利用傅里叶模方法分析厚层光刻胶内衍射光场

建立了描述厚层光刻胶内衍射光场形成过程的物理模型，并利用傅里叶模方法模拟计算和分析了其内部衍射光场分布。该方法考虑了其界面反射、透射及光刻胶复折射率在空间上的缓慢变化对衍射光场的影响，采用该方法模拟光刻胶内衍射光场具有数值计算结果准确、计算速度快的优点。对厚层光刻胶折射率在几种特殊分布情况下衍射光场分布的数值模拟表明，衍射光场与其复折射率的空间分布有关。由于厚层光刻胶折射率在空间上呈缓慢变化的特点，为降低其数值计算量和编程难度，可以将厚层光刻胶近似为折射率随曝光时间变化的光栅。

Analysis of Diffractive Image Field in Thick Film Photo-Resist by Using Fourier Modal Method

According to the lithographic characteristics of thick film photo resist, a novel physical model is established. Then Fourier model method, mostly applied to study the diffractive properties of gratings is adopted to analyze the diffractive image field in thick film photo resist. The factors such as reflection and transmission at the interface, complex diffraction in the photo resist, are taken into account. This method has higher computing precision and smaller computation cost. Numerical simulation results show that the distribution of diffractive image field is relevant to that of complex refractive index. As a result, it is reasonable to regard the thick film photo resist as grating with variable refractive index during exposure process.