Browse Prior Art Database

Low Temperature Self Aligned TiN/TiSi2 Process

IP.com Disclosure Number: IPCOM000103601D
Original Publication Date: 1993-Jan-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 2 page(s) / 81K

Publishing Venue

IBM

Related People

Joshi, RV: AUTHOR [+3]

Abstract

Titanium silicide plays an important role in VLSI technology, as it is widely used for source drain gate metallization. Selective tungsten would be directly deposited on TiSi2 for via filling applications (e.g., CMOS-LUNA Program). However, selective tungsten technology uses corrosive gases like WF6 and if TiSi2 is directly exposed to WF6, it results in poor contact resistance and the delamination of the selective tungsten film. The poor contact resistance is due the formation of non-volatile TiF3 which is formed by the following reaction: 23WF6 + 12TiSi2 T 23W + 6TiF36TiF4 I + 24SiF4 I

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Low Temperature Self Aligned TiN/TiSi2 Process

       Titanium silicide plays an important role in VLSI
technology, as it is widely used for source drain gate metallization.
Selective tungsten would be directly deposited on TiSi2 for via
filling applications (e.g., CMOS-LUNA Program).  However, selective
tungsten technology uses corrosive gases like WF6 and if TiSi2 is
directly exposed to WF6, it results in poor contact resistance and
the delamination of the selective tungsten film.  The poor contact
resistance is due the formation of non-volatile TiF3 which is formed
by the following reaction:
        23WF6 + 12TiSi2 T 23W + 6TiF36TiF4 I + 24SiF4 I

      The SIMS data (not shown here) indicates that fluorine
concentration in the silicide film increases by orders of magnitude.
Thus, there is definitely a need to prevent such reaction using a
self aligned barrier, TiN on TiSi2.  The importance and the
application of such a structure is brought out in [*].  The
conventional techniques use high temperatures (above 700oC) to form
self-aligned TiN barrier.  These high temperature anneals may lead to
high junction leakages.  The need for low temperature, in-situ
conversion of silicide to TiN is obvious.  This article presents a
novel process scheme which enables forming self aligned TiN scheme at
low temperature.

      The experiments were carried out on blanket TiSi2 wafer on
silicon wafer.  Ammonia plasma was used to nitridize silicide.  The
sheet resistance was measured before and after nitridization of
silicide.  The process conditions used were as follows:
Wafer I.D.    NH3   Pressure    Power   Temperature   Time
            (sccm)    (mT)      (Watt)      (oC)      (min)
  2          200       65         300        400       20
  4          200      358         300 ...