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Browse Prior Art Database

Silicide Formation Improvement

IP.com Disclosure Number: IPCOM000100651D
Original Publication Date: 1990-May-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Chanclou, R: AUTHOR [+3]

Abstract

A problem was detected on a CMOS technology using titanium disilicide (TiSi2) to improve ohmic contact. This problem consists of a lack of TiSi2 formation over the polysilicon lands above the PFETs.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

Silicide Formation Improvement

       A problem was detected on a CMOS technology using
titanium disilicide (TiSi2) to improve ohmic contact. This problem
consists of a lack of TiSi2 formation over the polysilicon lands
above the PFETs.

      An enhanced SiO2 growth rate over the polysilicon lands during
the activation anneal has been pointed out.  The purpose of this
active anneal is to activate the source-drain ion implant and restore
the SILICIDE FORMATION crystal. Ambient during this anneal at
insertion and ramping steps is oxygen as standard.

      It has been demonstrated that the use of fluorine species as
BF2+ at P+ source-drain implant step (Fig. 1) leads to the
introduction of fluorine atoms in the polysilicon, which causes the
enhanced growth rate mentioned above.

      The SiO2 layer grown up over the polysilicon lands cannot be
removed completely by the conventional BHF strip before titanium
evaporation. This phenomena explains the lack of TiSi2 over
polysilicon.

      The novel idea disclosed herein is to control and monitor the
oxide growth over P+implanted polysilicon lands by diluting the
oxygen with nitrogen so to decrease the oxygen partial pressure in
the type at insertion and ramping steps. The details are shown in
Fig. 2.