ExactoJoin LLC v. Twinhead Intl Corp

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: ExactoJoin LLC (New Mexico)
  • Defendant: Twinhead International Corporation (Taiwan)
  • Plaintiff’s Counsel: Rabicoff Law LLC
• Case Identification: 2:26-cv-00838, E.D. Tex., 09/17/2026
• Venue Allegations: Venue is asserted based on the defendant being a foreign corporation and allegations that it has committed acts of patent infringement within the district.
• Core Dispute: Plaintiff alleges that Defendant’s unspecified products infringe a patent related to compact semiconductor memory device architecture.
• Technical Context: The lawsuit concerns the design of semiconductor memory, such as DRAM, focusing on methods to increase density and reduce manufacturing complexity by minimizing the number of electrical contacts required in a memory array.
• Key Procedural History: The asserted patent claims priority from a chain of applications dating back to 2007, indicating a long development and prosecution history for the underlying technology. The complaint does not mention any prior litigation, inter partes review proceedings, or licensing history related to the patent-in-suit.

Case Timeline

Date	Event
2007-11-29	'581 Patent Priority Date
2014-02-11	'581 Patent Application Filing Date
2015-04-07	'581 Patent Issue Date
2026-09-17	Complaint Filing Date

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

U.S. Patent No. 9,001,581 - Compact semiconductor memory device having reduced number of contacts, methods of operating and methods of making

• Patent Identification: U.S. Patent No. 9,001,581, titled “Compact semiconductor memory device having reduced number of contacts, methods of operating and methods of making,” issued on April 7, 2015. Compl. ¶9

The Invention Explained

• Problem Addressed: The patent’s background section identifies a "continuing need for semiconductor memory devices that are smaller in size than currently existing devices." ’581 Patent, col. 2:10-12 It notes the difficulty of scaling conventional one-transistor, one-capacitor (1T/1C) DRAM cells due to the need to maintain capacitance values. ’581 Patent, col. 1:63-66
• The Patented Solution: The invention describes a semiconductor memory device that uses an "electrically floating body" transistor to store data, which eliminates the need for a separate capacitor. ’581 Patent, col. 1:66-68 ’581 Patent, col. 11:25-27 To further increase density, the patent discloses connecting multiple memory cells in series to form a "string" or in parallel to form a "link." ’581 Patent, col. 17:19-24 This architecture reduces the total number of electrical contacts required to access the memory array, as intermediate cells in the string or link can be "contactless." ’581 Patent, abstract ’581 Patent, col. 17:25-34
• Technical Importance: This approach of creating "contactless" memory cells arranged in strings aims to overcome a key manufacturing challenge, allowing for smaller, more densely packed memory arrays. ’581 Patent, col. 17:1-15

Key Claims at a Glance

• The complaint does not identify any specific claims, instead referring to "one or more claims" and "Exemplary '581 Patent Claims" identified in an unprovided exhibit. Compl. ¶11 Compl. ¶16
• As a representative example, independent claim 10 recites:
  • A semiconductor memory device comprising a plurality of semiconductor memory cells;
  • A first contact and a second contact configured to electrically connect the memory cells to respective first and second control lines;
  • The plurality of memory cells being "directly connected to one another" such that at least one of the cells is not directly connected to the contacts; and
  • Wherein at least one of the cells comprises a "floating body region" to store data as charge. ’581 Patent, col. 49:4-21

III. The Accused Instrumentality

Product Identification

• The complaint does not identify any specific accused products by name. It refers generally to "Exemplary Defendant Products" that are purportedly identified in charts attached as Exhibit 2. Compl. ¶11 This exhibit was not provided with the complaint document.

Functionality and Market Context

• The complaint does not provide sufficient detail for analysis of the accused instrumentality's functionality or market context. It makes only general allegations that Defendant makes, uses, sells, and imports infringing products. Compl. ¶11

IV. Analysis of Infringement Allegations

The complaint alleges that the "Exemplary Defendant Products" infringe the "'581 Patent Claims' literally or by the doctrine of equivalents." Compl. ¶11 It states that infringement allegations are detailed in claim charts provided as Exhibit 2. Compl. ¶16 Compl. ¶17 As Exhibit 2 was not provided, a detailed analysis of the plaintiff's infringement theory is not possible. No probative visual evidence provided in complaint.

• Identified Points of Contention: Based on the technology and the exemplary claim language noted in Section II, the infringement analysis may raise several technical and legal questions for the court:
  • Scope Questions: A central issue may be the construction of the phrase "directly connected to one another" as it applies to the memory cells. The resolution of this issue will bear on whether the defendant's memory array architecture, whatever it may be, falls within the scope of the claims.
  • Technical Questions: A key question of fact will be whether the accused devices utilize the specific technology of an "electrically floating body region" for data storage, as required by the claims. ’581 Patent, col. 49:18-21 The case may turn on evidence demonstrating whether the accused products operate on this principle or use a different, non-infringing data storage mechanism.

V. Key Claim Terms for Construction

The complaint provides no basis for an analysis of specific claim terms that may be in dispute. However, based on the technology described in the ’581 Patent and the representative claim language of claim 10, the following terms may become central to the case.

• The Term: "contactless semiconductor memory cell"

  • Context and Importance: This term is explicitly defined in the patent and appears to be a cornerstone of the invention. Practitioners may focus on this term because the plaintiff's infringement case may depend on classifying certain components of the accused products as "contactless."
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The patent provides a functional definition: "a memory cell which does not have a contact (or contacts) forming a direct connection(s) to a control line (or control lines)." ’581 Patent, col. 10:62-65 A party could argue that any cell lacking such a direct physical contact structure meets this definition, regardless of its specific implementation.
    • Evidence for a Narrower Interpretation: A party might point to the detailed embodiments, such as the memory string in FIG. 16A, to argue that the term implies a specific series-connected NAND architecture where intermediate cells are physically and electrically situated between two end cells that do have contacts. ’581 Patent, Fig. 16A ’581 Patent, col. 17:49-55

• The Term: "floating body region configured to store data"

  • Context and Importance: This term defines the core data-storage mechanism. An infringement finding may require proof that the accused devices use this specific physical phenomenon.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specification describes the floating body effect in general terms, noting that memory states are represented by the "charge in the floating body 24." ’581 Patent, col. 12:7-9 This could support an interpretation covering any device that stores charge in a region that is electrically floating.
    • Evidence for a Narrower Interpretation: The detailed description explains the operation via specific physical mechanisms, such as hole accumulation and the resulting change in the transistor's threshold voltage. ’581 Patent, col. 12:10-16 A party could argue that the term is limited to devices that operate using these specific bipolar effects and excludes other forms of charge storage.

VI. Other Allegations

• Indirect Infringement: The complaint alleges induced infringement, stating that Defendant sells products to customers and distributes "product literature and website materials" that instruct end users on how to use the products in a manner that allegedly infringes the ’581 Patent. Compl. ¶14 Compl. ¶15
• Willful Infringement: The complaint alleges that service of the complaint itself constitutes "actual knowledge of infringement." Compl. ¶13 It further alleges that despite this knowledge, Defendant "continues to make, use, test, sell, offer for sale, market, and/or import" infringing products, which may form the basis for a claim of post-suit willful infringement. Compl. ¶14 No allegations suggest pre-suit knowledge.

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

This case appears to be in its earliest stages, with the complaint providing minimal factual detail. The central questions for the court will likely be:

• A primary evidentiary question: What are the specific accused products, and what is their precise physical architecture and principle of operation? The current complaint lacks the necessary detail to adjudicate the claims, and this information will be critical as the case proceeds.
• A question of claim construction: Can the patent’s term "contactless semiconductor memory cell," which is explicitly defined in the specification, be applied to the architecture of the yet-unidentified accused products? The outcome of this construction will likely be dispositive for infringement.
• A fundamental technical question: Do the accused devices operate using the "floating body" charge storage mechanism described and claimed in the ’581 Patent, or do they rely on a different technology? A mismatch in the underlying physics of operation could present a significant hurdle for the plaintiff’s infringement case.