Linear Technology Corp v. In Depth Test LLC

1. Case Identification

• Case #: IPR2015-00421
• Patent #: 6,792,373
• Filed: December 11, 2014
• Petitioner(s): Linear Technology Corporation
• Patent Owner(s): In-Depth Test LLC
• Challenged Claims: 1-20

2. Patent Overview

• Title: System for Testing Semiconductors
• Brief Description: The ’373 patent describes a system for testing semiconductor components to identify defective or potentially defective devices, referred to as "outliers." The system uses test equipment connected to a computer that analyzes test data, identifies outliers based on statistical relationships, and generates an output report.

3. Grounds for Unpatentability

Ground 1: Anticipation and Obviousness over O’Neill and Rostoker - Claims 1-20 are anticipated by or obvious over O’Neill, alone or in view of Rostoker.

• Prior Art Relied Upon: O’Neill (Patent 6,366,108) and Rostoker (Patent 5,442,282).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that O’Neill anticipates nearly all claims by disclosing a test system for detecting defects in semiconductor circuits. O’Neill’s system comprises test equipment (state generator, power supply, current meter) that generates test data (quiescent current measurements) and a connected computer with a software analyzer. This analyzer identifies defects by comparing the test signal against calculated upper and lower threshold values (i.e., identifying “outliers”) and generates an output report on a display or printer indicating a defect was found. This maps directly to the elements of independent claims 1, 8, and 15. For dependent claims 3, 10, and 17, which require testing a "section group of components on a wafer," Petitioner argued these were obvious over O'Neill in view of Rostoker.
  • Motivation to Combine (for §103 grounds): Petitioner asserted a person of ordinary skill in the art (POSITA) would combine Rostoker with O'Neill because both relate to semiconductor testing. Rostoker’s mechanism for selecting and testing specific groups of dies on a wafer would have been seen as an efficient and logical addition to O'Neill's testing method to conveniently test groups of components in a specific section of a wafer.
  • Expectation of Success (for §103 grounds): A POSITA would have had a reasonable expectation of success in combining the references, as it involved applying Rostoker's known die-selection method to O'Neill's known testing process, a predictable integration of known technologies.

Ground 2: Anticipation and Obviousness over Ekstedt and Ghaemi - Claims 1, 8, and 15 are anticipated by Ekstedt or obvious over Ekstedt in view of Ghaemi.

• Prior Art Relied Upon: Ekstedt (Patent 5,206,582) and Ghaemi (a 1989 non-patent publication on data screening).

• Core Argument for this Ground:

  • Prior Art Mapping: Petitioner argued that Ekstedt anticipates the independent claims by disclosing an automated test equipment (ATE) system for identifying defects on a semiconductor wafer. Ekstedt’s system uses a desktop computer (controller) to execute a test program, generate test data from measurement instruments, identify defective devices where a result is not within a "desired limit," and generate run-time output reports (e.g., a "run-time CRT report"). Petitioner contended this discloses all elements of the independent claims. Alternatively, Petitioner argued that even if Ekstedt did not explicitly teach identifying statistical "outliers," the claims are obvious over Ekstedt in view of Ghaemi. Ghaemi explicitly discloses a method for automatically screening semiconductor test data to detect abnormalities, including "clusters and outliers," using statistical variables like mean and standard deviation.
  • Motivation to Combine (for §103 grounds): A POSITA would combine Ghaemi’s statistical outlier detection method with Ekstedt’s ATE system because both are in the same field of semiconductor testing and address the same problem of analyzing large amounts of test data. Ghaemi's method provides a specific, automated statistical technique that would have been a natural and advantageous improvement to Ekstedt’s more general defect detection, furthering Ekstedt’s goal of facilitating test development and data analysis.
  • Expectation of Success (for §103 grounds): Success was predictable because it involved applying Ghaemi's known statistical screening software to the test data generated by Ekstedt's established ATE system.

• Additional Grounds: Petitioner asserted numerous additional obviousness challenges for various dependent claims, primarily based on combinations of O'Neill or Ekstedt with Rostoker (for testing component groups), Ghaemi (for calibrating sensitivity), La (Patent 5,761,064, for data correlation), and Daasch (a 2000 non-patent publication, for data smoothing).

4. Key Claim Construction Positions

• "outlier": Petitioner proposed this term be construed as "any semiconductor device or part or data point associated with the device or part that on some measure falls above or below a threshold value." This broad construction was important because it allowed Petitioner to map prior art references that identified "defects" or values outside a "desired limit" to the claimed "outlier" limitation, even if the reference did not use that specific word.
• "identify the outlier at run time": Petitioner proposed this phrase be construed as "identifying a part or data point falling above or below a given threshold value within minutes of the test equipment measuring the component and producing the data point." This construction was key to arguing that prior art systems like O'Neill and Ekstedt, which performed analysis immediately or "continuously," met the temporal requirements of the claims.
• "recipe file": Petitioner proposed construing this term broadly as "configuration data of any kind that would assist in the testing of the device under test or in the analysis of the test results." This allowed Petitioner to argue that prior art disclosing storage of test parameters or threshold values in memory-resident files or configuration file libraries met this limitation.

5. Relief Requested

• Petitioner requested institution of an inter partes review and cancellation of claims 1-20 of the ’373 patent as unpatentable under 35 U.S.C. §§ 102 and/or 103.