PTAB

IPR2015-01377

ASML Netherlands BV v. Energetiq Technology Inc

Log In
Key Events
Petition
petition Intelligence

1. Case Identification

2. Patent Overview

  • Title: Laser Sustained Plasma Light Source
  • Brief Description: The ’982 patent discloses a light source that uses an ignition source (e.g., electrodes or a pulsed laser) to generate a plasma within a chamber, and a separate, sustaining laser to provide energy to the plasma to produce high-brightness light for applications such as semiconductor manufacturing inspection.

3. Grounds for Unpatentability

Ground 1: Claims 23 and 60 are obvious over Gärtner in view of Beterov.

  • Prior Art Relied Upon: Gärtner (French Patent Publication No. FR2554302A1) and Beterov (I.M. Beterov et al., Resonance radiation plasma, Sov. Phys. Usp. 31(6) (1988)).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Gärtner, a 1985 publication, disclosed all elements of the base claims, including a light source for photolithography comprising a sealed chamber, an ignition source (a pulsed nitrogen laser), and a sustaining laser (a CO2 laser) to heat a plasma and produce high-brightness light. The key limitation of challenged dependent claims 23 and 60—that the sustaining laser emits a wavelength "strongly absorbed" by the ionized medium—is taught by Beterov. Beterov described "photoresonance plasmas" where a laser is tuned to a resonance transition wavelength of a gas to achieve efficient and "practically complete absorption of the laser radiation."
    • Motivation to Combine: A POSITA would combine Gärtner's foundational plasma light source with Beterov's teachings on resonance absorption for several predictable benefits. Beterov explicitly taught that this technique increases the brightness of the light output, allows the plasma to be sustained with lower power, and achieves more efficient energy transfer. A POSITA would have been motivated to replace Gärtner's general-purpose CO2 laser with a tunable laser matched to a strong absorption line of the plasma gas, as taught by Beterov, to create a more efficient and brighter light source.
    • Expectation of Success: Petitioner asserted that combining these known elements for their stated purposes would require only routine skill. The principles of resonance absorption were well-understood, and applying this known efficiency-improving technique to Gärtner’s standard plasma light source architecture would have yielded the expected result of a more efficient, brighter light.

Ground 2: Claims 23 and 60 are obvious over Gärtner in view of Wolfram.

  • Prior Art Relied Upon: Gärtner (French Patent Publication No. FR2554302A1) and Wolfram (Patent 4,901,330).
  • Core Argument for this Ground:
    • Prior Art Mapping: As in the first ground, Petitioner contended that Gärtner disclosed the basic structure of the claimed light source. The "strongly absorbed" wavelength limitation was met by Wolfram. Wolfram, which teaches an optically pumped laser, disclosed tuning a laser to provide energy precisely at an "absorption peak" of a target material to create a more efficient light emission. Wolfram specifically taught tuning a laser to a wavelength within 2 nm of the material's absorption peak, which a POSITA would understand to be a strongly absorbed wavelength.
    • Motivation to Combine: The motivation to combine was to improve the efficiency and performance of Gärtner's light source. Wolfram directly addressed the need to provide laser energy efficiently within a light-generating system by matching the laser wavelength to the target's absorption peak. A POSITA would have recognized the benefit of applying Wolfram's precise energy coupling technique to Gärtner's plasma system to increase the absorption of laser energy by the plasma, thereby increasing the brightness of the resulting light.
    • Expectation of Success: Petitioner argued that a POSITA would have a reasonable expectation of success in this combination. It involved the simple modification of one known element (Gärtner's laser) for another (Wolfram's tuned laser) to achieve the predictable advantage of improved energy absorption and, consequently, a brighter light source for Gärtner’s stated photolithography applications.

4. Key Claim Construction Positions

  • "Light source": Petitioner proposed this term be construed broadly as "a source of electromagnetic radiation" across a wide spectrum (e.g., EUV, UV, visible, infrared). This construction was based on the specification's explicit references to "ultraviolet light," preventing a narrow interpretation limited to only visible light and ensuring the prior art's teachings were applicable.
  • "High brightness light": Petitioner proposed a functional construction: "light sufficiently bright to be useful for inspection, testing or measuring properties associated with semiconductor wafers" or other applications listed in the patent. This construction was derived from the patent's own background section and description of intended uses, arguing against any specific, non-disclosed numerical threshold for brightness.

5. Key Technical Contentions (Beyond Claim Construction)

  • Petitioner preemptively addressed the Patent Owner's arguments from a parallel district court litigation that Gärtner's system could not produce "high brightness light" because its disclosed plasma was too large. Petitioner contended this argument was flawed because the claims of the ’982 patent were not limited to a specific plasma size. Furthermore, Petitioner argued that Gärtner’s optical system was capable of producing plasmas as small as, or even smaller than, those described in the ’982 patent, and that the ’982 patent itself explicitly contemplated the use of CO2 lasers (as used in Gärtner) for producing high brightness light.

6. Relief Requested

  • Petitioner requested the institution of an inter partes review and the cancellation of claims 23 and 60 of the ’982 patent as unpatentable under §103.