DCT

1:23-cv-00333

Greenthread LLC v. Micron Technology Inc

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:23-cv-00333, D. Del., 03/24/2023
  • Venue Allegations: Venue is asserted based on Defendants being incorporated and registered as citizens and residents of Delaware.
  • Core Dispute: Plaintiff alleges that Defendant’s semiconductor memory products, including certain DRAM and NAND flash devices, infringe six patents related to the use of graded dopant regions to improve device performance.
  • Technical Context: The technology concerns fabricating semiconductor structures with non-uniform dopant concentrations to create internal electric fields that aid or control the movement of charge carriers, thereby improving device speed, efficiency, and scalability.
  • Key Procedural History: The complaint alleges that claim terms central to the asserted patents have been construed in Plaintiff’s favor in prior litigations against other defendants in the Eastern District of Texas, the Western District of Texas, and the District of Oregon.

Case Timeline

Date Event
2004-09-03 Priority Date for all six asserted patents
2013-04-16 U.S. Patent No. 8,421,195 Issues
2015-04-27 Inventor Dr. Rao assigns patents to Greenthread
2015-08-10 Alleged first notice of infringement to Micron
2015-11-17 U.S. Patent No. 9,190,502 Issues
2019-12-17 U.S. Patent No. 10,510,842 Issues
2020-08-04 U.S. Patent No. 10,734,481 Issues
2021-09-14 U.S. Patent No. 11,121,222 Issues
2022-04-26 U.S. Patent No. 11,316,014 Issues
2022-04-29 Date after which Micron allegedly received further notice
2023-01-27 Alleged further notice via complaint in Greenthread v. Intel
2023-03-24 Complaint Filed

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

U.S. Patent No. 8,421,195 - Semiconductor Devices with Graded Dopant Regions

The Invention Explained

  • Problem Addressed: The patent describes performance limitations in conventional semiconductor devices that use uniformly doped regions. For example, spurious minority charge carriers generated during clock switching can degrade performance in memory devices like DRAMs by causing unwanted discharge of storage nodes, which reduces data retention ("refresh") time (’195 Patent, col. 1:49-67).
  • The Patented Solution: The invention introduces a "graded" (i.e., non-uniform) concentration of dopants within the semiconductor substrate. This gradient creates a built-in electric "drift field" designed to sweep unwanted minority carriers away from the sensitive active surface regions and deep into the substrate, where they can be harmlessly recombined (’195 Patent, col. 4:1-12). This is illustrated in Figure 5(b), which depicts a "Graded dopant region to pull minority carriers from surface."
  • Technical Importance: This technique of actively managing stray charge carriers using built-in fields was aimed at improving the performance and reliability of high-density integrated circuits, allowing for faster and more efficient operation (’195 Patent, Abstract).

Key Claims at a Glance

  • The complaint asserts infringement of at least one claim without specifying which one (Compl. ¶45). The first independent claim is Claim 1.
  • Essential elements of Claim 1 include:
    • A surface layer, a substrate, and an active region (with a source and drain).
    • A "single drift layer" between the surface layer and substrate with a "graded concentration of dopants" that creates a "first static unidirectional electric drift field" to move minority carriers from the surface layer to the substrate.
    • At least one "well region" within the drift layer, also having a graded concentration of dopants creating a "second static unidirectional electric drift field" for the same purpose.
  • The complaint reserves the right to assert other claims (Compl. ¶41).

U.S. Patent No. 9,190,502 - Semiconductor Devices with Graded Dopant Regions

The Invention Explained

  • Problem Addressed: The patent addresses the same technical challenge as the ’195 Patent: performance degradation in semiconductor devices due to the effects of unwanted charge carriers and the limitations of uniform doping profiles (’502 Patent, col. 1:22-42).
  • The Patented Solution: The solution is also the creation of a graded dopant profile to generate a drift field. However, the claims of this patent frame the solution slightly differently, focusing on moving carriers from the substrate to the surface layer (’502 Patent, col. 4:18-35). This architecture is useful for applications like improving programming time in nonvolatile memory, where carriers must be accelerated toward the surface (’502 Patent, col. 3:13-19; Fig. 5C).
  • Technical Importance: This variation on the graded dopant concept addresses a different but related set of performance bottlenecks in other types of semiconductor devices, particularly flash memory (’502 Patent, Abstract).

Key Claims at a Glance

  • The complaint asserts infringement of at least one claim (Compl. ¶51). The first independent claim is Claim 1.
  • Essential elements of Claim 1 include:
    • A surface layer, a substrate, and an active region (with a source and drain).
    • A "single drift layer" with a "graded concentration of dopants" creating a "first static unidirectional electric drift field" to aid movement of minority carriers from the substrate to the surface layer.
    • At least one "well region" within the drift layer, also having a graded concentration of dopants creating a "second static unidirectional electric drift field" for the same purpose (moving carriers from substrate to surface).
  • The complaint reserves the right to assert other claims (Compl. ¶48).

U.S. Patent No. 10,510,842 - Semiconductor Devices with Graded Dopant Regions

  • Technology Synopsis: Continuing the same inventive theme, this patent claims a semiconductor device with a substrate and multiple active regions. The key feature is that at least a portion of the active regions has a "graded dopant concentration" to aid carrier movement from the device surface to the substrate (’842 Patent, Abstract; col. 4:45-60). This structure is described as enhancing performance in applications like VLSI logic, DRAM, and image sensors (’842 Patent, col. 3:44-56).
  • Asserted Claims: At least one claim is asserted; independent claims include 1 and 9 (Compl. ¶57).
  • Accused Features: The accused features are Micron's semiconductor devices alleged to contain regions with graded dopant concentrations (Compl. ¶30).

U.S. Patent No. 10,734,481 - Semiconductor Devices with Graded Dopant Regions

  • Technology Synopsis: This patent claims a device with multiple active regions and at least one adjacent well region. Both the active regions and the well region contain a "graded dopant region" designed to aid carrier movement from the surface to the second surface (i.e., deep into the substrate), improving performance (’481 Patent, col. 4:56-col. 5:3).
  • Asserted Claims: At least one claim is asserted; independent claims include 1 and 20 (Compl. ¶63).
  • Accused Features: The accused features are Micron's semiconductor devices alleged to contain regions with graded dopant concentrations (Compl. ¶30).

U.S. Patent No. 11,121,222 - Semiconductor Devices with Graded Dopant Regions

  • Technology Synopsis: This patent claims a VLSI (Very Large Scale Integration) semiconductor device for digital logic. It requires a graded dopant region to aid carrier movement from the active surface regions "towards an area of the substrate where there are no active regions," thereby mitigating the effects of spurious carriers in complex logic circuits (’222 Patent, Abstract; col. 4:36-54).
  • Asserted Claims: At least one claim is asserted; independent claims include 1, 21, 39, 41, 42, 43, and 44 (Compl. ¶69).
  • Accused Features: The accused features are Micron's semiconductor devices alleged to contain regions with graded dopant concentrations (Compl. ¶30).

U.S. Patent No. 11,316,014 - Semiconductor Devices with Graded Dopant Regions

  • Technology Synopsis: This patent claims an "electronic system" that includes a semiconductor device. The claimed device requires a graded dopant region in a well to move carriers toward a non-active area of the substrate, with the additional limitation that the graded concentration can be "linear, quasilinear, error function, complementary error function, or any combination thereof" (’014 Patent, col. 6:21-41).
  • Asserted Claims: At least one claim is asserted; independent claims include 1 and 21 (Compl. ¶75).
  • Accused Features: The accused features are Micron's semiconductor devices, and the electronic systems incorporating them, alleged to contain regions with graded dopant concentrations (Compl. ¶30).

III. The Accused Instrumentality

Product Identification

  • The complaint identifies the "Micron Accused Products" as a category including flash memory products ("Accused Flash Products") and DRAM products ("Accused DRAM Products") (Compl. ¶9). Specific exemplary products identified are "Micron 16 nm node NAND flash memory" and "20 nm node Micron MT58K256M32JA-100:A GDDR5X DRAM" (Compl. ¶¶33-34).

Functionality and Market Context

  • The complaint alleges that Micron designs and fabricates these memory products using processes that create "regions with graded dopant concentrations" (Compl. ¶¶36-37). The complaint incorporates by reference an "Exhibit 8," which allegedly contains claim charts demonstrating infringement, but this exhibit was not filed with the complaint (Compl. ¶10, ¶35). The complaint includes a visual of a one-megabit DRAM display from the Smithsonian, crediting the inventor Dr. Rao, to provide historical context for his pioneering work in memory technology (Compl. p. 8). No specific allegations regarding the commercial importance of the accused products are made, beyond their identification as widely used memory types.

IV. Analysis of Infringement Allegations

The complaint does not contain claim charts in the body of the document, instead incorporating by reference an external "Exhibit 8" that was not publicly filed (Compl. ¶10). The infringement allegations in the complaint are therefore conclusory. The following tables summarize the core of the infringement theory for the lead patents by mapping the central claim limitations to the general allegations made in the complaint.

U.S. Patent No. 8,421,195 Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
a single drift layer... having a graded concentration of dopants extending between said surface layer and said substrate, said drift layer further having a first static unidirectional electric drift field... Micron's DRAM and NAND flash products allegedly utilize "regions with graded dopant concentrations." ¶36, ¶37 col. 4:18-26
at least one well region disposed in said single drift layer, said well region having a graded concentration of dopants and a second static unidirectional electric drift field to aid the movement of minority carriers from said surface layer to said substrate. The complaint alleges that exemplary accused products meet "each and every one of the claim limitations," which would include the well region with graded dopants, but provides no specific facts. ¶33, ¶34, ¶43 col. 4:27-33

U.S. Patent No. 9,190,502 Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
a single drift layer... having a graded concentration of dopants generating a first static unidirectional electric drift field to aid the movement of minority carriers from said substrate to said surface layer... Micron's DRAM and NAND flash products allegedly utilize "regions with graded dopant concentrations." ¶36, ¶37 col. 4:21-28
at least one well region disposed in said single drift layer, said well region having a graded concentration of dopants generating a second static unidirectional electric drift field to aid the movement of minority carriers from said substrate to said surface layer. The complaint alleges that exemplary accused products meet "each and every one of the claim limitations," which would include the well region with graded dopants, but provides no specific facts. ¶33, ¶34, ¶49 col. 4:29-35

Identified Points of Contention

  • Scope Questions: The central dispute will likely involve claim construction. A primary question for the court will be how to define "graded concentration of dopants." Does this term cover any non-uniform doping profile, or is it limited to specific profiles (e.g., linear, exponential) that achieve the functions described in the specification? Similarly, the construction of "static unidirectional electric drift field" will be critical, raising the question of what level of proof is required to show the existence and properties of such a field in an accused device.
  • Technical Questions: The complaint's infringement allegations rely on "information and belief" and the missing Exhibit 8 (Compl. ¶¶36-37). A key factual question will be whether discovery and reverse engineering of Micron’s products reveal the specific structures recited in the claims. Does the manufacturing process for a "16 nm node NAND flash" or "20 nm node...DRAM" inherently create the claimed graded dopant profiles and resulting electric fields, or is there a technical mismatch?

V. Key Claim Terms for Construction

"graded concentration of dopants"

  • Context and Importance: This term is the technological core of all asserted patents. Its scope will be determinative of infringement. Practitioners may focus on this term because the plaintiff will likely advocate for a broad definition covering many types of non-uniform doping, while the defendant will likely argue for a narrower definition tied to the specific embodiments and purposes disclosed in the patent.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specification states the gradient "can be linear, quasi linear, exponential or complimentary error function," suggesting the term is not limited to a single type of profile (’195 Patent, col. 3:1-3).
    • Evidence for a Narrower Interpretation: The specification consistently links the graded dopant region to a specific purpose, such as creating an "aiding drift field" to "sweep" or "pull" carriers in a particular direction (’195 Patent, col. 3:3-5, col. 4:9-12; Fig. 5B). A party could argue the term is limited to gradients that are intentionally designed and structured to perform this specific function.

"static unidirectional electric drift field"

  • Context and Importance: This term defines the required functional result of the "graded concentration." Infringement requires proving not just the physical structure but also the existence of this specific field. The dispute will be over what "static" and "unidirectional" mean in the context of a complex, operating semiconductor device.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The patents describe the field's purpose as to "aid the movement" of carriers, which could be interpreted to mean any field that provides a net directional bias, even if it has minor fluctuations or non-uniformities (’195 Patent, col. 4:24-26).
    • Evidence for a Narrower Interpretation: A party could argue that "static" implies the field must be persistent and substantially constant during the device's relevant operational state, not transient. "Unidirectional" could be argued to require a consistently oriented field vector throughout the claimed region, precluding fields that are multi-directional or swirling.

VI. Other Allegations

Indirect Infringement

  • The complaint includes boilerplate language regarding Defendants placing products into the stream of commerce with "awareness, knowledge, and intent" (Compl. ¶7). However, it does not plead a separate count for indirect infringement or allege specific facts, such as inducement through user manuals, that would typically support such a claim.

Willful Infringement

  • The complaint makes detailed allegations of willful infringement based on alleged pre-suit knowledge. It asserts that Micron was first informed its products infringed on August 10, 2015 (Compl. ¶38). It further alleges that Micron was repeatedly made aware of its infringement through Greenthread's litigation against Dell and Intel, including via a third-party subpoena and access to infringement contentions against Micron products sold to those parties, with specific events cited after April 29, 2022, and on January 27, 2023 (Compl. ¶¶38-39).

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

  • A central issue will be one of claim construction: how will the court define the foundational term "graded concentration of dopants" and the functional requirement for a "static unidirectional electric drift field"? The resolution of these terms will govern the scope of all six patents and likely be dispositive on the question of infringement.
  • A second key issue will be evidentiary: can Greenthread, through discovery and expert analysis, demonstrate that Micron's highly complex, nanometer-scale devices actually contain the specific physical structures and resulting electrical fields required by the claims as construed by the court? The complaint's reliance on "information and belief" and an unfiled exhibit places the entire burden of proof on evidence to be developed during litigation.
  • Finally, a major question will concern willfulness: given the extensive litigation history of this patent family and the specific, dated instances of notice alleged in the complaint, the court will have to determine whether Micron’s continued activities, if found to be infringing, rise to the level of egregious conduct necessary to justify an award of enhanced damages.