Intel Corp v. Godo Kaisha IP Bridge 1

1. Case Identification

• Case #: IPR2018-00854
• Patent #: 7,417,289
• Filed: March 27, 2018
• Petitioner(s): Intel Corporation
• Patent Owner(s): Godo Kaisha IP Bridge 1
• Challenged Claims: 1-27 and 29

2. Patent Overview

• Title: Semiconductor Device and Method for Fabricating the Same
• Brief Description: The ’289 patent discloses a semiconductor device, such as a metal-insulator-semiconductor field effect transistor (MISFET), that includes an internal stress film. This film is formed over the source/drain regions to generate stress in the channel region, thereby increasing the mobility of charge carriers and improving device performance.

3. Grounds for Unpatentability

Ground 1: Claims 1-6, 8-13, 15-23, and 25-27 are obvious over Hoffmann in view of Kumagai.

• Prior Art Relied Upon: Hoffmann (Patent 7,045,408) and Kumagai (WO 02/47167).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued Hoffmann taught nearly all elements of independent claim 1. Hoffmann disclosed a semiconductor device with both NMOS and PMOS transistors having an etch stop layer (mapping to the claimed "internal stress film") formed over the source/drain regions. Critically, Hoffmann taught removing this layer from the top surface of the gate electrode, which Petitioner asserted meets the key negative limitation "the internal stress film is not formed on an upper surface of the gate electrode."
  • Motivation to Combine: Hoffmann taught that its etch stop layer creates "lateral tension" to enhance performance. Petitioner asserted that to the extent Hoffmann was not explicit that this stress should be in the "gate length direction," Kumagai provided this teaching. Kumagai expressly disclosed using a similar silicon nitride stress film to impart stress "aligned with the direction of flow of drain current" (i.e., the gate length direction) to improve carrier mobility, providing quantitative data to support the benefit. A person of ordinary skill in the art (POSITA) would combine Kumagai's explicit directional teaching with Hoffmann's structure to optimize the known technique of stress-induced mobility enhancement for its intended purpose.
  • Expectation of Success: Both references disclosed using silicon nitride stress films on similar MISFET structures to achieve the same goal of improved performance. A POSITA would have had a high expectation of success in ensuring the stress in Hoffmann's device was applied in the optimal direction taught by Kumagai, as it was a predictable application of known engineering principles.

Ground 2: Claim 10 is obvious over Hoffmann, Kumagai, and Buynoski.

• Prior Art Relied Upon: Hoffmann (Patent 7,045,408), Kumagai (WO 02/47167), and Buynoski (Patent 5,729,045).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground addressed claim 10, which required the semiconductor substrate to be a {100} plane and the gate length direction to be a <011> direction. Petitioner contended that Kumagai's disclosure of a test transistor fabricated on a Si (001) surface (symmetrically equivalent to a {100} plane) with the drain current parallel to the <110> axis (symmetrically equivalent to a <011> direction) met these limitations. Buynoski was cited to demonstrate that fabricating FETs on {100} wafers with a [110] channel direction was a well-known and optimal configuration for achieving higher carrier mobility.
  • Motivation to Combine: A POSITA seeking to maximize the performance benefits of the stress-film technique taught by Hoffmann and Kumagai would be motivated to consult prior art like Buynoski to select the optimal crystal orientation. Combining these teachings was a straightforward optimization to achieve the best possible device performance.

Ground 3: Claim 14 is obvious over Hoffmann, Kumagai, and Wu.

• Prior Art Relied Upon: Hoffmann (Patent 7,045,408), Kumagai (WO 02/47167), and Wu (Patent 5,880,508).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground targeted claim 14, which required the gate insulating film to be a silicon oxynitride film. Hoffmann and Kumagai disclosed a conventional gate oxide. Wu taught replacing traditional gate oxides with a silicon oxynitride layer to improve reliability and reduce gate oxide leakage, particularly for "deep sub-micron" transistors.
  • Motivation to Combine: Petitioner argued that the composition of the gate insulator was not pertinent to the core invention of Hoffmann or Kumagai. A POSITA, working within the well-established trend of device scaling, would have been motivated to substitute the conventional gate oxide in the Hoffmann/Kumagai device with the superior silicon oxynitride film taught by Wu to gain its known reliability benefits. This was a simple substitution of one known element for another to obtain predictable results.

Ground 4: Claims 7, 24, and 29 are obvious over Hoffmann, Kumagai, and Tsubone.

• Prior Art Relied Upon: Hoffmann (Patent 7,045,408), Kumagai (WO 02/47167), and Tsubone (Patent 5,100,820).
• Core Argument for this Ground:
  • Prior Art Mapping: These grounds addressed claims requiring source/drain regions that include a lightly doped impurity region, a heavily doped impurity region, and a silicide layer. Hoffmann taught heavily doped (P+/N+) regions and a silicide layer. Tsubone taught that lightly-doped drain (LDD) structures—which incorporate both lightly and heavily doped regions—were a standard solution to the "hot carrier" problem that degrades transistor lifetime in scaled devices.
  • Motivation to Combine: A POSITA building a modern, high-performance transistor based on the teachings of Hoffmann and Kumagai would have been motivated to incorporate the well-known LDD structure from Tsubone. This was not an inventive step but the application of a standard, universally used technique to ensure the resulting device was reliable and had a commercially acceptable lifetime.

4. Key Claim Construction Positions

• "gate length direction": Petitioner proposed this term should be construed as "the direction in which charge carriers move." This construction was based on explicit definitions within the ’289 patent's specification and was crucial to Petitioner's argument that Kumagai's teaching of applying stress parallel to the "direction of flow of drain current" directly corresponded to the claimed direction.

5. Relief Requested

• Petitioner requests institution of IPR and cancellation of claims 1-27 and 29 of the '289 patent as unpatentable.