PTAB

IPR2024-00758

Qorvo Inc v. Cornell Research Foundation Inc

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1. Case Identification

2. Patent Overview

  • Title: Process for Nucleation and Epitaxial Growth on a Lattice Mismatched Substrate
  • Brief Description: The ’360 patent discloses a process for growing an epitaxial layer on a substrate with which it has a lattice mismatch. The claimed process involves a pre-treating step using group II or III reactants at an elevated temperature, followed by introducing a group V or VI reactant to grow a nucleation layer, and subsequently growing a buffer layer upon which the final epitaxial layer is formed.

3. Grounds for Unpatentability

Ground 1: Claims 1-4 and 6-14 are obvious over Urashima.

  • Prior Art Relied Upon: Urashima (Application # 2002/0155712).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Urashima teaches all steps of independent claim 1 through its method for fabricating high-quality group-III nitride semiconductor crystals. Urashima’s initial step of depositing group III metal particles on a substrate at an elevated temperature (above 900° C) prior to introducing a nitrogen source was mapped to the claimed "pre-treating" step. Petitioner contended that Urashima’s subsequent step of "nitriding" these particles with a nitrogen source to form "growth nuclei" corresponds to "growing a nucleation layer." Finally, Urashima's growth of an additional gallium nitride-based layer on these nuclei was mapped to the claimed "growing a buffer layer," which provides a surface for the final epitaxial crystal.

Ground 2: Claims 1-4, 6-9, and 11-14 are obvious over Guo.

  • Prior Art Relied Upon: Guo (Application # 2004/0119063).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Guo’s method for making a semiconductor structure on a silicon substrate independently discloses all limitations of claim 1. Guo’s process begins with a "pretreatment" step of depositing aluminum (a group III reactant) on a substrate at an elevated temperature (600-900° C) before introducing ammonia, which Petitioner mapped to the "pre-treating" limitation. Subsequently, Guo introduces ammonia (a group V reactant) to deposit a thin AlN "nucleation layer." Finally, Guo grows a "buffer structure" on this nucleation layer, providing a surface for the final "operative structure," which Petitioner asserted corresponds to the claimed epitaxial layer.

Ground 3: Claims 18-24 are obvious over Urashima in view of Manabe.

  • Prior Art Relied Upon: Urashima (Application # 2002/0155712), Manabe (Patent 5,122,845).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner asserted this combination teaches the specific reactant flow sequences required by independent claim 18. Urashima was argued to teach a pre-treatment using first and second group III reactants and stopping the flow of both before the subsequent nitriding step. Manabe was cited for its teaching of continuing the flow of at least one group III reactant (e.g., trimethylaluminium or TMA) during the introduction of the nitrogen source, and then ceasing that flow while introducing a different group III reactant (e.g., trimethylgallium or TMG). Petitioner argued that combining these teachings results in the process of claim 18, which includes stopping a first reactant flow, introducing a nitrogen source while maintaining a second reactant flow, and then resuming the first while reducing the second.
    • Motivation to Combine: A POSITA would combine Manabe's technique with Urashima's foundational process to achieve the known benefits taught by Manabe, namely the growth of higher-quality crystals with improved uniformity and fewer lattice defects.
    • Expectation of Success: A POSITA would have a high expectation of success because both references operate in the same technical field of epitaxial growth, utilize similar MOCVD processes, and address the common objective of improving semiconductor crystal quality.

  • Additional Grounds: Petitioner asserted additional obviousness challenges based on the combinations of Urashima with Nagata (for adding group II/VI reactants) and Keiper (for using organic precursors), and Guo with Ashby (for adding a cleaning step and group II/VI reactants), relying on similar art-substitution and process-optimization rationales.

4. Arguments Regarding Discretionary Denial

  • Petitioner argued that discretionary denial under 35 U.S.C. §325(d) is inappropriate because the asserted prior art references and invalidity arguments were not previously presented to or considered by the USPTO. Petitioner also argued against discretionary denial under Fintiv factors, asserting that the scheduled trial date in a co-pending district court litigation is uncertain and may occur after the Final Written Decision in this proceeding. Furthermore, Petitioner emphasized that this IPR challenges all 24 claims of the ’360 patent, whereas the litigation involves only a subset of those claims. To further weigh against denial, Petitioner offered a Sotera-type stipulation, agreeing not to pursue in the district court any invalidity grounds raised or that reasonably could have been raised in this IPR if the petition is instituted.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-24 of Patent 7,250,360 as unpatentable.