DCT

2:23-cv-00179

Greenthread LLC v. OSRAM GmbH Pursuant To Court Order Docket In Lead Case 2 23cv212

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 2:23-cv-00179, E.D. Tex., 04/19/2023
  • Venue Allegations: Venue is alleged to be proper in the Eastern District of Texas because Defendant ams Sensors USA Inc. maintains its principal place of business in Plano, Texas, and because the Defendants collectively have a regular and established place of business in the district.
  • Core Dispute: Plaintiff alleges that Defendant’s semiconductor devices, including Time-of-Flight sensors, infringe six patents related to using graded dopant regions to improve the performance and efficiency of integrated circuits.
  • Technical Context: The technology concerns the fundamental structure of semiconductor devices, proposing specific modifications to dopant concentrations to better control the flow of electrical charge carriers, thereby improving the speed, power efficiency, and signal quality of components used in a wide array of electronics.
  • Key Procedural History: The complaint alleges that claim constructions for the asserted patent family have been adopted in prior litigation involving other defendants (Samsung, Intel) in the Eastern District of Texas, the Western District of Texas, and the District of Oregon, which may streamline or influence claim construction proceedings in this case.

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 Plaintiff Greenthread
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
2023-04-19 Complaint Filed

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

U.S. Patent No. 8,421,195 - "Semiconductor Devices with Graded Dopant Regions", Issued April 16, 2013

The Invention Explained

  • Problem Addressed: The patent describes performance limitations in conventional semiconductor devices that use uniform dopant concentrations. In devices like Bipolar Junction Transistors (BJTs), this uniformity constrains operating frequency. In other integrated circuits like DRAMs and image sensors, "spurious minority carriers" (unwanted electrical charges) generated during operation can degrade performance, leading to reduced data retention time in memory or lower quality in image sensors (’195 Patent, col. 1:40-52; col. 2:10-26).
  • The Patented Solution: The invention proposes intentionally creating a non-uniform, or "graded," dopant concentration within specific regions of a semiconductor device, such as a "drift layer." This gradient establishes an internal electric field that helps to actively direct the flow of charge carriers. This field can be used to accelerate desired carriers to increase switching speed or to sweep unwanted "spurious" carriers away from sensitive areas and into the substrate, thereby improving device reliability and performance (’195 Patent, col. 4:56-62; Fig. 5B).
  • Technical Importance: This technique provides a method to improve key performance metrics in semiconductor devices by manipulating their fundamental physical structure, potentially offering an alternative to more complex and costly manufacturing process changes (’195 Patent, Abstract).

Key Claims at a Glance

  • The complaint asserts at least one claim of the '195 Patent (Compl. ¶49). Independent claim 1 is representative:
    • A CMOS Semiconductor device comprising:
    • a surface layer;
    • a substrate;
    • an active region including a source and a drain, disposed on one surface of said surface layer;
    • a single drift layer disposed between the other surface of said surface layer and said substrate, said 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 to aid the movement of minority carriers from said surface layer to said substrate; and
    • 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 reserves the right to assert additional claims (Compl. ¶47).

U.S. Patent No. 9,190,502 - "Semiconductor Devices with Graded Dopant Regions", Issued November 17, 2015

The Invention Explained

  • Problem Addressed: As a continuation in the same family, the '502 Patent addresses the same technical problems as the '195 Patent: performance bottlenecks in semiconductor devices caused by uniform doping, such as limited switching speeds and performance degradation from unwanted charge carriers (’502 Patent, col. 1:41-52; col. 2:16-25).
  • The Patented Solution: The solution is likewise the use of graded dopant regions to create built-in electric fields that manage charge carrier movement. The specification explains this can "accelerate majority carriers towards the drain" in MOS devices or, in imaging ICs, "sweep these unwanted minority carriers from the active circuitry at the surface into the substrate" to enhance pixel resolution and color sensitivity (’502 Patent, col. 4:8-9, col. 4:58-64).
  • Technical Importance: The invention provides a structural approach to simultaneously address issues of speed and noise that become more acute as semiconductor feature sizes continue to shrink (’502 Patent, Abstract).

Key Claims at a Glance

  • The complaint asserts at least one claim of the '502 Patent (Compl. ¶55). Independent claim 1 is representative:
    • A semiconductor device comprising:
    • a surface layer;
    • a substrate;
    • an active region including a source and a drain, disposed on one surface of said surface layer;
    • a single drift layer disposed between the other surface of said surface layer and said substrate, said 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; and
    • 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 reserves the right to assert additional claims (Compl. ¶54).

U.S. Patent No. 10,510,842 - "Semiconductor Devices with Graded Dopant Regions", Issued December 17, 2019

  • Technology Synopsis: This patent, also in the same family, discloses semiconductor devices with graded dopant concentrations in active regions or underlying layers. This gradient creates an electric field to control charge carrier movement, aiming to improve performance characteristics such as operating frequency, refresh time in DRAMs, and pixel resolution in image sensors (’842 Patent, Abstract; col. 4:44-55).
  • Asserted Claims: At least one claim, including independent claims 1 and 9 (Compl. ¶61).
  • Accused Features: The complaint alleges that the accused products contain infringing "regions with graded dopant concentrations" (Compl. ¶45).

U.S. Patent No. 10,734,481 - "Semiconductor Devices with Graded Dopant Regions", Issued August 4, 2020

  • Technology Synopsis: This patent continues the theme of using graded dopant regions to establish drift fields within a semiconductor device. These fields are designed to sweep unwanted minority carriers away from active surface circuitry into the substrate, thereby reducing electrical noise and improving the performance of devices like logic ICs and image sensors (’481 Patent, Abstract; col. 4:56-65).
  • Asserted Claims: At least one claim, including independent claims 1 and 20 (Compl. ¶67).
  • Accused Features: The complaint alleges that the accused products contain infringing "regions with graded dopant concentrations" (Compl. ¶45).

U.S. Patent No. 11,121,222 - "Semiconductor Devices with Graded Dopant Regions", Issued September 14, 2021

  • Technology Synopsis: This patent describes VLSI semiconductor devices containing graded dopant regions in or adjacent to active areas. The resulting electric fields are intended to aid carrier movement away from the surface to an area of the substrate without active regions, improving the performance of digital logic in the device (’222 Patent, Claim 1).
  • Asserted Claims: At least one claim, including independent claims 1, 21, 39, 41, 42, 43, and 44 (Compl. ¶73).
  • Accused Features: The complaint alleges that the accused products contain infringing "regions with graded dopant concentrations" (Compl. ¶45).

U.S. Patent No. 11,316,014 - "Semiconductor Devices with Graded Dopant Regions", Issued April 26, 2022

  • Technology Synopsis: This patent claims an electronic system that includes a semiconductor device with graded dopant regions. The graded regions are structured to create electric fields that direct charge carriers toward an area of the substrate where no active regions exist, with a specific focus on systems where the transistors form digital logic (’014 Patent, Claim 1).
  • Asserted Claims: At least one claim, including independent claims 1 and 21 (Compl. ¶79).
  • Accused Features: The complaint alleges that the accused products contain infringing "regions with graded dopant concentrations" (Compl. ¶45).

III. The Accused Instrumentality

Product Identification

The complaint names the "AMS-OSRAM Accused Products" as a broad category of semiconductor devices (Compl. ¶21). It specifically identifies the TMF8828 configurable 8x8 multi-zone Time-of-Flight Sensor as an exemplary accused product (Compl. ¶44).

Functionality and Market Context

  • The TMF8828 is a direct time-of-flight (dToF) sensor that uses single-photon avalanche diode (SPAD) technology to perform distance measurements up to 5000 mm (Compl., p. 7, Visual 1). The complaint includes a screenshot of the Defendant's product page for the TMF8828, which describes its technical features and on-chip data processing capabilities (Compl., p. 7, Visual 1).
  • The complaint alleges that these products are sold in the United States through authorized distributors, such as the Texas-based "Channel Partner" Mouser Electronics (Compl. ¶19, ¶44). The complaint provides a screenshot of a pop-up window on Defendant's website directing customers to distributors including Mouser and Digi-Key for purchase (Compl., p. 7, Visual 2).

IV. Analysis of Infringement Allegations

The complaint alleges that the accused products, exemplified by the TMF8828, meet every element of at least one claim of each of the Greenthread Patents (Compl. ¶¶ 49, 55, 61, 67, 73, 79). The complaint states that this infringement is "shown in Exhibit 8" (Compl. ¶44). However, this exhibit was not filed with the complaint document, and therefore a detailed, element-by-element infringement analysis based on the provided filings is not possible.

The narrative infringement theory is that the accused products are semiconductor devices that are fabricated using "regions with graded dopant concentrations" (Compl. ¶45). The complaint alleges, "upon information and belief," that the accused products are "substantially similar to the exemplary TMF8828 shown in Exhibit 8" and that they utilize these graded regions in a manner that infringes the patents, for example, by improving transistor switching time (Compl. ¶45). The core of the infringement allegation rests on the physical structure of the accused semiconductor devices, which Plaintiff asserts will be proven through technical analysis presumably contained in the un-filed Exhibit 8.

Identified Points of Contention

  • Evidentiary Question: A central issue will be evidentiary. The complaint makes its infringement allegations "upon information and belief" and relies on an external exhibit. The key question is what technical evidence (e.g., from reverse engineering or circuit analysis) the Plaintiff will produce to show that the accused products actually contain the specific "graded dopant concentration" structures, "drift layers," and "well regions" as required by the asserted claims.
  • Technical Questions: A likely area of dispute will be the technical comparison of the accused device structures to the claim limitations. This may raise questions such as: Does the dopant profile in the accused products constitute a "graded concentration" intended to create a "static unidirectional electric drift field," or is it a profile that arises from standard manufacturing processes with a different technical purpose?

V. Key Claim Terms for Construction

"graded dopant concentration"

  • Context and Importance: This term is the technological core of all asserted patents. The outcome of the infringement analysis will heavily depend on its construction. Practitioners may focus on this term because the complaint alleges that its construction has been addressed and upheld in Plaintiff's favor in multiple prior lawsuits, making its application to the facts of this case paramount (Compl. ¶16, n.19).
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specification states that the gradient "can be linear, quasi linear, exponential or complimentary error function," suggesting the term is not limited to a single mathematical profile (’195 Patent, col. 3:1-3).
    • Evidence for a Narrower Interpretation: The specification consistently links the graded concentration to the function of creating an "aiding drift electric field" to achieve a specific purpose, such as helping charge carriers "transverse from emitter to collector" or sweeping "unwanted minority carriers... into the substrate" (’195 Patent, col. 3:4-6, col. 4:60-62). A defendant may argue the term should be limited by these stated functional objectives.

"drift layer"

  • Context and Importance: This structural limitation, appearing in independent claims of the '195 and '502 Patents, defines where the "graded dopant concentration" is located. Mapping this claimed layer onto the physical layout of the accused products will be critical for proving infringement.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specification describes the "drift region" in multiple contexts, noting it "can also be a non-epitaxial silicon substrate," which may support an interpretation that it is not limited to a specific type of manufactured layer (’502 Patent, col. 3:28-30).
    • Evidence for a Narrower Interpretation: The primary embodiment illustrating this feature is in the context of an Insulated Gate Bipolar Transistor (IGBT), where it is shown as an "epitaxial drift region" (Fig. 4). A party could argue that the term's meaning is informed by this specific, detailed embodiment.

VI. Other Allegations

Indirect Infringement

The complaint does not plead specific facts to support claims of induced or contributory infringement, such as knowledge of the patents combined with acts encouraging infringement by others. The allegations focus on direct infringement by Defendants for making, using, selling, and importing the accused products (Compl. ¶43).

Willful Infringement

The complaint does not contain an explicit allegation of willful infringement or facts to support pre-suit knowledge of the patents. It does request that the case be found "exceptional" under 35 U.S.C. § 285 to recover attorneys' fees, but it does not plead the elements typically required for seeking enhanced damages for willful infringement (Compl., p. 22, ¶D).

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

  • A primary issue will be one of evidentiary proof: Can Greenthread produce technical evidence, presumably from the reverse engineering analysis referenced in its missing exhibit, that is sufficient to prove the AMS-OSRAM products contain the specific "graded dopant" structures required by the claims, as they were allegedly construed in prior litigation?
  • A key legal and technical question will be one of infringement scope: Assuming the validity of the prior claim constructions cited by the Plaintiff, do the specific doping profiles and layer structures within the accused Time-of-Flight sensors fall within the scope of terms like "graded dopant concentration" and "drift layer," or will the Defendant be able to demonstrate a fundamental mismatch in structure or technical operation?