PTAB

IPR2019-00001

Samsung Electronics Co Ltd v. Invensas Bonding Technologies Inc

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Method for Bonding at Low or Room Temperature
  • Brief Description: The ’744 patent discloses a method for low-temperature semiconductor wafer bonding intended to achieve high bond strength. The process involves activating a wafer surface via etching, terminating the activated surface with a desired chemical species, and then bonding it to a second surface.

3. Grounds for Unpatentability

Ground 1: Claims 41, 44, and 45 are obvious over Li in view of Reiche.

  • Prior Art Relied Upon: Li (a 1998 journal article on low-temperature silicon bonding) and Reiche (a 1997 conference proceeding on plasma pretreatment for Si/Si bonding).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Li taught the core processing method of claim 41, including activating a silicon or SiO₂ surface with an ammonia or oxygen plasma in a reactive ion etcher (RIE) to create a strong bond after annealing at 200°C. This process allegedly met the limitations for plasma activation, termination with a species capable of forming a chemical bond exceeding 500 mJ/m², and subsequent bonding. For dependent claim 44, Petitioner asserted that Reiche explicitly taught that oxygen RIE treatments could be performed with a minimal change in surface roughness (e.g., 0.029 nm), rendering the post-etching roughness "substantially the same" as the pre-etching roughness. For dependent claim 45, Petitioner argued Li’s disclosure of an ammonia plasma treatment inherently taught the use of a "nitrogen-based" terminating species.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine Li and Reiche because both references address improving wafer bonding processes. Petitioner contended that Reiche provided specific, beneficial details on controlling surface roughness—a critical parameter for the plasma activation process broadly described in Li.
    • Expectation of Success: A POSITA would have a high expectation of success because both references employed similar RIE plasma processes on silicon wafers using oxygen as a reagent gas. This commonality would make the application of Reiche's roughness control parameters to Li's process predictable and straightforward.

Ground 2: Claims 41 and 44 are obvious over Kräuter in view of Reiche.

  • Prior Art Relied Upon: Kräuter (a 1998 journal article on low-temperature silicon direct bonding) and Reiche (a 1997 conference proceeding).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued Kräuter disclosed a low-temperature bonding method meeting the limitations of claim 41. Kräuter’s method included an oxygen plasma activation step using a "plasma etching apparatus," followed by a chemical termination step (using TMOS to create Si-OH groups), which achieved high bond strengths (>1000 mJ/m²) after annealing at 200°C. Similar to Ground 1, Petitioner relied on Reiche to demonstrate the obviousness of claim 44’s limitation, arguing Reiche taught that this type of oxygen plasma etching could be controlled to ensure surface roughness remained "substantially the same."
    • Motivation to Combine: A POSITA would combine Kräuter and Reiche as they operate in the same technical field. Reiche provided a known solution for controlling surface roughness, which was a well-understood and important factor for the plasma activation processes described by Kräuter.
    • Expectation of Success: Success was expected because both Kräuter and Reiche described oxygen plasma activation on silicon wafers with native oxide layers. This overlap in materials and process steps would make Reiche's teachings on roughness control directly applicable to improving Kräuter's method.

Ground 3: Claim 45 is obvious over Kräuter and Reiche in view of Tong (1994).

  • Prior Art Relied Upon: Kräuter (a 1998 journal article), Reiche (a 1997 conference proceeding), and Tong (1994) (a review article on semiconductor wafer bonding).

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground built upon the combination of Kräuter and Reiche, arguing that modifying the process to use a "nitrogen-based" species (claim 45) was obvious. While Kräuter taught termination with OH-groups, Petitioner asserted that Tong (1994) explicitly taught the superiority of an ammonium hydroxide (NH₄OH) treatment, which yields a nitrogen-based termination and results in significantly stronger bonds compared to OH-group termination.
    • Motivation to Combine: A POSITA seeking to maximize bond strength in the Kräuter/Reiche process would be motivated to replace Kräuter's OH-group termination step with the superior nitrogen-based ammonium hydroxide treatment taught by Tong. Petitioner characterized this as a simple substitution of one known technique for another to achieve a predictable improvement.
    • Expectation of Success: Success was expected because the combination involved applying a known, superior termination technique (from Tong) to a known bonding process (from Kräuter) to achieve the expected benefit of higher bond strength.

  • Additional Grounds: Petitioner asserted additional obviousness challenges based on combinations of Kissinger with Reiche and Tong, relying on similar arguments regarding plasma activation, surface roughness control, and nitrogen-based termination.

4. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 41, 44, and 45 of Patent 7,553,744 as unpatentable.