PTAB

IPR2025-01484

Taiwan Semiconductor Mfg Co Ltd v. Marlin Semiconductor Ltd

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Fin-Shaped Structure
  • Brief Description: The ’510 patent discloses fin-shaped structures for FinFETs with varied profiles and dimensions. The invention involves creating groups of fins with different heights, widths, and spacing to form transistors that meet specific electrical demands for different areas of an integrated circuit.

3. Grounds for Unpatentability

Ground 1: Claims 1, 2, and 6 are obvious over Oh

  • Prior Art Relied Upon: Oh (Application # 2013/0244392).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued Oh teaches all limitations of independent claim 1. Oh discloses a method of fabricating FinFETs where fin portions have different widths. The process starts with uniformly spaced fins across two regions. The fins in one region are then masked while the upper sidewalls of the fins in the other region are etched. Petitioner asserted this process inherently results in the claimed structure: the etched fins ("second fin-shaped structures") have a greater distance between their adjacent top corners than the un-etched fins ("first fin-shaped structures"), while the distance between the lower, un-etched parts of all fins remains the same. Oh also discloses that the un-etched fins are wider (claim 2) and taller (claim 6) than the etched fins.
    • Motivation to Combine (for §103 grounds): Not applicable as this ground is based on a single reference. Petitioner contended that Oh’s disclosure alone renders the claims obvious.
    • Expectation of Success (for §103 grounds): Not applicable.

Ground 2: Claims 3-5 are obvious over Oh in view of Rachmady

  • Prior Art Relied Upon: Oh (Application # 2013/0244392) and Rachmady (Application # 2010/0276756).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Oh teaches the basic fin structure of claim 1, including an isolation layer disposed beside the fins (limitation 3a). Rachmady was introduced to teach modifying the height of fins relative to this isolation structure. Specifically, Petitioner asserted that applying Rachmady’s selective etching of the isolation layer to Oh's structure would result in the "second fin-shaped structures" having ladder-shaped profile parts higher than the isolation surface (limitation 3b). This combination would also make it obvious to have different isolation layer heights between regions (claim 4) and to have the height of the first fins protruding from the isolation structure be lower than the second fins (claim 5).
    • Motivation to Combine (for §103 grounds): A POSITA would combine Oh and Rachmady to achieve greater flexibility in circuit design. Oh teaches adjusting fin width to control threshold voltage, while Rachmady teaches adjusting fin height to control drive current. A POSITA designing complex circuits like 4T SRAM would be motivated to use both known techniques to simultaneously optimize these critical, predictable transistor characteristics.
    • Expectation of Success (for §103 grounds): A POSITA would have a high expectation of success, as both references disclose well-known semiconductor fabrication processes (selective etching) that could be predictably combined to achieve the desired fin geometries and resulting electrical properties.

Ground 3: Claims 1-6 are obvious over Wann in view of Lin

  • Prior Art Relied Upon: Wann (Application # 2013/0093026) and Lin (Application # 2014/0256093).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner contended that Wann discloses a five-fin FinFET embodiment with multiple fin types (e.g., "2 regular fins, 2 fins shaped a particular way, and 1 fin shaped a different way"), which maps to the "first" and "second" fin-shaped structures of claim 1. However, Wann does not explicitly teach uniform spacing for the fin bases. Lin was introduced to supply this teaching, disclosing a mandrel/spacer process that forms fins with uniform dimensions and "substantially equal" spacing. The combination, referred to as the "Wann-Lin" structure, allegedly meets all limitations of claims 1-6, including the relative spacing, width, height, and isolation structure features, through one of a finite number of permutations of Wann's disclosure.
    • Motivation to Combine (for §103 grounds): A POSITA would combine the references to improve the manufacturability and reliability of the flexible fin structures taught by Wann. Applying Lin's precise mandrel/spacer process to form the initial fins for Wann's device would yield predictable, uniformly spaced fins, which is a known benefit for mitigating etch-loading effects and improving performance. Petitioner argued this was an "obvious to try" scenario, as Wann’s disclosure of a five-fin structure created a finite, small number of predictable arrangements to combine with Lin's teachings.
    • Expectation of Success (for §103 grounds): A POSITA would reasonably expect success because both references disclose well-known semiconductor fabrication techniques, and applying Lin’s standard process for creating uniform fins as a preliminary step to Wann’s shaping process is a straightforward and predictable combination.

4. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-6 of the ’510 patent as unpatentable.