PTAB

IPR2017-00391

Micron Technology Inc v. Flamm Daniel

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Process Depending on Plasma Discharges Sustained by Inductive Coupling
  • Brief Description: The ’221 patent discloses a process for semiconductor fabrication using an inductively-coupled plasma source. The alleged invention is a method for controlling undesirable capacitive coupling by using a wave adjustment circuit to "selectively balance" the phase and anti-phase portions of capacitive currents coupled from the inductive structure to the plasma, thereby improving process uniformity and reducing potential damage to the substrate.

3. Grounds for Unpatentability

Ground 1: Obviousness over Lieberman - Claims 1 and 5-7 are obvious over Lieberman.

  • Prior Art Relied Upon: Lieberman (M. A. Lieberman and R. A. Gottscho, Design of High-Density Plasma Sources for Materials Processing, 1994).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Lieberman, a foundational text on plasma sources, discloses all limitations of claim 1. Lieberman described using an inductive coil for semiconductor etching and deposition. Critically, Lieberman taught that the coil can be driven "push-pull using a balanced transformer." Petitioner contended this "balanced transformer" is a wave adjustment circuit that inherently creates the claimed "selectively balanced" phase and anti-phase portions of capacitive currents. Lieberman explained this configuration "places a virtual ground in the middle of the coil," which Petitioner asserted is functionally identical to the balancing method described in the ’221 patent to reduce capacitive coupling.
    • Motivation to Combine (for §103 grounds): Not applicable as this is a single-reference ground. Petitioner argued Lieberman alone renders the claims obvious.
    • Expectation of Success (for §103 grounds): Not applicable.
    • Key Aspects: Petitioner asserted that Lieberman's disclosure of a push-pull arrangement using a balanced transformer was a well-understood technique to achieve the very goal of the ’221 patent—reducing capacitive coupling by symmetrically distributing voltage along the coil.

Ground 2: Obviousness over Lieberman and Dible - Claims 1 and 5-7 are obvious over Lieberman in view of Dible.

  • Prior Art Relied Upon: Lieberman (1994 publication) and Dible (Patent 5,573,595).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground relied on Lieberman for the base plasma system, as detailed in Ground 1. Dible was introduced for its teaching of a control circuit for dynamically adjusting the phase relationship between currents to control the proportions of inductive and capacitive coupling. Petitioner argued Dible’s control circuit, which receives a user-variable signal to achieve a desired phase difference, directly taught the adjustability aspect of the "selectively balanced" and "wave adjustment circuit" limitations.
    • Motivation to Combine (for §103 grounds): Petitioner argued a person of ordinary skill in the art (POSITA) would combine Lieberman and Dible to gain enhanced process control. Lieberman taught a static method of balancing, while Dible provided a dynamic control circuit for fine-tuning the plasma characteristics (from purely inductive to a mix of inductive/capacitive). A POSITA would have been motivated to add Dible’s dynamic control to Lieberman’s high-density plasma source to improve flexibility and optimize different semiconductor fabrication steps.
    • Expectation of Success (for §103 grounds): Petitioner contended that since both references address plasma generation for semiconductor processing and manipulate RF field phases, their combination would be straightforward, with a high expectation of success.

Ground 3: Obviousness over Qian - Claims 1 and 5-7 are obvious over Qian.

  • Prior Art Relied Upon: Qian (Patent 5,683,539).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner asserted that Qian, like Lieberman, disclosed an inductively coupled RF plasma reactor that inherently achieved the claimed invention. Qian taught using an "isolation transformer" with a ferrite core between the RF power supply and the inductive coil to reduce capacitive coupling by allowing the coil to float electrically. Petitioner argued a POSITA would recognize this "isolation transformer" as a balun that drives the coil in a push-pull manner, creating a virtual ground and thereby "selectively balancing" the capacitive currents as claimed. Qian explicitly stated its method reduces capacitive coupling by more than a factor of two, providing experimental data to support this.
    • Motivation to Combine (for §103 grounds): Not applicable as this is a single-reference ground.
    • Expectation of Success (for §103 grounds): Not applicable.
    • Key Aspects: The argument mirrors that of Ground 1 but uses a different primary reference (Qian) that specifically employs a ferrite core "isolation transformer" to achieve the same technical result of balanced operation.

  • Additional Grounds: Petitioner asserted additional obviousness challenges, including combining Lieberman or Qian with Hanawa (Patent 5,688,357) for its teachings on using a variable frequency power supply for impedance matching (for claims 2-3), and combining Lieberman or Qian with Collins (Patent 5,065,118) for its disclosure of using transmission lines as part of a matching network (for claim 4).

4. Key Claim Construction Positions

  • Petitioner argued that the key term "selectively balanced" should be construed to mean "chosen to be made substantially equally distributed."
  • This construction was based on the ’221 patent’s specification, which distinguished between "balanced" and "imbalanced" states. Petitioner argued the term requires an affirmative choice to create a symmetric, balanced distribution of phase and anti-phase currents to reduce capacitive coupling, consistent with the patent’s figures and description of a push-pull arrangement.
  • Petitioner also noted that the claims are unpatentable even under the Patent Owner’s allegedly broader construction from a related IPR, which covered a range "between 100% balanced to various lesser percentages."

5. Key Technical Contentions (Beyond Claim Construction)

  • A central technical argument was that the "balanced transformer" in Lieberman and the "isolation transformer" in Qian are functionally baluns (balanced-unbalanced transformers).
  • Petitioner contended that a POSITA would have immediately understood that implementing these transformers in a "push-pull" configuration, as taught by the prior art, necessarily establishes a virtual RF ground at the electrical midpoint of the inductive coil. This configuration inherently results in a symmetric voltage distribution and balanced phase/anti-phase capacitive currents, thus directly teaching the core mechanism of the challenged claims for reducing capacitive coupling.

6. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 1-7 of Patent 6,017,221 as unpatentable under 35 U.S.C. §103.