Browse Prior Art Database

Gallium-Doped Titanium Silicide for Low Contact Resistivity

IP.com Disclosure Number: IPCOM000039102D
Original Publication Date: 1987-Apr-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 60K

Publishing Venue

IBM

Related People

d'Heurle, FM: AUTHOR [+5]

Abstract

VLSI technology at the micron and sub-micron level usually employs salicide technology. Here, titanium silicide is thermally reacted in a selective manner over the source, drain, and gate regions of an N or P channel FET. The thermal reaction includes annealing at 800oC. During this anneal, it has been observed that there is some loss of dopant from the silicon regions into the silicide and possibly some eventual evaporation of the dopant. This is shown in Fig. 1, where the loss of dopant (in this case boron) from single-crystal silicon, after the salicide process, is clearly seen. The consequence of this loss is as follows: The contact of the silicide to the silicon that is heavily doped is really a tunneling contact.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 64% of the total text.

Page 1 of 2

Gallium-Doped Titanium Silicide for Low Contact Resistivity

VLSI technology at the micron and sub-micron level usually employs salicide technology. Here, titanium silicide is thermally reacted in a selective manner over the source, drain, and gate regions of an N or P channel FET. The thermal reaction includes annealing at 800oC. During this anneal, it has been observed that there is some loss of dopant from the silicon regions into the silicide and possibly some eventual evaporation of the dopant. This is shown in Fig. 1, where the loss of dopant (in this case boron) from single-crystal silicon, after the salicide process, is clearly seen. The consequence of this loss is as follows: The contact of the silicide to the silicon that is heavily doped is really a tunneling contact. When the doping is lowered, the effective barrier width is increased and the probability of tunneling is greatly reduced. As a result, there is increased contact resistance. This publication describes a technique for increasing the interface concentration of the p-type dopant to lower the contact resistiv

(Image Omitted)

ity. This is accomplished by doping the silicide after formation with a p-type dopant. Unfortunately, boron may not be used as the dopant. This is because titanium diboride, a stable compound, is formed during subsequent heatings which prevents the boron from reaching the interface. The essence of this invention is to use gallium as the dopant for the silicide. The Ga-Ti i...