However, everything changed in 1997. That year, Jos Benschop, ASML’s head of technology, reassessed whether EUV technology could be a viable option. After conducting initial tests, Benschop discovered that German company Zeiss was capable of developing the highly sophisticated mirrors required to guide the ultraviolet light. His insight proved accurate. A technological revolution began that enabled manufacturers to equip phones and computers with advanced chips.
Zeiss’ Greatest Feat
One of the most complex components of EUV lithography machines is the ultraviolet light source, which is manufactured by Cymer. Since 2013, Cymer is no longer an independent entity. That year, ASML executives acquired it to accelerate the development of technologies related to EUV lithography.
Notably, the ultraviolet light is essential for transporting the geometric patterns described by the mask. This enables them to be transferred with remarkable precision onto the surface of the silicon wafer. The mask is a physical template that contains the design of the integrated circuit to be transferred onto the silicon wafer.
Another crucial component involved in this process is mirrors. In 1997, Benschop suspected that Zeiss could produce these mirrors, which are vital for the lithography task.
The optical elements produced by Zeiss play a crucial role in lithography equipment. They’re responsible for transferring ultraviolet light with a wavelength of 13.5 nm from the emission source to the mask. The mirrors involved in the propagation of the UV light need to be manufactured with extreme precision. If not, the geometric pattern defined by the mask will be altered, potentially resulting in damaged chips.
Interestingly, the choice of the UV light wavelength for these machines was a delicate decision. Initially, engineers had four options: 13.5 nm, 11.4 nm, 6.6 nm, and 4.8 nm. The two shorter wavelengths, 6.6 nm and 4.8 nm, were ultimately discarded due to the limitations of organic photoresist materials. The 11.4 nm wavelength was also ruled out because it required the use of beryllium in the mirrors, which is a toxic chemical element.
The 13.5 nm wavelength utilizes molybdenum and silicon in the mirrors. As such, it posed no problems, making it the chosen option for UV machines. This highlights the extraordinary level of precision required in mirror manufacturing. Zeiss employs argon ions and other techniques to polish the mirrors layer by layer at the atomic level. Then, the company identifies and corrects defects using a subnanometer analysis technique. This method can detect imperfections with an accuracy of less than 1 nanometer.
Image | Daniel Pantu
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The post German Scientists Made the Impossible Possible in the 1990s: They Developed a Critical Component for Today’s Chip Manufacturing Machines appeared first on Xataka On.
