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Low-Temperature Chemical Vapor Deposition of Cobalt from Tetracobalt Dodecacarbonyl

IP.com Disclosure Number: IPCOM000117287D
Original Publication Date: 1996-Jan-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 78K

Publishing Venue

IBM

Related People

Reynolds, SK: AUTHOR [+2]

Abstract

Disclosed is a method for chemical vapor deposition of cobalt using tetracobalt dodecacarbonyl as a precursor. This method is: 1. compatible with typical applications for CVD cobalt and CVD cobalt disilicide, 2. operable at relatively low temperatures (less than 200 degrees C), and 3. more reproducible than the currently used dicobalt octacarbonyl process.

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Low-Temperature Chemical Vapor Deposition of Cobalt from Tetracobalt
Dodecacarbonyl

      Disclosed is a method for chemical vapor deposition of cobalt
using tetracobalt dodecacarbonyl as a precursor.  This method is:
  1.  compatible with typical applications for CVD cobalt and CVD
       cobalt disilicide,
  2.  operable at relatively low temperatures
       (less than 200 degrees C), and
  3.  more reproducible than the currently used dicobalt octacarbonyl
       process.

      Organometallic CVD of cobalt has been known for over twenty
years (1) and has recently been improved by the use of the
organometallic precursor dicobalt octacarbonyl, Co2.(CO)8..2
(2).  By the use of dicobalt octacarbonyl, the required substrate
temperature was lowered to 200 degrees C or less.  At these
temperatures, very pure cobalt was obtainable.

      Unfortunately, CVD processes using dicobalt octacarbonyl are
difficult to control.  Dicobalt octacarbonyl is thermally unstable
above 0 degree C even under a blanket of inert gas.  In the presence
of traces of oxygen or water vapor, the situation is exacerbated.
This phenomenon, while it does not prevent the deposition of cobalt
films from the precursor which has not yet decomposed, does make the
reproducibility of the process nearly impossible to control.  The
amount of active precursor relative to the decomposed precursor in
the source material reservoir is constantly changing, consequently
changing precursor conductance into the reactor and the film growth
rate.  Additionally, use of hydrogen as a carrier or reagent gas is
impracticable due to the formation (even at room temperature) of a
mononuclear tetracarbonyl hydride.

      The decomposition chemistry of tetracobalt dodecacarbonyl is
very similar to that for dicobalt octacarbonyl in that the only
products formed during themoly...