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Chemical-Mechanical Polishing of Copper with Ammonium Persulfate

IP.com Disclosure Number: IPCOM000114011D
Original Publication Date: 1994-Oct-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Baran, EF: AUTHOR [+4]

Abstract

Described is a method of chemical-mechanical (chem-mech) polishing of copper lines, as used in the patterns of circuit boards, using an ammonium persulfate-silicon dioxide slurry to reproducibly resolve the copper lines and studs without the need for via etching.

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Chemical-Mechanical Polishing of Copper with Ammonium Persulfate

      Described is a method of chemical-mechanical (chem-mech)
polishing of copper lines, as used in the patterns of circuit boards,
using an ammonium persulfate-silicon dioxide slurry to reproducibly
resolve the copper lines and studs without the need for via etching.

      In prior art, the patterning of copper lines and vertical
interconnects between lines of circuit boards has been difficult to
achieve by using processes such as reactive ion etching (RIE).  The
concept described herein uses the Damascene process along with an
ammonium persulfate-silicon dioxide slurry in resolving copper lines
and studs.  The remaining adhesion/diffusion barriers, such as Ta,
Ti-N, can be etched away using dry etch processes, such as RIE or ion
sputtering or by selective wet etching.
 The process involves the following steps:
 1.  Deposition and planarization of a dielectric material.  In this
    case SiO&sub2.
 2.  Pattern the dielectric material.
 3.  Define the dielectric material.
 4.  Deposit the copper filling the via lines and covering the
    dielectric surface.
 5.  Chem-mech polish the metal at the dielectric surface leaving
only
    copper in the via lines.

      Dilute solutions of NH&sub4.S&sub2.O&sub8.  provide the
chemical etchant while 250-350 &angstrom.  beads of SiO&sub2.
provides the mechanical abrasive for Cu Damascene.  The process
enables the copper to be remov...