Corning has introduced a brand new ultra-low expansion (ULE) material designed to meet the demands of the upcoming low-NA and high-NA EUV lithography systems. This innovative Extreme ULE glass is expected to become the preferred choice for the next-generation photomasks and lithography mirrors in future fabrication tools.
Exceptional Features
The standout characteristic of Extreme ULE is its remarkably low thermal expansion, which ensures outstanding stability for photomask applications. Additionally, its flatness helps combat the annoying issue of "photomask waviness," reducing unwanted variations during chip production. Thanks to these qualities, advanced pellicles and photoresists can be employed to boost yields and enhance performance.
Handling Heat
EUV lithography systems utilize a plasma source to produce extremely intense EUV light, generating significant heat in the process. However, most of this heat remains contained within the source chamber, away from the photomask. The EUV light is directed towards the photomask using sophisticated lithography mirrors, which can be quite sensitive to temperature changes.
Photomask Composition
Photomasks are constructed from multilayer reflective materials that are highly efficient at reflecting EUV radiation. While they excel at reflecting light, they still absorb a small portion of the EUV energy, resulting in a slight increase in thermal load on the photomask.
As EUV tools enhance their capabilities and process a greater number of wafers per hour (WPH), they introduce more powerful light sources. This leads to pellicles, photomasks, and photoresists being exposed to elevated levels of EUV radiation and heat. Corning's Extreme ULE glass, an evolution of the traditional ULE family, offers remarkable thermal stability and uniformity—exactly what next-gen high-NA and upcoming low-NA EUV tools require.
Future Innovations
"As the needs of integrated chip manufacturing increase with the growth of artificial intelligence, the innovation in glass is crucial," stated Claude Echahamian, Vice President & General Manager, Corning Advanced Optics. "Extreme ULE Glass will enhance Corning's essential role in the ongoing journey of Moore's Law by facilitating higher-powered EUV manufacturing and improved yields."
