應用於極紫外光波段之柱狀多層膜反射鏡

High-reflective Cylindrical-nanostructure Multilayer Mirrors for Extreme Ultraviolet Radiation

王志中(Chih-Chung Wang)；李昭德(Chao-Te Lee)；李佳翰(Jia-Han Li)

科儀新知

240期（2024 / 09 / 30）

30 - 34

繁體中文;英文

目前的半導體製造流程中使用極紫外線（extreme ultraviolet, EUV）技術，並且通常設計和使用鉬（Mo）和矽（Si）多層膜作為反射鏡。我們提出了利用圓柱形鉬（Mo）和矽（Si）的混合結構多層，每層矽柱體都有空氣空間，我們稱之為多層柱面鏡，可以應用於目前的半導體製程製造。因此，這導致每層矽柱體中的折射率增加並降低消光係數，並且其導致多層堆疊內相長干涉的增強。根據使用時域有限差分方法的數值模擬結果，我們提出的多層柱面鏡的反射率可以從傳統40週期Mo/Si多層的74.5%提高到76.6%。由於EUV微影中通常需要8至12個反射鏡，因此我們在本研究中提出的設計有潛力用作EUV輻射的高反射率反射鏡，並在相同的EUV光源下有機會提高晶片產量。

In the current semiconductor manufacturing process, extreme ultraviolet (EUV) technology is employed, and molybdenum (Mo) and silicon (Si) multilayer films are typically designed and used as mirrors. We propose using a hybrid multilayer structure of cylindrical Mo and Si with air spaces in each Si layer, referred to as multilayer cylindrical mirrors, which can be applied in the existing semiconductor manufacturing process. This design increases the refractive index in each Si layer and reduces the extinction coefficient, enhancing constructive interference within the multilayer stack. According to numerical simulations using the finite-difference time-domain (FDTD) method, the reflectivity of our proposed multilayer cylindrical mirrors can be increased from 74.5% in traditional 40-cycle Mo/Si multilayers to 76.6%. Given that EUV lithography typically requires 8 to 12 mirrors, the design we propose in this study has the potential to serve as high-reflectivity mirrors for EUV radiation, potentially increasing wafer throughput under the same EUV light source.