Yangtze Memory Technologies Sues Micron for Patent Infringement, Demands Halt in Sales and Patent Fees

Semiconductor manufacturer Yangtze Memory Technologies Co., Ltd. (YMTC) has recently filed a patent lawsuit against Micron Technology in the United States District Court for the Northern District of California. YMTC accuses Micron of using 11 of its patented technologies without authorization. These patents concern various aspects of 3D NAND flash memory chips.

YMTC is requesting the court to order Micron to cease the sale of its memory products in the U.S. market and to pay YMTC for the use of its patents.

In court documents, YMTC claims that Micron's 96-layer (B27A), 128-layer (B37R), 176-layer (B47R), and 232-layer (B58R) series of 3D NAND flash memory chips, as well as certain Micron DDR5 SDRAM memories (Y2BM series), infringe on 11 patents or patents pending.

The eight patents cited by YMTC in the court documents include:

• US10950623: 3D NAND memory device and its manufacturing method
• US11501822: Non-volatile storage device and its control method *(application submitted but not yet approved)
• US10658378: Through array contact (TAC) for three-dimensional memory devices
• US10937806: Through array contact (TAC) for three-dimensional memory devices
• US10861872: 3D memory device and its manufacturing method
• US11468957: NAND memory architecture and method *(application submitted but not yet approved)
• US11600342: Read timing for 3D memory devices *(application submitted but not yet approved)
• US10868031: Multi-stack 3D memory device and its manufacturing method

In 2022, the U.S. Department of Commerce added YMTC to its export control list, prohibiting U.S. tech companies or foreign companies using U.S. technology from providing any software, hardware, or other services containing U.S. technology to YMTC. This has hindered YMTC's progress in developing memory chips.

Despite these restrictions, YMTC has successfully developed advanced 3D NAND chips, including its mass-produced Xtacking 3.0 and the under-development Xtacking 4.0 3D NAND flash memory chips.

Moreover, YMTC has revealed that it has significantly improved the durability of its 3D QLC NAND chips to match the level of 3D TLC NAND, achieving 4000 program/erase cycles. This significantly enhances the lifespan and isolation of QLC, aiding in the mass-market introduction of QLC solid-state drives.