PTAB

IPR2022-00105

Microchip Technology Inc v. HD Silicon Solutions LLC

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Metal Stack for Local Interconnect Layer
  • Brief Description: The ’033 patent discloses a method for forming a local interconnect structure in a semiconductor integrated circuit. The method involves depositing a first film comprising titanium nitride (TiN) over an oxide layer, followed by depositing a second film comprising tungsten (W) over the first film to form a metal stack.

3. Grounds for Unpatentability

Ground 1: Obviousness over Lin - Claim 1 is obvious over Lin.

  • Prior Art Relied Upon: Lin (Patent 6,083,827).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Lin taught every element of claim 1. Lin discloses a method for fabricating a local interconnect by forming a conformal titanium-nitride barrier layer (the claimed "first film") over various oxide layers on a substrate. Subsequently, Lin deposits a tungsten conductive layer (the claimed "second film") over the TiN barrier layer. Petitioner asserted that this structure constitutes the claimed "metal stack of the local interconnect layer" connecting a gate to a source/drain region.
    • Motivation to Combine (for §103 grounds): Not applicable as this ground is based on a single reference anticipating or rendering the claim obvious.
    • Expectation of Success (for §103 grounds): Not applicable.

Ground 2: Obviousness over Lin and Huang - Claim 2 is obvious over Lin in view of Huang.

  • Prior Art Relied Upon: Lin (Patent 6,083,827), Huang (Application # 2002/0137356).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground challenged dependent claim 2, which adds the limitation that the first (TiN) and second (W) films are deposited "in-situ." Petitioner contended that while Lin taught the foundational method of claim 1, Huang supplied the in-situ teaching. Huang discloses a similar metallization process where a TiN layer and a subsequent tungsten layer are formed sequentially within the same chemical vapor deposition (CVD) chamber without breaking vacuum.
    • Motivation to Combine (for §103 grounds): A person of ordinary skill in the art (POSITA) would combine Huang’s well-known in-situ deposition technique with Lin’s process to achieve predictable benefits. These benefits included increased manufacturing efficiency, reduced equipment complexity, and lower production costs by eliminating the need to move wafers between separate, non-integrated process chambers.
    • Expectation of Success (for §103 grounds): A POSITA would have a high expectation of success, as combining known process steps from the same technical field (semiconductor fabrication) to gain established advantages was routine.

Ground 3: Obviousness over Lin and Peng - Claims 3, 5, 9-11, and 15 are obvious over Lin in view of Peng.

  • Prior Art Relied Upon: Lin (Patent 6,083,827), Peng (Patent 6,043,148).

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground addressed claims requiring specific deposition and removal techniques. For claims requiring deposition by sputtering (claims 3 and 15), Petitioner argued that while Lin’s method is general, Peng explicitly teaches forming both TiN and tungsten layers using sputtering processes (e.g., DC magnetron and reactive sputtering). For claims requiring etching (claims 9 and 11), Peng teaches etching a tungsten layer using a fluorine-based etchant, with an underlying TiN layer serving as an effective etch stop. For claim 15, Peng’s disclosure of forming both layers via sputtering in a single tool taught the "same tool" limitation.
    • Motivation to Combine (for §103 grounds): A POSITA would be motivated to apply Peng’s specific, well-understood fabrication techniques to Lin’s more general interconnect structure. Using sputtering for both layers, as taught by Peng, would simplify the manufacturing process. Furthermore, substituting Lin’s suggested polishing step with Peng’s etching process represented a simple substitution of one known material removal technique for another to predictably avoid known polishing defects like surface scratching and mechanical stress.
    • Expectation of Success (for §103 grounds): Success was expected, as applying specific known deposition and etching methods from Peng to a similar structure in Lin would yield predictable improvements in process control and yield.

  • Additional Grounds: Petitioner asserted additional obviousness challenges, including that claims 8 and 13 are obvious over Lin in view of Lo (Patent 5,643,632) for teaching a metal stack with a specific sheet resistance and the use of a probe to test it. Further grounds combined Lin, Peng, and Lo to challenge claim 17.

4. Arguments Regarding Discretionary Denial

  • Petitioner argued that discretionary denial under 35 U.S.C. §314(a) would be inappropriate based on both General Plastic and Fintiv factors. As a follow-on petition, Petitioner contended it was based on entirely new prior art combinations discovered after a diligent search that was complicated by the nature of the technology. Regarding the parallel district court litigation, Petitioner asserted that the court’s trial date was scheduled for November 2023, well after the statutory deadline for a Final Written Decision in this inter partes review (IPR), and that minimal substantive investment had occurred in the court proceeding, strongly favoring institution.

5. Relief Requested

  • Petitioner requests institution of IPR and cancellation of claims 1-3, 5, 8-11, 13, 15, and 17 of Patent 6,774,033 as unpatentable under 35 U.S.C. §103.