METHOD FOR PRODUCING THREE-DIMENSIONAL STRUCTURE USING DISTRIBUTED DENSITY MASK

摘要

PROBLEM TO BE SOLVED: To smoothen the surface shape of an objective article. SOLUTION: A photosensitive material pattern with a three-dimensional structure is formed on a substrate by exposure using a distributed density mask and transferred to the substrate by etching to produce an objective article having a surface shape with a three-dimensional structure. The distributed density mask is obtained by forming a light shielding pattern with a two-dimensional light intensity distribution on a transparent substrate, dividing the pattern by unit cells of appropriate shape and size without leaving a gap and setting a light shielding pattern in each of the unit cells in such a way that light is transmitted or shielded in proportion to the height of the corresponding position of the photosensitive material pattern. A photosensitive material layer is formed on a substrate and the photosensitive material pattern is formed by a photolithographic step which is carried out while varying the extent of defocusing under preset conditions within exposure time in exposure using the distributed density mask.