Microstructure control of Al-Cu films for improved electromigration resistance

Patent · Tue Apr 05 00:00:00 EDT 1994

OSTI ID:5121792

Frear, D R; Michael, J R; Romig, Jr, A D

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.

• DOE Contract Number: AC04-76DP00789
• Assignee: Dept. of Energy, Washington, DC (United States)
• Patent Number(s): A; US 5300307
• Application Number: PPN: US 7-944865
• OSTI ID: 5121792
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360101* -- Metals & Alloys-- Preparation & Fabrication
360102 -- Metals & Alloys-- Structure & Phase Studies
360104 -- Metals & Alloys-- Physical Properties
42 ENGINEERING
426000 -- Engineering-- Components
Electron Devices & Circuits-- (1990-)
ALLOYS
ALUMINIUM ALLOYS
COPPER ALLOYS
ELECTRONIC CIRCUITS
ELECTROPHORESIS
FABRICATION
FILMS
INTEGRATED CIRCUITS
MATERIALS WORKING
MICROELECTRONIC CIRCUITS
MICROSTRUCTURE
PRECIPITATION
SEPARATION PROCESSES
THIN FILMS