Your patent is invalid if you’re not the first inventor: The Fox Group, Inc. v. Cree, Inc.

01 Dec

The Federal Circuit recently handed down a decision affirming a lower district court ruling that found the claims of U.S. Pat. No. 6,562,130 asserted against Cree, Inc. by The Fox Group, Inc. to be invalid, since Cree had produced the claimed single-crystal silicon carbide (SiC) material before the priority date of the ‘130 patent.

This result was based on the “first to invent” requirement under current U.S. patent law, which is scheduled to change to a “first inventor to file” requirement on March 16, 2013 as part of the Leahy-Smith America Invents Act (AIA).  But as described at the end of this post, under the facts of this case, the result would be the same even if the upcoming “first inventor to file” requirement were used instead.

SiC is a man-made material that has been around for more than a century in a multicrystalline and high defect density form, primarily used as an abrasive.  But in single-crystal form with low intrinsic defect densities (e.g., dislocations, micropipes, and inclusions of a secondary phase within the crystal), SiC is a semiconductor that can be used in LED light sources and electronics designed to withstand high power levels and high temperatures.  In addition, single-crystal SiC can be used as a substrate material for epitaxial growth of bulk Group III nitrides (e.g., gallium nitride) for high speed electronics.


Cree markets a wide variety of LED-based lighting components, power MOSFETs, and electronic devices for RF communications, all  based on single-crystal SiC.  For fiscal year 2012, Cree reported revenues of $1.16 billion.  The Fox Group is apparently affiliated with Nitride Crystals, Inc., a supplier of SiC wafers which lists the ‘130 patent on its website as one of its patents.

Under current U.S. patent law’s “first to invent” requirement, a patent is invalid if the listed inventors were not the first inventors of the claimed invention (i.e., the claimed invention was first invented by someone else), as long as the first inventors had not “abandoned, suppressed, or concealed” the invention (35 U.S.C. 102(g)).  To get a patent deemed invalid under this provision, the accused infringer can prove that the invention was made by someone else prior to the listed inventors doing so.  The prior inventor does not have to be the accused infringer, but in many cases, this is the case since the accused infringer typically has much more information and evidence regarding its activities than it does of the activities of some third party.

Cree showed that in 1995 it had produced a SiC wafer that included a region with an exceptionally low intrinsic defect density, as evidenced by x-ray topographs, and that this wafer met the features of the material claimed in the ‘130 patent.  Cree also showed that it had publicized this result at a technical conference in 1995 and in a journal article in 1996.  Since the priority date of the ‘130 patent was in 1997, the district court held that the asserted claims of the ‘130 patent were invalid, and granted summary judgement to Cree.  The Federal Circuit affirmed the lower court ruling on the basis that Cree had proved that (i) it had once made the claimed material in 1995 so its researchers were prior inventors to those of the ‘130 patent and (ii) it had promptly and publicly disclosed its findings regarding the wafer’s low defect density to the public, so it had not abandoned, suppressed, or concealed the invention.

Since the claims of the ‘130 patent were directed to the SiC material itself, and not the process of making the material, it was enough for Cree to have shown that it once made the claimed material before the priority date of the ‘130 patent, and that Cree had promptly publicized this result.  Had the claims of the ‘130 patent been directed instead to a process of making such materials, Cree’s proof might have been insufficient, since it is not clear whether Cree’s public disclosure was sufficiently detailed to enable someone skilled in the technology to perform such a process.

It’s interesting to consider how the same facts would play out under the AIA’s upcoming “first inventor to file” requirement scheduled to go into effect on March 16, 2013.  Under the AIA, 35 U.S.C. 102 omits subsection (g), and the relevant portion states that “a person shall be entitled to a patent unless …  the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention.”  Since Cree publicized the properties of its low-defect-density SiC wafer in 1995 and 1996, before the effective filing date of the ‘130 patent in 1997, the ‘130 patent would be held invalid under this statute as well.

(The AIA’s statute includes an exception if the public disclosure was made by the inventors listed on the patent within one year of the patent’s effective filing date, but since the disclosure at issue was by Cree and not the listed inventors of the ‘130 patent, this exception does not apply under these facts.)


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One response to “Your patent is invalid if you’re not the first inventor: The Fox Group, Inc. v. Cree, Inc.

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