Browse Prior Art Database

Fabrication of High Quality Defect Free Metal Carriers

IP.com Disclosure Number: IPCOM000103559D
Original Publication Date: 1993-Jan-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 2 page(s) / 69K

Publishing Venue

IBM

Related People

Grebe, K: AUTHOR [+7]

Abstract

Present metal carriers, such as Cu/Mo/Cu or Cu/invar/Cu, are made of Cu cladding. This fabrication technique gives Cu films with large grains and grain boundary cracking after the 850oC post annealing that must be carried out to relieve the stresses introduced by the cladding process. Migration of the Cu grains occurs during thin film fabrication; this results in opening up of the grain boundaries which leads to fracturing of fabricated metal lines.

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Fabrication of High Quality Defect Free Metal Carriers

       Present metal carriers, such as Cu/Mo/Cu or Cu/invar/Cu,
are made of Cu cladding.  This fabrication technique gives Cu films
with large grains and grain boundary cracking after the 850oC post
annealing that must be carried out to relieve the stresses introduced
by the cladding process.  Migration of the Cu grains occurs during
thin film fabrication; this results in opening up of the grain
boundaries which leads to fracturing of fabricated metal lines.

      We have invented a method of fabricating metal carriers with
superior mechanical, thermal and metallurgical properties.  This
involves:
  1.  Identifying the raw substrate (Mo) and annealing it to relieve
any residual stresses resulting from cutting and so on.
  2.  Polishing and/or lapping both sides so that they are flat and
parallel.
  3.  Standard clean and then sputter clean both sides.
  4.  Sputter or evaporate or plate Cu on both sides.
  5.  Anneal the structure at 500oC.
  6.  Micro-mil both sides, if needed, for flatness and parallelism.

      Results (see the figure) indicate that sputtered or plated Cu
substrates are superior to Cu-cladded substrates because they have
      o    Much smaller grain sizes
      o    No grain boundary cracking
      o    Much higher mechanical strength
      o    Little or no bending or warping
      o    Uniform Cu.