SK hynix is ​​actively working on 400-layer NAND flash memory with plans to begin mass production by the end of 2025. The company intends to use “hybrid connection” (W2W) technology to achieve this goal. In the development process, SK hynix explores new materials and technologies for joining individual wafers, including polishing, etching, deposition and electrical assembly.

The company already demonstrated a 321-layer NAND sample in August 2023, and is now targeting a density of 400 layers. Using a hybrid wafer-to-wafer connection avoids problems associated with increasing the number of layers, such as damage to peripherals due to high temperature and pressure during cell stacking. This method involves creating cells and peripheral components on separate wafers before connecting them, which provides a stable increase in the number of layers and protects the peripheral components.

Development of the technology and infrastructure for 400-layer NAND should be completed by the end of next year. The introduction of the hybrid connection is a key step for SK hynix in solving technical problems and increasing the density of flash memory.

Achievements by other NAND semiconductor manufacturers:

• Samsung recently began mass production of 290-layer V-NAND and plans to reach over 1,000 layers by 2030.
• Micron released a 276-layer 3D NAND product in July 2024.
• Kioxia reached 218 layers in 2023 and expects to reach 1,000 layers by 2027.

These achievements indicate the industry’s continued desire to increase the density and performance of NAND flash memory, which will contribute to the further development of data storage technologies.