Studying the impact of depth of focus on 3D profile of negative photoresist material: a simulation approach

Abstract

For quality patterning of microstructures, it is essential that all process parameters are optimized to ensure well-developed 3D profile of the resist. Advances in direct laser lithography have provided maskless and rapid prototyping methods of manufacturing microstructures. Among all other process parameters, the quality of the patterned structure is critically affected by the depth of focus adjustments of the laser spot. In this study, a simulation approach is adopted and the LAB Module of GenISys lithography simulation software is implemented to determine the optimum depth of focus for negative photoresist material. Modeling and studying straight-line structure at different focusing depths at constant exposure dosages is carried out in this work. At the constant dosage of 45 mJ/cm2, the 15 µm depth of focus yields the best quality for the 3D resist profile.