PTAB

IPR2025-01052

GlobalFoundries Inc v. Oak IP LLC

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Metal-Semiconductor Junctions with Interface Layers
  • Brief Description: The ’691 patent relates to metal-semiconductor junctions featuring an interface layer between the metal and the semiconductor. This interface layer includes a metal oxide layer and a passivating dielectric tunnel barrier layer intended to reduce contact resistance by depinning the Fermi level.

3. Grounds for Unpatentability

Ground I: Anticipation over Grupp - Claims 5-12, 14-19, 21, and 26-29 are anticipated by Grupp under 35 U.S.C. §102.

  • Prior Art Relied Upon: Grupp (Patent 7,176,483).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that the challenged claims are not entitled to their purported 2002 priority date, making the 2007-issued Grupp patent valid prior art. Grupp, which shares a common ancestor application with the ’691 patent and has a significantly overlapping disclosure, allegedly anticipates all limitations. Specifically, Grupp was argued to disclose an interface layer with a passivation layer (semiconductor oxide) and a separation layer (metal oxide). For claims requiring an "oxide of titanium," Grupp’s disclosure of a TiO2 "spacer layer" was cited. For claims requiring a "stack of metals," Grupp was argued to teach depositing a single metal or a stack of different conductors on the interface layer. For claims reciting a specific contact resistivity of less than 1 Ω-µm², Grupp was asserted to disclose achieving this exact range.
    • Key Aspects: The central thrust of this ground is a priority date challenge. Petitioner asserted that the challenged claims lack adequate written description and/or enablement in the ancestor applications for key limitations. These include the broad genus "oxide of titanium" (supported only by a single TiO2 example), the "stack of metals" limitation, and the open-ended resistivity range of "less than 1 Ω-µm²." By defeating the claimed priority dates, Petitioner positioned Grupp as anticipating prior art.

Ground II: Obviousness over Grupp and Wu - Claims 23 and 24 are obvious over Grupp in view of Wu under 35 U.S.C. §103.

  • Prior Art Relied Upon: Grupp (Patent 7,176,483) and Wu (Patent 7,727,882).
  • Core Argument for this Ground:
    • Prior Art Mapping: Grupp disclosed the foundational structure of a semiconductor device with an interface layer, and suggested using copper as a metal contact. Wu addressed the well-known problem of copper atom diffusion in semiconductor devices, a significant reliability concern. Wu taught that for dielectrics containing residual moisture, "titanium-based diffusion barriers are particularly advantageous" and disclosed forming a TiOx layer to prevent such diffusion and improve adhesion. Claim 23 requires a metal electrical contact comprising an "oxide of titanium."
    • Motivation to Combine: A POSITA implementing Grupp's device with a copper contact would have recognized the known problem of copper diffusion. To solve this predictable problem, the POSITA would have looked to analogous art for diffusion barriers. A POSITA would combine Wu’s teaching of a titanium-based (TiOx) barrier layer with Grupp’s copper-contact structure to improve device reliability and performance. This combination was presented as a straightforward application of known solutions to known problems.
    • Expectation of Success: The petition argued that integrating Wu's TiOx-based diffusion barrier into the metal contact of Grupp's disclosed structure was a combination of known elements according to known methods. A POSITA would have had a reasonable expectation of success in achieving a more reliable copper interconnect with predictable results.

4. Key Claim Construction Positions

  • The petition adopted several constructions from a Markman order in a related district court case for terms like "a metal oxide layer, and a passivating dielectric tunnel barrier layer."
  • For claim 21, the petition contended that the term "specified contact resistivity" is not a standard term in the art. A POSITA would have understood it to mean "specific contact resistance," a term used in the specification and disclosed in Grupp. This interpretation was crucial for the anticipation argument against claim 21.

5. Key Technical Contentions (Beyond Claim Construction)

  • A central technical argument was that the '691 patent and its parent applications failed to provide adequate written description support for the full scope of the genus "oxide of titanium." Petitioner argued that the specification’s sole disclosure of titanium dioxide (TiO2), a semiconductor, is not representative of the entire claimed genus.
  • The genus "oxide of titanium" is extremely broad and includes numerous binary and ternary compounds (e.g., TiSiOx) with drastically different and often opposing physical, structural, and electrical properties (ranging from conductors like TiO to insulators like TiSiO4). Because the single disclosed species cannot support the full, unpredictable scope of the genus, claims containing this limitation were argued to be unentitled to any priority date before the filing of the '691 patent application itself (February 19, 2016).

6. Relief Requested

  • Petitioner requests institution of IPR and cancellation of claims 5-12, 14-19, 21, 23-24, and 26-29 of the ’691 patent as unpatentable.