DCT

2:22-cv-00298

Alidouble Inc v. Taiwan Semiconductor Mfg Co

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 2:22-cv-00298, E.D. Tex., 07/26/2023
  • Venue Allegations: Venue is alleged to be proper because Defendant is not a resident of the United States and therefore may be sued in any judicial district.
  • Core Dispute: Plaintiff alleges that Defendant’s processes for manufacturing Back-Side Illumination (BSI) image sensors, and the resulting sensor products, infringe four U.S. patents.
  • Technical Context: The technology at issue is back-side illumination for CMOS image sensors, a fundamental manufacturing approach used to increase light sensitivity and performance in digital cameras, particularly those in smartphones and other compact devices.
  • Key Procedural History: The complaint alleges that Defendant has known of the ’965 and ’319 patents since at least 2006, based on Defendant citing these patents during the prosecution of its own patent applications. For the more recent ’169 and ’455 patents, knowledge is alleged based on a prior lawsuit filed by Plaintiff against Defendant on December 14, 2021. These allegations form the basis for claims of willful infringement.

Case Timeline

Date Event
1999-08-12 ’965 and ’319 Patents Priority Date
2001-01-02 ’965 and ’319 Patents Issue Date
2006-06-15 Alleged knowledge of ’965/’319 patents via citation in TSMC patent application
2006-09-18 Alleged knowledge of ’965/’319 patents via citation in another TSMC patent application
2008-01-01 TSMC announces development of BSI technology (approx. date from 2008 Annual Report)
2009-01-01 TSMC and OmniVision announce development of 1.4µm pixel node for BSI sensors (approx. date)
2014-07-06 ’169 Patent Priority Date
2014-11-09 ’455 Patent Priority Date
2016-05-31 ’169 Patent Issue Date
2016-08-30 ’455 Patent Issue Date
2019-08-12 ’965 and ’319 Patents Expiration Date (approx.)
2021-12-14 Plaintiff files first lawsuit against TSMC
2023-07-26 First Amended Complaint Filing Date

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

U.S. Patent No. 6,168,965 - Method for Making Backside Illuminated Image Sensor (Issued Jan. 2, 2001)

The Invention Explained

  • Problem Addressed: In conventional "frontside" illuminated image sensors, metal wiring and other circuits are placed on the same surface that receives light, partially blocking photons from reaching the light-sensitive silicon and reducing the sensor's efficiency, or "fill factor" (’965 Patent, col. 4:4-9). Existing methods for creating "backside" illuminated sensors to solve this were often expensive and involved non-standard fabrication steps (’965 Patent, col. 4:10-24).
  • The Patented Solution: The patent discloses a method where standard CMOS sensor circuits are first fabricated on the front of a silicon wafer. This wafer is then flipped and bonded front-side-down to a "protective substrate" for support. The back of the original wafer is then thinned down by grinding and etching until the light-sensitive regions of the pixels are exposed. Finally, a transparent substrate (e.g., glass) is secured to this newly thinned backside, creating a "waferwise sandwich" that protects the delicate, thinned silicon and is ready to be diced into individual sensors (’965 Patent, Abstract; col. 4:35-54).
  • Technical Importance: This method provided a pathway to manufacture higher-efficiency BSI sensors by integrating complex thinning and bonding steps with otherwise standard and cost-effective CMOS fabrication processes (’965 Patent, col. 4:43-54).

Key Claims at a Glance

  • The complaint asserts independent claim 1 and dependent claims 7, 8, and 10 (Compl. ¶70).
  • Independent Claim 1 requires the following steps:
    • producing a plurality of image sensor circuits on a wafer;
    • securing the wafer onto a protective substrate such that the circuit-side (first surface) faces the protective substrate;
    • removing material from the second surface of the wafer until the light-sensitive pixel regions are effectively exposed;
    • securing a transparent substrate onto the second surface, thereby producing a waferwise sandwich; and
    • slicing the waferwise sandwich to define a plurality of sensors.

U.S. Patent No. 6,169,319 - Backside Illuminated Image Sensor (Issued Jan. 2, 2001)

The Invention Explained

  • Problem Addressed: As with the parent ’965 patent, the invention addresses the fill-factor limitations of frontside-illuminated image sensors (’319 Patent, col. 4:5-9).
  • The Patented Solution: This patent, a divisional of the ’965 patent, claims the resulting apparatus rather than the method. It describes the physical structure of a BSI sensor comprising three main layers: a protective substrate, a thinned semiconductor substrate containing the pixel circuits, and a transparent substrate. The metal lines for the circuits are located between the semiconductor substrate and the protective substrate, away from the light path, which enters through the transparent substrate on the opposite side (’319 Patent, Abstract; Fig. 5).
  • Technical Importance: The patent defines the physical architecture for a BSI image sensor that allows for improved light collection efficiency by placing the metal circuitry behind the light-sensitive pixel regions (’319 Patent, col. 9:1-12).

Key Claims at a Glance

  • The complaint asserts independent claim 1 and dependent claims 2 and 6 (Compl. ¶81).
  • Independent Claim 1 requires a sensor comprising:
    • a semiconductor substrate with a first and second surface;
    • a plurality of light-sensitive pixel regions on the first surface;
    • a metal line adjacent to the first surface;
    • a protective substrate secured to the semiconductor substrate, with the metal line positioned between them;
    • a transparent substrate secured to the second surface, creating a sandwich structure; and
    • wherein the semiconductor substrate is thinned to effectively expose the pixel regions through the second surface.

U.S. Patent No. 9,356,169 - Apparatus, System and Method of Back Side Illumination (BSI) Complementary Metal-Oxide-Semiconductor (CMOS) Pixel Array

  • Issued: May 31, 2016 (Compl. ¶26).
  • Technology Synopsis: This patent addresses the problem of electronic "crosstalk" where electrons generated by light in one pixel can leak into an adjacent pixel, degrading image quality. The invention discloses a BSI pixel structure that includes a "barrier layer" to electrically isolate the light absorption area from the transistor well regions, and a specially configured "collection area" to more effectively guide electrons to the correct photodiode (’169 Patent, Abstract; col. 5:11-45).
  • Asserted Claims: Independent Claim 1 and multiple dependent claims are asserted (Compl. ¶91).
  • Accused Features: The complaint alleges that TSMC’s BSI sensors, particularly modern sensors with small pixels, incorporate structures that perform the function of the claimed barrier and collection layers to manage electron crosstalk (Compl. ¶61, 91).

U.S. Patent No. 9,431,455 - Back-End Processing Using Low-Moisture Content Oxide Cap Layer

  • Issued: August 30, 2016 (Compl. ¶41).
  • Technology Synopsis: This patent addresses a manufacturing problem where hydrogen generated during the "back-end" process of depositing metal layers can contaminate and degrade the performance of the underlying sensor. The invention is a fabrication method that uses a specific "high-density, low-moisture content oxide" material as a "cap layer" during processing to act as a barrier, preventing the formation and migration of this harmful hydrogen (’455 Patent, Abstract).
  • Asserted Claims: Independent Claim 1 is asserted (Compl. ¶100).
  • Accused Features: The complaint alleges that TSMC's back-end-of-line manufacturing processes for its BSI sensors utilize a method covered by the claims to control hydrogen contamination (Compl. ¶46, 100).

III. The Accused Instrumentality

Product Identification

The complaint identifies the accused instrumentalities as BSI sensors manufactured by Defendant TSMC and imported into the United States (Compl. ¶70). Specific examples include Omnivision sensors (e.g., OV64B, OS02C10), ONsemi sensors (e.g., AR0233, AR0521), and Sony sensors (e.g., IMX324, IMX586), which are incorporated into various consumer products (Compl. ¶61).

Functionality and Market Context

The complaint alleges that TSMC is a dedicated semiconductor foundry that manufactures these BSI sensors for its customers (e.g., Omnivision, ONsemi, Sony), who then sell them for inclusion in products sold in the U.S., such as Apple's iPhones (Compl. ¶48, 52, 59, 62-65). The complaint provides a technical paper, Exhibit E, which includes a diagram describing TSMC's BSI process flow. This process involves bonding a device wafer to a carrier wafer, thinning the device wafer from the back, and then performing surface treatments and adding components like color filters and micro-lenses (Compl. ¶51). The complaint references a schematic from this paper to illustrate the accused manufacturing process. A visual from the complaint depicts TSMC's alleged BSI process flow, showing steps of wafer bonding, thinning, and subsequent surface treatment. (Compl. ¶51, Ex. E, Fig. 1).

The complaint alleges TSMC has touted its BSI technology in numerous annual reports from 2007 through 2020, highlighting its ongoing development and mass production of increasingly advanced BSI sensors with smaller pixel sizes and improved performance (Compl. ¶48-49).

IV. Analysis of Infringement Allegations

’965 Patent Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
producing a plurality of image sensor circuits on a wafer having first and second surfaces each of the image sensor circuits being formed on the first surface... TSMC manufactures BSI sensors on device wafers, completing the "Back-End-of-Line (BEOL)" process to form the circuits. ¶51 col. 6:5-15
securing the wafer onto a protective substrate such that the first surface faces the protective substrate TSMC's process includes bonding the device wafer to a "carrier wafer" after the BEOL process is complete. ¶51, Ex. E, Fig. 1 col. 6:26-34
removing material from the second surface of the wafer until the light-sensitive pixel regions of each image sensor circuit are effectively exposed through the second surface The bonded wafer is "mechanically and chemically thinned down from the bottom side of the device wafer to the target thickness." ¶51, Ex. E, Fig. 1 col. 6:45-56
securing a transparent substrate onto the second surface of the wafer, thereby producing a waferwise sandwich After thinning, TSMC performs processes such as pad opening, color filter array, and packaging, which involves adding transparent layers to the thinned surface. ¶51, Ex. E, Fig. 1 col. 11:27-30
slicing the waferwise sandwich, thereby defining a plurality of backside illuminated image sensors The final manufactured BSI sensors are sold and imported into the U.S., which necessitates them being separated (diced) from the wafer. ¶70 col. 11:31-33
  • Identified Points of Contention:
    • Scope Questions: A central question may be whether the "carrier wafer" described in TSMC's public process documents functions as the "protective substrate" required by the claim. The defense could argue the carrier wafer is a temporary manufacturing aid, not the claimed substrate.
    • Technical Questions: The complaint's allegations are based in part on a 2010 technical paper (Compl. ¶51). A key question for the court will be whether this publicly disclosed process accurately reflects TSMC's proprietary manufacturing methods for the specific Accused Products, which were made years later.

’319 Patent Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
a semiconductor substrate having a first surface and a second surface The accused BSI sensors are built on a semiconductor substrate, referred to as the "Device wafer" in the alleged process flow. ¶51, Ex. E, Fig. 1 col. 9:3-5
a plurality of light-sensitive pixel regions formed on the first surface of the semiconductor substrate... The sensors contain pixel circuits formed on the first surface (the BEOL side). ¶48, 51 col. 9:6-10
a metal line formed adjacent the first surface of the semiconductor substrate The sensor circuits include metal lines as part of the BEOL. ¶51 col. 9:11-12
a protective substrate secured to the semiconductor substrate such that the metal line is located between the protective substrate and the semiconductor substrate The "carrier wafer" is bonded to the BEOL side of the device wafer, placing it behind the metal lines. ¶51, Ex. E, Fig. 1 col. 9:13-16
a transparent substrate secured to the second surface of the semiconductor substrate such that the semiconductor substrate is sandwiched... After thinning, layers such as color filters and micro-lenses are added to the second surface, forming the final sandwich structure. ¶51, Ex. E, Fig. 1 col. 9:17-21
wherein the semiconductor substrate has a thickness defined such that the light-sensitive pixel region is effectively exposed through the second surface. The "Device Wafer Thinning" step reduces the substrate thickness to expose the pixels to light from the back side. ¶51, Ex. E, Fig. 1 col. 11:39-42
  • Identified Points of Contention:
    • Scope Questions: The term "protective substrate" is critical. Because the ’319 patent claims an apparatus, this limitation suggests the substrate is a permanent component of the final sensor. The key question is whether the "carrier wafer" in TSMC's process is a permanent part of the accused sensors or a temporary manufacturing tool that is later removed. If it is temporary, this may support a non-infringement position.
    • Technical Questions: What is the final structure of the accused sensors? Discovery will be required to determine if they contain a distinct layer that meets the definition of a "protective substrate" located on the side with the metal lines, as distinct from the "transparent substrate" on the light-incident side.

V. Key Claim Terms for Construction

  • The Term: "protective substrate" (asserted in Claim 1 of both the ’965 and ’319 patents)
  • Context and Importance: The definition of this term is fundamental to the infringement analysis for the two earliest patents. Practitioners may focus on this term because its interpretation—whether it can be a temporary manufacturing aid or must be a permanent part of the final device—could be dispositive. The infringement theory relies on equating TSMC's "carrier wafer" with this claimed element.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The primary function described in the specification is providing structural support during the thinning process (’965 Patent, col. 4:50-51). The claims do not explicitly state the substrate must be permanent, only that it is "secured" to the wafer.
    • Evidence for a Narrower Interpretation: The ’319 patent claims an apparatus, and its figures (e.g., ’319 Patent, Fig. 5) depict the protective substrate as an integral component of the final, packaged sensor, sandwiched with the semiconductor and transparent substrates. This suggests an intent for it to be a permanent structural element, not a temporary tool.

VI. Other Allegations

  • Indirect Infringement: The complaint alleges active inducement. The factual basis includes TSMC's public statements and annual reports promoting its BSI technology, its technical publications describing the infringing processes, and its direct collaboration with customers like Sony and Omnivision to design, develop, and manufacture the accused BSI sensors for importation into the U.S. market (Compl. ¶48-53, 74, 95).
  • Willful Infringement: The complaint alleges that TSMC’s infringement was willful. For the ’965 and ’319 patents, this is based on pre-suit knowledge dating back to at least 2006, evidenced by TSMC citing these specific patents in its own patent prosecution filings (Compl. ¶72-73, 83-84). For the ’169 and ’455 patents, willfulness is based on knowledge acquired no later than December 14, 2021, the date Plaintiff filed its first lawsuit against TSMC (Compl. ¶93, 102).

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

  • A core issue will be one of claim scope and permanence: For the ’965 and ’319 patents, can the term "protective substrate" be construed to read on a temporary "carrier wafer" that may be removed during manufacturing, or must it be a permanent component of the final sensor apparatus? The resolution of this question will significantly impact the infringement analysis.
  • A second key issue will be an evidentiary one: Can Plaintiff demonstrate through discovery that TSMC's modern, proprietary manufacturing processes for the accused sensors—made years after the cited public documents—still fall within the scope of the claims, particularly for the older ’965 and ’319 patents?
  • Finally, the case will likely feature a significant dispute over willfulness: Given the allegation that TSMC cited the earliest patents-in-suit in its own patent applications over 15 years ago, a central question for the court will be whether TSMC's continued activities constituted objective recklessness, which could expose it to enhanced damages if infringement is found.