Focusing And Leveling System For Lithography Tool Based On Machine Vision

The development of microelectronics and the rapid increase of IC(integrated circuit) integration in the past few years which brought a sharp reduction in the depth of focus(DOF). The leveling and focusing of chip can compensate the influence of focus error factors, and then improve the quality of exposal. With the imburse of the important practical item "Focusing and leveling System and Automatic Alignment System of advanced Photolithography for lithography tool" of National Hi-tech Research and Development Program, for the sake of improving the nation's independent development and innovation ability of strategic equipment in semiconductor chip manufacture .The focusing and leveling system is mainly developed while the whole framework and the principle of lithography being widely researched in this project.The leveling and focusing of the chip combining field-by-field focusing and whole-filed leveling and focusing is proposed, and then mathematical model for single-point measurement of height and focusing and leveling for chip are studied. Calibration model for the leveling and focusing system is also introduced.An experiment system of the leveling and focusing for the chip is designed. Optical structure of the system is introduced, the control cell of the experiment system is designed with the hiberarchy, software of the experiment system is done with Client-server model.Study on image processing algorithm for single-point measurement of height based on the linear CCD. Explore the median filter, Gaussian filtering, smoothing filter and other image preprocessing algorithms. Analyzing the effect of these filters in the image preprocessing for the leveling and focusing system. The location algorithm of barycenter and center of spot base on a threshold processing is proposed. Study the different thresholds for measuring barycenter of spot. and obtain the optimal threshold...