厚胶接近式光刻中掩模优化研究（英）

随着光刻胶厚度的不断增大,制作的光刻图形畸变愈发严重,这极大的影响了微结构器件的性能与应用。针对高深宽比柱状微结构在光刻胶厚度方向上畸变的特点,提出了双面曝光和亮衬线、灰阶掩模相结合的办法,利用遗传算法对失真影响最大的区域进行搜索,光刻胶内部各层的衍射光场分布作为评价函数,对光刻过程引起的畸变进行优化。仿真结果显示,优化后光刻胶各层面型质量得到极大的改善,特征尺寸和边墙角等参数与理论值吻合得更好。优化算法具有很好的灵活性,因此在用于更厚光刻胶、更复杂掩模图形的优化上,具有重要的指导意义。

Mask optimization in proximity lithography of thick resist

The thickness increase of photoresist can cause serious distortion of the resist patterns, which greatly affects the performance and application of the device. In this paper, the distortion characteristics of the two-dimensional slices of a high-aspect-ratio microstructure were theoretically investigated in the thickness direction. Meanwhile, an effective correction strategy that includes a doubleside exposure method and a combination of bright serif and gray-scale technique was proposed. The parameters of the mask shape and transmittance were optimized to correct the pattern distortions with the genetic algorithms. The diffracted light field modulation of various layers in the thick resist was employed as a merit function. Simulation results show that the pattern quality of internal layers of resist can be significantly improved by the proposed optimization method. The characteristic parameters such as feature size and sidewall angle match the design goal. Due to its flexibility, the optimization method proposed in this paper can be applied to more complex pattern by using appropriate extrapolation technique.