DCT
2:19-cv-00147
Greenthread LLC v. Samsung Electronics Co Ltd
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Greenthread, LLC (Texas)
- Defendant: Samsung Electronics Co., Ltd. (Republic of Korea); Samsung Semiconductor, Inc. (California); Samsung Electronics America, Inc. (New York); Samsung Austin Semiconductor, LLC (Delaware)
- Plaintiff’s Counsel: Coghlan Crowson LLP; Robins Kaplan LLP
- Case Identification: 2:19-cv-00147, E.D. Tex., 04/30/2019
- Venue Allegations: Plaintiff alleges venue is proper because Defendants are subject to personal jurisdiction, have committed acts of infringement, and maintain a regular and established place of business within the Eastern District of Texas, including through corporate offices and sales of products via authorized retailers.
- Core Dispute: Plaintiff alleges that Defendant’s semiconductor products, including DRAM, NAND flash memory, and CMOS image sensors, infringe four patents related to the use of graded dopant concentrations to improve semiconductor device performance.
- Technical Context: The technology at issue involves intentionally varying the concentration of dopants (impurities) within semiconductor materials to create electric fields that control the movement of charge carriers, aiming to enhance the speed, efficiency, and reliability of integrated circuits.
- Key Procedural History: All four patents-in-suit name G.R. Mohan Rao as the sole inventor and claim priority to the same U.S. patent application filed in 2004, suggesting a common technical disclosure and prosecution lineage. The complaint provides extensive background on Dr. Rao's career in the semiconductor industry but does not mention any prior litigation, licensing, or inter partes review proceedings involving the patents.
Case Timeline
| Date | Event |
|---|---|
| 2004-09-03 | Earliest Priority Date for '195, '502, '481, and '070 Patents |
| 2012-01-31 | U.S. Patent No. 8,106,481 Issues |
| 2013-04-16 | U.S. Patent No. 8,421,195 Issues |
| 2015-11-17 | U.S. Patent No. 9,190,502 Issues |
| 2017-05-09 | U.S. Patent No. 9,647,070 Issues |
| 2019-04-30 | 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 background identifies performance limitations in conventional semiconductor devices caused by the movement of charge carriers. These include slow operational frequency, poor data retention (refresh time) in DRAM, and "soft errors" from transient radiation, which can be exacerbated by unwanted minority carriers interfering with critical charge storage nodes near the device surface (Compl. ¶35; ’195 Patent, col. 2:5-10, col. 2:60-65).
- The Patented Solution: The invention proposes using a "graded concentration of dopants" to create a built-in, or static, electric "drift field" within the semiconductor structure. This field is engineered to control carrier movement, such as by "sweeping" unwanted minority carriers away from the active surface layer down into the substrate, thereby improving device performance and reliability ('195 Patent, Abstract; col. 4:36-44).
- Technical Importance: This technique of creating internal drift fields was intended to enable the design of faster, more efficient, and more reliable semiconductor devices, particularly as manufacturers continued to scale down feature sizes (Compl. ¶23).
Key Claims at a Glance
- The complaint asserts at least independent claim 1 (Compl. ¶55).
- Claim 1 requires:
- A surface layer and a substrate.
- An active region (e.g., source and drain) on the surface layer.
- A single drift layer between the surface layer and substrate with a graded concentration of dopants.
- This drift layer must have a "first static unidirectional electric drift field" to aid the movement of 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.
- This well region must have a "second static unidirectional electric drift field" to also aid minority carrier movement from the surface layer to the substrate.
- The complaint reserves the right to assert additional claims (Compl. ¶55).
U.S. Patent No. 9,190,502 - Semiconductor Devices with Graded Dopant Regions, issued November 17, 2015
The Invention Explained
- Problem Addressed: Similar to the '195 patent, the '502 patent addresses performance issues in semiconductor devices related to controlling charge carrier movement. A specific problem noted is the need to accelerate carriers toward the surface during the programming of non-volatile memory cells to decrease programming times ('502 Patent, col. 4:51-56; Compl. ¶35).
- The Patented Solution: The invention also uses graded dopant concentrations to create static electric drift fields. However, unlike the '195 patent's asserted claim, which focuses on moving carriers away from the surface, the '502 patent's claims describe creating fields that can move carriers in either direction depending on the device's needs. The asserted claim specifically requires a field that aids carrier movement from the substrate to the surface ('502 Patent, Claim 7; col. 4:44-51).
- Technical Importance: This approach provides a method to enhance different aspects of device performance, such as improving programming speeds in flash memory, by actively pulling required carriers toward the surface circuitry (Compl. ¶23).
Key Claims at a Glance
- The complaint asserts at least independent claim 7 (Compl. ¶80).
- Claim 7 requires:
- A surface layer and a substrate.
- An active region (e.g., source and drain) on the surface layer.
- A single drift layer with a graded concentration of dopants.
- This drift layer must have a "first static unidirectional electric drift field" to aid the movement of minority carriers from the substrate to the surface layer.
- At least one well region within the drift layer with a graded concentration of dopants.
- This well region must have a "second static unidirectional electric drift field" to aid minority carrier movement from the surface layer to the substrate.
- The complaint reserves the right to assert additional claims (Compl. ¶80).
Multi-Patent Capsule: U.S. Patent No. 8,106,481
- Patent Identification: U.S. Patent No. 8,106,481, Semiconductor Devices with Graded Dopant Regions, issued January 31, 2012 (Compl. ¶19).
- Technology Synopsis: The ’481 patent discloses a CMOS integrated circuit built on a non-epitaxial substrate containing a plurality of well regions (e.g., n-wells and p-wells). The key feature is the use of "2-way graded dopants" within these wells to create a plurality of electric fields that simultaneously aid the movement of one type of carrier up toward the device's surface area and another type of carrier down toward the substrate, thereby creating both "aiding" and "retarding" fields within the same structure ('481 Patent, Claim 1, Abstract, Fig. 8).
- Asserted Claims: At least independent claim 1 is asserted (Compl. ¶105).
- Accused Features: The complaint alleges that Samsung's DRAM and NAND products utilize a non-epitaxial substrate with p-wells and n-wells that contain 2-way graded dopants, creating the claimed bidirectional electric fields (Compl. ¶¶109-112, 116-119).
Multi-Patent Capsule: U.S. Patent No. 9,647,070
- Patent Identification: U.S. Patent No. 9,647,070, Semiconductor Devices with Graded Dopant Regions, issued May 9, 2017 (Compl. ¶20).
- Technology Synopsis: The ’070 patent is directed to a semiconductor device, such as a CMOS image sensor, comprising a substrate of a first doping type and an active region of a second, opposite doping type. The invention describes using a graded dopant concentration proximate to the substrate surface to create a field that aids carrier movement from an "emitter" in the active region to a "collector" in the substrate, while also having a separate region of higher conductivity within the active region itself (’070 Patent, Claim 1, Abstract).
- Asserted Claims: At least independent claim 1 is asserted (Compl. ¶130).
- Accused Features: The complaint accuses Samsung's CMOS image sensors, alleging they have a p-type substrate (collector) and an n-type active region (emitter), with a graded dopant concentration that aids carrier movement between them as claimed (Compl. ¶¶134-137).
III. The Accused Instrumentality
- Product Identification: The complaint identifies three main categories of "Accused Semiconductor Instrumentalities": Samsung DRAM chips (e.g., K4A8G045WB DDR4 SDRAM), Samsung NAND flash chips (e.g., K9DUGB8S7M V-NAND), and Samsung CMOS image sensor chips (e.g., S5K2X7SP) (Compl. ¶¶40, 56, 63, 131). The complaint also names dozens of downstream "Accused Consumer Electronics" that incorporate these chips, such as Samsung-branded SSDs, USB flash drives, and memory cards (Compl. ¶41).
- Functionality and Market Context: The complaint alleges that the accused semiconductor chips are manufactured using processes that create graded dopant concentrations to control charge carrier movement in a manner that maps onto the patent claims (Compl. ¶¶57, 64). The complaint supports its allegations with images and data from third-party teardown reports, including Scanning Electron Microscope (SEM) cross-sections and Spreading Resistance Profiling (SRP) graphs (Compl. ¶¶56, 63). The complaint asserts that Samsung is a global leader in the semiconductor market and derives significant revenue from these products (Compl. ¶¶36, 50). This is supported by an SRP graph, derived from a teardown report, which purports to show the carrier concentration varying with depth in the accused DRAM chip (Compl. p. 20, Fig. 2.1.2).
IV. Analysis of Infringement Allegations
'195 Patent Infringement Allegations (Claim 1)
| 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... | The accused DRAM and NAND chips are alleged to have layers with varying dopant concentrations, as shown in SRP analysis graphs. | ¶61, ¶68 | col. 4:36-44 |
| ...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; | The alleged graded dopant concentration shown in the SRP graphs creates an electric field that sweeps minority carriers from the device surface toward the underlying substrate. | ¶61, ¶68 | col. 4:36-44 |
| 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... | The accused devices contain p-wells and n-wells which are alleged to have their own graded dopant concentrations, creating a second electric field. The complaint shows an SRP analysis of a p-well embedded in an n-well to support this allegation. | ¶62, ¶69 | col. 4:36-44 |
'502 Patent Infringement Allegations (Claim 7)
| Claim Element (from Independent Claim 7) | 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; | The complaint alleges the accused devices have a field that aids movement of carriers "from said surface layer to said substrate," which is opposite to the direction required by the claim language. This allegation is supported by an SEM cross-section of the SDRAM array (Compl. p. 28, Fig. 2.1.3). | ¶86, ¶93 | col. 4:44-51 |
| at least one 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 surface layer to said substrate. | The complaint alleges the well regions also create a field that aids carrier movement from the surface layer to the substrate, a direction which matches this claim element. This allegation is supported by an SRP analysis graph (Compl. p. 30, Fig. 2.1.2). | ¶87, ¶94 | col. 4:31-37 |
- Identified Points of Contention:
- Technical Interpretation: A central dispute will likely involve the interpretation of the reverse-engineering data. The parties may contest whether the measured variations in carrier concentration from the SRP graphs (e.g., Compl. p. 20, Fig. 2.1.2) constitute the specific "graded concentration of dopants" required to generate the claimed "static unidirectional electric drift field," or if they represent something else, such as artifacts of standard manufacturing processes.
- Factual Mismatch ('502 Patent): The complaint’s infringement theory for the first element of claim 7 of the '502 patent appears to be factually inconsistent with the claim's language. The claim requires a field aiding carrier movement from substrate-to-surface, but the complaint alleges movement in the opposite direction (surface-to-substrate) (Compl. ¶86). This raises the question of whether the plaintiff can produce evidence that the accused products meet the actual claim limitation.
V. Key Claim Terms for Construction
The Term: "graded concentration of dopants"
- Context and Importance: This term is the structural cornerstone of the asserted claims across all four patents. Its construction will be critical to determining infringement, as it defines the physical feature alleged to create the functional electric fields. Practitioners may focus on this term because the dispute will likely center on whether the dopant profiles in Samsung’s devices, as revealed by teardown reports, meet this definition.
- 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. 4:49-52).
- Evidence for a Narrower Interpretation: The claims consistently tie the "graded concentration" to the function of creating a specific "static unidirectional electric drift field." A party could argue that only intentionally engineered dopant profiles designed to achieve this specific function meet the definition, excluding incidental variations from other manufacturing steps.
The Term: "static unidirectional electric drift field"
- Context and Importance: This term defines the required function of the "graded concentration." Proving infringement will require showing not just the structure, but also that this specific type of field results from it.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The patents describe the purpose of the field in general terms, such as to "sweep" or "aid the movement" of carriers, which could support an interpretation that any net field achieving this purpose qualifies ('195 Patent, col. 4:38-44).
- Evidence for a Narrower Interpretation: The use of "static" could be argued to mean a field that exists in the absence of an applied voltage, and "unidirectional" could be construed to require a field that is substantially uniform in one direction. The complaint supports its allegation of this field using a SIMS doping profile from a teardown of an accused image sensor (Compl. p. 54, Fig. 4.4.10).
VI. Other Allegations
- Indirect Infringement: The complaint alleges induced infringement under 35 U.S.C. § 271(b). The factual basis for this claim is that Samsung allegedly provides its customers (e.g., OEMs) with instructions, technical specifications, and marketing materials that encourage and enable them to incorporate the accused semiconductor chips into infringing end-products like SSDs, mobile devices, and server hardware (Compl. ¶¶48-49, 72-73).
- Willful Infringement: Willfulness is alleged based on knowledge of the patents "at least as of the filing of this Complaint" (Compl. ¶¶74, 99, 124, 142). The complaint does not allege any specific instances of pre-suit knowledge, framing the willfulness claim on conduct occurring after the lawsuit was initiated.
VII. Analyst’s Conclusion: Key Questions for the Case
Evidentiary Sufficiency: A primary focus of the case will be a battle of experts over the interpretation of reverse-engineering data. The key question is one of evidentiary proof: will the plaintiff's SEM, SRP, and SIMS analyses be sufficient to demonstrate, by a preponderance of the evidence, that the accused products contain the specific "graded concentration of dopants" and "static unidirectional electric drift fields" required by the claims, or will the defendant successfully argue that this data is ambiguous or shows structures created by conventional, non-infringing manufacturing techniques?
Claim Scope: The case will turn on the definitional scope of the core claim terms. How the court construes "graded concentration of dopants" will be critical. If construed broadly to cover any non-uniform profile that produces a net directional field, the plaintiff's position may be strengthened. If construed narrowly to require a specific, intentionally engineered gradient distinct from other common structures (like halo implants), the defendant's non-infringement arguments may be more persuasive.
Correction of Allegations ('502 Patent): A significant procedural and substantive question is one of factual accuracy: can the plaintiff overcome the apparent contradiction in its complaint for the '502 patent, where its infringement allegation describes carrier movement in the opposite direction of that required by the asserted claim? How the plaintiff addresses this discrepancy in its infringement contentions and expert reports will be a key indicator of the strength of this part of its case.