Yangtze Memory Technologies Co (YMTC), China’s leading flash memory chipmaker, has published nearly 20 new patents for processes that can boost computing efficiency and optimise chip-stacking structures, in a show of technological prowess, according to records from the country’s intellectual property agency.

YMTC is known for its design and fabrication of 3D NAND, a flash memory in which transistor dies are stacked vertically to increase storage density. Patent applications made public in late March include an improved stacking structure to resist potential deformation, a way to shield from electromagnetic interference, and a method to boost storage density, according to records posted on the website of the China National Intellectual Property Administration.

Several of the innovations involve software optimisation. For example, one patent titled “a memory system and a method of operating the memory system” innovates the way a flash memory refreshes data, thus “reducing the frequency of erasing the memory device, delaying the wear-out failure of the memory device and, to some extent, expanding the service life of the memory system”, according to the application.

The patents, applied for between 2021 and 2023, were all “published” on March 28.

You Yunting, a senior partner at Shanghai Debund Law Firm, said that the patent examination would take about a year in the best case. “Three years is also normal. In more complex cases, four or five years is possible,” You said.

The disclosure of the YMTC patents comes as China is making significant progress in building up its semiconductor self-sufficiency amid US technology restrictions.

Huawei Technologies last month disclosed a September 2023 patent application in ternary logic for the design of integrated circuits, while SiCarrier, a chip tool maker backed by Huawei, demonstrated its capabilities by unveiling a series of new products during last month’s Semicon China exhibition.

Privately-held YMTC maintains a low profile even though it is closely watched by global competitors such as South Korea’s Samsung Electronics and SK Hynix, the firms which still lead the global memory market.

Samsung reportedly plans to use a hybrid bonding patent from YMTC for its next-generation NAND chip, which would be mass-produced in the second half of the year, according to a February report by ZDNet Korea.

YMTC is a leader in the hybrid bonding technology known as Xtacking. Its first patent in this field, which was able to “achieve higher storage density, simpler fabrication processes, and less [write-and-erase] cycle time”, was made public in 2021, and became effective in 2023, according to China’s intellectual property authority.

YMTC was added to Washington’s Entity List in 2022, a trade blacklist that restricts it from dealing with American suppliers. It was also added to the US Defence Department-administered 1260H list, rendering it ineligible for defence-related contracts.

By: DocMemory
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