PTAB

IPR2016-00013

TDK Corp v. Lambeth Magnetic Structures

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: MAGNETIC MATERIAL STRUCTURES, DEVICES AND METHODS
  • Brief Description: The ’988 patent relates to magnetic film structures designed to achieve high magnetization and anisotropy. The core technology involves using a template layer with a specific atomic structure to control the growth of an overlying magnetic layer, forcing it into a "symmetry broken" structure that enhances its magnetic properties.

3. Grounds for Unpatentability

Ground 1: Obviousness over Shen in View of Dill - Claims 1 and 27 are obvious over Shen in view of Dill.

  • Prior Art Relied Upon: Shen (a 1997 journal article describing magnetic phase transitions of iron films on copper) and Dill (Patent 6,023,395).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Shen disclosed all elements of the independent claims except for an explicit teaching of a "uniaxial" structure. Shen described growing a body-centered cubic (bcc) iron (Fe) film (a "bcc-d layer") on a copper substrate with a (111) surface (a "hexagonal atomic template"). Shen further taught that using a "stepped" template surface causes "symmetry breaking" in the grown Fe film, resulting in a dominance of certain crystallographic variants and a significant increase in magnetization.
    • Motivation to Combine (for §103 grounds): Petitioner contended that Dill explicitly taught inducing uniaxial anisotropy in a bcc magnetic layer by growing it in the presence of a magnetic field to improve device performance. A POSITA would have been motivated to apply Dill’s well-known method for inducing uniaxial properties to the symmetry-broken structure in Shen to further enhance and stabilize its magnetic properties for use in a magnetic device.
    • Expectation of Success (for §103 grounds): A POSITA would have had a high expectation of success because applying a magnetic field during deposition was a conventional and predictable method for inducing uniaxial anisotropy in ferromagnetic films like those described by Shen.

Ground 2: Obviousness over Dill in View of Shen - Claims 1, 3, 6-11, 13, 14, 17-19, 22, 24, 27-30, 34, and 38 are obvious over Dill in view of Shen.

  • Prior Art Relied Upon: Dill (Patent 6,023,395) and Shen (a 1997 journal article).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted that Dill disclosed a multi-layer magnetic tunnel junction (MTJ) device that met most limitations of claim 1. Dill’s structure included a substrate, a (111) textured face-centered cubic (fcc) template layer, and an overlying magnetic bcc layer grown on the template. Dill also taught making this bcc layer uniaxial. However, Dill did not explicitly disclose that the bcc layer had a "symmetry broken" structure.
    • Motivation to Combine (for §103 grounds): Shen taught that epitaxially growing a bcc film on a (111) fcc template, as in Dill's device, induces a structural transition that naturally breaks symmetry, favoring certain variants and increasing magnetization. A POSITA would combine Shen’s teachings with Dill’s device structure to intentionally create and leverage this symmetry breaking effect, thereby improving the magnetic field strength and uniaxial anisotropy of Dill’s device.
    • Expectation of Success (for §103 grounds): Success was expected because Shen demonstrated that the very act of growing a bcc layer on a (111) fcc template (the structure disclosed by Dill) was sufficient to induce the desired symmetry-breaking effect.

Ground 3: Obviousness over Dill, Shen, and Heim - Claims 12, 15, 16, 21, and 23 are obvious over Dill in view of Shen and Heim.

  • Prior Art Relied Upon: Dill (Patent 6,023,395), Shen (a 1997 journal article), and Heim (Patent 5,465,185).

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground built upon the combination of Dill and Shen to address dependent claims reciting multi-layer magnetic structures, such as a "laminated fixed layer" comprising two ferromagnetic layers separated by a thin metallic layer (claim 12). While Dill disclosed such a structure and cited Heim for further detail, Heim explicitly taught that the thin metallic separating layer could be chromium (Cr) or ruthenium (Ru).
    • Motivation to Combine (for §103 grounds): A POSITA, seeking to implement the laminated structure described in Dill, would have been directly motivated to consult Heim, as Dill itself referenced it. Heim provided specific, suitable materials (like Cr) for the separating layer that were known to achieve the desired antiferromagnetic coupling between the ferromagnetic layers. The motivation to add Shen’s teachings remained the same as in Ground 2: to improve magnetic properties through symmetry breaking.
    • Expectation of Success (for §103 grounds): The combination was predictable because Dill explicitly pointed to Heim for implementing the claimed laminated structure, and using materials like Cr for coupling layers was a well-established technique in the field.

  • Additional Grounds: Petitioner asserted additional obviousness challenges for specific dependent claims based on combinations including Lambeth I (a 1998 journal article on crystalline texture control) and Noguchi (Patent 5,862,022), but relied on similar modification theories to enhance device performance.

4. Key Claim Construction Positions

  • "uniaxial": Petitioner proposed that this term should be construed as "having a single easy magnetization axis aligned in a particular direction." This construction was argued to be consistent with the specification and the understanding of a POSITA, and was central to showing how Dill’s teachings on inducing anisotropy met the claim limitation.
  • "symmetry broken": Petitioner proposed the construction "a structure with unequal volumes of crystallographic variants in either a three or six variant system." This construction was crucial for mapping Shen’s disclosure of creating a "dominance" of two variants out of six onto the claim language.

5. Relief Requested

  • Petitioner requests institution of an inter partes review (IPR) and cancellation of claims 1-3, 6-19, 21-31, 34, 38, and 39 of the ’988 patent as unpatentable.