Browse Prior Art Database

Utilization of Copper Transition Alloys in Integrated Circuits

IP.com Disclosure Number: IPCOM000110539D
Original Publication Date: 1992-Dec-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 2 page(s) / 65K

Publishing Venue

IBM

Related People

Gupta, D: AUTHOR [+4]

Abstract

A technique is described whereby copper transition metal alloys are used in very large-scale integration (VLSI) circuits to improve conductivity and electro-migration resistance.

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Utilization of Copper Transition Alloys in Integrated Circuits

       A technique is described whereby copper transition metal
alloys are used in very large-scale integration (VLSI) circuits to
improve conductivity and electro-migration resistance.

      The continuing advances in VLSI requirements require that the
resistivity and electro-migration resistance of the materials used
for interconnects be reduced.  The concept described herein provides
a method of reducing the resistance by using copper doped with a
transition metals, such as Cu-Zr, Cu-Hf, Cu-Ta, Cu-Ti, Cu-V with a
proper adhesion/diffusion barrier element, such as Hf, Ta, Cr, Ti,
etc.  The solutes are the transition metals with high melting
temperatures, known as refractory metals.  The metalizations can be
easily accomplished by an evaporation and/or by a sputtering
deposition process.

      In addition, the concept incorporates a sandwich structure
containing the previous transition elements between two copper alloy
conductors.  After suitable heat treatment, inter-metallic compounds
will be formed in the sandwich.

      For a film with a poly-crystalline grain structure, the mass
transport flux Jb, due to electro-migration, can be expressed as:
    Jb = n1wDbZ*eE/kT)
where n, 1 and w are the number and width of the grain boundaries, Z*
is the effective charge number of the fast moving atoms, Db is the
grain-boundary diffusion coefficient, E is the electric field and e
is the electron charge.

      For a given micro-structure, the combined qua...