Ex Parte Chandrachood et al

Patent Trial and Appeal BoardSep 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. Â§ 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. Â§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 Â§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 Examinerâ€™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. Â§ 1.136(a)(1)(iv). AFFIRMED cam