Tokyo ElecTron Ltd v. Flamm Daniel

1. Case Identification

• Case #: IPR2017-01072
• Patent #: RE40,264
• Filed: March 10, 2017
• Petitioner(s): Tokyo Electron Limited
• Patent Owner(s): Daniel L. Flamm
• Challenged Claims: 13-26, 64, and 65

2. Patent Overview

• Title: MULTI-TEMPERATURE PROCESSING
• Brief Description: The ’264 patent relates to methods for plasma processing of semiconductor substrates. The core technology involves changing the temperature of a substrate holder between a first etching step at one temperature and a second etching step at a different temperature within a specified time interval, enabled by selecting the thermal mass of the holder.

3. Grounds for Unpatentability

Ground 1: Anticipation/Obviousness of Claim 13 over Kadomura and Matsumura

• Prior Art Relied Upon: Kadomura (Patent 5,981,913) and Matsumura (Japanese Patent Publ. No. 3-196206).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Kadomura anticipated every limitation of claim 13. Kadomura disclosed a two-step etching method where the substrate holder temperature was changed from 50°C to -50°C in approximately 30-40 seconds. This was achieved using an embedded heater and a separate cooling jacket. Petitioner contended that Kadomura taught the "selected thermal mass" limitation by describing the design of its "wafer stage 1" using thin layers of high-thermal-conductivity materials (e.g., molybdenum, aluminum nitride) to achieve this rapid temperature change.
  • Motivation to Combine (for §103 alternative): Matsumura was introduced to reinforce the anticipation argument and provide a basis for obviousness. Matsumura disclosed the fundamental thermal diffusion equations governing the relationship between heat flux, material properties (density, specific heat), and the rate of temperature change. Petitioner argued that a person of ordinary skill in the art (POSITA), guided by Matsumura's principles, would understand that to achieve the rapid temperature change explicitly taught by Kadomura, the thermal mass of the substrate holder must have been selected to be low enough. Therefore, the selection of an appropriate thermal mass was either inherent or obvious.
  • Expectation of Success: A POSITA would have a high expectation of success, as applying the well-understood physical principles from Matsumura to optimize the Kadomura system would yield predictable results in thermal performance.

Ground 2: Anticipation/Obviousness of Claim 13 over Okada, Matsumura, and Kadomura

• Prior Art Relied Upon: Okada (Japanese Patent Publ. No. 5-136095), Matsumura, and Kadomura.
• Core Argument for this Ground:
  • Prior Art Mapping: This ground was presented as an alternative based on a narrower claim construction where the temperature change is caused by changing the temperature of a heat transfer fluid. Petitioner asserted that Okada disclosed a multi-step etching process where the substrate holder temperature was rapidly changed by switching between different refrigerant fluids. Okada specified a temperature change time of 2-10 seconds.
  • Motivation to Combine: Petitioner argued the "selected thermal mass" limitation was inherent in Okada for the same reasons it was in Kadomura. The teachings of Matsumura demonstrated that Okada’s extremely rapid temperature change would be impossible unless the thermal mass of its substrate holder was necessarily selected to be sufficiently low. Kadomura was added to show that using thin, high-conductivity materials was a well-known method for achieving rapid temperature changes in plasma etching systems. A POSITA would have been motivated to apply the known thermal optimization techniques taught by Kadomura and Matsumura to the fluid-based system of Okada to ensure its intended rapid performance.
  • Expectation of Success: Success was expected because the combination involved applying established thermal management principles and known material selection techniques to an existing etching process to achieve a desired, predictable performance characteristic.

Ground 3: Obviousness of Claims 14-16, 19-23, 64, and 65 over Kadomura, Okada, and Matsumura

• Prior Art Relied Upon: Kadomura, Okada, and Matsumura.

• Core Argument for this Ground:

  • Prior Art Mapping: Petitioner argued the limitations of the dependent claims were taught by the primary references. For example, claim 14 (etching a multi-layer film) was taught by Kadomura’s example of etching a tungsten silicide layer followed by a polysilicon layer. Claim 15 (in-situ process) was met by both Kadomura and Okada performing the multi-step etch in a single chamber. Claim 64 (control circuit) was disclosed by Kadomura’s controller for the cooling system and Okada’s controller for selecting refrigerant tanks. Claim 65 (reaching temperature at a selected time) was met by Kadomura's disclosure of a ~30 second change and Okada's 2-10 second change.

• Additional Grounds: Petitioner asserted additional obviousness challenges, including combinations adding Kaji (Japanese Patent Publ. No. 3-145123) for radiation/ion bombardment (claims 17-18), Okada 2 (Japanese Patent Publ. No. 5-243191) for separate fluid passages (claim 24), and Edamura (Japanese Patent Publ. No. 08-191059) for plural heating elements (claims 25-26).

4. Key Claim Construction Positions

• Petitioner advanced two alternative interpretations for key terms, directly corresponding to its primary grounds of unpatentability.
• Substrate Holder:
  • First Interpretation (Broad): "A support structure... containing one or more elements responsible for changing the temperature." This interpretation encompasses systems like Kadomura's with embedded heaters/coolers.
  • Second Interpretation (Narrow): "A support structure... containing a heat transfer fluid responsible for changing the temperature... by changing the temperature of the heat transfer fluid." This interpretation aligns with the ’264 patent’s embodiments and systems like Okada’s.
• Selected Thermal Mass: Petitioner argued the term should be construed as "Thermal mass selected by selecting the mass of the substrate holder, the material of the substrate holder, or both," clarifying that the selection need only "allow or facilitate" a predetermined temperature change and is not a unique parameter for a given change.

5. Key Technical Contentions (Beyond Claim Construction)

• A central technical contention was that the selection of an appropriate thermal mass was inherent in any prior art system that successfully performed rapid, multi-temperature etching.
• Petitioner relied on Matsumura's thermal diffusion equations to argue that, as a matter of physics, a system's rate of temperature change is inversely proportional to its thermal mass. Therefore, any prior art (like Kadomura or Okada) that disclosed a rapid temperature change within a specific time necessarily must have used a substrate holder with a thermal mass selected to be low enough to achieve that result, even if the reference did not use the phrase "selected thermal mass."

6. Arguments Regarding Discretionary Denial

• Petitioner acknowledged that prior IPRs had been filed against the ’264 patent by other parties (Lam Research, Samsung).
• It argued this petition was not redundant and should not be denied because it relied on new primary prior art (Kadomura and Okada) not previously cited. Furthermore, the petition's dual claim construction strategy and reliance on Matsumura's technical teachings were specifically tailored to overcome deficiencies the Board had identified in prior institution decisions, particularly the failure to address the interdependent relationship between thermal mass, temperature change, and time.

7. Relief Requested

• Petitioner requested institution of an inter partes review and cancellation of claims 13-26, 64, and 65 of Patent RE40,264 as unpatentable.