DCT

2:10-cv-00314

Fox Group Inc v. Cree Inc

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 2:10-cv-00314, E.D. Va., 06/29/2010
  • Venue Allegations: Venue is alleged to be proper in the Eastern District of Virginia because Defendant Cree acquired IntrinSiC Semiconductor Corporation, located in Dulles, Virginia, and maintained a regular and established place of business in the district. The complaint also alleges that Cree has committed acts of infringement and has customers within the judicial district.
  • Core Dispute: Plaintiff alleges that Defendants’ silicon carbide substrates and related semiconductor products infringe two patents directed to methods and materials for manufacturing high-quality, low-defect-density silicon carbide crystals.
  • Technical Context: Silicon carbide (SiC) is a wide-bandgap semiconductor material critical for high-power, high-frequency, and high-temperature electronic devices, where the reduction of crystalline defects is essential for performance and reliability.
  • Key Procedural History: The complaint notes that Defendant Dow Corning filed a declaratory judgment action regarding the same patents-in-suit in the Southern District of New York on April 21, 2010. Plaintiff also alleges providing pre-suit notice of infringement to Dow Corning on February 23, 2007, and to Cree on April 18, 2007, which forms the basis of its willfulness claims.

Case Timeline

Date Event
1997-01-22 ’130 Patent Priority Date
2000-02-15 ’026 Patent Priority Date
2003-03-18 ’026 Patent Issue Date
2003-05-13 ’130 Patent Issue Date
2006 Cree acquires IntrinSiC Semiconductor Corp.
2007-02-23 Plaintiff gives notice of infringement to Dow Corning
2007-04-18 Plaintiff gives notice of infringement to Cree
2009-09-15 Dow Corning announces "state-of-the-art defect densities"
2010-04-21 Dow Corning files declaratory judgment action in S.D.N.Y.
2010-06-29 Complaint Filing Date

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

U.S. Patent No. 6,534,026 - “Low Defect Density Silicon Carbide,” issued March 18, 2003

The Invention Explained

  • Problem Addressed: The patent’s background section states that conventional silicon carbide (SiC) crystal growth techniques produced material with high densities of dislocations and micropipes, which limited the material's utility for many semiconductor applications ('026 Patent, col. 1:32-51). Existing high-quality SiC material was still considered "at least an order of magnitude too high" in defect density for certain uses ('026 Patent, col. 1:47-51).
  • The Patented Solution: The invention proposes a two-stage sublimation growth method to create a bulk SiC crystal with lower defect density ('026 Patent, Abstract). In the first stage, the crystal grows both axially (in length) and laterally (in diameter). The patent teaches that defect propagation is substantially reduced in the laterally grown portion ('026 Patent, col. 2:19-22; Fig. 1). In the second stage, lateral growth is suppressed while axial growth continues, propagating the low-defect crystal structure established in the first stage’s lateral region ('026 Patent, col. 2:22-29).
  • Technical Importance: This method provided a pathway to create larger-diameter bulk SiC crystals with significantly improved crystalline quality, addressing a key manufacturing bottleneck for advanced semiconductor devices.

Key Claims at a Glance

  • The complaint asserts at least independent claim 1 (Compl. ¶¶ 25, 30).
  • Claim 1 recites a silicon carbide material comprising three key components:
    • A single crystal SiC seed crystal with a first defect density.
    • An "axial region" of re-crystallized SiC grown from the seed, having a second defect density.
    • A "lateral region" of re-crystallized SiC grown from the seed, having a third defect density that is less than the first and second defect densities, and specifically less than 10⁴ defects per square centimeter.

U.S. Patent No. 6,562,130 - “Low Defect Axially Grown Single Crystal Silicon Carbide,” issued May 13, 2003

The Invention Explained

  • Problem Addressed: The patent identifies several issues with prior art sublimation growth, including the depletion of silicon from the vapor phase, which leads to carbon-rich conditions, source graphitization, and crystal defects ('130 Patent, col. 1:43-56). It also notes that using tantalum crucibles could lead to contamination and the formation of low-melting-point alloys that destroy the container ('130 Patent, col. 2:36-56).
  • The Patented Solution: The invention is a method and apparatus for growing SiC that uses a specially treated crucible made of tantalum or niobium. The crucible's inner surfaces are processed to form a refractory, depth-variable composition (e.g., Ta-Si-C) that does not absorb SiC vapors during growth ('130 Patent, Abstract; col. 3:36-49). This allows the process to maintain a stable, silicon-rich vapor composition, which is necessary to grow high-quality, low-defect crystals ('130 Patent, col. 3:44-53).
  • Technical Importance: By controlling the chemical interactions between the vapor and the crucible, this invention provided a more stable and controlled environment for SiC crystal growth, enabling the production of material with higher purity and fewer structural defects.

Key Claims at a Glance

  • The complaint asserts at least independent claim 1 (Compl. ¶¶ 38, 43).
  • Claim 1 recites a silicon carbide material comprising an axial region of re-crystallized single crystal SiC with specific quantitative defect limits:
    • A density of dislocations of less than 10⁴ per square centimeter.
    • A density of micropipes of less than 10 per square centimeter.
    • A density of secondary phase inclusions of less than 10 per cubic centimeter.

III. The Accused Instrumentality

Product Identification

The accused instrumentalities are silicon carbide substrates, silicon carbide wafers, and products incorporating them, such as Schottky diodes, metal semiconductor field effect transistors (MESFETs), high electron mobility transistors (HEMTs), and light emitting diodes (LEDs), that are manufactured, used, and sold by Defendants Cree and Dow Corning (Compl. ¶¶ 11, 15, 21, 34).

Functionality and Market Context

The complaint characterizes the accused products as "high-quality" and "state-of-the-art" SiC wafers with low defect densities (Compl. ¶¶ 13, 16). Specifically, the complaint cites a 2009 press release in which Dow Corning announced it was producing wafers with "state-of-the-art defect densities" and had "significantly improved micropipe densities, to about 10 such defects per square centimeter of material" (Compl. ¶¶ 16-17). These products are fundamental components for the power electronics and solid-state lighting industries.

No probative visual evidence provided in complaint.

IV. Analysis of Infringement Allegations

The complaint references claim chart exhibits that were not included with the filing. The infringement theories are therefore summarized from the complaint’s narrative allegations.

’026 Patent Infringement Allegations

The complaint alleges that Cree and Dow Corning infringe one or more claims of the ’026 patent, including at least claim 1, by making, using, and selling SiC substrates and wafers (Compl. ¶¶ 21, 25, 26, 30). The implicit theory is that the defendants' manufacturing processes for creating "low defect density" SiC result in a material that has the claimed structure of a central axial region and a surrounding lateral region with a lower defect density, as recited in claim 1.

’130 Patent Infringement Allegations

The complaint alleges that the defendants' SiC products infringe one or more claims of the ’130 patent, including at least claim 1 (Compl. ¶¶ 34, 38, 39, 43). The infringement theory is that the accused SiC substrates and wafers are materials that possess the specific, quantitative defect characteristics recited in claim 1. The complaint points to a Dow Corning press release claiming micropipe densities of "about 10... per square centimeter" as evidence that its products meet at least one of the claimed defect thresholds (Compl. ¶17).

Identified Points of Contention

  • Scope & Technical Questions (’026 Patent): A primary question will be whether the defendants' commercial SiC wafers can be shown to possess the specific "axial region" and "lateral region" structure required by claim 1. The infringement analysis may turn on whether these regions, which are defined by the growth process, remain physically distinct and identifiable in the final, processed wafer.
  • Technical Questions (’130 Patent): The dispute may focus on evidentiary proof and measurement methodology. While the complaint provides a public statement from Dow Corning regarding micropipe density, discovery will be required to determine if the accused products meet all three quantitative limitations of claim 1 (dislocations, micropipes, and secondary phase inclusions). The lack of a specified measurement protocol in the patent for determining these densities could become a point of contention, with parties potentially disputing the appropriate characterization techniques.

V. Key Claim Terms for Construction

Term: "lateral region" (’026 Patent, Claim 1)

  • Context and Importance: The existence of a distinct "lateral region" with lower defect density is the core of the asserted claim’s structure. The construction of this term will be critical to determining infringement, as it defines the physical characteristic Plaintiff must prove is present in the accused products.
  • Intrinsic Evidence for a Broader Interpretation: The specification describes a first stage of growth where the crystal "simultaneously expand[s] laterally" ('026 Patent, col. 2:15-16). This could support an argument that any portion of the crystal formed by diametrical expansion constitutes the "lateral region."
  • Intrinsic Evidence for a Narrower Interpretation: Figure 1 depicts the lateral region (103) as structurally distinct from the axial core region (101). The specification also ties the first growth stage to a specific ratio of lateral-to-axial growth rate ('026 Patent, col. 2:15-17). This may support a narrower construction requiring a physically identifiable region formed under specific process conditions.

Term: "density of dislocations" (’130 Patent, Claim 1)

  • Context and Importance: This is one of the three quantitative limitations defining the patented material. The method used to measure this density will be dispositive for infringement. Practitioners may focus on this term because different measurement techniques can yield different results, and the patent does not prescribe a specific protocol.
  • Intrinsic Evidence for Interpretation: The patent does not define "density of dislocations" or provide a measurement method. The specification speaks of achieving dislocation densities of less than 10⁴, 10³, and 10² per square centimeter, framing the invention in terms of order-of-magnitude improvements common in the field ('130 Patent, col. 7:40-41, 8:4-6). The parties will likely rely on extrinsic evidence, such as industry standards and expert testimony on accepted characterization methods (e.g., etch pit density analysis, X-ray topography) at the time of the invention, to argue for a particular construction or testing protocol.

VI. Other Allegations

Indirect Infringement

The complaint does not plead separate counts for indirect infringement. The allegations are centered on direct infringement by the defendants for making, using, and selling the accused SiC materials (Compl. ¶¶ 21, 26, 34, 39).

Willful Infringement

The complaint explicitly alleges willful infringement against both defendants. The basis for this allegation is the claim that both Cree and Dow Corning received actual notice of infringement on April 18, 2007, and February 23, 2007, respectively, and continued their allegedly infringing activities thereafter (Compl. ¶¶ 24, 29, 37, 42).

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

  • A central issue for the ’026 patent will be one of structural evidence: Can the plaintiff prove, through discovery and materials analysis, that the defendants’ commercially sold SiC wafers contain the distinct "axial" and "lateral" growth regions as claimed, or will the defense successfully argue that the final product is a homogenous material lacking such identifiable structures?
  • A key question for the ’130 patent will be one of quantitative verification: The dispute will likely focus on whether the accused products meet all three numerical defect density limits of claim 1. This raises a critical sub-issue regarding the method of measurement: Lacking a prescribed test in the patent, the case may turn on a battle of experts to define the appropriate industry-standard protocol for counting dislocations, micropipes, and secondary phase inclusions.
  • Finally, a threshold issue is the procedural conflict arising from Dow Corning’s prior-filed declaratory judgment action in another district. How the courts resolve the competing lawsuits through transfer, dismissal, or consolidation will significantly shape the venue, timing, and strategic landscape of the litigation.