Huawei’s 2022 patent details novel technique to make 2-nm-class chips without EUV tool

Huawei Technologies’ three-year-old patent for advanced patterning comparable with 2-nanometre grade technology without extreme ultraviolet (EUV) lithography tools has intensified speculation about a potential breakthrough in advanced chips.\nThe US-sanctioned company is working to patent a metal integration technique for manufacturing semiconductors, which allows narrow metal structures to be integrated using deep ultraviolet (DUV) technology even for “metal pitches below 21nm”, a feature required for 2nm-class chips.\nThe proposed solution offered a technical pathway to support a 2-nm process using older DUV technology, aiming to bypass US sanctions that block China’s access to the most advanced EUV tools from Dutch firm ASML.\nThe patent, currently pending, was originally submitted by Huawei in June 2022 and made public by China’s national intellectual property regulator in January this year. There is no evidence that the patent has been put to use.\nAmid growing talk of China’s tech breakthroughs, a Chinese chip industry veteran argued that 14-nm logic chips could rival the performance of Nvidia’s 4-nm chips through integration with advanced memory and novel architecture.\nHuawei declined to comment on the patent.\n\nHowever, the patent has grabbed industry attention as it opens the possibility of overcoming a key obstacle to match Taiwan Semiconductor Manufacturing Company (TSMC)’s 2-nm process. TSMC’s process is considered the most advanced in the world, although the technology has yet to be used for mass production.\nAdvanced lithography technology is essential for high-end chipmaking. It has proved to be a bottleneck for China’s ambitions, as the country is restricted from acquiring ASML’s top DUV and EUV systems due to US curbs.\nHuawei’s solution, using a variation of self-aligned quadruple patterning (SAQP), employed an advanced “spacer-defined patterning” scheme with dual hard-mask materials to allow the creation of two sets of interwoven metal lines, reducing reliance on ultra-tight lithographic overlay.\nIt remains to be seen whether the complicated method, which requires more steps than EUV lithography, can work and achieve commercially viable yields for large-scale production.\nThe patent is part of Huawei’s ongoing efforts to seek breakthroughs in semiconductors, as the US-blacklisted company has been cut off from accessing advanced technologies, including high-end chips and tools needed to produce them.\nIn recent years, the Shenzhen-based company has submitted patents related to post-2-nm technologies, including 20 patents in 2023 on gate-all-around, a cutting-edge transistor for the 2-nm process, according to a report by Nikkei Xtech, which cited data from the Japanese patent analysis platform Patentfield.\nThere were also records for a complementary field-effect transistor, which is used for process nodes beyond 1nm, the report said.\nHuawei has also seen a spike in patent applications for graphics processing units (GPUs) – the backbone for artificial intelligence development.\nIn 2023, Huawei filed 3,091 GPU-related patents – a tenfold increase from 2018. This total was also three times that of Intel and five times that of Nvidia.\nA patent application filed by Huawei in September 2021, but made public last year, outlined the use of SAQP to “increase the design freedom of circuit patterns”. The process is similar to a patent granted to SiCarrier, a state-backed chip tool developer affiliated with Huawei.\nSiCarier’s patent describes making chips on a 5-nm process node using DUV tools, the Post reported last year.\n