This case highlights another facet to the perils of prosecution history estoppel – not only can it be used against you in litigation, but it can also be used against you at the PTO if you need to broaden your claims at a later date through reissue. Remember, you are bound by all arguments made before the Examiner and/or the Board. “It does not matter whether the examiner or the Board adopted a certain argument for allowance; the sole question is whether the argument was made.” From a strategy perspective, I think this case also gives further credence to the approach of filing continuations to keep important cases alive if you ever do need to generate broader claims (e.g., if a particular infringer is discovered down the road that does not fit well within the framework of your existing claims). From the 2-year limit to the rule against recapture, broadening reissue claims present unique challenges that limit their practicality.
Background / Facts: The reissue patent under consideration discloses improvements to electronic memory devices, specifically EEPROM circuits, in which “the presence or absence of charge on a floating gate electrode indicates a binary one or zero.” The improved tunneling oxide layer disclosed reduces defects and stress, and thereby improves, among other things, processing yields, reliability, and the useful life of EEPROM memory. During original prosecution, Xicor amended the “tunneling layer” element to specify that (1) the layer is “formed by low pressure chemical vapor deposition,” and (2) the deposition “compris[es] the use of tetraethylorthosilicate,” also referred to as “TEOS.” During reissue, Xicor added new claims 12 and 13, which omitted the “comprising the use of [TEOS]” limit.
Issue(s): Whether broadening claims 12 and 13 of the reissued patent (the claims at issue in this case) improperly recaptured claim scope that Xicor had previously surrendered during the prosecution of its predecessor patent.
Holding(s): Yes. Under the rule against recapture, a patentee’s reissue claims are invalid when those claims were broadened to include subject matter that the patentee previously surrendered during prosecution of the original patent. The standard for deciding whether a patentee surrendered certain subject matter is “whether an objective observer viewing the prosecution history would conclude that the purpose of the patentee’s amendment or argument” concerning a particular claim was for reasons of patentability, that is, “to overcome prior art and secure the patent.” During the prosecution of the original patent, Xicor both amended claim 13 to add the TEOS limit and relied on the TEOS limit appearing in claims 13 and 14 to overcome prior art. Xicor submitted a fact declaration and repeatedly used that declaration to argue before the examiner, and more importantly before the Board, that forming the claimed tunneling layer by a low pressure chemical vapor deposition with TEOS imparted structural differences that distinguished the claimed tunneling layer from the prior art. 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. The court found no merit to Xicor’s argument that these multiple references to the use of TEOS should be dismissed as mere “nomenclature … used by Xicor as a label to distinguish” between different tunneling layers.