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Browse Prior Art Database

Selective W on Si-Ge Alloys

IP.com Disclosure Number: IPCOM000110490D
Original Publication Date: 1992-Nov-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 1 page(s) / 50K

Publishing Venue

IBM

Related People

Iyer, S: AUTHOR [+2]

Abstract

Si-Ge alloys are being explored for hetrojunction BIPOLAR and MODFET technology. However, the need for metallization of such device structure especially in self-aligned manner is essential. The metallization should be such that it should not affect the underlying Si-Ge substrate. Also the process should be a low temperature process which would not degrade Si-Ge electrical properties. One of the easiest and low temperature processes is selective W. It has been well known that the selective W process results in encroachment and wormholes when deposited on silicon. Until now the effect of selective W on Si-Ge alloys was unknown. The present invention proposes a scheme of utilizing selective W directly on Si-Ge alloys.

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Selective W on Si-Ge Alloys

      Si-Ge alloys are being explored for hetrojunction BIPOLAR and
MODFET technology.  However, the need for metallization of such
device structure especially in self-aligned manner is essential.  The
metallization should be such that it should not affect the underlying
Si-Ge substrate.  Also the process should be a low temperature
process which would not degrade Si-Ge electrical properties.  One of
the easiest and low temperature processes is selective W.  It has
been well known that the selective W process results in encroachment
and wormholes when deposited on silicon.  Until now the effect of
selective W on Si-Ge alloys was unknown.  The present invention
proposes a scheme of utilizing selective W directly on Si-Ge alloys.

      Various Si-Ge alloys were selected (0% to 100%) and low
temperature silane process was used to deposit W.  The actual
experimental conditions were:
      Turret Temperature - 470~C (350~C)
      Pressure - 200 mT
      SiH4/WF6 = 0.3-0.5
      Thickness - 65 - 75 nm

      The resistivity of such a thin film was 15-16mmLcm.  The RBS
data confirms that the SiGe alloys were unaffected by WF6.  Ge in the
Si-Ge alloy suppresses encroachment which is really favorable for
device fabrication.  Another experiment was carried out where pure Ge
was subjected to WF6 for 5 min at turret temperature of 370~C and no
reaction between Ge and WF6 was observed.  These two experiments
confir...