Chinese memory fab YMTC (Yangtze Memory Technologies) won injunction rulings in Munich against Micron over 3D NAND patents in an ongoing three-year cross-border dispute.

A German court has granted injunctions against Micron Technology, marking a significant win for YMTC in their 3-year legal battle over 3D NAND memory patents. On September 18, the court ruled that Micron infringed YMTC's patented 3D NAND technology in two instances. The injunctions could restrict Micron's supply in Germany and impact the broader European NAND market. Micron has disagreed with the ruling and already filed an appeal, while also challenging the validity of the related patents in separate legal cases across multiple countries.

YMTC filed the lawsuit at Munich's Regional Court in late 2025, opening five cases involving four German utility models and one European patent. The court granted injunctions on two utility models—DE202020006166U1 (case 7O12615/25) and DE202021004551U1 (case 12614/25)—each with 10-year protection periods, and adjourned the others. These injunctions are first-instance rulings that can be suspended if Micron successfully appeals to the Munich Higher Regional Court.

The ruling represents the latest escalation in a dispute that began in 2023, when YMTC sued Micron in California over alleged violations of eight 3D NAND architecture patents. The conflict has since expanded into a multi-front legal war spanning over 20 patents. Suits and countersuits cover patent infringement, declaratory judgment, spyware, libel, false advertising, and invalidation actions, with cases filed across China, the United States, the United Kingdom, Germany, and other European jurisdictions.

Micron has consistently denied any wrongdoing and has filed multiple patent invalidation challenges since 2024, following YMTC's court action against the company in China. Seven of the disputed patents have already been declared invalid, and Micron says it will continue defending its intellectual property.

3D NAND is a flash-memory storage technology used in smartphones, solid-state drives, and enterprise storage systems. Unlike traditional planar NAND, where memory cells are arranged side-by-side on a flat surface, 3D NAND stacks cells vertically in multiple layers. This enables manufacturers to pack greater storage capacity into a given footprint while increasing density and lowering cost per bit. Modern NAND chips can contain hundreds of these layers, making the underlying architecture and manufacturing techniques commercially valuable intellectual property.

The Micron-YMTC dispute unfolds against the broader U.S.-China technology competition. Washington has tightened restrictions on China's access to advanced semiconductor manufacturing equipment and other chip technologies, while Beijing has placed export restrictions on critical raw materials.