PTAB

IPR2017-01417

Samsung Electronics Co Ltd v. ProMOS Technologies Inc

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Method of Forming a Contact Via
  • Brief Description: The ’027 patent describes a method for fabricating a contact via to a substrate surface in a semiconductor device. The method is intended to prevent damage to the substrate that occurs in prior art techniques from a "double etch" process by first forming a protective dielectric layer over the substrate before performing the etching steps.

3. Grounds for Unpatentability

Ground 1: Claims 1, 2, 4, 6-8, and 10 are anticipated by Ono under 35 U.S.C. §102.

  • Prior Art Relied Upon: Ono (Japanese Patent Publication JP H10-144788).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Ono, which discloses a manufacturing method for semiconductor devices, teaches every limitation of the challenged claims. Ono describes forming connection holes (contact vias) to a substrate surface while preventing damage by using a semiconductor coating layer as an "etching stopper layer." Petitioner mapped the steps of claim 1 to Ono’s process: (1) forming a first dielectric layer (Ono’s insulation film 21 and coating layer 22) on the substrate; (2) forming a second dielectric layer (Ono’s interlayer insulation film 23); (3) providing a first aperture (contact hole CH) that extends toward the substrate but is stopped by the first dielectric layer; (4) providing a third dielectric layer (contact hole coating layer 25); and (5) removing portions of the first and third dielectric layers to expose the substrate surface. The dependent claims were also argued to be disclosed, such as depositing silicon nitride (claim 2) and using an anisotropic etch process (claim 6).

Ground 2: Claims 3 and 5 are obvious over Ono in view of Ngo under 35 U.S.C. §103.

  • Prior Art Relied Upon: Ono (Japanese Patent Publication JP H10-144788) and Ngo (Patent 6,060,393).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner contended that Ono taught all limitations of claim 3 except for using silicon oxynitride for the first dielectric layer; Ono’s coating layer 22 is silicon nitride. Ngo was argued to remedy this deficiency by disclosing a semiconductor manufacturing process that uses a stop layer made of silicon oxynitride for the same purpose as Ono’s silicon nitride etch stop layer.
    • Motivation to Combine: A POSITA would combine the references because both relate to semiconductor fabrication and disclose etch stop layers. Petitioner argued a POSITA would have been motivated to substitute the silicon nitride in Ono's process with the silicon oxynitride taught by Ngo, as Ngo itself suggests silicon nitride and silicon oxynitride are interchangeable materials for forming a stop layer. This modification was presented as a simple substitution of one known element for another to obtain a predictable result—reducing over-etching.
    • Expectation of Success: A POSITA would have had a high expectation of success because substituting silicon oxynitride for silicon nitride was a well-known, routine practice in the art for forming etch stop films, yielding the predictable result of a functional etch stop.

Ground 3: Claims 1, 2, 4, 6-8, and 10 are anticipated by Koyama under 35 U.S.C. §102.

  • Prior Art Relied Upon: Koyama (Application # 2003/0049920).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner asserted that Koyama, which describes a method for forming a minute contact structure, independently anticipates the same set of claims as Ono. Koyama’s method uses an "etching stopper film" (film 43) made of silicon nitride to terminate etching at a precise depth, thereby preventing substrate damage. Petitioner mapped claim 1’s steps to Koyama’s process: (1) forming a first dielectric layer (Koyama’s etching stopper film 43) on the substrate; (2) forming a second dielectric layer (interlayer insulating film 5); (3) providing a first aperture (opening 6) that stops upon reaching the etching stopper film; (4) providing a third dielectric layer (insulating film 7); and (5) performing an etch back to remove portions of the first and third layers to expose the substrate. The dependent claims were also argued to be disclosed, including the use of plasma chemical vapor deposition (CVD) to form the silicon nitride layer (claim 4) and using a reactive ion etch (RIE) process (claim 10).

  • Additional Grounds: Petitioner asserted additional obviousness challenges, including that claims 3 and 5 are obvious over Koyama and Ngo; and that claim 9 is obvious over Ono and Cronin (Patent 5,654,238) or Koyama and Cronin. These grounds relied on similar theories of combining the primary references (Ono or Koyama) with secondary references that explicitly teach using silicon oxynitride as an alternative etch stop material (Ngo) or using RIE for the etch process (Cronin).

4. Relief Requested

  • Petitioner requests the institution of an inter partes review and the cancellation of claims 1-10 of the ’027 patent as unpatentable.