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Al/ Co/ Cu Ternary Metallurgy for Narrow Line Conductors

IP.com Disclosure Number: IPCOM000083804D
Original Publication Date: 1975-Jul-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Ho, P: AUTHOR [+2]

Abstract

As stripe width decreases, the mean lifetime t(50) decreases and the standard deviation sigma increases, particularly when the width approaches the grain size of the material. In Al-Cu lines in integrated circuit structures, there is migration of the Cu solute at the grain boundary as a consequence of electromigration and thermal diffusion.

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Al/ Co/ Cu Ternary Metallurgy for Narrow Line Conductors

As stripe width decreases, the mean lifetime t(50) decreases and the standard deviation sigma increases, particularly when the width approaches the grain size of the material. In Al-Cu lines in integrated circuit structures, there is migration of the Cu solute at the grain boundary as a consequence of electromigration and thermal diffusion.

If a second solute forms a stable complex with Cu, the Cu solute can be kept at grain boundaries and in solution, thus maintaining its effectiveness in reducing electromigration damage. This is particularly useful if grain size is to be reduced in order to decrease sigma. It is desirable that addition of the solute does not increase substantially the resistivity of the Al-Cu alloy.

The addition of Co into Al-Cu alloy is proposed to improve the electromigration resistance of Al-Cu narrow-line conductors. The proposed ternary alloy structure consists of a sandwich deposition of Al-Cu/Co/Al-Cu with a Co layer of about 100 Angstroms thick (-/< 1 wt.% Co) or codeposition of Al-Cu- Co. This structure can be fabricated in conventional deposition equipment. The metallurgy system is compatible with both E-beam lift-off technology and chemical-etch fabrication of narrow lines.

Electromigration life test of Al-Cu-Co (co-dep) stripes (1 mu m wide) at 350 degrees C and 1 x 10/6/amp/cm/2/, showed at least a factor of thirty improvement in lifetime over comparable Al-4% Cu stripes.

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