- 學位論文
遠場相移式圖案之設計與實現
Designs and Implementation of the Far Field Phase-Shift Patterns
摘要
傳統的光罩加入相位移的設計可以在微影製程中能夠有效的縮小曝光的線寬，近場相位移光罩的優點是能夠將線寬縮小到1/6~1/4的曝光波長，但這技術需要高精密的系統和更多的製程，且產生的圖形多為封閉式圖形，近場相位移技術對具有變化式的圖形有製作上的困難。本文希望在遠場藉由光繞射的方式來達到相位移微影的效果，利用簡單的光學架構，能夠產生具有變化式的圖形，且使光罩和光阻之間距離增大，減少因接觸造成的損壞。 本篇論文主要是使用遞迴傅立葉演算法來設計相位式光學元件，藉由純量理論，模擬出遠場相位移光強度變化的情形，提出並比較三種最佳化收斂的方法，分別在繞射場的振幅和相位收歛，探討其優缺點，接著在繞射場的訊號區加入相位步階量化的觀念，試著改善之前效率過低和訊號區增大時元件設計不易的問題，並且增加遠場相位移圖像的變化性，設計包含ㄇ字形、十字形、變化均勻式、漸變式相位移圖像等等。最後，將最佳化相位元件於液晶空間相位調變器上實現，在所建立的光學系統架構中，成功的在遠場得到相位移圖像，其破壞性干涉條紋寬度為繞射極限寬度的1/2至1/3間。
並列摘要
In this thesis, we first presented a method to produce the near-field phase-shift patterns using diffractive optical elements (DOEs) in the optical far field. The DOEs were designed using the iterative Fourier transform (IFTA) combined with the dummy area method. By using the developed method, the phase and amplitude of the sampling points were well controlled. Thus, we were able to obtain DOEs with high uniformity and generate diffractive images of specific speckle pattern. Then we applied the concept of the phase of stepwise quantization to the phase-shift pattern of the signal window in order to increase the diffraction efficiency and to solve the problem which occurs when the signal window is large. We also improve the variability of the designed patterns. Finally, the simulation results show that the width of the dark fringes, resulted from the destructive interference of two phase regions in the field disturbance in the Fourier plane, was between 1/3 to 1/2 of the diffraction limit. The input device was a reflective phase-mode spatial light modulator with 256 phase levels, ranging in [0, 2π].