ASML Netherlands BV v. Energetiq Technology Inc

1. Case Identification

• Case #: IPR2015-01368
• Patent #: 8,525,138
• Filed: June 12, 2015
• Petitioner(s): ASML Netherlands B.V., Excelitas Technologies Corp., and Qioptiq Photonics GmbH & Co. KG
• Patent Owner(s): Energetiq Technology, INC.
• Challenged Claims: 1-5

2. Patent Overview

• Title: Laser Sustained Plasma Light Source
• Brief Description: The ’138 patent discloses a high-brightness light source for applications such as semiconductor manufacturing inspection. The system uses an ignition source, such as electrodes, to excite a gas within a pressurized chamber, and a separate laser to provide energy to sustain the resulting plasma, which in turn produces light. A key feature of the claimed invention is that the sustaining laser is configured to operate at a wavelength within 10 nm of a strong absorption line of the excited gas to improve performance.

3. Grounds for Unpatentability

Ground 1: Claims 1-5 are obvious over Gärtner in view of Beterov.

• Prior Art Relied Upon: Gärtner (French Patent Publication No. FR2554302A1) and Beterov ("Resonance radiation plasma (photoresonance plasma)," Sov. Phys. Usp. 31(6), 1988).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Gärtner, which was not considered during prosecution, disclosed the core elements of the claimed light source. Gärtner taught a system for photolithography comprising a pressurized, gas-tight chamber containing an ionizable gas (e.g., xenon), an ignition source (disclosing both electrodes and lasers as options), and a continuous laser to sustain the plasma and produce light. Petitioner contended the only key element not explicitly taught by Gärtner was configuring the sustaining laser to operate within 10 nm of a strong absorption line of the gas. This limitation, Petitioner argued, was taught by Beterov, which described creating and sustaining "photoresonance plasmas" by tuning a laser's wavelength to a strong absorption line of a gas. Beterov explained that this technique results in highly efficient energy absorption.
  • Motivation to Combine: A POSITA would combine Beterov’s teachings with Gärtner’s system to improve its performance. Beterov explicitly taught that tuning a laser to a gas’s resonance absorption line achieves nearly complete ionization and absorption of laser radiation, allows the plasma to be sustained with very low power, and increases the brightness of the light output. These known benefits of efficiency and brightness would have motivated a POSITA to modify Gärtner’s known laser-sustained plasma source by applying the laser tuning principles taught by Beterov.
  • Expectation of Success: A POSITA would have had a reasonable expectation of success. Gärtner already disclosed using a laser to sustain a plasma. Modifying Gärtner’s system by selecting a laser that operates at a specific wavelength taught by Beterov to improve energy transfer was a simple substitution of one known element for another to achieve a predictable improvement in performance.

Ground 2: Claims 1-5 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 Ground 1, Petitioner asserted that Gärtner taught the foundational laser-sustained plasma light source. The secondary reference, Wolfram, which was also not considered during prosecution, taught the principle of tuning a laser to a precise wavelength for efficient light generation. Specifically, Wolfram disclosed an optically pumped laser system where the pumping laser is tuned to emit light at a wavelength within 2 nm of an "absorption peak" of the target material. Petitioner argued that this "absorption peak" corresponds to the claimed "strong absorption line." Therefore, the combination of Gärtner's system with Wolfram's laser tuning teachings rendered the claims obvious.
  • Motivation to Combine: The motivation to combine Wolfram with Gärtner was to create a more efficient and brighter light source. Wolfram taught that tuning a laser to the absorption peak of a target material results in more efficient light emission. A POSITA seeking to improve the efficiency of Gärtner’s light source for demanding applications like lithography would have been motivated to apply Wolfram's known principle of tuning the sustaining laser to the absorption peak of the plasma gas.
  • Expectation of Success: The combination would have been obvious to try with a high expectation of success. Both references were directed to generating light by supplying laser energy to a target material. Implementing Wolfram's laser tuning method in Gärtner's system would have been a routine modification, as employing lasers at different wavelengths to improve efficiency was a known design choice that would have yielded the expected results of a brighter and more efficient light source.

4. Key Claim Construction Positions

• "Light source": Petitioner argued that this term should be construed broadly to mean "a source of electromagnetic radiation" across a wide spectrum, including extreme ultraviolet, vacuum ultraviolet, visible, and infrared regions. This construction was proposed to ensure that prior art references discussing light generation outside the visible spectrum were properly considered and to prevent the Patent Owner from arguing a narrower, undisclosed definition to avoid the prior art.

5. Relief Requested

• Petitioner requested institution of an inter partes review (IPR) and cancellation of claims 1-5 of the ’138 patent as unpatentable under 35 U.S.C. §103.