DCT

5:26-cv-10832

Toyo Co Ltd v. First Solar Inc

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 4:26-cv-10832, N.D. Cal., 09/23/2026
  • Venue Allegations: Plaintiffs allege venue is proper in the Northern District of California because Defendant First Solar maintains a research and development facility in Santa Clara, purposefully directed activities related to the patents-in-suit into the district by sending notice letters to entities there, acquired the patents from a predecessor located in the district, and previously alleged that Plaintiffs imported accused products through the port of Oakland.
  • Core Dispute: Plaintiffs seek a declaratory judgment that their Tunnel Oxide Passivated Contact (TOPCon) solar cells and modules do not infringe two patents owned by Defendant related to high-efficiency solar cell structures and manufacturing methods.
  • Technical Context: The dispute involves advanced manufacturing techniques for high-efficiency crystalline silicon solar cells, a key technology in the renewable energy market aimed at increasing power conversion efficiency while managing production costs.
  • Key Procedural History: This declaratory judgment action was filed after Defendant First Solar initiated an investigation at the International Trade Commission (ITC) alleging that Plaintiffs’ TOPCon solar cells infringed the ’074 Patent. First Solar later moved to dismiss its ITC complaint without prejudice, while publicly stating its intent to continue enforcing its patent portfolio in U.S. District Court, prompting Plaintiffs to file this action to resolve the controversy.

Case Timeline

Date Event
2009-04-21 Priority Date for ’074 and ’732 Patents
2015-09-08 U.S. Patent No. 9,130,074 Issues
2017-05-30 U.S. Patent No. 9,666,732 Issues
2026-02-24 First Solar files ITC complaint against TOYO
2026-09-15 First Solar issues press release on withdrawal of ITC complaint
2026-09-23 Complaint for Declaratory Judgment filed

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 9,130,074 - "High-Efficiency Solar Cell Structures and Methods of Manufacture"

The Invention Explained

  • Problem Addressed: The patent background describes the challenge of manufacturing highly efficient solar cells (e.g., 20% or more) in a cost-effective, high-volume manner, noting that known methods often suffer from structural and manufacturing complexity, which limits their economic viability ’074 Patent, col. 1:32-42
  • The Patented Solution: The invention proposes a streamlined manufacturing method where an amorphous, silicon-containing compound with a dopant is deposited over a passivation layer on a silicon wafer. A subsequent high-temperature thermal treatment (about 500° C or higher) is used to achieve multiple objectives simultaneously: it crystallizes the deposited layer, activates the dopants, and facilitates the diffusion of those dopants through the passivation layer into the wafer to form a junction ’074 Patent, claim 1 ’074 Patent, col. 16:15-21 This multi-purpose thermal step is designed to simplify the production process ’074 Patent, abstract
  • Technical Importance: By combining layer crystallization, dopant activation, and junction formation into a single thermal treatment step, the method aims to reduce the complexity and cost of producing advanced passivated contact solar cells.

Key Claims at a Glance

  • The complaint asserts non-infringement of independent claim 1 and dependent claims 2-8 Compl. ¶¶31-32
  • Independent Claim 1 of the ’074 Patent includes the essential elements of:
    • Providing a wafer as a central substrate.
    • Depositing or growing at least one amorphous interface passivation layer over the substrate.
    • Depositing at least one conductive and passivating layer (comprising a dopant) on the interface passivation layer.
    • Providing a thermal treatment at about 500° C or higher, which crystallizes the conductive/passivating layer and facilitates diffusion of the dopant through the interface passivation layer.
    • Providing metallization as electrodes that directly contact the conductive/passivating layer after the thermal treatment.
    • Wherein the diffused dopant provides shortened charge carrier flow paths between the substrate and electrodes.

U.S. Patent No. 9,666,732 - "High-Efficiency Solar Cell Structures and Methods of Manufacture"

The Invention Explained

  • Problem Addressed: As a divisional of the ’074 Patent, the ’732 Patent addresses the same problem of reducing manufacturing complexity for high-efficiency solar cells ’732 Patent, col. 1:35-42
  • The Patented Solution: This invention discloses a method where a single "amorphous silicon-containing compound" that includes both an oxygen dopant and a conductive dopant is deposited on the substrate. A thermal treatment then causes the oxygen dopant to diffuse into the substrate's surface to form an oxide layer (which becomes the "interface passivation layer"). The remaining amorphous compound above this newly formed oxide layer defines the "passivating film" ’732 Patent, claim 1 This process effectively forms two distinct layers from a single deposited precursor material in one thermal step ’732 Patent, col. 16:40-50
  • Technical Importance: This "in-situ" formation of a passivating oxide layer from a single deposited material offers a potentially even more integrated and simplified manufacturing process for passivated contact solar cells.

Key Claims at a Glance

  • The complaint asserts non-infringement of independent claim 1 and dependent claims 2-9 Compl. ¶¶38-39
  • Independent Claim 1 of the ’732 Patent includes the essential elements of:
    • Providing an interface passivation layer and a passivating film over it, where the film comprises a passivating material and a conductive dopant.
    • This is achieved by providing an "amorphous silicon-containing compound" (containing oxygen and conductive dopants) over the substrate's upper surface.
    • Thermally treating this compound to diffuse the oxygen dopant into the substrate surface to form an oxide layer (the interface passivation layer).
    • Wherein the remaining amorphous silicon-containing compound above the oxide layer defines the passivating film.
    • Providing at least one electrode over the passivating film, where the conductive dopant provides a direct electrical connection to the substrate.

III. The Accused Instrumentality

Product Identification

The accused instrumentalities are "TOYO’s TOPCon solar cells and modules" Compl. ¶2, including products from the "Vesta N and TYMN lines" Compl. ¶26 and specific modules such as "VSUN590N-144BMH-DG" Compl. ¶19

Functionality and Market Context

The complaint describes TOYO as a provider of "full-service solar solutions" that manufactures TOPCon solar cells and modules for the U.S. market in facilities in Ethiopia and Texas Compl. ¶21 The accused products are part of the high-efficiency solar technology segment, which is critical for the global energy market.
No probative visual evidence provided in complaint.

IV. Analysis of Infringement Allegations

The complaint for declaratory judgment alleges that TOYO's manufacturing processes for its TOPCon products do not perform certain steps required by the asserted claims.

’074 Patent Infringement Allegations

Claim Element (from Independent Claim 1) Plaintiff's Basis for Non-Infringement Complaint Citation Patent Citation
depositing at least one conductive and passivating layer on the at least one interface passivation layer, the at least one conductive and passivating layer comprising a dopant The complaint alleges that TOYO does not perform this step. ¶31 col. 16:30-31
providing thermal treatment at a temperature of about 500° C. or higher, the thermal treatment crystallizing, at least in part, the at least one conductive and passivating layer and facilitating diffusion of the dopant from the at least one conductive and passivating layer through the at least one interface passivation layer The complaint alleges that TOYO does not perform this step. ¶31 col. 16:25-28
providing metallization as electrodes which directly contact the at least one conductive and passivating layer following the thermal treatment thereof The complaint alleges that TOYO does not perform this step. ¶31 col. 16:36-39
wherein the dopant diffused through the at least one interface passivation layer provides shortened charge carrier flow paths between the substrate and the electrodes through the at least one conductive and passivating layer and the at least one interface passivation layer The complaint alleges that TOYO does not achieve this result. ¶31 col. 4:4-15

’732 Patent Infringement Allegations

Claim Element (from Independent Claim 1) Plaintiff's Basis for Non-Infringement Complaint Citation Patent Citation
providing a passivating film over the interface passivation layer, the passivating film comprising a passivating material and a conductive dopant The complaint alleges that TOYO does not perform this step. ¶38 col. 16:40-43
providing an amorphous silicon-containing compound over an upper surface of the substrate, the compound comprising oxygen dopant and the conductive dopant The complaint alleges that TOYO does not perform this step. ¶38 col. 16:40-43
thermally treating the amorphous silicon-containing compound to diffuse the oxygen dopant, at least in part, into the upper surface of the substrate to form an oxide layer over the substrate, the oxide layer defining the interface passivation layer The complaint alleges that TOYO does not perform this step. ¶38 col. 16:43-46
wherein remaining amorphous silicon-containing compound above the oxide layer defines the passivating film The complaint alleges that TOYO does not perform this step. ¶38 col. 16:46-48
providing at least one electrode over the passivating film, wherein the conductive dopant within the passivating film and throughout the interface passivation layer provides direct electrical connection between the at least one electrode and the substrate The complaint alleges that TOYO does not perform this step. ¶38 col. 16:36-39
  • Identified Points of Contention:
    • Factual Dispute over Process Steps: The core of the dispute, as framed by the complaint, is entirely factual. The complaint makes a series of negative allegations, stating that TOYO's manufacturing process simply does not include the specific deposition, thermal treatment, and metallization steps recited in the claims Compl. ¶31 Compl. ¶38 The case will turn on evidence establishing the precise nature of TOYO's manufacturing methods.
    • Technical Questions on Layer Formation: For the '732 patent, a key question is whether TOYO's process involves the in-situ formation of an oxide layer by diffusing oxygen out of a precursor compound, as claimed. For the '074 patent, a central question is whether TOYO's thermal treatment performs the dual functions of crystallization and dopant diffusion through a separate passivation layer.

V. Key Claim Terms for Construction

The complaint does not provide sufficient detail to identify specific claim construction disputes, as it focuses on factual non-infringement. However, based on the technology, certain terms may become central to the dispute.

  • The Term: "crystallizing...and facilitating diffusion" (from ’074 Patent, claim 1)

  • Context and Importance: This phrase links two distinct physical phenomena to a single thermal treatment step. Practitioners may focus on this term because the infringement analysis will likely depend on whether TOYO's process, if it includes a thermal treatment, is proven to cause both the crystallization of one layer and the diffusion of a dopant from it through another layer, as required by the claim's conjunctive "and."

  • Intrinsic Evidence for Interpretation:

    • Evidence for a Broader Interpretation: The specification discusses crystallization and diffusion as potential outcomes of thermal treatment more generally, which could support an argument that any process where both occur is covered ’074 Patent, col. 16:5-21
    • Evidence for a Narrower Interpretation: The claim language explicitly ties both outcomes to the same thermal treatment step, suggesting a specific, integrated process. The specification describes this as a key benefit, where the treatment "drives the dopants" while also "crystalliz[ing]" the layer, potentially supporting a narrower view that the two effects must be simultaneous and causally linked by the single treatment ’074 Patent, col. 17:9-12

  • The Term: "amorphous silicon-containing compound" (from ’732 Patent, claim 1)

  • Context and Importance: The definition of this precursor material is critical because claim 1 requires it to contain both "oxygen dopant and the conductive dopant," which are then used to form two different parts of the final cell structure. The dispute may turn on whether the material TOYO uses for deposition meets this specific compositional definition.

  • Intrinsic Evidence for Interpretation:

    • Evidence for a Broader Interpretation: The term itself is general, and the specification lists various materials that can be used in solar cell layers, potentially supporting a broader reading of what constitutes a "silicon-containing compound."
    • Evidence for a Narrower Interpretation: The claim explicitly requires the compound to comprise "oxygen dopant and the conductive dopant" (’732 Patent, claim 1). The specification further explains that this allows a single deposited layer to "split into two (or more) layers" upon thermal treatment, with oxygen migrating to form an oxide layer ’732 Patent, col. 16:40-46 This specific functional context suggests the term refers to a specially formulated precursor designed for this in-situ layer separation.

VI. Other Allegations

  • Indirect Infringement: The complaint seeks a declaratory judgment of non-infringement "directly or indirectly" Compl. ¶35 Compl. ¶42 It notes that First Solar’s prior ITC complaint alleged both direct infringement and inducement Compl. ¶2, but provides no specific factual allegations from First Solar that would form the basis of an indirect infringement claim in this case.
  • Willful Infringement: Willful infringement is not at issue in this complaint for declaratory judgment.

VII. Analyst’s Conclusion: Key Questions for the Case

This declaratory judgment action positions the dispute as a factual contest over manufacturing processes, raising several key questions for the court.

  • A central issue will be one of evidentiary proof: Can TOYO demonstrate, through technical evidence of its manufacturing lines, that its process for making TOPCon solar cells omits the specific, multi-step deposition and thermal treatment sequences required by claim 1 of the ’074 and ’732 patents?
  • A key technical question will be one of process functionality: For the ’732 patent, does TOYO’s process rely on the claimed "in-situ" mechanism of diffusing oxygen from a single deposited precursor to form a separate oxide passivation layer? For the ’074 patent, does TOYO’s thermal process perform the claimed dual function of simultaneously crystallizing a layer and driving dopant diffusion from it through an underlying passivation layer?
  • A secondary question may relate to definitional scope: If TOYO's process is found to be similar to the claimed methods, the focus may shift to claim construction, particularly whether materials used by TOYO fall within the scope of terms like "amorphous silicon-containing compound" as defined and used in the context of the ’732 patent’s specific layer-splitting mechanism.