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Selectively Lined Vias Formed into Organic or Inorganic Dielectrics

IP.com Disclosure Number: IPCOM000109701D
Original Publication Date: 1992-Sep-01
Included in the Prior Art Database: 2005-Mar-24
Document File: 2 page(s) / 65K

Publishing Venue

IBM

Related People

Joshi, RV: AUTHOR [+2]

Abstract

CVD W (blanket or selective)-polyimide technology has been proposed for BEOL applications. Selective W is an elegant choice for filling vias which interconnect the metal lines, as the technique requires an order of magnitude less polishing time, and results in higher deposition rates compared to blanket W. However, the drawbacks of the selective W is the poor contact resistances and high junction leakages if directly deposited on the shallow junctions. To avoid these drawbacks and take the advantages of selective deposition of W, we have proposed a scheme to first deposit liner selectively in the via followed by selective W deposition.

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Selectively Lined Vias Formed into Organic or Inorganic Dielectrics

       CVD W (blanket or selective)-polyimide technology has
been proposed for BEOL applications.  Selective W is an elegant
choice for filling vias which interconnect the metal lines, as the
technique requires an order of magnitude less polishing time, and
results in higher deposition rates compared to blanket W.  However,
the drawbacks of the selective W is the poor contact resistances and
high junction leakages if directly deposited on the shallow
junctions.  To avoid these drawbacks and take the advantages of
selective deposition of W, we have proposed a scheme to first deposit
liner selectively in the via followed by selective W deposition.

      The scheme for forming a liner in the via can be described as
follows.  First, a thin layer comprising Ti and then a diffusion
layer such as TiN or W is deposited in a blanket manner.  Then,
polystyrene is coated on the wafer.  Polystyrene self-planarizes.
Then etch-back of polystyrene is performed  by O2 plasma (Fig. 1).
This exposes the polystyrene on the surface, leaving the liner and
polystyrene in the vias (Fig. 1).  This technique works in spite of
the negative slopes.  The exposed liner is removed from the field by
wet etching in a solution such as H2O2 at 63oC.  This solution does
not attack polystyrene.  Polystyrene is subsequently removed in
organic solvent which doesn't attack the liner.  Thus, the liner is
left selectively in...