Ex Parte Chandrachood et al

Patent Trial and Appeal Board

Sep 10, 2013

11867740 (P.T.A.B. Sep. 10, 2013)

UNITED STATES PATENT AND TRADEMARKOFFICE
UNITED STATES DEPARTMENT OF COMMERCE
United States Patent and Trademark Office
Address: COMMISSIONER FOR PATENTS
P.O. Box 1450
Alexandria, Virginia 22313-1450
www.uspto.gov
APPLICATION NO. FILING DATE FIRST NAMED INVENTOR ATTORNEY DOCKET NO. CONFIRMATION NO.
11/867,740 10/05/2007 Madhavi R. Chandrachood 011453
ETCH/MASK-ETCH
9597
44257 7590 09/10/2013
PATTERSON & SHERIDAN, LLP - - APPM/TX
3040 POST OAK BOULEVARD, SUITE 1500
HOUSTON, TX 77056
EXAMINER
REMAVEGE, CHRISTOPHER
ART UNIT PAPER NUMBER
1713
MAIL DATE DELIVERY MODE
09/10/2013 PAPER
Please find below and/or attached an Office communication concerning this application or proceeding.
The time period for reply, if any, is set in the attached communication.
PTOL-90A (Rev. 04/07)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE PATENT TRIAL AND APPEAL BOARD
____________

Ex parte MADHAVI R. CHANDRACHOOD,
AMITABH SABHARWAL, TOI YUE LEUNG,
and MICHAEL GRIMBERGEN
____________

Appeal 2012-007987
Application 11/867,740
Technology Center 1700
____________

Before EDWARD C. KIMLIN, HUBERT C. LORIN, and DONNA M.
PRAISS, Administrative Patent Judges.

KIMLIN, Administrative Patent Judge.

DECISION ON APPEAL

This is an appeal from the final rejection of claim 26, the only claim
remaining in the present application. We have jurisdiction under 35 U.S.C.
§ 6(b). Claim 26 reads as follows:
26. A method for processing a photolithographic reticle, comprising:

positioning the reticle on a support member in a processing chamber,
wherein the reticle comprises a metal photomask layer formed on an
optically transparent substrate and a patterned resist material deposited on
the metal photomask layer;
Appeal 2012-007987
Application 11/867,740

2

introducing a processing gas comprising an oxygen containing gas, a
fluorocarbon gas, and trifluoromethane (CHF3) into the processing chamber;

delivering power to the processing chamber to generate a plasma
formed from the processing gas by applying a source RF power to a coil in
the processing chamber and applying a bias power to a reticle support in the
processing chamber; and

etching exposed portions of the metal photomask layer using the
plasma.

The Examiner relies upon the following references as evidence of
obviousness:
Buxbaum et al. (Buxbaum) US 2004/0209477 A1 Oct. 21, 2004
Mathuni et al. (Mathuni) 6,919,147 B2 Jul. 19, 2005

Appellants' claimed invention is directed to a method for processing a
photolithographic reticle comprising etching exposed portions of a metal
photomask layer with a plasma formed from a gas comprising an oxygen
containing gas, a fluorocarbon gas, an trifluoromethane (CHF3).
Appealed claim 16 stands rejected under 35 U.S.C. §103(a) as being
unpatentable over Buxbaum in view of Mathuni.
We have thoroughly reviewed each of Appellants' arguments for
patentability. However, we are in complete agreement with the Examiner
that the claimed subject matter would have been obvious to one of ordinary
skill in the art within the meaning of §103 in view of the applied prior art.
Accordingly, we will sustain the Examiner's rejection for essentially those
reasons expressed in the Answer, and we add the following primarily for
emphasis.
Appeal 2012-007987
Application 11/867,740

3
There is no dispute that Buxbaum, like Appellants, discloses a method
for processing a photolithographic reticle by etching exposed portions of a
metal photomask layer with a plasma formed from a processing gas
comprising an oxygen containing gas and CHF3. As recognized by the
Examiner, Buxbaum does not teach that the plasma is generated from a
processing gas comprising a fluorocarbon gas in addition to an oxygen
containing gas and CHF3. However, the Examiner correctly points out that
Mathuni evidences that it was known in the art to etch a pattern in a metal
photomask with a plasma generated from a processing gas comprising an
oxygen containing gas and either CHF3 or a fluorocarbon. Accordingly, we
find no error in the Examiner's legal conclusion that it would have been
obvious for one of ordinary skill in the art to substitute a fluorocarbon for
the CHF3 of Buxbaum, or include a mixture of a fluorocarbon and CHF3 in
the processing gas of Buxbaum. It is well settled that it is a matter of
obviousness for one of ordinary skill in the art to combine two or more
materials when each is taught by the prior art to be useful for the same
purpose. In re Kerkhoven, 626 F.2d 846, 850 (CCPA 1980). In the present
case, Mathuni expressly discloses that it was known in the art to generate a
plasma from a processing gas comprising an oxygen containing gas and
either CHF3 or a fluorocarbon for etching a chromium photomask. Hence,
we are satisfied that the Examiner properly concluded that it would have
been obvious for one of ordinary skill in the art to use a mixture of an
oxygen containing gas, CHF3 and a fluorocarbon to etch the chromium
photomask of Buxbaum.
Appeal 2012-007987
Application 11/867,740

4
The principal argument advanced by Appellants is that Mathuni, in
discussing prior art, discloses a disadvantage of poor etching selectivity
when using a plasma generated from CHF3 or a fluorocarbon. We agree
with the Examiner, however, that it would have been obvious for one of
ordinary skill in the art to etch a chromium photomask with a plasma
generated from a processing gas comprising a mixture of CHF3 and a
fluorocarbon with the reasonable expectation of poor etching selectivity.
Just as it is a matter of obviousness for one of ordinary skill in the art to
eliminate a feature of the prior art along with its attendant advantage, it is
also a matter of obviousness for the skilled artisan to employ a known
process along with its known disadvantage. Appellants have not established
on this record that they have achieved an unexpected result by utilizing a
processing gas comprising CHF3 and a fluorocarbon without experiencing
poor etching selectivity. Furthermore, Mathuni discusses the disadvantage
in association with producing halftone phase masks and the claimed method
presently on appeal is not directed to making a halftone phase mask.
As a final point, we note that Appellants base no argument upon
objective evidence of nonobviousness, such as unexpected results.
In conclusion, based on the foregoing and the reasons well stated by
the Examiner, the Examiner’s decision rejecting the appealed claims is
affirmed.
The decision of the Examiner is affirmed.
Appeal 2012-007987
Application 11/867,740

5
No time period for taking any subsequent action in connection with
this appeal may be extended under 37 C.F.R. § 1.136(a)(1)(iv).
AFFIRMED

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