Appeal No. 1999-0874
Application 08/726,733
have somewhat corresponding etch rates but different etch rates with respect to
different etchants, which are beyond apparatus claims 1-13 on appeal. Collectively
taken then, the teachings and suggestions in Teng, Muller and Kirk-Othmer indicate
that the materials comprising claimed second insulation layer, corresponding to silicon
oxide layer 11 of appellants’ prior art Figure 38 and 39, would have a correspondingly
or relatively higher etch rate than the claimed first insulation layer, correspondingly
comprising the silicon nitride layer 10 in prior art Figures 38 and 39.
As to independent claim 1 on appeal, this claim does not recite the relative hole
size as independent claim 7 does, but does recite that a sidewall insulation layer exists
at an inner sidewall of the second insulation layer defining the second hole, in contrast
to independent claim 7 on appeal. The bulk of the teachings in Teng apply to this
feature such as is shown in Figure 2C, Figure 4 and Figure 6C as relied upon by the
examiner. Since the hole size in claim 1 may be the same or even reversed from that
recited in independent claim 7 on appeal, the teaching value of Teng is pertinent. The
most succinct statement of the teachings of this reference appear to be in the first
paragraph at column 3. The discussion in the initial paragraphs of column 5 are also
pertinent to the point of indicating that the use of the techniques in Teng allow for
"sublithographic hole sizes that are smaller than could be directly patterned with normal
lithographic techniques." Note column 5, lines 29-32. Various advantages are
discussed at columns 6 and 7 including in the paragraph bridging these columns that
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