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Representing to PTO That a Product-by-Process Claim Limitation Is Structurally Distinct from the Prior Art Prevents Recapture in Reissue

11-1514
August 22, 2012
Cooley, Daniel C.

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Last Month at the Federal Circuit - September 2012

Judges: Linn, Plager, Dyk (author)

[Appealed from: N.D. Cal., Judge Chen]

In Greenliant Systems, Inc. v. Xicor LLC, No. 11-1514 (Fed. Cir. Aug. 22, 2012), the Federal Circuit affirmed the district court’s grant of SJ of invalidity relating to claims of reissued U.S. Patent No. RE38,370 (“the RE’370 patent”) for violation of the rule against recapture.

The RE’370 patent was a broadening reissue of U.S. Patent No. 5,977,585 (“the ’585 patent”). The specifications of both the ’585 patent and the RE’370 patent disclose improvements to electronic memory devices, such as EEPROM circuits. In an EEPROM, charge is transferred to and from a floating gate electrode through a tunneling oxide layer that acts as an insulator when not actively tunneling. The improved tunneling oxide layer disclosed in the ’585 and RE’370 patents reduces pin-hole defects and stress present in traditional tunneling oxide layers.

During examination of the ’585 patent, the examiner rejected claims 13 and 14 as obvious. In response, Xicor LLC (“Xicor”) amended claim 13 to include “said silicon dioxide layer being formed by low pressure chemical vapor deposition comprising the use of [tetraethylorthosilicate (‘TEOS’)].” Slip op. at 6. The examiner stated that the process limitations of the device claims (i.e., how the tunneling layer is formed by a low-pressure chemical vapor deposition comprising the use of TEOS) would not be given patentable weight over the prior art of record unless Xicor established that those process limits imparted “structural limitations” that distinguished the claimed device from prior art devices. Xicor responded that deposited TEOS oxide did in fact have significant structural benefits over the prior art. The examiner maintained the rejections, but the Board reversed the examiner’s rejections and the ’585 patent issued.

Xicor filed a reissue application based on the ’585 patent adding new claims 12 and 13. Claims 12 and 13 omitted the “comprising the use of [TEOS]” limitation, but otherwise duplicated claims 1 and 4 of the ’585 patent. The reissue examiner ultimately found that claims 12 and 13 were not barred by the recapture rule and the ’585 patent reissued as the RE’370 patent.

Greenliant Systems, Inc. (“Greenliant”) filed a DJ action against Xicor, seeking a declaration that it did not infringe any claims of the RE’370 patent and that all claims of the RE’370 patent were invalid. The parties agreed that an SJ order in another case involving Silicon Storage Technology, Inc. (“SST”), determining that claims 12 and 13 of the RE’370 patent were invalid under the recapture rule, applied equally and should be entered in this case. The district court entered a final judgment in favor of Greenliant, holding claims 12 and 13 invalid and dismissing the request for declaratory relief as to claims 1-11, per the agreement of the parties. The district court also granted SST’s motion to intervene in the Greenliant case, allowing SST to participate in Xicor’s appeal.

On appeal, the Federal Circuit addressed Xicor’s arguments regarding recapture. As a preliminary matter, the Court noted that the claims in dispute were written in product-by-process form. To distinguish the product from the prior art, the Court noted that the process must impart “structural and functional differences” to the product. Id. at 12 (citing Amgen Inc. v. F. Hoffman-La Roche Ltd., 580 F.3d 1340, 1370 (Fed. Cir. 2009)).

In favor of validity, Xicor argued that the TEOS process limitation did not actually impart any distinctive structural characteristics to the claimed device, but rather it was the deposition conditions, such as temperature and pressure, that determined the physical characteristics of the claimed device’s tunneling layer. Xicor argued, therefore, that it did not surrender non-TEOS reactants because the TEOS did not have structural characteristics that distinguished the prior art. Id. at 12-13. The Court disagreed.

The Court noted that during the prosecution of the ’585 patent, Xicor both amended claim 13 to add the TEOS limitation and relied on the TEOS limitation appearing in claims 13 and 14 to overcome prior art. The examiner made various rejections and stated that process limitations in the product-by-process claims were not given patentable weight over the prior art. The Court noted that Xicor responded by arguing that a “deposited TEOS oxide layer” was “structurally distinct from the prior art thermal oxide layers” taught by the prior art used by the examiner. Id. at 15 (citation omitted). The Court also referenced Xicor’s statements regarding the structural benefits of deposited TEOS, including Xicor’s statement that the “industry has acknowledged that the use of deposited TEOS oxide has significant structural benefits over prior art thermal oxide layers when used as tunneling layers.” Id. at 16 (citation omitted). The Court referenced similar statements that Xicor made before the Board.

The Court found that Xicor’s arguments “clearly and unmistakably represented to the examiner and the Board that TEOS was a necessary component of the deposition process that imparted the distinct structural characteristics upon Xicor’s claimed tunneling oxide layer.” Id. at 17. The Court further held that there was no merit to Xicor’s argument that these multiple references to the use of TEOS could be dismissed as mere “nomenclature . . . used by Xicor as a label to distinguish” between different tunneling layers. Id. at 17-18 (citation omitted).

The Court rejected Xicor’s argument that, as a technical matter, it was the deposition conditions that determine the physical characteristics of the claimed tunneling oxide layer, not the reactant that is used (e.g., TEOS), and, thus, the TEOS limitation could not have influenced the Board’s decision to allow the claims. The Court stated that Xicor was bound by the arguments that it made before the examiner and before the Board, and that “[i]t does not matter whether the examiner or the Board adopted a certain argument for allowance; the sole question is whether the argument was made.” Id. at 18. Accordingly, the Court affirmed the district court’s determination of invalidity for claims 12 and 13 of the RE’370 patent.