| 摘要: | 極紫外光(EUV)反射鏡對於反射率的要求極高，在使用過程中會因為污染造成反射率下降，生產良率也會大幅下降，為了維持良好的反射鏡品質，將碳汙染、錫汙染、表面氧化層及蝕刻時所造成的碎片清理乾淨，需使用氫離子對反射鏡表面做清潔，由於氫離子轟擊時間拉長會讓反射鏡表面產生氣泡，使反射鏡受到損壞造成反射率降低，因此本論文探討極紫外光反射鏡覆蓋層對於氫離子轟擊後的結果。
本研究使用離子束濺鍍機在Si基板上鍍製B4C/Mo/B4C/Si多層膜，固定每個材料的離子束電壓電流，利用原子力顯微鏡分析表面粗糙度並代入X射線反射儀做初步的薄膜厚度判斷，再利用高解析掃描穿透式電子顯微鏡互相交叉比對分析，改變鍍膜時間，即可獲得較高的反射率，使用EUV反射儀量測到在19°入射時獲得51.6%的反射率。
由於覆蓋層會因為EUV曝光機運作時，受到高能輻射汙染造成表面氧化，以及在清潔時造成的氫起泡，有文獻提到氧化物覆蓋層具有良好的抗氧化性和抗氫能力。因此本研究在反射鏡完成後，使用原子層沉積系統在鏡面上鍍製氧化物覆蓋層，利用氫離子源固定電壓電流在不同時間轟擊下，利用掃描式電子顯微鏡、原子力顯微鏡以及高解析穿透式電子顯微鏡進行量測分析，觀察反射鏡表面形貌及粗糙度以及剖面狀況。;Extreme ultraviolet (EUV) reflectors require exceptionally high reflectivity. However, during usage, contaminants can reduce reflectivity, significantly affecting production yield. To maintain high-quality reflectors, it is essential to remove carbon contamination, tin contamination, surface oxidation layers, and etching debris. This can be achieved by cleaning the mirror surface with hydrogen ions. Prolonged hydrogen ion bombardment can cause bubbles on the mirror surface, leading to damage and reduced reflectivity. Therefore, this paper investigates the effects of hydrogen ion bombardment on EUV mirror capping layers.
In this study, a B4C/Mo/B4C/Si multilayer film was deposited on a Si substrate using an ion beam sputtering machine. The ion beam voltage and current for each material were fixed. Surface roughness was analyzed using an Atomic Force Microscope, and preliminary film thickness was determined with an X-Ray Reflectivity. Cross-analysis was performed using a High-Resolution Scanning Transmission Electron Microscope. By adjusting the deposition time, higher reflectivity was achieved. Measurements using an EUV Reflectometer showed a reflectivity of 51.6% at a 19° incident angle.
Due to the high-energy radiation exposure during the operation of EUV lithography machines, the capping layer can be contaminated, leading to surface oxidation and hydrogen bubbles during cleaning. Literature indicates that oxide capping layers exhibit good oxidation resistance and hydrogen resistance. Therefore, in this study, an oxide capping layer was deposited on the mirror surface using an Atomic Layer Deposition system after the reflector was completed. The mirrors were subjected to hydrogen ion bombardment at a fixed voltage and current for various durations. Scanning Electron Microscopy, Atomic Force Microscopy, and High-Resolution Transmission Electron Microscopy were used to measure and analyze the surface morphology, roughness, and cross-sectional conditions of the mirrors. |
