Chien Cheng-Wei, Lee Yun-Chih, Lee Po-Shen, Chang Jenq-Yang, Chen Jyh-Chen
Department of Mechanical Engineering, National Central University, Jhongli 32001, Taiwan.
Appl Opt. 2007 Jun 1;46(16):3196-204. doi: 10.1364/ao.46.003196.
An interferometric lithographic technique and double exposure method are applied to theoretically and experimentally investigate several kinds of 2D periodic structures. The shape, lattice symmetries, and lattice constants of the 2D structures, for different substrate rotational angles, are obtained from the simulated predictions. The shape of the 2D structures can be varied by controlling the rotational angle of the substrate and the development process, and they are validated experimentally. The variation of the lattice symmetry of the 2D structure with the substrate rotational angle is discussed in detail in relation to the axial angle and lattice constant. It is found that square, circular, rectangular, and elliptical scatterers which are arranged in parallelogram, triangular, and square lattices (with different lattice constants) can be obtained. The photonic bandgaps for each condition are also investigated. When the substrate rotational angles are the same, the normalized frequency (omega a/2 pi c) of photonic bandgap structures with an equal filling factor are very similar regardless of the interference angle. The results are helpful in designing the forbidden frequency when the lattice constant and the scatterer shape can be controlled by the interferometric lithographic technique.
采用干涉光刻技术和双曝光方法，从理论和实验上研究了几种二维周期结构。通过模拟预测，获得了不同衬底旋转角度下二维结构的形状、晶格对称性和晶格常数。二维结构的形状可通过控制衬底的旋转角度和显影过程来改变，并通过实验进行了验证。结合轴角和晶格常数，详细讨论了二维结构晶格对称性随衬底旋转角度的变化。结果发现，可以得到排列在平行四边形、三角形和正方形晶格（具有不同晶格常数）中的方形、圆形、矩形和椭圆形散射体。还研究了每种条件下的光子带隙。当衬底旋转角度相同时，填充因子相等的光子带隙结构的归一化频率（ωa/2πc）与干涉角无关，非常相似。这些结果有助于在晶格常数和散射体形状可通过干涉光刻技术控制时设计禁带频率。
