Computational Lithography for 3-Dimensional Fine Photolithography using Sophisticated Built-in Lens Mask

Built-in lens mask lithography realizes 3D imaging by a single exposure using a conventional proximity exposure system. 3D structures are divided into seed elements with different depth of focus, and the complex amplitude of the mask is designed by combining the wavefronts that image these elements. However, due to the interference of the seeds, the three-dimensional image may be missing. For this reason, it has been necessary to set the seed pattern based on empirical knowledge. In this paper, we have developed a system to automatically design the seed pattern. The system calculates the light intensity-distribution in space and places seeds with opposite phases to cancel where excessive image remains. On the other hand, additional seeds are placed in space where light intensity is not sufficient. This procedure is repeated step by step until the required image is obtained. Computational lithography will show that this results in the required 3D image.