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Browse Prior Art Database

Elimination of Transient Enhanced Diffusion by Silicidation Reactions

IP.com Disclosure Number: IPCOM000108922D
Original Publication Date: 1992-Jul-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 2 page(s) / 58K

Publishing Venue

IBM

Related People

Fahey, P: AUTHOR [+2]

Abstract

A method is disclosed by which silicide reactions are used to eliminate transient enhanced dopant diffusion, which occurs during annealing of ion implanted layers in silicon.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 72% of the total text.

Elimination of Transient Enhanced Diffusion by Silicidation Reactions

       A method is disclosed by which silicide reactions are
used to eliminate transient enhanced dopant diffusion, which occurs
during annealing of ion implanted layers in silicon.

      In a typical IC fabrication sequence, dopant atoms are
implanted into silicon.  The sample is subsequently annealed to
repair implant damage to the crystal and electrically activate the
dopant.  Unfortunately, during the annealing step, some dopants,
particularly, boron, exhibit large diffusion rates for the first few
seconds of the anneal and the dopants redistribute in an uncontrolled
fashion.

      The method for eliminating this problem is shown in the figure.
The substrate is first preamorphized with a suitable species, for
example, Ge or Si.  Then, the dopant is implanted.  Annealing at
temperatures around 600oC will recrystallize the layer and
electrically activate the dopant.  At this point no diffusion has
occurred.  If the sample is heated to temperatures greater than about
700oC, interstitial point defects frozen in the crystal will become
mobile and cause transient enhanced diffusion.

      Silicide reactions are used to annihilate  the frozen point
defects and thereby eliminate transient enhanced diffusion.  As shown
in the figure, a thin metal layer is deposited on the surface and
then annealed to form a silicide.  Some silicides are believed to
inject vacancies into the bulk, w...