China is exploring the use of a new extreme ultraviolet (EUV) light source in making its own lithography facility but technology experts said such an ambitious goal may take many years to achieve.
Over the past few days articles and videos have gone viral on the Internet in China claiming that Tsinghua University has made breakthroughs in steady-state microbunching (SSMB) technology, which can create an EUV light source with a power several times higher than that of ASML’s EUV lithography.
They say the future launch of a SSMB accelerator, nicknamed “lithographic cannon,” will help China bypass the export controls of the United States and the Netherlands.
These came after Huawei Technologies on August 29 commenced the sale of its flagship smartphone Mate60 Pro, which used a 7 nanometer chip produced with Semiconductor Manufacturing International Corp (SMIC) N+2 processing technology and ASML deep ultraviolet (DUV) lithography.
“We understand that it’s difficult to have more breakthroughs in chip-processing if we follow the current technological path,” a Chongqing-based writer says in an article published by the Huxiao Business Review on September 16. “It will be more feasible to walk on a new path.”
He says Tsinghua’s suggestion to use the SSMB technology in lithography can help China break the technological blockage of ASML.
He adds that what Tsinghua proposes is not a lithography machine but a huge factory that involves a lot of land and workers – resources that China does not lack.
Bu Xiaotong, a Henan-based columnist, says in an article published on Sunday that China might not be able to make a lithography machine but it could make a lithography factory.
“An article published by Acta Physica Sinica (a Chinese academic journal) has proposed to create SSMB-EUV lithography while Tsinghua’s research has already proved the feasibility of this idea,” he says.
Citing news about China’s plan to build an SSMB facility in Xiongan New Area near Beijing, he says that with this project, if it’s successful, China can bypass the US sanctions.
Another writer says China should develop the SSMB technology because it can obtain neither the EUV lithography from ASML nor key parts needed such as lenses from German’s Zeiss and laser beam tools from the United States’ Cymer and German’s Trumpf.
How SSMB works
In 2010, Daniel Ratner and Alexander Chao, two scientists at Stanford University, first proposed the concept of SSMB. Their idea was that electrons circulating in a synchrotron are organized into small bunches that support the emission of coherent light.
In 2016, Chao and scientists from Tsinghua University and Helmholtz-Zentrum Berlin jointly started a project to do SSMB experiments at the Metrology Light Source, a synchrotron in Berlin owned by the Physikalisch-Technische Bundesanstalt.
In February 2021, Tsinghua’s Deng Xiujie and Tang Chuanxiang, Chao and other physicists jointly published an article with the title “Experimental demonstration of the mechanism of steady-state microbuching” in Nature Physics, an academic journal.
They said their experiment represents a milestone towards the implementation of an SSMB-based high-repetition, high-power photon source.
In March 2022, Tang and Deng co-wrote an article with the title “Steady-state micro-bunching accelerator light source” in Acta Physica Sinica, saying that SSMB can be used to create EUV light source for lithography.
“The realization of SSMB-EUV light source will help China’s EUV lithography achieve leapfrog development,” they say in the article. “It is expected that the SSMB accelerator light source will be used as a light source for the lithography industry and scientific research. Its performance will also continue to improve while its cost will gradually decrease.”
Currently, ASML’s EUV lithography is using a light source originating from a laser-produced plasma (LPP) source that has a maximum power of 500 watts. A ring-shaped SSMB accelerator can create an EUV light source with a power of about 1 kilowatt. Its circumference may range from 100 to 150 meters.
Another EUV light source comes from superconducting radio-frequency free electron laser (SRF-FEL), which can achieve maximum power of between 1 and 10 kW. Such a facility can stretch out for as long as 200 meters. More technological breakthroughs are needed to achieve this.
In general, the power of a laser beam should reach 250W for making 7nm chips, 350W for 5nm and 500W for 3nm. It needs 1kW to make 2nm chips.
Xiongan project
Last November, Pan Zhilong, a professor in the Department of Engineering Physics of Tsinghua University, said in a speech at the China Physics Society autumn meeting that the SSMB technology can be used in lithography.
On February 23 this year, Pan and some Hebei officials and academics held a forum to discuss SSMB-EUV. They looked for a site to build such a facility in Xiongan.
All these long-term developments have recently caught the attention of Chinese netizens, who wish to see China move on to making its own EUV lithography after the successful launch of Mate60 Pro.
However, some Chinese columnists say it’s too early to say that China can have its own EUV lithography.
A Shanghai-based writer says that, even if China has a SSMB accelerator, it still needs a lot of efforts in making lenses and work platforms for lithography. He says SSMB for the moment would better be used for research on high-energy particle collisions.
Read: US curbs on TSMC ex-engineer Liang ‘won’t hurt SMIC’
Follow Jeff Pao on Twitter at @jeffpao3