PTAB

IPR2019-00006

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 Temperature
  • Brief Description: The ’898 patent describes a method for achieving high-strength bonds between semiconductor wafers at low or room temperatures. The process involves etching a bonding surface to activate it, terminating the activated surface with desired chemical species, and then bringing it into contact with another surface to form a chemical bond.

3. Grounds for Unpatentability

Ground 1: Obviousness over Li and Reiche - Claims 1-4, 9, 13-16, 21, 26, 32, and 37 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 journal article on plasma pretreatment for Si/Si bonding).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Li disclosed all elements of the claimed bonding method. Li teaches a systematic process for low-temperature direct bonding of silicon and/or SiO2 surfaces, beginning with a surface activation step using ammonia or oxygen plasma in a reactive ion etcher (RIE). This process, which creates strong bonds after low-temperature annealing, allegedly disclosed the claimed steps of etching a planar surface, terminating it with a species (e.g., nitrogen-containing species from ammonia plasma or OH groups from oxygen plasma), bringing the surfaces into contact, and forming a chemical bond with a strength exceeding 1000 mJ/m².
    • Motivation to Combine: Petitioner contended that both references address increasing bond strength in wafer bonding. A person of ordinary skill in the art (POSITA) would combine their teachings because Li identifies the need for smooth, flat samples, and Reiche provides a detailed investigation into the effect of RIE plasma treatments on surface roughness. Reiche specifically teaches how to minimize changes in roughness by controlling plasma gas concentrations, providing an explicit solution to a known issue in the art discussed by Li.
    • Expectation of Success: A POSITA would have an expectation of success because both references disclose applying similar oxygen or ammonia RIE plasma processes to the same types of silicon or SiO2 surfaces, making the outcome of the combination predictable.

Ground 2: Obviousness over Kräuter and Reiche - Claims 1-4, 13-16, 26, 32, and 37 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.
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted that Kräuter disclosed a low-temperature bonding method for silicon wafers using oxygen plasma activation in a "plasma etching apparatus" to create a highly hydrophilic surface. Kräuter explicitly teaches that this plasma exposure terminates the surface with silanol (Si-OH) groups. The wafers are then bonded at room temperature and annealed at 200°C to achieve bond energies over 1000 mJ/m². This process allegedly meets the limitations of etching, terminating, contacting, and forming a strong chemical bond.
    • Motivation to Combine: A POSITA would combine Kräuter and Reiche to optimize the plasma activation process. Kräuter acknowledges that bonding layers must be "sufficiently smooth," and Reiche teaches how to control and minimize surface roughness during the exact type of oxygen RIE treatments used by Kräuter. Therefore, a POSITA would apply Reiche's teachings to Kräuter's method to ensure surface smoothness was maintained while achieving high bond strength.
    • Expectation of Success: The combination was asserted to be predictable because both references describe oxygen plasma activation on silicon wafers with native oxide layers, and Reiche's process controls were directly applicable to the plasma etching apparatus disclosed in Kräuter.

Ground 3: Obviousness over Kissinger and Reiche - Claims 1-2, 4, 13-14, 16, 26, 32, and 37 are obvious over Kissinger in view of Reiche.

  • Prior Art Relied Upon: Kissinger (a 1993 journal article on low-temperature wafer-bond strengthening) and Reiche.

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner argued that the combination of Kissinger and Reiche renders the claims obvious. Kissinger discloses using oxygen plasma to activate silicon wafer surfaces, which increases the number of bonding sites. This is followed by a subsequent RCA clean that terminates the surface with OH-groups. After room-temperature bonding and annealing at 200°C, Kissinger achieved surface energies of almost 2000 mJ/m². The combined teachings of Kissinger (plasma activation) and Reiche (RIE process) allegedly disclosed an "etching" step that activates the surface.
    • Motivation to Combine: A POSITA would be motivated to combine these references because Kissinger teaches the importance of surface roughness for its plasma activation process, and Reiche provides explicit instructions for controlling roughness during such treatments. Reiche’s disclosure of adjusting gas concentrations to maintain smoothness would have been seen as a way to optimize the plasma activation step described by Kissinger.
    • Expectation of Success: A POSITA would expect success in applying Reiche’s process controls to Kissinger’s method, as both references focus on the common goal of using oxygen plasma to enhance bond strength on silicon wafers.

  • Additional Grounds: Petitioner asserted additional obviousness challenges, including grounds that add Tong (a 1994 publication) to the Kräuter/Reiche and Kissinger/Reiche combinations to explicitly teach terminating the bonding surface with a nitrogen-comprising species via an ammonium hydroxide treatment.

4. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-4, 9, 13-16, 21, 26, 32, and 37 of the ’898 patent as unpatentable under 35 U.S.C. §103.