Modeling and simulation of an integrated digital micromirror device-based grayscale lithography system

DMD maskless lithography (also referred to as “digital mask lithography”) is an emerging technology that has been widely adopted in micro-manufacturing in recent years. By enabling instantaneous switching between different mask patterns, DMD lithography offers enhanced flexibility and cost-effectiveness. However, its unique internal structure and imaging principles fundamentally differentiate digital mask lithography from traditional projection lithography systems. Furthermore, the methodology for obtaining photoresist latent images in grayscale lithography differs significantly from conventional direct laser writing techniques, presenting greater complexity in image formation mechanisms. In this paper, an accurate simulation model of DMD-based grayscale lithography is built for image quality analysis, including 2D aerial image analysis, 3D photoresist latent image analysis, and final photoresist contour analysis. By integrating these important functions, the simulation model can help researchers/manufacturers to identify problems in the patterning solution at every critical stage and achieve the purpose of saving experiment and trial-and-error costs. A process flow for a micro-lens with a target diameter of 2.8 µm has been accurately simulated in this study and compared with experimental data.