstructure control of Al-Cu films for improved electromigration resistance. United States.
Frear, Darrel R, Michael, Joseph R, and Romig, Jr., Alton D.. Sat . "Microstructure control of Al-Cu films for improved electromigration resistance". United States. https://www.osti.gov/servlets/purl/869221.
@article{osti_869221,
title = {Microstructure control of Al-Cu films for improved electromigration resistance},
author = {Frear, Darrel R and Michael, Joseph R and Romig, Jr., Alton D.},
abstractNote = {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.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1994},
month = {1}
}

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Works referenced in this record:

Grain Boundary Chemistry in Al-Cu Metallizations as Determined by Analytical Electron Microscopy
journal, January 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


Effect of Cu at Al grain boundaries on electromigration behavior in Al thin films
conference, December 1991

  • 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