Chip war heats up: CXMT’s 3nm breakthrough defies US blockade

A leading Chinese memory chip maker may have achieved another technological breakthrough amid tight US trade restrictions, according to third-party analysis of a company paper delivered to an international conference.

ChangXin Memory Technologies (CXMT), China’s top dynamic random access memory (DRAM) developer, this week presented a paper to the 69th annual IEEE International Electron Devices Meeting (IEDM) in San Francisco, giving an indication of its design capabilities for gate-all-around (GAA) transistors – the most advanced transistor type for cutting-edge 3-nanometre grade chips.

While CXMT has not provided a sample product, evidence that the Chinese company has an understanding of next-generation memory chip production has grabbed the attention of industry analysts, as the design of such chips typically involves technologies that are subject to US export restrictions.

Frederick Chen, a memory chip expert at Winbond Electronics, a Taiwan-based company, said the evidence of progress by CXMT is “impressive”, as it shows that the Chinese company is not far away from state-of-the-art research and products.

“It’s significant because Samsung Electronics is trying to do the same,” Chen said.

In a statement to the South China Morning Post on Wednesday, CXMT said the paper “describes fundamental research related to DRAM structure and the feasibility of 4F2 design” and “it has nothing to do with CXMT’s current production processes”, suggesting that the design on paper is far from becoming a marketable product.

“Any accusation that CXMT is violating US sanctions or export controls is completely inaccurate,” the company’s export control experts said. “We firmly believe that the free flow of ideas that IEDM seeks to foster is essential for the industry’s innovation and development.”

CXMT said two weeks ago that it had produced China’s first lower power Double Data Rate 5 (LPDDR5) DRAM chip, narrowing its gap with leading players such as South Korea’s Samsung and SK Hynix.

Like other Chinese chip makers, CXMT is subject to broad US export restrictions targeting the country, but the company has not been added to Washington’s Entity List like Wuhan-based rival Yangtze Memory Technologies Co.

In an escalating tech war with China, the US Bureau of Industry and Security in October set an even higher export bar on a slew of gear needed for key chip manufacturing, including lithography, etching, deposition, implant and cleaning, doubling down on its efforts to cap China’s chip-making capabilities.

Founded in 2016, CXMT represents China’s best hope to catch up with South Korean memory chip giants Samsung Electronics and SK Hynix, and US-based Micron Technology, in the global DRAM market.

Dylan Patel, chief analyst at San Francisco-based semiconductor research firm SemiAnalysis, acknowledged the CXMT paper in a post on X, saying the company’s progress with the most advanced transistor architecture “breaks US sanctions”.

Patel highlighted an excerpt from the paper that states, “We have successfully fabricated the junction-less GAA [vertical channel transistor] … with a hexagonal capacitor to realise a compact … DRAM architecture.”

In August 2022, the US Commerce Department slapped export controls on four semiconductor-related technologies, including software specially designed for the development of integrated circuits (IC) with gate-all around transistor structure. These four technologies are also covered by the multilateral 1996 Wassenaar Arrangement on Export Controls for Conventional Arms and Dual-Use Goods and Technologies – of which China is not a member.

Since the imposition of controls, analysts have said that electronic design automation (EDA) software constraints would affect China’s abilities to develop advanced 3-nm process design and fabrication. But China has proved its resilience, with Huawei Technologies surprising the world with its 5G-capable Mate 60 Pro smartphone – powered by a home-grown chip – earlier this year.

CXMT has also been developing high-bandwidth memory (HBM) chips, a type of memory that has seen growing adoption for AI applications to hike data transfer speeds between memory stack and processors, the Post reported earlier.

Research on GAA dates back to 2000. GAA is considered important to the development of next-generation logic chips because it can allow continued transistor scaling, meaning packing more transistors on an IC, as leading chip-making processes at global foundries such as Taiwan Semiconductor Manufacturing Co and Samsung edge further below 3-nm.

Global memory semiconductor giant Samsung started developing GAAs in 2017 for application to the 3nm-class process, with mass production of the world’s first 3-nm GAA process in 2022, according to a Samsung tech blog published in June 2023.

The technology requires specialised EDA software, an area in which China lags behind global peers. Engineers require such software to design ICs, and the market is dominated by US-based firms Cadence Design Systems, Synopsis and Mentor Graphics.

Meanwhile, Bloomberg reported on Tuesday that CXMT is delaying its initial public offering, citing people familiar with the situation, and will instead consider raising funds at a valuation of about 140 billion yuan (US$19.5 billion), becoming the latest Chinese company to call off a debut because of volatile market conditions. South China Morning Post