DCT

2:19-cv-10439

North Plate Semiconductor LLC v. OmniVision Tech Inc

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Key Events
Complaint

I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 2:19-cv-10439, E.D. Mich., 02/13/2019
  • Venue Allegations: Plaintiff alleges venue is proper because Defendant maintains a regular and established place of business within the district and has committed acts of infringement there.
  • Core Dispute: Plaintiff alleges that Defendant’s CMOS image sensor products infringe seven patents related to the design, structure, and manufacturing of semiconductor image sensing devices.
  • Technical Context: The patents relate to technologies for improving performance and enabling miniaturization in CMOS image sensors, which are critical components in markets such as mobile devices, automotive systems, and digital cameras.
  • Key Procedural History: The complaint alleges that Defendant has had notice of its infringement of the patents-in-suit since at least 2015, based on correspondence between Defendant and Toshiba, the original assignee of several of the asserted patents. A specific letter identifying the patents was allegedly sent on March 3, 2016, forming a basis for the willfulness allegations.

Case Timeline

Date Event
1998-03-31 Priority Date for ’676 and ’926 Patents
2000-11-21 ’676 Patent Issued
2003-02-18 ’926 Patent Issued
2008-02-22 Priority Date for ’483 and ’913 Patents
2009-09-11 Priority Date for ’123 Patent (Reissue)
2010-03-01 Priority Date for ’509 Patent
2011-04-19 ’483 Patent Issued
2011-09-14 Priority Date for ’521 Patent
2012-05-08 ’509 Patent Issued
2012-05-15 ’913 Patent Issued
2014-10-07 ’521 Patent Issued
2015-01-01 Alleged Pre-Suit Notice of Infringement
2016-03-03 Alleged Pre-Suit Notice Letter Sent
2016-08-23 ’123 Patent (Reissue) Issued
2019-02-13 Complaint Filed

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

U.S. Patent No. 6,211,509 - "Solid-State Image Sensor"

(Analyst Note: The complaint incorrectly lists the issue date as May 8, 2012; the patent front page indicates an issue date of Apr. 3, 2001.)

The Invention Explained

  • Problem Addressed: The patent describes technical problems in MOS-type solid-state image sensors, including the leakage of electrons generated by long-wavelength light into adjacent pixel units, which causes "color mixture" and "blooming." This problem is exacerbated as pixel density increases and pixel unit size decreases, which also causes an expansion of the photodiode's depletion layer (US 6,211,509 B1, col. 1:12-20, col. 2:20-25).
  • The Patented Solution: The invention discloses an element isolation region structure designed to confine signal charges within their respective pixel units. The solution involves forming this isolation region with a "bottom portion positioned deeper than a bottom portion of a depletion layer extending from the p-n junction." This deep barrier, created for example by a deep p-type diffusion layer (24-2 in FIG. 1A) under a field oxide film, effectively prevents electrons from leaking into neighboring pixels (US 6,211,509 B1, Abstract; col. 6:38-55).
  • Technical Importance: This structural approach was intended to enable higher pixel density in image sensors while mitigating the signal degradation, color mixing, and blooming that would otherwise occur with miniaturization (US 6,211,509 B1, col. 3:1-17).

Key Claims at a Glance

  • The complaint asserts independent claim 1 and dependent claims 2, 3, 17, 18, 21, and 22 (Compl. ¶33).
  • Independent Claim 1 requires:
    • A plurality of pixel units arranged on a semiconductor substrate layer, each having a photoelectric conversion portion (e.g., a photodiode) and a signal extraction portion (e.g., a transistor).
    • A scanning circuit connected to the signal extraction portions.
    • Element isolation regions for isolating the pixel units from each other.
    • A key limitation wherein each element isolation region has "a bottom portion positioned deeper than a bottom portion of a depletion layer extending from the p-n junction to the substrate layer in an equilibrium state."
  • The complaint reserves the right to assert additional claims (Compl. ¶33).

U.S. Patent No. 6,150,676 - "MOS Type Image Sensor"

The Invention Explained

  • Problem Addressed: The patent addresses the challenge of miniaturizing MOS image sensors. As transistor gate lengths are reduced (a "short-channel effect"), leakage current increases, which degrades sensitivity. A conventional solution—increasing the impurity concentration of the well regions to suppress leakage—creates new problems, including "white pixels" (a form of noise) and deteriorated spectral sensitivity in the long-wavelength spectrum (’676 Patent, col. 1:47–col. 2:20).
  • The Patented Solution: The invention proposes a structure where the pixel area and the peripheral circuitry area are formed in different well regions with distinct impurity concentrations. Specifically, the pixels are formed in a "second well region" having a lower impurity concentration than the "first well region" where the peripheral driving circuits are located. This allows the transistors in the peripheral circuits to have a higher impurity concentration to manage performance, while the pixel transistors have a lower concentration to maintain high sensitivity and low noise (’676 Patent, Abstract; col. 8:19-30).
  • Technical Importance: This differential well structure enabled the use of finer design rules for manufacturing denser image sensors without the typical trade-offs in image quality, such as increased noise or reduced light sensitivity (’676 Patent, col. 2:21-36).

Key Claims at a Glance

  • The complaint asserts independent claim 17 and dependent claims 19 and 20 (Compl. ¶43).
  • Independent Claim 17 requires:
    • A photodiode comprising a first main electrode region (a well region) and a second main electrode region (a diffusion layer).
    • A "semiconductor region that surrounds the first diffusion layer," which is "sandwiched between the first diffusion layer and the well region, having a lower impurity concentration than the well region."
    • A read transistor.
    • An amplification transistor.
  • The complaint reserves the right to assert additional claims (Compl. ¶43).

U.S. Patent No. 6,521,926 - "MOS Type Image Sensor"

  • Technology Synopsis: This patent, related to the ’676 Patent, also addresses performance issues arising from miniaturization in MOS image sensors. It claims a structure where the well region for the image area has a lower impurity concentration than the well region for the peripheral circuitry, a design intended to suppress short-channel effects in the pixel transistors without introducing the noise ("white pixels") associated with higher impurity levels (Compl. ¶15; ’926 Patent, Abstract).
  • Asserted Claims: Claims 8 and 14 (Compl. ¶53).
  • Accused Features: The complaint accuses Omnivision's OV13850 CMOS image sensor product of infringing the ’926 patent (Compl. ¶54).

U.S. Patent No. 7,928,483 - "Semiconductor Device and Method for Manufacturing the Same"

  • Technology Synopsis: This patent describes a semiconductor structure and manufacturing method for creating element isolation using a "half-buried dielectric film." This structure is designed to isolate elements like photodiodes in an imaging device to prevent charge leakage between pixels, while being compatible with device downscaling and avoiding crystal defects that can cause image noise (Compl. ¶18; ’483 Patent, Abstract).
  • Asserted Claims: Claims 1 and 2 (Compl. ¶63).
  • Accused Features: The complaint accuses the OV8850 and OV13850 CMOS image sensor products (Compl. ¶64).

U.S. Patent No. 8,854,521 - "Solid-State Image Sensing Device and Control Method of Solid-State Image Sensing Device"

  • Technology Synopsis: The patent discloses a control method for an image sensor that uses three distinct potential levels for the reset drain signal line. By applying a high potential during pixel read, a low potential when the pixel is unselected, and a medium potential during standby, the invention aims to improve dynamic range, reduce charge leakage, and enhance device reliability by avoiding prolonged exposure to high voltages (Compl. ¶21; ’521 Patent, Abstract).
  • Asserted Claims: Claim 1 (Compl. ¶73).
  • Accused Features: The complaint accuses the OV8850 CMOS image sensor product (Compl. ¶74).

U.S. Reissued Patent No. RE46,123 - "Solid-State Image Sensor and Method of Manufacturing the Same"

  • Technology Synopsis: This patent relates to back-illuminated image sensors, where light enters from the surface opposite the interconnects. The invention describes using buried interconnects and dummy layers within the interlayer insulating films to create a flatter surface for adhering the support substrate, which improves manufacturing yield and reliability for high-density sensors (Compl. ¶24; ’123 Patent, Abstract).
  • Asserted Claims: Claims 1-4 and 6-8 (Compl. ¶83).
  • Accused Features: The complaint accuses the OV8850 and OV13850 CMOS image sensor products (Compl. ¶84).

U.S. Patent No. 8,178,913 - "Semiconductor Device And Method For Manufacturing Same"

  • Technology Synopsis: Related to the ’483 patent, this invention also concerns element isolation structures in semiconductor devices. It specifies a structure combining a buried dielectric film and an element isolation film (like STI) where the lower surface of the isolation film is located below the lower surface of the buried dielectric film, a configuration aimed at improving performance and manufacturability in image sensors (Compl. ¶27; ’913 Patent, Abstract).
  • Asserted Claims: Claim 1 (Compl. ¶93).
  • Accused Features: The complaint accuses the OV8850 and OV13850 CMOS image sensor products (Compl. ¶94).

III. The Accused Instrumentality

Product Identification

  • The Accused Products are Defendant's CMOS image sensor products, including but not limited to the OV8850 and OV13850 devices (Compl. ¶30).

Functionality and Market Context

  • The complaint states that these image sensors are components used across a range of industries, including automotive, medical imaging, mobile devices, surveillance, robotics, and computing (Compl. ¶30). The allegations focus on the physical structure and manufacturing methods of these sensors rather than their operational software features. The complaint alleges these products are sold and offered for sale throughout the United States (Compl. ¶30).

No probative visual evidence provided in complaint.

IV. Analysis of Infringement Allegations

The complaint references preliminary claim chart exhibits for each asserted patent (e.g., Exhibit I for the '509 Patent and Exhibit J for the '676 Patent), but these exhibits were not filed with the complaint. The narrative infringement theories are summarized below.

  • U.S. Patent No. 6,211,509 Infringement Allegations
    The complaint alleges that Defendant’s Accused Products, including the OV8850 and OV13850, possess the structural elements required by the asserted claims (Compl. ¶33-35). The central infringement theory appears to be that the accused sensors are manufactured with element isolation regions designed to prevent electrical crosstalk between pixels. The complaint alleges that these isolation structures are built with a depth relative to the photodiode's depletion layer that meets the specific limitations of the claims, such as those in independent claim 1 (Compl. ¶34).

  • U.S. Patent No. 6,150,676 Infringement Allegations
    The complaint alleges that the Accused Products, such as the OV8805 and OV13850, embody the claimed invention (Compl. ¶43-45). The core of this infringement theory is that the accused sensors are constructed using a dual-well structure. Specifically, Plaintiff alleges that the pixel array is formed in a p-well region with a lower impurity concentration than the p-well region used for the peripheral circuitry, a design feature claimed by the patent to enable miniaturization while maintaining performance (Compl. ¶44).

  • Identified Points of Contention:

    • Structural Questions: A primary factual dispute may concern the physical characteristics of the accused sensors at a microscopic level. A key question is whether discovery and reverse engineering will confirm that the devices possess the specific structural relationships required by the claims, such as the isolation region depth relative to the depletion layer (’509 Patent) and the differential impurity concentrations between pixel and peripheral well regions (’676 Patent).
    • Scope Questions: The case may raise questions of claim scope. For the ’676 Patent, a point of contention could be whether the term "lower impurity concentration" requires a specific, functionally significant difference intended to solve the problems described in the patent, or if any measurable variation is sufficient. For the ’509 Patent, a dispute may arise over the proper methodology for defining the "bottom portion of a depletion layer" to assess whether an isolation region is "deeper" as claimed.

V. Key Claim Terms for Construction

  • ’509 Patent

    • The Term: "a bottom portion positioned deeper than a bottom portion of a depletion layer" (from claim 1)
    • Context and Importance: This phrase is the central structural limitation defining the novel isolation region. The infringement analysis for the ’509 patent will depend entirely on whether the accused products' physical structures satisfy this relative depth requirement. Practitioners may focus on this term because its components—"bottom portion" and "depletion layer"—may be subject to differing technical definitions and measurement methodologies.
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Broader Interpretation: Parties may argue that the specification's objective is to "prevent leakage and diffusion of signals" (US 6,211,509 B1, col. 2:5-15). This suggests the term should be construed functionally to encompass any structure where one part is sufficiently deep relative to another to achieve electrical confinement, without being limited to the exact embodiments shown.
      • Evidence for a Narrower Interpretation: Parties may point to specific embodiments, such as the "second diffusion layer 24-2" in FIG. 1A, as defining the required structure. This could support a narrower construction limited to a specifically formed barrier layer rather than just an inherent property of a well boundary.

  • ’676 Patent

    • The Term: "a second well region... having a lower impurity concentration than the first well region" (from claim 1)
    • Context and Importance: This limitation defines the core inventive concept of using differential doping levels for the pixel array versus the peripheral circuitry. Proving infringement requires demonstrating this specific relative difference in the accused devices.
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Broader Interpretation: The plain language of the claim suggests that any measurable difference where one well's concentration is "lower" than the other's would suffice. The purpose of this structure—to solve problems like "white pixels" and short-channel effects (’676 Patent, col. 2:5-36)—could support reading the term to cover any concentration difference that achieves this technical benefit.
      • Evidence for a Narrower Interpretation: The specification provides an example with specific concentration levels ("1×10¹⁷ cm⁻³" for the pixel well versus "2×10¹⁷ cm⁻³" for the peripheral well) (’676 Patent, col. 8:31-33). Parties may argue these figures provide context for the required magnitude of the "lower" concentration, suggesting that an insignificant or incidental variation would not meet the claim's requirement.

VI. Other Allegations

  • Indirect Infringement: The complaint alleges intentional inducement of infringement for all asserted patents. The factual basis is Defendant's alleged actions of selling the Accused Products to U.S. distributors (e.g., Arrow Electronics, Mouser Electronics, Digi-Key) and providing technical and marketing collateral such as datasheets, application notes, and product briefs on its website. These materials allegedly instruct and encourage third parties to incorporate, use, and sell the infringing products within the United States (Compl. ¶36, ¶46, ¶56, ¶66, ¶76, ¶86, ¶96).
  • Willful Infringement: For each asserted patent, the complaint alleges that Defendant's infringement has been and continues to be willful. The allegations are based on purported pre-suit knowledge of the patents and infringement dating back to at least 2015, arising from correspondence between Defendant and Toshiba. The complaint further specifies a letter sent on or about March 3, 2016, that allegedly identified the asserted patents to Defendant's executive leadership and general counsel (Compl. ¶37-38, ¶47-48, ¶57-58, ¶67-68, ¶77-78, ¶87-88, ¶97-98).

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

  1. A central issue will be one of structural verification: can Plaintiff demonstrate through discovery and technical analysis that the accused CMOS sensors possess the specific microscopic structures required by the claims, such as the relative well impurity concentrations (’676 Patent) and the precise depth of isolation regions relative to photodiode depletion layers (’509 Patent)?
  2. The case will likely involve a key question of claim scope: can the term "deeper than a... depletion layer" (’509 Patent) be construed to cover the accused structures, and what is the proper technical methodology for defining and measuring these features? Similarly, for the ’676 Patent, must the "lower impurity concentration" reflect a technologically significant difference designed to achieve the patent's stated objectives, or is any measurable variation sufficient?
  3. A critical issue for damages will be willfulness: what was the specific content of the alleged 2015-2016 correspondence between Toshiba and Omnivision, and did it constitute notice sufficient to trigger a duty of care to avoid infringement, thereby exposing Defendant to potential enhanced damages for its subsequent conduct?