Ex parte Chen et al.

Board of Patent Appeals and Interferences

Nov 18, 1998

08418122 (B.P.A.I. Nov. 18, 1998)

Application for patent filed April 6, 1995. According1
to appellants, this application is a continuation of
Application 08/146,825 filed November 1, 1993, now abandoned;
which is a continuation of Application 07/835,731 filed
February 11, 1992, now abandoned; which is a continuation of
U.S. Patent No. 5,108,951 issued April 28, 1992, based on
Application 07/609,883 filed November 5, 1990.
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journal and (2) is not binding precedent of the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. 34
UNITED STATES PATENT AND TRADEMARK OFFICE
____________
BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
____________
Ex parte FUSEN E. CHEN, FU-TAI LIOU, YIH-SHUNG LIN,
GIRISH A. DIXIT and CHE-CHIA WEI
____________
Appeal No. 97-3530
Application No. 08/418,1221
____________
ON BRIEF
____________
Before KRASS, MARTIN, and SMITH, Administrative Patent Judges.
KRASS, Administrative Patent Judge.
DECISION ON APPEAL
Appeal No. 97-3530
Application No. 08/418,122
2
This is a decision on appeal from the final rejection of
claims 15 through 25, 27 through 39, 41 through 53, 55 and 56,
all of the claims pending in the application.
The invention pertains to a method for forming a metal
contact in an integrated circuit. More particularly, an
improved interlevel contact is said to be achieved by
improving the coverage in contact vias through the manner in
which aluminum is deposited therein.
Representative independent claim 15 is reproduced as
follows:
15. A method for forming an aluminum contact in an
integrated circuit, comprising the steps of:
forming an insulating layer over a conducting layer;
forming an opening through the insulating layer to expose
a portion of the conducting layer;
forming a barrier layer over the insulating layer, in the
opening, and over the exposed portion of the conducting layer;
raising the temperature of the integrated circuit from
below approximately 350°C to a value between approximately
400°C and approximately 500°C;
during said temperature raising step, beginning to
deposit aluminum on the barrier layer, and continuing to
deposit aluminum on the integrated circuit during the
remainder of the temperature raising step;
Appeal No. 97-3530
Application No. 08/418,122
3
after the temperature raising step, continuing to deposit
an aluminum layer on the integrated circuit to a first
thickness, at a temperature between approximately 400°C and
approximately 500°C; and
during said first thickness depositing step, controlling
the rate at which aluminum is deposited to allow deposited
aluminum to migrate into the opening so as to provide a
substantially complete fill thereof.
The examiner relies on the following references:
Armstrong et al. (Armstrong) 4,994,162 Feb. 19,
1991
Wolf et al. (Wolf), “Aluminum Thin Films and Physical Vapor
Deposition in VLSI,” Silicon Processing for the VLSI Era,
Volume 1, California (1986) pp. 332-334 and 367-374.
In addition, the examiner relies on admitted prior art
[APA].
Claims 15 through 25, 27 through 39, 41 through 53, 55
and 56 stand rejected under 35 U.S.C. 103 as unpatentable over
the combination of Armstrong, APA and Wolf.
All of the claims also stand rejected under the doctrine
of obviousness-type double patenting over claims 11 through 19
of U.S. Patent No. 5,108,951.
Appeal No. 97-3530
Application No. 08/418,122
4
The claims stand still further rejected, provisionally,
under obviousness-type double patenting over claims 19 and 28
of copending Application Serial No. 08/418,257.
The examiner also enters new grounds of rejection against
all of the claims in the answer but the grounds of rejection
are essentially the same ones noted supra with slightly more
explanation.
Reference is made to the briefs and answer for the
respective positions of appellants and the examiner.
OPINION
Turning first to the rejection of the claims under 35
U.S.C. 103, we will not sustain this rejection.
As argued by appellants, the independent claims all
require that aluminum is begun to be deposited on the barrier
layer during the temperature raising step. Armstrong is
silent as to any barrier layer. Further, the aluminum
deposited in Armstrong during a temperature raising step is
deposited on another aluminum layer which was produced during
a first step in Armstrong’s process. Since there is no
indication that this first aluminum layer may be considered
Appeal No. 97-3530
Application No. 08/418,122
5
the “barrier layer,” as claimed, again, Armstrong fails to
teach or suggest the claimed deposit of aluminum on a barrier
layer, said deposit beginning during the temperature raising
step.
While a barrier layer may have been well known in the
art, as apparently contended by the examiner in referring to
admitted prior art, we find no reason, and certainly no reason
clearly articulated by the examiner, as to why the skilled
artisan would have combined the statements of admitted prior
art in the instant specification with the Armstrong disclosure
in such a manner as to arrive at the instant claimed invention
wherein aluminum is begun to be deposited on a barrier layer
during a temperature raising step. Wolf, applied as a
standard text to show that there is inherent heating during an
aluminum sputter deposition process, is of no help in this
regard. The claimed temperature raising step entails raising
the temperature from below approximately 350 degrees
Centigrade to a value between approximately 400 and 500
degrees Centigrade. The sputter deposition first step in
Armstrong is done at a temperature below 200 degrees
Centigrade (column 3, lines 12-13 of Armstrong). Thus, we
Appeal No. 97-3530
Application No. 08/418,122
6
find no connection between the teaching of Wolf and the
temperatures required by the instant claims when viewed in
light of the sputtering temperature disclosed by Armstrong.
Further, with regard to the claimed controlled rate of
aluminum deposition, as indicated by appellants, at page 10 of
the principal brief, Armstrong lowers the deposition rate at
the same time as heating begins which is contrary to the
instant claimed invention which lowers the deposition rate
after the device has been brought up to the desired
temperature. Thus, Armstrong, again, fails to teach or
suggest a specific claim limitation, a deficiency which is not
remedied by the addition of the combination of the admitted
prior art and Wolf.
We now turn to the rejection of the claims based on
obviousness-type double patenting over claims 11 through 19 of
U.S. Patent No. 5,108,951 and the provisional rejection of the
claims based on obviousness-type double patenting over claims
19 and 28 of copending application Serial No. 08/418,257.
We remand the case to the examiner for clarification of
the rejections.
Appeal No. 97-3530
Application No. 08/418,122
7
The examiner merely contends that the instant application
and the patent and/or copending application are “claiming
common subject matter” but fails to elucidate. Accordingly,
if the examiner maintains these rejections, the examiner is
required to specifically and particularly point out how each
of the rejected/provisionally rejected claims is found to be
obvious over the specifically identified claim limitations of
the patent/application, explaining the differences between the
instant claimed subject matter and the claimed subject matter
in the patent/application and why the instant claimed subject
matter would have been obvious thereover.
We further note, regarding the obviousness-type double
patenting rejection and provisional rejection, that while the
examiner has fallen far short of a complete explanation of the
rejections, appellants’ arguments, at pages 11-12 of the
principal brief, appear to concede the propriety of the
rejections with regard to the Group A claims (15-18, 20, 21,
24, 25, 27, 29-32, 34, 35, 38, 39, 41, 43-46, 48, 49, 52, 53,
55) by failing to make any argument thereagainst. We also
note that the only argument that appellants do make, regarding
the deposition rate features of the Group B and C claims, does
Appeal No. 97-3530
Application No. 08/418,122
8
not appear to be accurate. For example, instant claim 19
appears to be directed to the same subject matter as patented
claim 15 regarding deposition rates.
Since appellants have offered to file a terminal
disclaimer, obviating these rejections, in the event of
allowability of a claim, and we have reversed the rejection of
the claims under 35 U.S.C. 103, should the examiner find the
instant claims otherwise allowable, perhaps it would be best
for all parties involved if a proper terminal disclaimer is
filed. We leave these decisions up to appellants and the
examiner. In any event, if no proper terminal disclaimer is
filed and the examiner wishes to pursue the obviousness-type
double patenting rejections, the examiner is instructed to
indicate specific reasons for such rejections, indicating how
the claims of the aforementioned patent and patent application
are being applied against each claim of the instant
application.
Appeal No. 97-3530
Application No. 08/418,122
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Accordingly, it is
ORDERED that the application is remanded to the
Examiner for appropriate notification to applicant and for
such further action as may be appropriate.
It is important that the Board of Patent Appeals and
Interferences be informed promptly of any action affecting the
appeal.
REVERSED and REMANDED
ERROL A. KRASS )
Administrative Patent Judge )
)
)
)
) BOARD OF PATENT
JOHN C. MARTIN ) APPEALS
Administrative Patent Judge ) AND
) INTERFERENCES
)
)
)
JERRY SMITH )
Administrative Patent Judge )
Appeal No. 97-3530
Application No. 08/418,122
10
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