Browse Prior Art Database

Novel Diffusion Barrier between Copper-Silicon

IP.com Disclosure Number: IPCOM000113727D
Original Publication Date: 1994-Sep-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 62K

Publishing Venue

IBM

Related People

Brady, MJ: AUTHOR [+3]

Abstract

Future challenges of device fabrication will lie in the area of multilevel metallization. One key concern for interconnect metals is prevention of diffusion through dielectrics, such as thermal silicon dioxide. Aluminum has become the standard interconnect metal in present day devices, however, as applications develop, line widths below 0.35 microns will be increasing. Thus, severe electromigtation and conductivity limitations will arise. Alternatives for Aluminum are Copper, Silver, and Gold. Of these, only Copper has both conductivity and electromigration advantages. The challenges of using Copper are: Copper diffusion through dielectrics, limited etch technology, oxide adherence and surface passivation.

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Novel Diffusion Barrier between Copper-Silicon

      Future challenges of device fabrication will lie in the area of
multilevel metallization.  One key concern for interconnect metals is
prevention of diffusion through dielectrics, such as thermal silicon
dioxide.  Aluminum has become the standard interconnect metal in
present day devices, however, as applications develop, line widths
below 0.35 microns will be increasing.  Thus, severe electromigtation
and conductivity limitations will arise.  Alternatives for Aluminum
are Copper, Silver, and Gold.  Of these, only Copper has both
conductivity and electromigration advantages.  The challenges of
using Copper are: Copper diffusion through dielectrics, limited etch
technology, oxide adherence and surface passivation.  This invention
teaches a way of solving the diffusion of copper through a dielectric
using a novel compound of Copper Germanium (Cu&sub3.Ge) as the
diffusion barrier.

      Single crystal <100> silicon was processed with a device grade
of thermally grown Silicon dioxide using standard semiconductor
photolithographic techniques to generate a silicon dioxide membrane
by anisotropic etching of the bulk silicon wafer.  The oxide
thickness was on the order of 0.5 microns (membrane), and the
windows, or apertures were 1000 microns square.  A control sample was
blanket coated with 0.5 microns of copper on the planar or oxide side
of the etched silicon wafer using electron beam deposition
techniques.  Rutherford Back Scattering (RBS) was then performed on
the as-deposited sample, and then aga...