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A Novel Interconnect Process Using Selective Tungsten Deposition

IP.com Disclosure Number: IPCOM000109038D
Original Publication Date: 1992-May-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 1 page(s) / 55K

Publishing Venue

IBM

Related People

Bartush, T: AUTHOR [+4]

Abstract

The use of selective tungsten deposition to fill contact windows or interconnect stencils has been limited because of two major problems. First, selectivity of the reaction tends to break down resulting in nucleation on Si containing insulator surfaces which can cause line to line shorts. Second, selective tungsten deposition often results in a defect called wormholing or tunneling in which voids are etched into the underlying silicon regions.

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A Novel Interconnect Process Using Selective Tungsten Deposition

      The use of selective tungsten deposition to fill contact
windows or interconnect stencils has been limited because of two
major problems.  First, selectivity of the reaction tends to break
down resulting in nucleation on Si containing insulator surfaces
which can cause line to line shorts. Second, selective tungsten
deposition often results in a defect called wormholing or tunneling
in which voids are etched into the underlying silicon regions.

      The authors have developed a process to selectively deposit
tungsten into contact windows and interconnect stencils without
deposition on the surrounding insulator. The process begins with
following the deposition of the interlevel dielectric.  A 30 nm layer
of aluminum oxide (AlOx) is deposited on the dielectric.  The contact
window level is patterned using photolithography.  The photoresist
pattern is transferred into the A1Ox layer using a C1 based Reactive
Ion Etch (RIE) process.  With the photoresist mask still in place,
the pattern is transferred into the interlevel dielectric with a F
based RIE process.  The photoresist mask is then removed.  A 25 nm
conformal layer of titanium nitride (TiN) is deposited over the
contact window.  The TiN layer is blanket etched to form spacers on
the sidewalls of the contact window.  These TiN spacers form the
liners which prevent the tunneling defect.  Tungsten is selectively
deposited in the conta...