Browse Prior Art Database

Alloying of Tisi2

IP.com Disclosure Number: IPCOM000102703D
Original Publication Date: 1990-Dec-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 53K

Publishing Venue

IBM

Related People

d'Heurle, FM: AUTHOR [+2]

Abstract

Titanium disilicide is widely used in integrated silicon technology because it allows at the same time the fabrication of contacts as well as the formation of low resistance interconnections. This latter feature is possible because of the low resistivity, 13mL-cm, of the C-54 crystallographic form of this compound. Unfortunately, regardless of the mode of preparation (*) the compound always forms initially with the C-49 structure, which is characteristic of ZrSi2, and has a resistivity 3 to 5 times greater than that of the C-54 structure. Transition from the C-49 to the C-54 (*) can only be obtained by heat treatment at temperatures in excess of 650oC. The actual transition temperature varies with the history and (generally unknown) contaminations of the samples.

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Alloying of Tisi2

       Titanium disilicide is widely used in integrated silicon
technology because it allows at the same time the fabrication of
contacts as well as the formation of low resistance interconnections.
This latter feature is possible because of the low resistivity,
13mL-cm, of the C-54 crystallographic form of this compound.
Unfortunately, regardless of the mode of preparation (*) the compound
always forms initially with the C-49 structure, which is
characteristic of ZrSi2, and has a resistivity 3 to 5 times greater
than that of the C-54 structure.  Transition from the C-49 to the
C-54 (*) can only be obtained by heat treatment at temperatures in
excess of 650oC.  The actual transition temperature varies with the
history and (generally unknown) contaminations of the samples.
Moreover, because the transition is modulated by nucleation effects,
the transformation becomes increasingly difficult as the size of the
conductors, or interconnections, or contacts become smaller.  That is
so because nucleation effects originate at discrete sites, usually
with a finite density, such that when details become small enough
some of them may not contain any nucleation site at all.  (This
phenomenon is well known in classical nucleation theory, where
phenomena occur in three dimensions.  But the exact equivalent is
found in the nearly two dimensional films of TiSi2 used in silicon
integrated technology.)

      A key observation when attempting to suppress the f...