The resistivity of
titanium nitride films is reduced, by about 40% (to less than about 60 muOhm-cm), for example; and, the film
surface roughness is reduced, by about 45% (to less than 6 Å) by using a combination of particular
process conditions during deposition of the film. In particular,
titanium atoms produced by
impact of
inert gas ions upon a
titanium target travel through a
high density, inductively coupled rf
plasma, an
ion metal plasma (IMP), in which the titanium atoms are at least partially ionized. The ionized titanium ions are contacted with ionized
nitrogen atoms also present in the
processing chamber. The
resultant gas phase composition is contacted with the surface of a
semiconductor substrate on which a
titanium nitride barrier layer is to be deposited. By controlling the
gas phase deposition mixture composition, the quantity of the deposition mixture contacting the
substrate surface over a given time period, and the pressure in the process vessel, the resistivity and
surface roughness of the
titanium nitride layer is adjusted. The resistivity of the
titanium nitride barrier layer is principally determined by the
crystal orientation of the titanium
nitride. The more nearly the
crystal orientation approaches 100% of the {200} orientation (the lower the percentage of {111} orientation), the lower the film resistivity.
Crystal orientation is obtained by increasing the ionized content of the deposition mixture and by slowing the rate of deposition of the titanium
nitride film (
barrier layer). The
surface roughness of the titanium nitride layer is reduced principally by reducing the pressure in the process vessel, which affects the film formation dynamics. An increase in ionized content of the deposition mixture helps reduce surface roughness until an inflection point is reached, after which surface roughness increases with increased ionized content.