PTAB

IPR2019-01145

REC Solar Pte Ltd v. Hanwha Q Cells & Advanced Materials Corp

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Method for Manufacturing a Solar Cell with a Surface-Passivating Dielectric Double Layer, and Corresponding Solar Cell
  • Brief Description: The ’215 patent describes a solar cell structure designed to improve efficiency by reducing surface recombination losses. The invention comprises a silicon substrate with a surface-passivating dielectric double layer, where a first thin layer of aluminum oxide is positioned between the silicon substrate and a second, different dielectric layer containing embedded hydrogen.

3. Grounds for Unpatentability

Ground 1: Anticipation - Claims 12-14 are anticipated by Agostinelli '086 under 35 U.S.C. §102.

  • Prior Art Relied Upon: Agostinelli '086 (EP Application # 1,763,086).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Agostinelli '086 discloses every limitation of the challenged claims. Specifically, Agostinelli '086 teaches a solar cell device with a silicon substrate, a first dielectric layer comprising aluminum oxide, and a second "passivation layer" of hydrogenated silicon nitride (SiN) deposited directly on top of the first layer. Petitioner asserted that Agostinelli '086 discloses a thickness for the first layer of "more than 10nm, 40nm," which satisfies the "less than 50 nm" limitation of claim 12 and the "less than 30 nm" limitation of claim 14. Furthermore, the hydrogenated SiN layer was argued to meet the limitations of a differing second dielectric layer (claim 12) with embedded hydrogen (claim 12) and comprising silicon nitride (claim 13).
    • Key Aspects: This ground asserted that a reference which the Examiner did not substantively analyze during prosecution, Agostinelli ’086, contains express disclosures that overcome the patentability arguments made by the applicant regarding a different Agostinelli reference (’303 application).

Ground 2: Obviousness over Nakano and Hoex - Claims 12-14 are obvious over Nakano in view of Hoex 2006 under §103.

  • Prior Art Relied Upon: Nakano (Patent 4,463,216) and Hoex 2006 ("Ultralow surface recombination of c-Si substrates..." Applied Physics Letters).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner contended that Nakano, a 1984 patent, discloses a solar cell with a silicon substrate, a first aluminum oxide layer with a thickness of about 8 nm (satisfying the <50 nm and <30 nm limitations), and a second antireflective layer of tantalum pentoxide directly on the first layer. Petitioner argued this combination teaches every element of the claims except for the "embedded hydrogen" in the second dielectric layer. Hoex 2006, published in 2006, teaches that hydrogenated amorphous silicon nitride (a-SiNx:H) was routinely used as a state-of-the-art antireflection coating in solar cells.
    • Motivation to Combine: A POSITA reviewing Nakano’s decades-old technology would be motivated to improve its performance by substituting the outdated tantalum pentoxide antireflective layer with the modern, more efficient hydrogenated silicon nitride layer described in Hoex 2006. This modification was presented as a simple substitution of one known element for another to obtain predictable results, namely improved solar cell efficiency.
    • Expectation of Success: Because hydrogenated silicon nitride was the industry standard for antireflective coatings by 2006, a POSITA would have had a high expectation of success in achieving known antireflective properties and improved performance by making the proposed substitution.

Ground 3: Anticipation - Claims 12-14 are anticipated by Narwankar under §102.

  • Prior Art Relied Upon: Narwankar (Application # 2005/0260347).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner argued that Narwankar, which describes semiconductor processing, discloses a structure meeting all limitations of the challenged claims. Narwankar teaches a silicon substrate, a first dielectric layer of aluminum oxide deposited on the substrate with a preferred thickness range of 2 nm to 50 nm, and a second dielectric layer (silicon oxide) deposited directly on the first. Petitioner contended that Narwankar's disclosed process for forming the second layer, which uses hydrogen-containing reactants (e.g., silane precursors, hydrogen gas), inherently results in a second dielectric layer with embedded hydrogen. This structure was argued to anticipate all structural limitations of claims 12-14.
    • Key Aspects: This ground relies on the claim construction argument (detailed in Section 4) that the preamble "A solar cell" is non-limiting, allowing a reference directed to general semiconductor structures to anticipate the claims if it discloses the required structural elements.

  • Additional Grounds: Petitioner asserted additional obviousness challenges, including a combination of Agostinelli '086 with Nakano and Hoex 2006 to reinforce teachings of thinner dielectric layers, and an alternative ground that claims 12-14 are obvious over Narwankar alone or in view of Tan (Patent 6,929,700) to further support the motivation to use the structure for a solar cell and the presence of embedded hydrogen.

4. Key Claim Construction Positions

  • "A solar cell" (Claim 12, preamble): Petitioner argued this preamble term is not limiting. It contended that the body of claim 12 describes a structurally complete semiconductor invention (a layered stack on a silicon substrate) and does not rely on the preamble for antecedent basis or structural definition. The term "solar cell" was argued to merely state an intended use for the claimed structure, which does not limit the claim's scope to only solar cell applications. This construction is critical to the anticipation ground based on Narwankar, which discloses a general semiconductor structure.

5. Arguments Regarding Discretionary Denial

  • Petitioner argued that discretionary denial would be inappropriate despite a co-pending IPR petition filed by a third party (LONGI, IPR2019-01072) against the same patent. The petition asserted it was materially different because it relied on different primary prior art references (Agostinelli '086, Nakano, and Narwankar) and the testimony of a different expert. Therefore, Petitioner contended the petition was not redundant and should be instituted.

6. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 12-14 of Patent 9,893,215 as unpatentable under 35 U.S.C. §102 and §103.