Research On Optimizing The Edge Smoothness Of Lithography Patterns Based On DMD Scanning Lithography System

Optical precision processing technology has developed rapidly in recent years and has broad development space in the field of microstructure surface processing.In the optical precision processing technology,the maskless scanning lithography technology based on the Digital Micro-mirror device(DMD)reduces the lithography cost while improving the lithography efficiency and the lithography precision.DMD scanning lithography can produce tiny,lightweight,integrated 3D microstructure devices,so DMD scanning lithography is used in military,biomedical,information processing and other fields.The digital micromirror device(DMD)in the DMD scanning lithography system has a frame rate of more than 20,000 Hz,enabling high-efficiency,continuous roll-scan lithography.Although DMD scanning lithography achieves a high-efficiency,high-precision,low-cost lithography process,lithographic patterns have significant aliasing at the edges of the scribe lines outside the rolling scan direction,reducing the quality of the lithographic patterns and the performance of the fabricated device.In this paper,the problem of lithographic graphics having jagged edges outside the scanning direction is proposed.The solution is proposed and the corresponding work is carried out.The work includes the following two parts:(1)For the problem that the edge of DMD scanning lithography patterns are jagged,the principle of DMD scanning lithography is deeply analyzed,and the reason why the lithographic patterns scribe line edge is sawtooth is obtained: DMD microstructure limitation and uneven distribution of single-pixel illumination energy.According to the scanning direction,the single-pixel illumination energy is accumulated and accumulated to make the direction energy uniform,and finally the direction is smooth.The method of linearly dislocation of the DMD micro-mirror array imaging in the vertical scanning direction is proposed to reduce the scanning direction.The line edges are serrated.Theoretically,the micro-mirror array imaging linear misalignment form and expression are obtained,and the software simulates the micro-mirror array to image the linearly misaligned “lined” exposure effect.The simulation results show that the micro-mirror array is linearly misaligned,which effectively reduces the sawtooth edge of the scribe line and improves the edge smoothness of the scribe line.At the same time,this method has the advantage of homogenizing the illumination energy and improving the utilization of illumination energy.(2)Using the free-form optical lens to flexibly adjust the spatial distribution of light and increase the freedom of light space.The free-form optical lens model is designed and optimized by Matlab and Zemax software,and installed near the 1mm position on the surface of the DMD window to realize micro The mirror array images linearly misaligned.The software simulation simulates the "tree" exposure effect of the lithographic patterns before and after the lens model.The simulation results show that the edge smoothness of the lithography patterns are improved without changing the lithography efficiency and the lithography patterns size.