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

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 C to 300 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 C and 300 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. 5 figures.
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Issue Date:
OSTI Identifier:
Dept. of Energy, Washington, DC (United States) SNL; EDB-94-075495
Patent Number(s):
US 5300307; A
Application Number:
PPN: US 7-944865
Contract Number:
Resource Relation:
Patent File Date: 14 Sep 1992
Country of Publication:
United States
36 MATERIALS SCIENCE; 42 ENGINEERING; ALUMINIUM ALLOYS; ELECTROPHORESIS; MATERIALS WORKING; MICROSTRUCTURE; COPPER ALLOYS; INTEGRATED CIRCUITS; FABRICATION; PRECIPITATION; THIN FILMS; ALLOYS; ELECTRONIC CIRCUITS; FILMS; MICROELECTRONIC CIRCUITS; SEPARATION PROCESSES; 360101* - Metals & Alloys- Preparation & Fabrication; 360102 - Metals & Alloys- Structure & Phase Studies; 360104 - Metals & Alloys- Physical Properties; 426000 - Engineering- Components, Electron Devices & Circuits- (1990-)