| 摘要: | 極紫外光微影技術為尋求高產能、高良率的方向前進，然而由於吸收層的設計上存在著一定的問題，吸收層幾乎決定了設計圖案的解析度以及線寬的大小， 加上很難以將反射率真正的降低至趨近於0，並且在線寬越來越小的半導體製程上，若有任何一點反射層與吸收層的光產生非破壞性的干涉，都會導致整體圖案的偏差，因此本論文主要探討吸收層的材料和結構如何選擇和設計。
本論文使用離子束濺鍍法在矽基板上鍍製B4C/Mo/B4C/Si 共40堆的週期性多層極紫外反射鏡，在離子束參數的選擇上沿用了過往的研究，固定Mo 400V 50mA、Si 500V 30mA、B4C 700V 40mA的離子束參數進行製程，並量測AFM、XRR和TEM判斷其薄膜結構、量測EUV反射率，並以此為基底在最上層疊加設計之吸收膜堆。
選定吸收層材料鎳和鋁後，使用macleod結合IMD去進行膜堆的設計，並在選定適當的膜堆設計及厚度後，分別討論此兩種材料於不同離子束參數下的光學特性與結構變化，利用光譜儀確認其反射率，結合macleod分析其光學常數與薄膜結構，透過AFM探究其表面形貌隨離子束參數的改變。最後選定最佳的離子束參數。
接著以此參數在先前確定的反射層結構上鍍製設計好的吸收膜堆，並利用AFM、XRR和TEM探討其薄膜結構，並量測EUV反射率，最後藉由比堆含吸收層和無吸收層之反射率結果，研究此新吸收層材料與結構的可行性。
;Extreme ultraviolet (EUV) lithography is progressing toward higher throughput and yield. However, the design of the absorber layer presents certain challenges, as it largely determines the resolution and critical dimension (CD) of the patterned structures. Moreover, achieving near-zero reflectivity from the absorber is extremely difficult. In advanced semiconductor manufacturing, where line widths continue to shrink, even minor non-destructive interference between the reflective and absorber layers can result in significant patterning deviations. Therefore, this study focuses on the selection and design of absorber materials and structures.
In this work, periodic EUV multilayer mirrors consisting of 40 bilayers of B₄C/Mo/B₄C/Si were deposited on silicon substrates using ion beam sputtering. The ion beam parameters were adopted from previous studies, with Mo deposited at 400V 50mA, Si at 500V 30mA, and B₄C at 700V 40mA. The resulting film structures were characterized using atomic force microscopy (AFM), X-ray reflectivity (XRR), and transmission electron microscopy (TEM). EUV reflectivity measurements were also conducted. The designed absorber stack was then deposited on top of the multilayer structure.
Nickel and aluminum were selected as candidate absorber materials. The multilayer absorber designs were developed using a combination of Macleod and IMD simulation software. After determining the optimal layer structures and thicknesses, the optical and structural properties of both materials were investigated under various ion beam parameters. Reflectivity measurements were performed using a spectrophotometer, and the optical constants and film structures were analyzed with Macleod. AFM was employed to examine the evolution of surface morphology with changing ion beam parameters. The optimal deposition conditions were then selected based on these results.
Finally, using the optimized parameters, the absorber stack was deposited on the previously confirmed reflective multilayer structure. The resulting films were analyzed by AFM, XRR, and TEM to evaluate their morphology and structural integrity. EUV reflectivity was measured, and by comparing the reflectivity of samples with and without the absorber layer, the feasibility of the newly developed absorber materials and structures was assessed. |
