Appeal No. 1998-1548 Page 6
Application No. 08/660,304
below the oxide layer, in order to increase the visibility of
the Oka mark.
Appellants assert (brief, pages 9-11) that there is no
motivation to combine the teachings of the APA with Oka and
Tominaga because in Oka, the pattern formed in the oxide layer
on the metal layer is only for visual observation. In
addition, Oka does not have an underlying ARC layer, but
rather has a metal layer, resulting in a different step
structure from that of appellants' invention. Appellants
further assert that in Tominaga, the step of the alignment
mark comprises an opaque conductive layer over a TiN layer,
and that the TiN layer of Tominaga is used as a diffusion
barrier layer and not as an ARC layer.
We find that in the APA, the alignment mark 36 shown in
Figures 2 and 3, is a raised area. However, later in the
manufacturing process, when the fuse access opening 34 and
window outline 30 of the alignment mark are etched, alignment
mark 36 has adjacent regions 32 that are deeply recessed, as
shown in Figure 4. The APA teaches (pages 6 and 7) that the
deep recesses harbor residues and other debris which cause
severe noise in the laser alignment scan.
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