over 24 hours. Application 09/128,143, Specification, p. 12, Table III, Examples 1-8. Apparently
based upon the examples in Table III, the 143 Specification states the following conclusion:
Thus titanium nitride resistivity can be markedly reduced and stability
dramatically improved, e.g., a 2% increase in resistivity over 24 hours, by a
post treatment of titanium nitride films applying a bias voltage to the substrate
in a nitrogen or other plasma.
Application 09/128,143, Specification, p. 12, l. 32 - p. 13, l. 1 (emphasis added).
The 143 Specification also reports the composition and density of some of the examples said
to have been post-treated in a biased plasma. The 143 Specification reports the results of Auger
analysis of the concentration vs. sputter depth etch of the TiN layers said to have been made in
Examples 1, 7, and 8. Application 09/128,143, Specification, p. 13, l. 2 - p. 14, l. 25. Example 1, 7,
and 8 were said to have been post-treated in a plasma biased with 400 volts. The Auger analysis of
these biased-plasma examples is said to show the “change in elemental composition of the films after
treatment in accordance with the invention.” Application 09/128,143, Specification, p. 13, ll. 13-15
(emphasis added).
The 143 Specification also reports the results of Rutherford back scattering spectrum (RBS)
density testing of Examples 7, 8 and the control. Application 09/128,143, Specification, p. 15, ll. 3-9.
The densities of Examples 7 and 8 were reported to be higher than the control. Application
09/128,143, Specification, p. 15, Table VI. The 143 Specification then concludes:
Thus plasma treatment and bombardment with high energy ions increased the
density of titanium nitride films as compared to the Control.
Application 09/128,143, Specification, p. 15, ll. 10-12 (emphasis added).
The entire written description of the 143 Specification emphasizes the importance of applying
a voltage bias during the plasma treatment to decrease resistivity and increase stability. For example,
the 143 Specification says that
it was highly unexpected that when a bias voltage was applied to the substrate
in a plasma, the sheet resistivity markedly decreased, and, more importantly,
remained stable over time.
Application 09/128,143, Specification, p. 11, ll. 21-24. The 143 Specification further notes that the
biased plasma treatment may improve the properties of other materials besides TiN:
The present invention is not meant to be limited to titanium nitride barrier
layers and the post deposition bias voltage in a plasma treatment of the
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