PTAB

IPR2018-00798

Samsung Electronics Co Ltd v. Tessera Advanced Technologies Inc

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1. Case Identification

2. Patent Overview

  • Title: Semiconductor Device Including A Diffusion Layer
  • Brief Description: The ’001 patent discloses a semiconductor device featuring first and second electrode portions formed on a semiconductor element. The core inventive concept relates to a diffusion layer formed between these electrodes, comprising metal components from both, to create a reliable electrical connection.

3. Grounds for Unpatentability

Ground 1: Obviousness over Furuya and Takizawa

  • Claims Challenged: 1-4, 6-8, 10-13, and 15-17 are obvious over Furuya in view of Takizawa.
  • Prior Art Relied Upon: Furuya (Japanese Unexamined Patent Application Bulletin No. JP-2001-053184-A) and Takizawa (Japanese Patent Application Publication No. 2000-260894).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Furuya taught a semiconductor device with nearly all the structural elements of the challenged claims, including a semiconductor element, a copper-containing first electrode portion (metal post and wiring), and a tin-containing second electrode portion (solder connection). Furuya also described the formation of a diffusion layer when its copper post dissolves into solder at high temperatures. Takizawa addressed the known problem of solder ball detachment by teaching an optimal thickness range for a copper-tin (Cu-Sn) diffusion layer (1.87 µm to 4 µm) to improve connection reliability. Petitioner asserted that combining Takizawa’s specific diffusion layer thickness with Furuya’s disclosed first electrode portion thickness (15.7 µm) resulted in a combined thickness (15.7 µm to 19.7 µm) that falls squarely within the range of 10 µm to 20 µm recited in claim 10.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSA) would combine these references because both addressed the same technical problem: improving the reliability of electrical connections in semiconductor packages. Petitioner contended that a POSA would have been motivated to apply Takizawa’s specific teaching on optimizing diffusion layer thickness—a known solution to a known problem—to improve the reliability of the similar device disclosed in Furuya.
    • Expectation of Success: A POSA would have had a reasonable expectation of success because the combination involved applying a known technique (optimizing an alloy layer thickness for reliability) to a predictable art (semiconductor packaging), yielding the expected and predictable result of improved connection strength.

Ground 2: Obviousness over Furuya, Takizawa, and Yaguchi

  • Claims Challenged: 5 and 14 are obvious over Furuya in view of Takizawa and further in view of Yaguchi.
  • Prior Art Relied Upon: Furuya, Takizawa, and Yaguchi (WO 00/55910).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground built upon the Furuya/Takizawa combination to address the limitations of claims 5 and 14, which require an insulating film with an opening where the surface of the first electrode is "flush with or higher than" the surface of the film. Petitioner argued Furuya disclosed a second insulating layer with an opening that exposed the top of its metal post (the first electrode), with the layer’s height being lower than the post. To the extent this was insufficient, Yaguchi explicitly taught improving connection reliability by using a protrusion (corresponding to the first electrode) that extends through and above a protective insulating film.
    • Motivation to Combine: A POSA, seeking to ensure a robust connection for the Furuya device, would have been motivated to incorporate Yaguchi’s teaching. Both references aimed to prevent disconnection due to thermal stress. A POSA would logically adopt Yaguchi's protrusion design to ensure the external terminal made a better, more reliable bond with the first electrode in Furuya's structure.
    • Expectation of Success: The combination was a predictable application of a known technique (using a raised contact point) to a similar system to achieve an expected improvement in connection reliability.

Ground 3: Obviousness over Furuya, Takizawa, and Nozawa

  • Claims Challenged: 9 and 18 are obvious over Furuya in view of Takizawa and further in view of Nozawa.
  • Prior Art Relied Upon: Furuya, Takizawa, and Nozawa (Patent 6,181,010).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground targeted claims 9 and 18, which add the limitation of a substrate with a wiring electrode electrically connected to the device’s second electrode portion. Petitioner asserted that Furuya’s device, being a chip-scale package, was inherently intended for connection to an external substrate like a mounting board. Nozawa confirmed this by explicitly teaching and illustrating the connection of a similar semiconductor device via solder bumps to an interconnect pattern on a circuit board substrate.
    • Motivation to Combine: A POSA would have understood that Furuya's device was useful only when connected externally. Nozawa provided a clear, conventional method for achieving this connection. Therefore, a POSA would have been motivated to apply the teachings of Nozawa to Furuya's device to integrate it into a larger electronic system, which was its intended purpose.
    • Expectation of Success: Connecting a chip-scale package to a substrate was a standard, well-understood process in the field. Applying Nozawa's conventional connection method to Furuya's device would have been a routine design choice with a high expectation of success.

4. Key Claim Construction Positions

  • Petitioner argued that no special claim construction was necessary for the inter partes review (IPR). It noted that in a related IPR, the Patent Owner had proposed a narrow construction for "first electrode portion," which the Board rejected. Petitioner asserted that the challenged claims were obvious under any reasonable construction, including those previously proposed by the Patent Owner.

5. Arguments Regarding Discretionary Denial

  • Petitioner argued that the petition should not be denied discretionarily as cumulative to a prior IPR filed by Broadcom (IPR2017-01486). The reasons asserted included that:
    • Samsung was not a party to the Broadcom IPR.
    • The grounds were materially different, as the present petition relied on Furuya as the primary reference, whereas Broadcom relied on Takizawa.
    • The Broadcom IPR had been terminated, meaning no other petition was pending on the same claims.

6. Relief Requested

  • Petitioner requested institution of an IPR and cancellation of claims 1-18 of the ’001 patent as unpatentable.