Appeal No. 2000-0239 Page 12
Application No. 08/839,843
Here, “[t]he objective of [Saito] is to offer a
semiconductor device whereby migration is prevented and the
reliability of the aluminum wiring is improved.” Saito
Translation, p. 2. Toward that objective, the reference
discloses an embodiment of its invention wherein “the aluminum
wiring is divided into sections by the tungsten layer (14). . .
.” Id. at 3. Although Saito describes the tungsten layer, it
invites the use of other materials. Specifically, “it goes
without saying that other materials such as titanium, molybdenum,
and the like may be used.” Id. at 5.
For its part, Drake discloses that using titanium “as a
barrier layer,” col. 5, l. 1, is desirable for several reasons.
Among these reasons is the prevention of electromigration.
Specifically, “[i]t has been found that the described structure
and method improved the electromigration resistance of the second
aluminum layer 44 because of the presence of the titanium
layer 42.” Id. at ll. 24-26. Other advantages include
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