How China’s award-winning EUV breakthrough sidesteps US chip ban
And one such project from the Harbin Institute of Technology was recently awarded first prize at the Harbin Provincial Innovation Achievement Transformation Competition for employees in universities and research institutes on December 30.
The research team took a completely different technological approach from Western methods to generate EUV laser light.
According to the institute’s website, the “discharge plasma extreme ultraviolet lithography light source” project, led by Professor Zhao Yongpeng from the school of aerospace engineering, “boasts high energy conversion efficiency, low cost, compact size and relatively low technical difficulty”.
“It can produce extreme ultraviolet light with a central wavelength of 13.5 nanometres, meeting the urgent demand for EUV light sources in the photolithography market,” the official report said.
In the semiconductor industry, the most complex and difficult-to-manufacture machine is the photolithography machine.
ASML’s EUV light source relies on using high-energy lasers to bombard liquid tin droplets, creating plasma in a process known as the laser-produced plasma (LPP) method. This process involves high-energy laser components and complex FPGA chip control, with the core technology long dominated by foreign companies.
Zhao’s team, on the other hand, uses the laser-induced discharge plasma (LDP) method, where a laser first vaporises a small amount of tin into a cloud between two electrodes. A high voltage is then applied across the electrodes to inject energy, converting the tin cloud into plasma. The resulting electrons and high-valence tin ions frequently collide and radiate, generating EUV light.
Compared with LPP technology, the LDP method is simpler, more cost-effective and directly converts electrical energy into plasma with higher energy utilisation efficiency.
However, optimising the parameters and timing of discharge pulses remains a significant technical challenge. Some also have concerns that LDP might struggle with power output limitations.
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EUV research is also being conducted by other Chinese teams, with multiple approaches being adopted.
A team from the Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, published details of its work in the LPP method in December 2023 in the journal Laser & Optoelectronics Progress.
Meanwhile, Professor Xuan Hongwen’s team at the Guangdong Bay Area Aerospace Information Research Institute published research in April 2023 in the Chinese Journal of Lasers, focusing on enhancing LDP EUV light output power and conversion efficiency.
Beyond the core light source system, manufacturing a complete lithography machine also requires high-precision components, such as mirrors.
In January 2024, Professor Zhao’s research group, in collaboration with a team led by Zhang Junyong at the Shanghai Institute of Optics and Fine Mechanics, made advances in controlling and focusing EUV light.