本論文旨在於建構一多尺度的分析方法可以容易地跨越傳統分子動力學法所能描述的系統大小，並搭配分子動力學法一併來研究奈米壓印/滾印製程的相關成形機制。在多尺度法的建構上，此法偶合了連續體和分子理論，其中連續體的部份是以單位晶格的形式作為放大基礎，再以能量的觀點配合最速下降法(Steeptest Descent Method)擬合出粗粒子的勢能參數。由於系統中分佈著不同大小的粒子，故我們把此法稱為多重粒子法(Multi-particle Method)，此法的粗粒子適合被應用於非特徴區域或遠離大變形的區域來節省數值運算時間。在本研究的測試中，單單以四倍晶格的粒子來描述時，計算效率比傳統分子動力學法高出108倍左右，而且此法的計算效率也比近來熱門的多尺度法-準連續法更好。為了因應大變形的情況，以應變的方式作定義，系統可以自動判別作細緻化的時機，依照需要和形狀函數的計算，最小可以細化到原子等級，以精確地描述材料局部特徵和缺陷傳遞行為。
奈米壓印探討的薄膜材料有金屬(Au)和高分子(PMMA)兩種，藉由變化模具尺寸、模穴大小和材料排列方向等參數再搭配壓印和拔模過程中的力-位移曲線、粒子軌跡、應力場與滑移場可以更清楚解析奈米壓印的成形機制與力學行為。在壓印金屬薄膜上，發現臨界影響範圍和模具壓深、模具尺寸成一正比的關係，特別於Z軸(平行於壓印方向)的敏感程度更大於X軸(垂直於壓印方向)。而在相同壓深下，當模穴寬度越大，材料的填充高度較高，填充密度變低。在壓印PMMA薄膜上，發現當PMMA分子鏈排列方向平行於壓印方向時所需的壓印力較少，壓印出來的圖案形狀比較完美。本研究也於模具表面上運用一強烈表面吸附勢能來模擬自組式單分子層的化學吸附行為。發現加入自組式單分子層會大大地降低圖案分子的缺陷程度和界面黏著力，使壓印後的圖案更平滑。在力學機制上，除了如實驗證明出可以有效地減少界面黏著力外，在模具施載過程中，模具受薄膜的正向力程度也會減輕許多，但是在模具壁面受到的摩擦力卻會增加，如同刷子的效應一般；然而在拔模的階段中，SAM的負值摩擦力則成為模具脫模時的助力。最後，本文也針對奈米滾印製程作一分析，設計了一移動式週期邊界條件並採用Tight-binding多體勢能來解析其成形機制和力學效應。為了和奈米壓印製程作一比較，在此使用相同的滾齒模型當作壓印模具。研究發現，兩種製程的高應力和應變的位置均發生於受壓處的正下方，而滾印製程尚有一個次應力和應變區則是分佈在圖案的鄰近區域。

The objective of this study is to build a multiscale analyzed method that can easy to span the system size described by classical molecular dynamics simulation, then to operate with molecular dynamics to detail investigate the deformation mechanisms of nanoimprint and roller nanoimprint processes. The multiscale method for coupling continuum and molecular models is described. In this method, the continuum model was assumed to be in a lattice form and the interaction parameters were provided. Because of many particles with different size existed in the system, this method is also called multi-particle method. Coarse particles in the method can be applied in non-characteristic areas or in regions far away from large deformations, thus highly improving the efficiency. Defining a critical strain for different lattice sizes makes lattice refinement easier to correctly capture the details of the dislocation core, stacking fault, and grain boundaries. In the thermal equilibrium case, the efficiency exceeded 108 times that of a classical molecular dynamics (MD) simulation with great numerical precision.
Both Au and PMMA films were used in nanoimprint simulation. To greatly understand the deformation mechanism and mechanics behaviours, the imprint forces, particle trajectories, stress distributions and slip vectors were evaluated during the loading and unloading processes for various parameters, including punch size, mold internal space and material orientation. In Au imprint process, the simulation results show the influence region were increased (on X- and Z-axles) as the mold width and the imprint depth increased and the sensitivity on Z-axle was more dramatic than on X-axle. Under the same imprint depth, the filling density decrease and raised height increase when mold width increased. For the formability characteristics on PMMA orientation, the required forming force is less and the pattern remained a good shape when PMMA chains parallel to the imprint direction. On the effect of SAM (self-assembly monolayer), the PMMA defects and adhesion between interfaces can be more reduced by the SAM molecules and made the pattern contour smoother. In a comparison of the imprint mechanisms with a vertical imprinting case, the main high stress and strain regions were concentrated on the film atoms underneath and around the mold during the rolling imprinting process.

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