were reported has having resistivities significantly higher than the controls. Application 09/128,143,
Specification, p. 10, Table 1, Example C1, C3 and C4.
The 143 Specification also describes three additional attempts to lower resistivity. Application
09/128,143, Specification, p. 11, ll. 4-20. In two of the attempts (Examples C5 and C6), the film was
said to be exposed to hydrogen and nitrogen plasmas, respectively, both before and after deposition
of TiN. Application 09/128,143, Specification, p. 11, Table II, Examples C5 and C6. The 143
Specification specifically notes that in making the films of Examples C5 and C6 the substrate was not
biased:
a plasma was initiated before and after chemical vapor deposition of titanium
nitride using a low power of 100 watts and without biasing the substrate silicon
wafer.
Application 09/128,143, Specification, p. 11, ll. 6-9 (emphasis added). The films of Examples C5 and
C6 were reported as having resistivities of 13,500 and 15,500 :ohms-cm. Application 09/128,143,
Specification, p. 11, Table II. Both of these values were far above the order of 1000 :ohms-cm said
to be desirable for TiN barrier layers (Application 09/128,143, Specification, p. 7, ll. 17-19) and
within the range identified as unacceptable for that purpose (Application 09/128,143, Specification,
p. 7, ll. 13-17). Comparing the results with the “prior art” control samples (Application 09/128,143,
Specification, p. 9, ll. 21-22 and p. 10, Table I), Leung states:
It is apparent that none of these pre- and post-treatments had much effect on
the sheet resistivity.
Application 09/128,143, Specification, p. 11, ll. 19-20.
The 143 Specification also presents examples comparing the resistivity achieved for another
control sample, apparently made according to the prior art process, with eight examples post-treated
with high energy ions from a nitrogen plasma subject to a bias voltage of 400 volts. Application
09/128,143, Specification, p. 12, ll. 1-32. The control sample was said to have an initial resistivity
of 11,020 :ohms-cm which increased by 130% in 24 hours. Application 09/128,143, Specification,
p. 12, Table III, Control. Examples 1-8, plasma post-treated while applying a bias of 400 volts, were
reported as having significantly lower resistivities and lower resistivity change over 24 hours.
Application 09/128,143, Specification, p. 12, Table III, Examples 1-8. The bias-treated films which
are said to have low resistivities ranging from 913 to 4,620 and increases in resistivity of 2 to 43%
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Last modified: November 3, 2007