IP Law Daily PTAB determination that Raytheon semiconductor patent was obvious upheld
Monday, April 2, 2018

PTAB determination that Raytheon semiconductor patent was obvious upheld

By Jody Coultas, J.D.

The U.S. Court of Appeals for the Federal Circuit affirmed an inter partes review decision by the Patent Trial and Appeal Board that certain claims of a patent held by Raytheon Company were unpatentable. The patent claims, covering advances in the manufacturing of semiconductors, was challenged by Sony Corporation and Samsung Electronics Co., Ltd. as obvious in light of three prior art references. The court found that substantial evidence supported the Board’s finding that the claims were obvious. While the Board did err in its interpretation of a limitation of the patent, that error did not affect the outcome (Raytheon Company v. Sony Corporation, April 2, 2018, O’Malley, K.).

U.S. Patent No. 5,591,678 (the ’678 patent), entitled "Process of Manufacturing a Microelectric Device Using a Removable Support Substrate and Etch-Stop," is directed to purported advances in the manufacture of stacked semiconductors found in everyday electronic devices. Rather than employ a conventional "front-side" fabrication process, whereby microelectronic circuits are formed and substrates are stacked on top of a wafer, the ’678 patent employs a "back-side" process, whereby many of the fabrication steps are performed on the bottom of the wafer.

Sony Corporation, Samsung Electronics Co., Ltd., Samsung Electronics America, Inc., and Samsung Semiconductor, Inc. filed a series of inter partes review petitions, which were consolidated into two proceedings. The Board held that all the claims were unpatentable under pre-AIA 35 U.S.C. § 103 as obvious over the prior art of record. Raytheon appealed with respect to claims 5, 13–14, and 16–18.

Liu-based findings. U.S. Patent No. 4,422,091 to Liu ("Liu"), which qualified as prior art under pre-AIA § 102(b), describes a gallium arsenide, multi-layer charge coupled device (CCD) for detecting electromagnetic radiation, as well as a method of fabrication. Raytheon argued that the Board failed to address its argument that using silicon in Liu’s devices would render them inoperable.

The court agreed with the Board’s finding that a skilled artisan would have been motivated to use silicon material with Liu’s CCD semiconductors in non-star sensor applications and affirmed the determination that Liu renders appealed claims 5, 13–14, and 16–18 of the ’678 patent obvious. Raytheon argued that using silicon in Liu’s CCDs would defeat Liu’s primary objectives of achieving low dark current and high optical responsivity, which, in turn, would render Liu’s devices inoperable for their intended purpose; thus, a skilled artisan would not be motivated to combine Liu with secondary references that teach using silicon in semiconductor devices. However, the court found that this argument was merely a slight variation of the argument that the Board squarely addressed, determining that Liu expressly teaches that silicon in semiconductor systems was generally known. Rather, Liu’s reference to silicon would not have convinced anyone to avoid it except for certain specific applications. The court also noted that a skilled artisan cannot be assumed to ignore Liu merely because it is primarily directed to a specific application that is different from the application claimed in the patent at issue. Thus, the Board’s finding was affirmed.

Bertin-based findings. U.S. Patent No. 5,202,754 to Bertin (Bertin) issued several months after the priority date of the ’678 patent, but was filed sixteen months prior thereto, and therefore nominally qualifies as prior art under pre-AIA § 102(e). Bertin discloses "[a] fabrication method and resultant three-dimensional multichip package" containing several layers of siliconbased material. Raytheon argues that the Board erred in finding that Bertin was not prior art because the inventors reduced to practice the claimed subject matter before Bertin’s filing date.

The court affirmed the Board’s determination that Raytheon failed to antedate Bertin. To antedate a prior art reference, a patentee must establish that it invented the subject matter recited in the patent claims before the reference’s priority date by showing "either an earlier reduction to practice, or an earlier conception followed by a diligent reduction to practice." A party seeking to establish an actual reduction to practice must show (1) the party must construct an embodiment or perform a process that satisfies every element of the claim at issue and (2) the embodiment or process must operate for its intended purpose. The inventors testified that they reduced to practice the subject matter recited in the claims by the end of 1990, more than nine months before Bertin’s September 1991 filing date. However, an internal report contradicted the inventors’ testimony. Thus, the Board’s finding was appropriate.

Morimoto-based findings. Japanese Unexamined Patent Application Publication No. 64-18248 to Morimoto, which qualified as prior art under pre-AIA § 102(b), discloses "a method for manufacturing semiconductor devices" containing multiple layers. One of those layers is a "supporting silicon substrate," which Morimoto teaches is removed during the fabrication process. Raytheon argued that the Board erroneously construed the claim term "second substrate" to encompass Morimoto’s temporary supporting substrate.

Although Raytheon was correct that the Board’s determination on Morimoto was predicated on an erroneous claim construction of the term "second substrate," that issue was rendered moot in light of the holdings above. The Board determined that the second substrate need not remain part of the final device, and that the claim limitation therefore encompasses Morimoto’s temporary substrate, which is removed during fabrication. This construction was too broad, and the correct construction requires that the second substrate remain attached to the device throughout the fabrication process and in the final product. The Board failed to consider the specification and instead focused solely on the "comprising" transition in the claims’ preambles, finding that the open-ended transition allows for subsequent removal of the second substrate. "The ’678 patent claims and specification clearly impose a limitation on the claim term "second substrate," requiring permanent attachment throughout the fabrication process. Morimoto’s additional step of removing the second substrate vitiates that limitation because it, in fact, removes the substrate from the device. Accordingly, the claims cannot be construed so broadly as to encompass such removal."

The case is Nos. 2017-1554, 2017-1556, and 2017-1557.

Attorneys: Thomas J. Filarski (Steptoe & Johnson LLP) for Raytheon Co. Matthew A. Smith (Smith Baluch LLP) and Zhuanjia Gu (Turner Boyd LLP) for Sony Corp. Ronald J. Pabis (Greenberg Traurig LLP) for Samsung Electronics Co., Ltd., Samsung Electronics America, Inc., and Samsung Semiconductor, Inc.

Companies: Raytheon Co.; Sony Corp.; Samsung Electronics Co., Ltd.; Samsung Electronics America, Inc.; Samsung Semiconductor, Inc.

MainStory: TopStory Patent TechnologyInternet FedCirNews

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