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Method for Elimination of Scratches in Polished Damascene Conductors

IP.com Disclosure Number: IPCOM000124029D
Original Publication Date: 1991-Feb-01
Included in the Prior Art Database: 2005-Apr-06
Document File: 1 page(s) / 41K

Publishing Venue

IBM

Related People

Cronin, JE: AUTHOR [+2]

Abstract

By heating metal which has been deposited and polished to form lines in etched troughs of an insulator, the metal is melted and surface tension of the molten metal eliminates surface scratches. Any of several heating and quick cooling methods may be used to obtain scratch-free metal lines which have low initial electrical resistance and have low susceptibility to electromigration failure.

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Method for Elimination of Scratches in Polished Damascene Conductors

      By heating metal which has been deposited and polished to form
lines in etched troughs of an insulator, the metal is melted and
surface tension of the molten metal eliminates surface scratches.
Any of several heating and quick cooling methods may be used to
obtain scratch-free metal lines which have low initial electrical
resistance and have low susceptibility to electromigration failure.

      Conductive lines are formed in the damascene process by filling
troughs previously etched in an insulator with a metal and then
polishing away metal deposited between troughs.  When the metal used
is soft, as is copper, aluminum or aluminum/copper alloy, the surface
of the metal lines may become scratched in the polishing process.
These metals have melting points sufficiently low that they may be
reflowed without damaging the insulator used in making the troughs.

      Repair of scratches and/or metal grain growth for further
electrical resistance reduction requires motion of metal for very
short distances.  Therefore, time during which the metal need be in
its molten state is very short. Metal lines left in their molten
state sufficiently long tend to deform toward droplet formation.  For
this reason, it is desirable to accomplish reflow heating by short
term application of energy to the polished surface, e.g., by rapid
thermal annealing apparatus, pulsed laser heating, etc.  Excessive
annea...