Maskless fabrication of three-dimensional microstructures with high isotropic resolution: practical and theoretical considerations.

A maskless three-dimensional (3D) microfabrication method based on a digital micromirror device (DMD) is proposed for high lateral and vertical resolution. A substrate is scanned laterally under virtual masks of the DMD. The masks are allocated to a large number of virtual slices, all of which are projected in a single scan of the stage. A theoretical model for the cumulative dose distribution in a photoresist is derived and used to predict the resulting 3D profile. Experiments showed that the proposed method is promising for avoiding the stair-step problem and preventing misalignment errors.