Hamamatsu Photonics K.K. v. SEMICAPS Pte Ltd.

1. Case Identification

• Patent #: 7,623,982 B2
• Filed: September 15, 2017
• Petitioner(s): HAMAMATSU PHOTONICS K.K.
• Patent Owner(s): SEMICAPS PTE LTD.
• Challenged Claims: 1, 4-7, 21-25

2. Patent Overview

• Title: Method and Apparatus for Testing an Electronic Circuit
• Brief Description: The ’982 patent discloses a method and apparatus for testing an electronic circuit to detect faults. The technology involves radiating a laser beam onto the circuit, determining a plurality of samples of a response signal during the radiation period, accumulating the samples to generate a value, and then generating a test result based on that value to identify defects.

3. Grounds for Unpatentability

Ground 1: Anticipation over Hamada - Claims 1, 21, and 22 are anticipated by Hamada under 35 U.S.C. §102(b).

• Prior Art Relied Upon: Hamada (JP Publication # JP2003-1719108A)
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Hamada, which describes an inspection device for semiconductor devices, discloses every limitation of independent claims 1 and 21. Hamada’s inspection device uses an optical beam (disclosed as potentially a laser) to irradiate locations on a device under test (DUT). Petitioner contended that Hamada’s teaching of calculating an "average current" at each test site inherently requires determining and accumulating a "plurality of samples" of the response signal, as averaging is mathematically impossible without multiple samples. Hamada’s "signal processing and display unit" was alleged to perform the claimed accumulation and generation of a test result (a contrast image). For dependent claim 22, Petitioner asserted that Hamada’s system, which scans and irradiates multiple sites (1, 2, and 3), teaches moving the laser source over a plurality of locations in a pattern.

Ground 2: Anticipation over Quah - Claims 1, 4-7, and 21-25 are anticipated by Quah under §102(b).

• Prior Art Relied Upon: Quah (a 2006 conference proceeding, “DC-Coupled Laser Induced Detection System for Fault Localization in Microelectronic Failure Analysis”)
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Quah, a publication by several inventors of the ’982 patent, anticipates all challenged claims. Quah describes a DC-coupled laser detection system that uses a scanned laser to stimulate failures in a DUT. Petitioner asserted that Quah’s disclosure of improving signal-to-noise ratio via "signal averaging" and "digitization of the laser induced signal response" explicitly teaches determining and accumulating a plurality of samples. The resulting DUT images were argued to be the claimed "test result." For dependent claims 4 and 23, Petitioner contended Quah’s disclosure of a laser being "On" and "Off" teaches a "pulsed laser beam." For claims 5-7 and 24-25, Petitioner argued that Quah discloses specific laser dwell times and sampling frequencies (20 MHz) that fall within the claimed ranges and satisfy the requirement that the sampling frequency is higher than the laser frequency.

Ground 3: Obviousness over Hamada and Beaudoin - Claims 4, 5, 7, 23, and 24 are obvious over Hamada in view of Beaudoin under §103.

• Prior Art Relied Upon: Hamada (JP Publication # JP2003-1719108A) and Beaudoin (a 2003 article, "From Static Thermal and Photoelectric Laser Stimulation (TLS/PLS) to Dynamic Laser Testing")

• Core Argument for this Ground:

  • Prior Art Mapping: This ground asserted that even if Hamada does not explicitly teach a "pulsed laser beam" (recited in claims 4 and 23), it would have been obvious to modify Hamada’s system with one. Beaudoin was introduced as teaching the advantages of using a pulsed laser in similar electronic circuit testing, such as improved signal-to-noise ratio and reduced thermal damage risk. The combination of Hamada's sampling frequency (disclosed as 1-100 MHz) and Beaudoin's laser frequency (up to 100 kHz) was argued to render the frequency limitations of claims 5, 7, and 24 obvious.
  • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine Hamada with Beaudoin to gain the known benefits of using a pulsed laser, as described by Beaudoin, in Hamada's established testing framework. This was presented as a predictable application of a known technique to improve a similar device.
  • Expectation of Success: A POSITA would have had a reasonable expectation of success in incorporating a pulsed laser into Hamada’s system to achieve predictable results like improved detection sensitivity.

• Additional Grounds: Petitioner asserted additional obviousness challenges, including combinations of Hamada in view of Bruce (Patent 6,897,664), Hamada in view of Quah, and Quah alone under §103. These grounds primarily relied on similar arguments: that if the primary reference was found not to teach a specific element (like a plurality of samples or a pulsed laser), it would have been obvious to a POSITA to incorporate that known element from the secondary art to achieve predictable improvements.

4. Key Claim Construction Positions

• "accumulating" and "accumulates": Petitioner argued these terms should be construed to mean "adding or performing any act that includes adding as a step, such as averaging." This construction was critical because the primary prior art references (Hamada and Quah) explicitly disclose "averaging," which Petitioner leveraged to argue they inherently teach the "accumulating" limitation.
• "pulsed laser beam": Petitioner proposed this term be construed as "a laser beam having a laser beam signal formed of pulses," based on the ’982 patent’s description of a beam alternating between "ON" and "OFF" states. This allowed Petitioner to map the term to prior art that showed similar alternating laser behavior, even if the term "pulsed" was not explicitly used.
• Means-Plus-Function: Petitioner asserted that none of the limitations in claim 21 were means-plus-function but provided alternative constructions for terms like "laser beam source," "control system," "measuring circuit," and "signal processor" if the Board disagreed.

5. Key Technical Contentions (Beyond Claim Construction)

• Averaging Requires Multiple Samples: A central technical contention was that the process of "averaging," as disclosed in both Hamada and Quah, necessarily and inherently requires the measurement and accumulation of a "plurality of samples." Petitioner argued that this was the basis for allowance during prosecution, and that the Examiner erred by not considering prior art that disclosed averaging. This technical inference was used to argue that the key claim limitations were, in fact, taught by the prior art.

6. Relief Requested

• Petitioner requested institution of an inter partes review and cancellation of claims 1, 4-7, and 21-25 of the ’982 patent as unpatentable.