Improved slicing strategy for digital micromirror device-based three-dimensional lithography with a single scan

To improve the profile quality of three-dimensional microstructures, an improved method was proposed in real-time maskless lithography based on digital micromirror device. First, to calculate the spatial distribution of exposure dose for the target profile in design, the relations of the exposure dose and the development depth were investigated. Moreover, a suitable development time was obtained. Second, an improved slicing strategy based on equal-arc algorithm was proposed to reduce the profile error. Different from traditional equal-expose-dose method, this method generated slicing layers with equal arc-length instead of equal-exposure dose. Such an approach has advantages in obtaining a series of suitable section patterns adapting to the curvature variation of the design profile. Finally, an aspheric microlens array was fabricated with this method and the equal-exposure-dose method. Results showed that the resulting microstructure profile by their method was more consistent with the design profile with the same slicing numbers. Moreover, results also showed that the method used can obtain as good profile quality as that of the equal-exposure-dose method with only a half of slicing numbers. This indicated that the proposed method is feasible for achieving good profile quality with slicing efficiency improved remarkably.