Browse Prior Art Database

Process to Make High Aspect Ratio Vias using the Al(Ge) Reflow Process with Good Electromigration Resistance

IP.com Disclosure Number: IPCOM000103726D
Original Publication Date: 1993-Jan-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 1 page(s) / 39K

Publishing Venue

IBM

Related People

Hu, CK: AUTHOR [+2]

Abstract

Shrinkage of VLSI chips demands very high density wiring. This requires vertical vias (or studs) between levels of wiring to use as little area space as possible and to allow planar levels of wiring. A process has been demonstrated using the Al(Ge) alloy to fill holes of radius about 0.2 micron with an aspect ratio (height to diameter) of about 4 [*]. This is an excellent process except this alloy of Al does not provide good electromigration resistance.

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Process to Make High Aspect Ratio Vias using the Al(Ge) Reflow Process with Good Electromigration Resistance

       Shrinkage of VLSI chips demands very high density wiring.
This requires vertical vias (or studs) between levels of wiring to
use as little area space as possible and to allow planar levels of
wiring.  A process has been demonstrated using the Al(Ge) alloy to
fill holes of radius about 0.2 micron with an aspect ratio (height to
diameter) of about 4 [*].  This is an excellent process except this
alloy of Al does not provide good electromigration resistance.

      Alloys of Al with Cu, in the range 0.5 to 4 percent, or Al
with Pd, in the range 0.1 to 0.3 percent (both weight percent), are
good for electromigration.  This invention is to: either polish away
the overburden of Al(Ge), that remains following the former process,
or not polish.  Then, sputter or otherwise deposit an alloy of Al(Cu)
or Al(Pd) or other suitable alloy and interdiffuse these alloys by
heating to a suitable temperature, 350 to 400 degrees Centigrade for
30 minutes, or other suitable time.  Because, especially if the
overburden of Al(Ge) has been polished away, the volume of Al(Ge)
material is small compared to the newly deposited layer, the
resulting composition of the interdiffused alloy will be dominated by
the newly deposited layer, so will its electromigration properties.

      By polishing off the new overburden, the composition of the
studs remaining will be essent...