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Browse Prior Art Database

Self-Aligned W Stud Formation by Etch-back Process

IP.com Disclosure Number: IPCOM000120665D
Original Publication Date: 1991-May-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Chan, KK: AUTHOR [+5]

Abstract

Disclosed is a process for tungsten (W) stud formation by using etch-back technique with self-aligned mask.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 87% of the total text.

Self-Aligned W Stud Formation by Etch-back Process

      Disclosed is a process for tungsten (W) stud formation by
using etch-back technique with self-aligned mask.

      Tungsten stud formation by etch-back technique generally has
two major problems.  The first problem is microloading effect, and
the second is W-seam erosion -1, 2, 3, 4-.  A self-aligned mask
scheme is capable of circumventing all these problems without
increasing the complexity of an additional lithography mask.

      In Fig. 1, deposit blanket CVD W over the via of the dielectric
layer.  The amount of W is sufficient to fill the via without closing
the top.  Spin-coated 0.5 mm layer of polystyrene is baked at 200~C
for 30 minutes to serve as planarization layer and mask for
etch-back.  Oxygen etch back the polystyrene to the tungsten
interface, as shown in Fig. 2.  This step leaves some polymer as a
mask protecting the tungsten material inside the via.  The
unprotected tungsten film is then removed by sulphur tetrafluoride,
Sf6, leaving the W inside the via still protected by the polystyrene,
the organic mask, as seen in Fig.  3.  The W stud formation is
completed by removing the remaining topography with slight polishing
or etch-back process.

      References
-1-  C. J. Mogab, "The Loading Effect in Plasma Etching," J.
Electrochem . Soc . 124 (8), 1262 (1977).
-2-  H. H. Sawin, "A Review of Plasma Processing Fundamentals," Solid
State Technology, 211 (April 1985).
-3-  L....