Research On Quality Control Of DMD-based Maskless Lithography

Lithography is the key technology of micro-nano manufacturing,which restricts the development of micro-optical processing technology.In this paper,the quality problem of DMD maskless lithography was studied based on the principle of digital lithography from two aspects of mask design and manufacturing process.A multiple-exposure technique was developed to improve the patterns quality,on the other hand in mask designing,the problem of contour distortion is optimized.The matching layered mask was designed according to DMD spatial modulation principle for gray scale mask.The surface shape of Spherical surface micro-lens array was controlled via choosing the appropriate process parameters such as exposure time,development time,etching gas flow-rate and so on.The surface shape of micro-lens array was measured by SEM and profilometer.The result shows that,using multiple-exposure method to fabricate Spherical surface micro-lens array,surface shape profile is smooth and natural,the average surface shape error of multiple-exposure is 0.54?m,0.39?m lower than 0.93?m of the conventional single mode exposure.Multiple-exposure method effectively reduces the gray level distortion of gray mask in projection lithography,alleviate the technical problems caused by focal depth limitation of objective lens and improves the quality of patterns.