(Bloomberg) -- Huawei Technologies Co. and a secretive chipmaking partner in China have filed patents for a low-tech but potentially effective way to make advanced semiconductors, raising the prospect that China could improve chip production techniques despite US efforts to halt its progress.

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The companies are developing technologies that involve self-aligned quadruple patterning, or SAQP, and should reduce their reliance on high-end lithography, according to patent filings to the Chinese intellectual property authority. That may allow them to produce advanced chips without ASML Holding NV’s state-of-the-art extreme ultraviolet lithography equipment. Netherlands-based ASML, the sole provider of EUV machines, cannot sell them into China because of export controls.

Quadruple patterning is a technique for etching lines on silicon wafers multiple times to increase transistor density — and therefore performance. Huawei’s patent application, released on Friday, describes a method that uses the technology to make more sophisticated semiconductors. “Adoption of this patent will increase the design freedom of circuit patterns,” said the filing to China National Intellectual Property Administration.

SiCarrier, a state-backed chipmaking gear developer that works with Huawei, was granted a patent that involves SAQP, in late 2023. Its patent employs deep ultraviolet lithography, or DUV, chipmaking machines and the SAQP technology to achieve certain technical thresholds seen on 5 nanometer chips, according to its filing. The practice can avoid the use of EUV machines while reducing manufacturing cost, it said.

Quadruple-patterning technology is good enough for China to make chips at 5nm, but China still needs to get its hands on EUV machines in the long run, according to Dan Hutcheson, vice-chairman at research firm TechInsights. “It can mitigate them, but not completely overcome the technical issues of not having EUV,” he said.

Leading chipmakers like Taiwan Semiconductor Manufacturing Corp. use EUV machines to produce advanced chips because they have the highest production yields — meaning the cost per chip is minimized. If Huawei and its partners use alternative methods for semiconductor production, their cost per chip may be higher than the industry’s standards.