Appeal 2006-3363
Application 10/873,363
OPINION
Appellants argue that Tehrani does not teach a magneto-restive bit
encapsulated by a conductive etch stop layer as claimed. Appellants state that
Tehrani teaches two distinct embodiments, one in which vias 47 and 50 are etched
separately and the other where vias 47 and 50 are etched in the same operation.
Appellants argue that the Examiner’s rejection is mixing embodiments, asserting
that in the first embodiment the magneto-resistive bit is encapsulated by a
dielectric layer, but that in the second embodiment, which uses a conductive etch
stop layer, Appellants argue the etch stop layer is not on the sides of the magneto-
resistive bit. Brief p. 3. Appellants state that in the second embodiment Tehrani
identifies that the etching of the vias 50 must not extend outside the magneto-
resistive bit. Appellants reason that this is because the conductive bit stop layer is
not present to provide protection on the sides of the magneto-resistive bit. Brief
pp. 4-5. Appellants also reason that the conductive bit stop layer of the second
embodiment does not cover the same area as the dielectric layer of the first
embodiment since, if this were the case, the conductive bit stop layer would short
out the circuit. Brief p. 5.
The Examiner responds, on page 7 of the Answer, stating that in the second
embodiment, where the vias are etched simultaneously, the same chemistry is used
to form both vias. The Examiner cites to column 5, lines 58-62 of Tehrani as
describing that to protect the magneto resistive element (bit) from corrosive agents,
the vias 50 must be enclosed and may not extend outside the ends of the bit.
Answer p. 7. The Examiner states “Tehrani does not indicate that it [the via being
enclosed by and not extending outside the ends of the bit] is because there is no
conductive barrier on the sidewalls of the bit.” Answer p. 9. Further, the
Examiner finds that the cap layer 45 “completely seals the bit structure 41 and
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