PTAB

IPR2017-01417

Samsung Electronics Co., Ltd. v. ProMOS Technologies, Inc.

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1. Case Identification

2. Patent Overview

  • Title: Method of Providing a Contact Via to a Substrate Surface
  • Brief Description: The ’027 patent describes a method for fabricating semiconductor contact vias. The method aims to prevent damage to the substrate from a "double etch" by first forming a protective dielectric layer on the substrate before etching an aperture for the contact.

3. Grounds for Unpatentability

Ground 1: Anticipation of Claims 1, 2, 4, 6-8, and 10 by Ono

  • Prior Art Relied Upon: Ono (JP H10-144788).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Ono discloses every limitation of the challenged claims. Specifically, Ono teaches a method for manufacturing semiconductor devices with contact vias that prevents damage to the underlying substrate. Petitioner asserted that Ono’s process maps to claim 1 by: (1) forming a "first dielectric layer" (comprising silicon oxide film 21 and silicon nitride layer 22) on a substrate; (2) forming a "second dielectric layer" (interlayer insulation film 23) on top; (3) etching a "first aperture" (contact hole CH) that stops on the first layer; (4) providing a "third dielectric layer" (coating layer 25); and (5) performing a final anisotropic etch to remove portions of the third and first layers to expose the substrate. Petitioner contended Ono’s disclosure of depositing silicon nitride and using a chemical vapor deposition (CVD) process anticipated dependent claims 2 and 4.

Ground 2: Anticipation of Claims 1, 2, 4, 6-8, and 10 by Koyama

  • Prior Art Relied Upon: Koyama (Application # 2003/0049920).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Koyama provides a parallel and independent disclosure that anticipates the claimed method. Unlike Ono, which uses a two-part first dielectric layer, Koyama discloses using a single etching stopper film 43 (made of a nitride film) as the "first dielectric layer" formed directly on the substrate. The subsequent steps taught by Koyama—forming a second dielectric layer (insulating film 5), etching a first aperture (opening 6) that stops on the first layer, depositing a third dielectric layer (insulating film 7), and performing a final etch-back using Reactive Ion Etching (RIE) to expose the substrate—were alleged to map directly to the limitations of claim 1 and several dependent claims.

Ground 3: Obviousness of Claims 3 and 5 over Ono in view of Ngo

  • Prior Art Relied Upon: Ono (JP H10-144788), Ngo (Patent 6,060,393).

  • Core Argument for this Ground:

    • Prior Art Mapping: The base process is from Ono. Independent claim 1 is met by Ono, but claim 3 requires the first dielectric layer to comprise silicon oxynitride, whereas Ono uses silicon nitride. Petitioner argued that Ngo teaches using silicon oxynitride as an etch stop layer for the same purpose and in a similar context.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine the references because both relate to semiconductor fabrication and disclose etch stop layers to prevent over-etching. Petitioner asserted a POSITA would look to Ngo to refine Ono's process, as Ngo teaches that silicon oxynitride is an effective and interchangeable alternative to silicon nitride for an etch-stop layer.
    • Expectation of Success: The substitution of silicon oxynitride for silicon nitride was a simple design choice between two well-known materials for the same function, yielding the predictable result of providing effective etch-stop functionality.

  • Additional Grounds: Petitioner asserted additional obviousness challenges, including that claim 9 is obvious over Ono in view of Cronin (Patent 5,654,238); claims 3 and 5 are obvious over Koyama in view of Ngo; and claim 9 is obvious over Koyama in view of Cronin. These grounds relied on similar arguments, primarily substituting known etching techniques (Cronin's RIE) or materials (Ngo's silicon oxynitride) into the primary processes taught by Ono and Koyama.

4. Key Claim Construction Positions

  • "on the surface": Petitioner argued this term, under the broadest reasonable interpretation, does not require direct physical contact and allows for intermediate layers between the recited layer and the substrate surface. This construction was central to the anticipation arguments, particularly regarding Ono, where an intervening silicon oxide film exists between the nitride etch-stop layer and the substrate.
  • "material": In claim 6, Petitioner argued the term "material" lacks a proper antecedent basis, rendering the claim indefinite. For the purpose of the IPR, Petitioner construed "material" to mean "substrate," asserting this was consistent with claim amendments the Patent Owner made during the patent's original prosecution to overcome a rejection.

5. Key Technical Contentions (Beyond Claim Construction)

  • A central technical argument was that the surface of a source/drain region, which is formed within a semiconductor substrate, is considered part of the "surface of the substrate" for the purposes of the invention. Petitioner contended that these surfaces are coplanar and that both the prior art (Ono and Koyama) and the ’027 patent itself treat them as equivalent, thereby allowing the prior art's formation of layers on source/drain regions to meet the claim limitation of forming a layer "on the surface of the substrate."

6. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 1-10 of Patent 7,375,027 as unpatentable.