South Korean prosecutors have indicted 10 individuals for allegedly leaking memory chip manufacturing technology to Chinese chipmaker ChangXin Memory Technologies (CXMT), a move authorities say contributed to China’s progress in high-bandwidth memory (HBM), a key component for AI computing.

The Seoul Central District Prosecutors' Office announced on Tuesday that five people, including a former Samsung Electronics executive and engineers, were charged and detained for violating South Korea’s industrial technology protection law, while the other five were charged but released on bail.

Prosecutors stated that a former Samsung researcher, who was leaving to join CXMT, manually copied hundreds of steps of proprietary DRAM manufacturing processes, documenting detailed process recipes including equipment specifications, sequencing, and yield optimization. These handwritten notes were later used by CXMT to replicate the manufacturing process.

The investigation also revealed that CXMT obtained additional DRAM technology from SK Hynix through a supplier, further speeding up its development. Samsung, SK Hynix, and CXMT declined to comment. Although the prosecutors’ statement did not specify the companies, they later confirmed the names to Reuters.

The leaked technology involved 10-nanometer DRAM processes that Samsung had invested 1.6 trillion won to develop, and which Samsung was the only company to have commercialized at the time. CXMT reportedly adapted and validated the stolen data to its own equipment, achieving 10-nanometer DRAM production in 2023, marking the first time a Chinese firm reached this milestone.

Prosecutors said the misuse of this technology laid the foundation for CXMT’s HBM development, with estimated losses for companies like Samsung totaling at least tens of trillions of won. CXMT, which is planning a Shanghai listing valued at $42 billion, last month unveiled its latest DRAM generation, DDR5, directly challenging South Korean rivals.