Browse Prior Art Database

Metallization for Shallow Junction Silicon Technology

IP.com Disclosure Number: IPCOM000087451D
Original Publication Date: 1977-Jan-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

d'Heurle, FM: AUTHOR [+3]

Abstract

A technique is proposed that will insure the following: (1) good ohmic contact to silicon (Si) planar technology with shallow junctions without deterioration of the junction during fabrication, (2) good electromigration resistance, and (3) ease of fabrication. The metal deposition over the diffused wafers with proper oxide windows is often made in the order Al-Cu-Al (with or without an additional layer of Si).

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Metallization for Shallow Junction Silicon Technology

A technique is proposed that will insure the following: (1) good ohmic contact to silicon (Si) planar technology with shallow junctions without deterioration of the junction during fabrication, (2) good electromigration resistance, and (3) ease of fabrication. The metal deposition over the diffused wafers with proper oxide windows is often made in the order Al-Cu-Al (with or without an additional layer of Si).

Without an additional layer of Si, there is a danger of damaging the underlying, diffused junctions because of Al penetration during the annealing required to obtain ohmic contact. With an additional layer of Si, this deficiency is reduced, but good ohmic contact is not obtained because of Si precipitation and epitaxial growth in the contact area. These two problems can be alleviated by use of a silicide of Pd, Pt or Ni. Pd or Pt require extra processing operations (annealing plus stripping of the Pd or Pt layer, and an extra vacuum cycle).

With a photoresist lift-off process and use of a Ni silicide, advantage may be taken of the characteristics of Ni (good adhesion to SiO(2), diffusion barrier for Cu, low temperature for silicide formation, and increased electromigration when alloyed to Al) to SiO(2) and its quality to eliminate the costly extra steps mentioned above. The Ni layer 500-1000Angstroms thick is deposited at a temperature as high as compatible with the silicide.

By depositing the Cu as a se...