New EUV lithography technology is introduced: achieving significant cost reduction and efficiency improvement

Recently, Professor Tsumoru Shintake from Okinawa University of Science and Technology (OIST) proposed a revolutionary extreme ultraviolet (EUV) lithography technology that not only surpasses the boundaries of existing semiconductor manufacturing, but also heralds a new chapter in the industry's future.

This innovation significantly improves stability and maintainability, as its simplified design only requires two mirrors and a light source of only 20W, reducing the total power consumption of the system to less than 100kW, which is only one tenth of the power consumption of traditional technologies (typically requiring over 1MW (=1000kW) to operate). The new system maintains a very high contrast while reducing mask 3D effects, achieving nanometer level accuracy required for accurate transmission of logic patterns from photomasks to silicon wafers.

The core of this innovation lies in the use of more compact and efficient EUV light sources, significantly reducing costs while greatly improving the reliability and lifespan of the equipment. What is particularly noteworthy is that its power consumption is only one tenth of that of traditional EUV lithography machines, paving the way for the green and sustainable development of the semiconductor industry.

The key to this technological breakthrough lies in solving two long-standing problems that have plagued the industry: firstly, designing a minimalist and efficient optical projection system consisting of only two carefully configured mirrors; The second is the development of a new method that can accurately guide EUV light to the logical pattern area on the plane mirror (light mask) without obstruction, achieving unprecedented optical path optimization.

Challenges faced by EUV lithography
The processors that make artificial intelligence (AI) possible, low-power chips for mobile devices such as smartphones, and chips for high-density DRAM memory - all of these advanced semiconductor chips are manufactured using EUV lithography technology.

However, the production of semiconductors faces issues of high power consumption and equipment complexity, which greatly increases the costs of installation, maintenance, and power consumption. And Professor Tsumoru Shintake's technological invention is a direct response to this challenge, which he calls a breakthrough achievement that "almost completely solves these hidden problems".

The traditional optical system relies on the symmetrical arrangement of lens and aperture to achieve the best performance, but the particularity of EUV light - extremely short wavelength and easy absorption by materials - makes this mode no longer applicable. EUV light needs to be reflected by a crescent shaped mirror and meanders through open space, sacrificing some optical performance. And OIST's new technology, through a linearly arranged axisymmetric dual mirror system, not only restores excellent optical performance, but also greatly simplifies the system structure.

Significant reduction in power consumption
Due to the fact that EUV energy is attenuated by 40% during each specular reflection, only about 1% of EUV light source energy reaches the wafer through the use of 10 mirrors according to industry standards, which means a very high EUV light output is required. To meet this demand, CO2 lasers that drive EUV light sources require a large amount of electricity and cooling water.

By contrast, by limiting the number of mirrors to only four in total from the EUV light source to the wafer, more than 10% of the energy can be transferred, meaning that even small EUV light sources of several tens of watts can work effectively. This can significantly reduce power consumption.

Overcoming two major challenges
Compared with existing industry standards, the OIST model demonstrates significant advantages with its streamlined design (only two mirrors), extremely low light source requirements (20W), and less than one tenth of the total power consumption of traditional technologies (less than 100kW). This innovation not only ensures pattern transmission with nanometer level accuracy, but also reduces the 3D effect of masks, improving overall performance.

Of particular note is that by reducing the number of mirror reflections to four, the new system has achieved an energy transfer efficiency of over 10%, allowing even small EUV light sources to operate efficiently and significantly reduce power consumption. This achievement not only reduces the burden of CO2 lasers, but also reduces the demand for cooling water, further reflecting the concept of environmental protection.
Professor Tsumoru Shintake also created the "dual line field" illumination optical method, which cleverly solves the problem of optical path interference and achieves precise pattern mapping from photomask to silicon wafer. He likened it to adjusting the angle of a flashlight to illuminate a mirror in the best way possible, avoiding light collisions while maximizing lighting efficiency, showcasing his extraordinary creativity and wisdom.

Source: OFweek