DCT
1:23-cv-00443
Greenthread LLC v. On Semiconductor Corp
Key Events
Amended Complaint
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Greenthread, LLC (Texas)
- Defendant: ON Semiconductor Corporation; Semiconductor Components Industries, LLC d/b/a ON Semiconductor LLC (Delaware / Arizona)
- Plaintiff’s Counsel: Farnan LLP; McKool Smith, PC
- Case Identification: 1:23-cv-00443, D. Del., 06/22/2023
- Venue Allegations: Plaintiff alleges venue is proper because Defendants are incorporated in or reside in Delaware, and have committed acts of infringement in the district.
- Core Dispute: Plaintiff alleges that Defendant’s semiconductor devices, including certain sensors and power modules, infringe patents related to the use of graded dopant concentrations to improve semiconductor performance.
- Technical Context: The technology concerns methods of fabricating semiconductor devices to improve their speed, efficiency, and reliability by creating internal electric fields that more effectively manage the flow of charge carriers.
- Key Procedural History: The complaint notes that claim terms from the asserted patent family have been construed in prior litigation involving other defendants (e.g., Greenthread, LLC v. Samsung Electronics Co., Ltd. and Greenthread, LLC v. Intel Corp), and that Greenthread’s proposed constructions were adopted in those cases.
Case Timeline
| Date | Event |
|---|---|
| 2004-09-03 | Priority Date for ’842 and ’222 Patents |
| 2019-12-17 | U.S. Patent No. 10,510,842 Issues |
| 2021-09-14 | U.S. Patent No. 11,121,222 Issues |
| 2023-06-22 | First Amended Complaint Filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 10,510,842 - "Semiconductor Devices with Graded Dopant Regions" (Dec. 17, 2019)
The Invention Explained
- Problem Addressed: The patent describes performance limitations in conventional semiconductor devices that use uniformly doped regions. This uniformity can limit operating frequency, slow the recombination of charge carriers when a device is switched off, and lead to unwanted effects like data degradation (poor refresh time) in memory devices and reduced image quality in sensors (’842 Patent, col. 1:47-53, col. 2:15-26).
- The Patented Solution: The invention introduces regions with a "graded" or non-uniform dopant concentration. This gradient creates a built-in electric "drift field" that actively aids the movement of charge carriers, such as by accelerating them from the emitter to the collector in a transistor or sweeping unwanted minority carriers away from sensitive areas on the device surface and into the substrate (’842 Patent, col. 1:54-58, col. 4:56-64). The result is a device that can operate faster and more reliably.
- Technical Importance: This approach provided a method to overcome performance bottlenecks inherent in uniformly doped designs, enabling the creation of faster logic, more reliable memory, and higher-quality image sensors (’842 Patent, Abstract).
Key Claims at a Glance
- The complaint asserts infringement of at least one unspecified claim. Independent claim 1 is representative.
- Essential elements of Independent Claim 1 include:
- A substrate of a first doping type.
- A first active region and a separate second active region, both disposed on the substrate and containing transistors.
- At least a portion of at least one active region having at least one graded dopant concentration.
- The graded dopant concentration is structured to aid carrier movement from the device surface toward the substrate.
- The complaint reserves the right to assert additional claims, including dependent claims (Compl. ¶36).
U.S. Patent No. 11,121,222 - "Semiconductor Devices with Graded Dopant Regions" (Sep. 14, 2021)
The Invention Explained
- Problem Addressed: As a continuation of the same patent family, the ’222 Patent addresses the same technical problem: performance degradation in semiconductor devices caused by uniform dopant concentrations, including slow switching speeds and the accumulation of spurious minority carriers that can corrupt data in memory or digital imaging devices (’222 Patent, col. 2:10-20).
- The Patented Solution: The solution is again the use of graded dopant concentrations to create a drift field. The ’222 Patent further details this solution in the context of Very Large Scale Integration (VLSI) devices, specifying that the graded region can be in a "well region" to aid carrier movement away from active regions and toward an area of the substrate where no active regions exist, thereby preventing interference (’222 Patent, col. 3:36-51; claim 1).
- Technical Importance: This technology aims to improve the performance and reliability of complex, high-density integrated circuits like modern processors and memory chips by actively managing internal charge carriers (’222 Patent, Abstract).
Key Claims at a Glance
- The complaint asserts infringement of at least one unspecified claim. Independent claim 1 is representative.
- Essential elements of Independent Claim 1 include:
- A substrate, first and second separate active regions with transistors.
- A portion of an active region having a graded dopant concentration to aid carrier movement from the active regions toward a non-active area of the substrate.
- At least one well region containing a graded dopant region to aid carrier movement from the surface toward the non-active substrate area.
- The transistors form the digital logic of the VLSI semiconductor device.
- The complaint reserves the right to assert additional claims, including dependent claims (Compl. ¶43).
III. The Accused Instrumentality
Product Identification
- The "ON Semiconductor Accused Products" are identified as a broad portfolio of semiconductor devices, including an exemplary image sensor product, AR0820AT (Compl. ¶14, ¶31).
Functionality and Market Context
- The complaint alleges that the accused products are semiconductor devices that contain infringing structures, specifically "regions with graded dopant concentrations" created through fabrication processes that improve device performance (Compl. ¶34). The complaint alleges these products are central to Defendant's business, which is described as a "leader in intelligent power and sensing" with a focus on "automotive and industrial" markets (Compl. ¶6). The complaint includes a photograph of a Smithsonian exhibit display of a 1-megabit CMOS memory device to highlight the historical importance of the work of the patents' inventor in the semiconductor field (Compl. p. 8).
IV. Analysis of Infringement Allegations
The complaint's substantive infringement allegations rely on "Exhibit 4," which is incorporated by reference but was not filed with the complaint (Compl. ¶15, ¶33, ¶44). The following analysis is based on the conclusory allegations in the complaint body.
’842 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| A semiconductor device, comprising: a substrate of a first doping type... having first and second surfaces; | The accused products, such as the AR0820AT, are alleged to be semiconductor devices containing a substrate. | ¶33, ¶37 | col. 4:46-47 |
| a first active region disposed adjacent the first surface... and a second active region separate from the first active region... | The accused products are alleged to be fabricated with multiple active regions on the substrate surface where transistors are formed. | ¶33, ¶37 | col. 4:48-54 |
| at least a portion of at least one of the first and second active regions having at least one graded dopant concentration... | The complaint alleges, upon information and belief, that the accused products are fabricated using process steps that create regions with graded dopant concentrations. | ¶34 | col. 4:55-60 |
| ...to aid carrier movement from the first surface to the second surface of the substrate. | The complaint alleges the graded dopant regions in the accused products serve the functional purpose of improving device performance, which the patent equates with aiding carrier movement. | ¶34, ¶37 | col. 4:58-60 |
’222 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| A VLSI semiconductor device, comprising: a substrate... first active region... a second active region... transistors formed... | The accused products are alleged to be VLSI semiconductor devices containing a substrate, multiple active regions, and transistors, and to be illustrative of products that meet the claim limitations. | ¶44, ¶45 | col. 3:36-41 |
| at least a portion of at least one of the first and second active regions having at least one graded dopant concentration to aid carrier movement from the first and second active regions towards an area of the substrate where there are no active regions; | The complaint alleges that the accused products contain graded dopant regions that aid carrier movement as claimed, referencing the unprovided Exhibit 4 for detailed support. | ¶44 | col. 3:45-51 |
| and at least one well region... containing at least one graded dopant region... to aid carrier movement from the surface towards the area of the substrate where there are no active regions... | The complaint alleges, via its incorporation of Exhibit 4, that the accused products contain well regions with graded dopants that perform the claimed function. | ¶44, ¶45 | col. 3:52-60 |
Identified Points of Contention
- Evidentiary Questions: A primary issue will be the lack of specific factual support for infringement in the body of the complaint. What evidence, beyond conclusory allegations and reference to an unprovided exhibit, shows that Defendant's products contain a "graded dopant concentration" that was designed "to aid carrier movement" as required by the claims? The allegations are made "upon information and belief" (Compl. ¶34), signaling that discovery will be critical.
- Technical Questions: Does the specific dopant profile in the accused products, if non-uniform, actually create the "aiding drift electric field" described in the patents, or is any gradient an incidental artifact of manufacturing that does not perform the claimed function?
V. Key Claim Terms for Construction
The Term: "graded dopant concentration"
Context and Importance: This term is the central inventive concept of both patents. Its construction will likely determine the scope of the claims and whether the dopant profiles in the accused products infringe. Practitioners may focus on this term because Defendant will likely argue that its products either use uniform doping or that any existing variations do not meet the definition of "graded."
Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The specification suggests the term is not limited to one specific profile, stating that the gradient can be "linear, quasi linear, exponential or complimentary error function" (’842 Patent, col. 3:1-3).
- Evidence for a Narrower Interpretation: The term is consistently tied to a function: creating a "suitable aiding drift electric field" (’842 Patent, col. 3:3-4). A defendant may argue that a concentration is only "graded" in the claimed sense if it is specifically engineered to create this functional field, not merely if it is non-uniform.
The Term: "to aid carrier movement"
Context and Importance: This is a functional limitation that modifies "graded dopant concentration." Infringement requires not just the structure, but also the performance of this function. The dispute will be over what constitutes "aiding" movement.
Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The patent abstract and background frame the invention as broadly improving performance, such as increasing operating frequency or improving refresh times (’842 Patent, Abstract). Plaintiff may argue any structure that achieves these results necessarily "aids carrier movement."
- Evidence for a Narrower Interpretation: The detailed description provides specific examples of aiding movement, such as "sweep[ing] these unwanted minority carriers from the active circuitry at the surface into the substrate" (’842 Patent, col. 4:60-63). A defendant could argue the term is limited to these specific, described mechanisms.
VI. Other Allegations
Indirect Infringement
- The complaint alleges induced infringement based on Defendants "designing and marketing infringing products for sale, use, and importation" (Compl. ¶40, ¶47). The complaint does not allege specific facts to support the element of intent, such as referencing user manuals or technical documentation that instruct customers to use the products in an infringing manner.
Willful Infringement
- The complaint does not explicitly allege "willful infringement" but seeks enhanced damages and attorneys' fees (Compl., Prayer for Relief ¶C, ¶D). The sole factual basis for knowledge is post-suit, stating that Defendant has knowledge of the patents "at least through the service of the Complaint" (Compl. ¶32). This allegation can only support a claim for infringement that occurs after the complaint was filed.
VII. Analyst’s Conclusion: Key Questions for the Case
A central evidentiary question will be whether Plaintiff can produce technical evidence, which is absent from the complaint itself, to demonstrate that Defendant's accused products actually contain the "graded dopant concentration" structures required by the asserted claims. The case's viability depends on the contents of the unprovided "Exhibit 4" and facts developed during discovery.
The dispute will likely focus on a core issue of claim construction: how should the court define the phrase "graded dopant concentration to aid carrier movement"? Whether this phrase requires a specific, intentionally engineered dopant profile that creates a measurable drift field, or whether it can read on more general non-uniformities that result in improved performance, will be a critical question, particularly in light of the prior claim construction rulings cited in the complaint.