Ex parte Lee et al.

Board of Patent Appeals and Interferences

Aug 7, 1998

08301536 (B.P.A.I. Aug. 7, 1998)

Application for patent filed September 6, 1994.1
-1-
THIS OPINION WAS NOT WRITTEN FOR PUBLICATION
The opinion in support of the decision being entered
today (1) was not written for publication in a law
journal and (2) is not binding precedent of the Board.
Paper No. 16
UNITED STATES PATENT AND TRADEMARK OFFICE
________________
BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
________________
Ex parte JIN-YUAN LEE, CHUE-SAN YOO
and HSIEN W. CHIN
________________
Appeal No. 96-2085
Application No. 08/301,5361
________________
ON BRIEF
________________
Before KIMLIN, PAK and WALTZ, Administrative Patent Judges.
KIMLIN, Administrative Patent Judge.
DECISION ON APPEAL
This is an appeal from the final rejection of claims 9-13,
15, 16 and 22-26. Claim 1-8 and 17-21, the other claims
remaining in the present application, stand withdrawn from
Appeal No. 96-2085
Application No. 08/301,536
-2-
consideration. Claims 9 and 22, as amended after final
rejection, are illustrative:
9. A method of fabricating a contamination resistant opening
for a fuse link on a semiconductor substrate comprising:
forming a first insulating layer over portions of the
substrate;
forming a fuse link on the first insulating layer;
forming a second insulating layer over the fuse link
and the first insulating layer;
forming a third insulating layer overlying the second
insulating layer;
forming a fourth insulating layer overlying the third
insulating layer;
forming a first opening over the fuse with vertical
sidewalls, the first opening extending through the second, third
and fourth insulating layers; said first opening exposing a
portion of said fuse;
forming a protective layer over the fourth insulating
layer, over at least the sidewalls of the first opening, and the
exposed portion of the fuse; said protective layer is formed of
silicon nitride having a thickness in the range of 3000 to 20,000
angstroms; and
forming a second opening in the protective layer over
the fuse thus exposing portions of said fuse.
22. A method of fabricating a contamination resistant opening
for a fuse link on a semiconductor substrate comprising:
forming a first insulating layer over portions of the
substrate;
forming a fuse link on the first insulating layer;
forming a second insulating layer over the fuse link
and the first insulating layer;
Appeal No. 96-2085
Application No. 08/301,536
-3-
forming a third insulating layer overlying the second
insulating layer;
forming a fourth insulating layer overlying the third
insulating layer;
forming a first opening with vertical sidewalls over
the fuse, the first opening extending through the third and
fourth insulating layers and at least through a portion of the
second insulating layer; said first opening exposing a portion of
said second insulating layer over said fuse; said remaining
portion of said second insulating layer having a thickness in the
range of 100 to 15,000 angstroms;
forming a protective layer over the fourth insulating
layer, over at least the sidewalls of the first opening, and the
exposed portion of the second insulating layer on the bottom of
the opening; said protective layer is formed of silicon nitride
having a thickness in the range of 3000 to 20,000 angstroms; and
forming a second opening in the protective layer over
the fuse thus exposing the remaining portion of said second
insulating layer.
In addition to the admitted prior art found in appellants'
specification, the examiner relies upon the following references
as evidence of obviousness:
Takayama et al. (Takayama) 4,536,949 Aug. 27, 1985
Udo et al. (Udo) 4,628,590 Dec. 16, 1986
Motonami et al. (Motonami) 5,241,212 Aug. 31, 1993
Appellants' claimed invention is directed to a method of
forming a silicon nitride protective layer over the sidewalls of
a window in insulation layers and over a fuse before the fuse is
cut by a laser. An opening is formed in the protective layer to
allow the laser to cut the fuse. According to appellants, the
Appeal No. 96-2085
Application No. 08/301,536
-4-
nitride protective layer prevents contamination of the exposed
sidewalls of the insulation layers in the window.
Appellants submit at page 7 of the Brief that the appealed
claims do not stand or fall together, but claims 9-16 are drawn
to a first embodiment of the invention whereas claims 22-27 are
drawn to a second embodiment of the invention. Since appellants
have not presented separate arguments for patentability for any
of the dependent claims, and claims 14 and 27 have been canceled,
claims 9-13, 15 and 16 stand or fall together, as a group, as
does the group of claims 22-26.
Appealed claims 9-11, 12, 13, 15 and 16 stand rejected under
35 U.S.C. § 103 over the admitted prior art in view of Udo and
Takayama. Claims 22-26 stand rejected under 35 U.S.C. § 103 as
being unpatentable over the stated combination of references
further in view of Motonami.
We will not sustain the examiner's rejection of claims 9-11,
12, 13, 15 and 16 over the admitted prior art in view of Udo and
Takayama. We agree with appellants that the collective teachings
of the references do not teach or suggest the claimed steps of
providing the silicon nitride protective layer over the sidewalls
of the fuse window and the exposed portion of the fuse before an
opening is made in the protective layer over the fuse to allow
the fuse to be cut with a laser. According to the examiner,
Appeal No. 96-2085
Application No. 08/301,536
-5-
Udo teaches that if there is no particular reliability
problem, the deposition of the first passivation layer
may be omitted (column 6, lines 11-14), leaving the
silicon nitride passivation layer as the sole
protection layer which may be then be [sic] etched so
that the fuse may be cut as previously done to the
first passivation layer. [Page 9 of Answer].
However, the examiner has apparently misread Udo at column 6,
lines 11-14. The relevant passage of Udo reads "[i]f there is no
particular reliability problem even if cracks 26 or 33 in the
bonding pad 20A or 30 are left exposed, only the fuses 4 need be
covered with the passivation film 27." Contrary to the
examiner's interpretation, there is no teaching here that first
passivation film 22 may be omitted in favor of only second
passivation film 27. Rather, the relevant passage relates that
only fuses 4, and not bonding pad 20A or 30, need be covered with
passivation film 27 if there is no reliability problem. As
depicted in Figure 1H, passivation layers 22 and 27 are both
present.
The examiner goes on to state that "[i]n either case, Udo
does teach that both the first and final passivation films are
etched (column 5, lines 26-34 and lines 44-60)" (page 9 of
Answer). However, the disclosures of Udo referenced by the
examiner teach etching the first and final passivation films in
the proximity of the opening 24, and not in the proximity of the
fuse. Indeed, Udo discloses that "[t]he fuses, whether or not
Appeal No. 96-2085
Application No. 08/301,536
-6-
they have been cut, are finally covered with the second final
passivation film" (column 6, lines 48 and 49).
We will sustain the examiner's rejection of claims 22-26
under § 103 over the collective teachings of the admitted prior
art, Udo, Takayama and Motonami. Claim 22 on appeal defines a
method wherein the protective silicon nitride layer is formed on
the exposed portion of the second insulating layer which covers
the fuse link. However, Motonami evidences that it was known in
the art to provide a protective silicon nitride layer over an
insulating layer which, in turn, covers a fuse link. Motonami
discloses that the silicon nitride protection film serves as a
stopper when the fuse link and the covering insulating film is
blown off by a laser beam. Although Motonami does not disclose
the claimed step of forming a second opening in the protective
layer over the fuse to allow for exposure to a laser, the
paragraph bridging pages 4 and 5 of appellants' specification
discloses that it was known in the art to expose the fuse to a
laser through an intervening insulating film, but "it is
conventional to have an opening 28 over the fuse in the area
where the fuse will be heated" since overlying layers inhibit the
laser. Accordingly, we find that it would have been obvious for
one of ordinary skill in the art to provide an opening in
Appeal No. 96-2085
Application No. 08/301,536
-7-
protective film 6 of Motonami before exposing the fuse to a
laser.
In conclusion, based on the foregoing, the examiner's
rejection of claims 9-11, 12, 13, 15 and 16 under 35 U.S.C. § 103
is reversed. The examiner's rejection of claims 22-26 under
§ 103 is affirmed. Accordingly, the examiner's decision
rejecting the appealed claims is affirmed-in-part.
No time period for taking any subsequent action in
connection with this appeal may be extended under 37 CFR
§ 1.136(a).
AFFIRMED-IN-PART
EDWARD C. KIMLIN )
Administrative Patent Judge )
)
)
)
CHUNG K. PAK ) BOARD OF PATENT
Administrative Patent Judge ) APPEALS AND
) INTERFERENCES
)
)
THOMAS A. WALTZ )
Administrative Patent Judge )
George O. Saile
20 McIntosh Dr.
Poughkeepsie, NY 12603