Appeal No. 2005-0123
Application No. 10/114,759
As explained supra, Xu also teaches that the third sublayer
ending in pure metal (titanium or tantalum) serves two purposes,
a wetting layer for sputtering aluminum and also for cleaning the
sputter target for the next wafer. Thus, Xu suggests that the
third sublayer could be useful, even when aluminum is not to be
sputtered, to clean the sputter target for the next wafer.
Returning to the choices for the seed layer, the skilled
artisan would have recognized that a copper seed layer would
require moving the wafer to a separate chamber for sputtering the
copper, and then moving the wafer again for electroplating the
copper. On the other hand, the skilled artisan would have
recognized that a seed layer of titanium or tantalum would have
required moving the wafer only for electroplating the copper,
since Xu's method already potentially includes a third sublayer
ending in pure titanium or tantalum. Thus, the skilled artisan,
given all of the teachings described supra, would have selected
Simpson's titanium or tantalum for the seed layer to serve Xu's
purpose of reducing the number of times the wafer gets moved for
another process step while improving the electroplating process,
as taught by appellant's admissions. We note that the deposition
time for sputtering the titanium or tantalum might need to be
lengthened to provide a seed layer. However, such a
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