Intel Corporation v. Godo Kaisha IP Bridge 1

1. Case Identification

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

2. Patent Overview

• Title: Semiconductor Device with Stress Film for Carrier Mobility Enhancement
• Brief Description: The ’289 patent discloses a semiconductor device, specifically a metal-insulator-semiconductor field effect transistor (MISFET), that incorporates an internal stress film. The film is designed to generate tensile or compressive stress in the transistor's channel region to increase the mobility of charge carriers, thereby improving device performance.

3. Grounds for Unpatentability

Ground I: 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 that Hoffmann disclosed all elements of independent claim 1. Specifically, Hoffmann taught a MISFET structure with an internal stress film (a silicon nitride "etch stop layer") formed over the source/drain regions. Crucially, Hoffmann also taught removing the portion of this film from the upper surface of the gate electrode, explaining this removal eliminates a "bridge" and allows the film to "pull more efficiently on the channel," thereby increasing lateral tension. Petitioner contended that Kumagai supplemented Hoffmann by explicitly teaching that applying stress in the gate length direction—the direction of carrier movement—is what enhances performance. Kumagai provided detailed data showing that tensile stress increases drain current for n-channel FETs and compressive stress does the same for p-channel FETs.
  • Motivation to Combine: A POSITA would combine Hoffmann and Kumagai because both references addressed the same problem of increasing carrier mobility using a stress-inducing film. Hoffmann provided the fundamental structure, including the key feature of removing the film from the gate top. Kumagai provided empirical data and clear teachings on the optimal directionality of the stress (i.e., parallel to the channel). A POSITA would have been motivated to apply Kumagai’s specific teachings on stress directionality to Hoffmann's structure to ensure the "lateral tension" mentioned by Hoffmann was optimally directed to achieve the predictable result of enhanced carrier mobility.
  • Expectation of Success: The combination was argued to be predictable because both references described analogous semiconductor structures using similar materials, such as silicon nitride for the stress film. The combination amounted to applying a known principle (directing stress along the channel) to a known device structure (Hoffmann's) to achieve a well-understood and expected benefit.

Ground II: 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 built upon Ground I to address dependent claim 10, which required the semiconductor substrate to be a {100} plane and the gate length direction to be a <011> direction. Petitioner asserted that Kumagai taught using a <110> direction (equivalent to <011>) on a (001) surface (equivalent to {100}). Buynoski was cited as further evidence, teaching that it was well-known in the late 1990s to fabricate FETs on {100} silicon wafers and align the channel with the [110] crystal direction specifically because it was known to have higher carrier mobility.
  • Motivation to Combine: A POSITA, seeking to optimize the performance of the device from Hoffmann and Kumagai, would have been motivated to implement the specific, well-documented crystal orientations taught by Kumagai and Buynoski. Using these known optimal orientations was a predictable design choice to maximize the desired effect of increased carrier mobility.

Ground III: 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 addressed dependent claim 14, which specified that the gate insulating film is a silicon oxynitride film. While Hoffmann and Kumagai taught using a generic oxide or dielectric film, Wu was introduced for its explicit teaching of using a silicon oxynitride layer as a gate insulator. Wu explained this material was a solution to reliability issues like gate oxide leakage in deep sub-micron devices.
  • Motivation to Combine: A POSITA would have been motivated to substitute the conventional gate oxide in the Hoffmann/Kumagai device with the silicon oxynitride film taught by Wu. This modification would be a simple substitution of one known insulating material for another to gain the predictable benefits of improved transistor reliability and resistance to leakage, especially as device dimensions continued to shrink.

• Additional Grounds: Petitioner asserted an additional obviousness challenge (Ground IV) against claims 7, 24, and 29 based on the combination of Hoffmann, Kumagai, and Tsubone (Patent 5,100,820). This ground addressed claims requiring source/drain regions to include a lightly doped impurity region, a heavily doped impurity region, and a silicide layer. Tsubone was cited to show these features were standard in the art to solve the well-known "hot carrier" problem in scaled-down transistors.

4. Key Claim Construction Positions

• Petitioner argued that the term "gate length direction" should be construed as "the direction in which charge carriers move." This construction was asserted to be consistent with the patent's own specification, which explicitly defined the term in this manner (e.g., '289 patent at 3:66-4:8). This construction was critical to the obviousness argument, as it directly linked the structural features of Hoffmann to the performance data and directional stress teachings of Kumagai.

5. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial under §325(d) would be improper. It was noted that the primary reference for all grounds, Hoffmann, was not considered during the original prosecution of the ’289 patent. Therefore, Petitioner contended that the asserted grounds did not rely on the same or substantially the same prior art or arguments that were previously presented to and considered by the PTO.

6. Relief Requested

• Petitioner requests institution of IPR and cancellation of claims 1-27 and 29 of Patent 7,417,289 as unpatentable.