疊對光柵結構參數最佳化分析(模擬退火演算法)與疊對誤差之比對

Abstract

本論文是以嚴格耦合波理論來分析疊對光柵的各項參數。光柵疊對誤差可利用零級繞射效率變化來求得，此方法為非接觸式和非破壞性量測，並可量測疊對誤差至奈米等級。 設計一矽基板上具有上下兩層光柵，其上層光柵材料為光阻，下層光柵材料為介質，控制上下層光柵的錯位量，使其從零至一光柵週期，再藉由Chateau所提出的嚴格耦合波理論來分析計算光柵之繞射效率，並經由上下層光柵的錯位使零級繞射效率產生變化來回推求得光柵的錯位量。 論文中將分析梯形光柵在錯位結構下的繞射情況，並利用全區域範圍與部分區域範圍之搜尋方法來進行疊對誤差的比對，以及使用網格法、N點法、模擬退火法與綜合法來搜尋光柵結構參數，使在模擬分析時具有最佳的靈敏度。

In this thesis, the rigorous coupled wave analysis (RCWA) is used to simulate the overlaid gratings. The overlay can be found by the zero order diffractive efficiency. This method, scatterometry, has the advantages of being noncontact and nondestructive, and an accuracy of nanometer. The structure in our simulation is the overlay of two linear gratings. On a silicon substrate, two layers with linear grating structure are overlaid and in between a thin film layer is deposited. We change the overlay of the overlaid gratings from zero to one pitch, and analyze the zero-order diffractive efficiency of the overlaid gratings by RCWA. Then, the overlay between the overlaid gratings can be found. We also analyze the zero order diffractive efficiencies of overlaid gratings with non-zero sidewall angles. The overlay can be regressed by global and partial-global searchs. The parameters of the overlaid gratings can be optimized for the highest sensitivity by the mesh-grid method, the N-point method, the simulated annealing method, and the hybrid method.