PTAB

IPR2019-00248

Daihen Corp v. Reno Sub Systems Inc

Log In
Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: RF Impedance Matching Network
  • Brief Description: The ’122 patent discloses electronic circuits and methods for radio frequency (RF) impedance matching. The technology uses an impedance matching network (IMN) with electronically variable capacitors (EVCs) and a control circuit to rapidly create an impedance match between a fixed-impedance RF source and a variable-impedance plasma chamber, achieving the match within specified time limits and with low reflected power.

3. Grounds for Unpatentability

Ground 1: Anticipation of Claims 1-4 and 6-11 over Zhang

  • Prior Art Relied Upon: Zhang (Patent 8,513,889).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Zhang discloses every limitation of claims 1-4 and 6-11. Zhang teaches an RF-IMN for a substrate processing chamber that includes series and shunt EVCs, a controller for tuning the capacitors, and a method for matching impedance. Crucially, Petitioner asserted that Zhang explicitly discloses that its matching networks may require between 100 microseconds and a few milliseconds to minimize reflected power, which anticipates the claimed limitation of achieving an impedance match in "less than about 150 µsec," especially under Petitioner's proposed claim construction. The method claims are met by Zhang's disclosure of a tuning method (Fig. 3) that repeats until reflected power is within an acceptable range.
    • Key Aspects: Petitioner noted that while Zhang was disclosed to the examiner during prosecution, it was never discussed.

Ground 2: Obviousness of Claims 1-12 over Howald in view of Chen

  • Prior Art Relied Upon: Howald (Patent 6,259,334) and Chen (Patent 6,472,822).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner contended that Howald discloses a complete RF-IMN for plasma processing, including a control circuit, series and shunt variable capacitors, and a tuning process. However, Howald’s system utilized slower, mechanically-adjusted variable capacitors. Chen was cited for its teaching of faster impedance matching using EVCs, specifically PiN-diode switched capacitors, and for disclosing that a match could be achieved in a continuous wave (CW) system within 100 microseconds. Chen also teaches the use of driver circuits and RF chokes (equivalent to the claimed "RF filters") to control its EVCs.
    • Motivation to Combine: A POSITA would combine Howald and Chen to improve the speed and efficiency of the RF-IMN. The semiconductor industry's constant demand for faster processing provides a strong motivation to replace the known, slower mechanical capacitors in Howald’s system with the known, faster PiN-diode EVCs and associated driver circuitry taught by Chen. This substitution would be an obvious and predictable design choice to achieve a faster impedance match.
    • Expectation of Success: A POSITA would have a reasonable expectation of success because the combination involves substituting known components (mechanical capacitors) with other well-understood components (EVCs) to achieve a predictable improvement (increased speed) in a conventional RF-IMN architecture.

  • Additional Grounds: Petitioner asserted additional obviousness challenges, including combinations of Howald, Chen, and Bhutta121 (Patent 7,251,121) to add teachings of specific EVC arrays; combinations adding Scanlan (Application # 2002/0048960) for standard plasma processing steps; and combinations of Zhang and Chen to add specific driver circuit and RF filter disclosures.

4. Key Claim Construction Positions

  • "elapsed time … is less than about 150 µsec": Petitioner argued this term should be construed to mean "one iteration of the match tune process occurs in less than 190.005 µsec." This construction was based on a Cohesive Techs. analysis, where the 26.67% variance between the specification's example of "approximately 110 µsec" and the claim's "about 150 µsec" was used to define the range of the term "about." This construction was critical to asserting that prior art disclosing a 100 µsec match time (like Chen) fell within the claimed range.
  • "about 500 µsec or less": Applying the same Cohesive Techs. analysis, Petitioner argued this term, recited in dependent claims for multiple iterations, means an impedance match is created in "less than 633.35 µsec." This allowed Petitioner to argue that multiple 100 µsec iterations taught by Chen would meet the limitation.
  • "RF filter": Petitioner proposed construing "RF filter" as "a component or circuitry that allows and/or blocks certain RF frequencies in an RF circuit." This broad construction was intended to encompass the "RF choke" disclosed in Chen, thereby allowing Chen to teach the RF filter limitation of claim 5.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-12 of the ’122 patent as unpatentable.