Research On Patterned Wafer Inspection Technology With Multi-scan Mode Based On Bright And Dark Field Imaging

Wafer refers to the silicon wafer used in the production of semiconductor circuits.Various electronic device circuits can be etched on the wafer.It is an important intermediate product in the manufacturing process of semiconductor circuits.With the gradual development of the semiconductor industry based on Moore's Law,the advanced chip process technology has reached the nanometer level.At the same time,the patterned wafer etching pattern has become more complex and finer with the progress of the process,which increases the difficulty of detecting defects in the patterned wafer.Therefore,accurate detection of fine defects is an important and key technology in the integrated circuit industry.Semiconductor manufacturers maintain and improve the yield of IC chip manufacturing through wafer inspection systems to reduce production costs.In this paper,aiming at technical difficulties such as the small defect size of patterned wafers and complex background patterns,a Multi-scanning Patterned Wafer Defect Detection System(MPWDS)was built and studied in this system.The corresponding technologies is following:Research on patterned wafer defects and surface scattering field.The patterned wafer production process is introduced.From the perspective of the production process and photolithography process,the reasons for the introduction of common defects on the wafer are analyzed,and the defects are classified according to different classification standards;The etching pattern of the patterned wafer surface is abstracted into the superposition of different fine line segment vectors,and the surface scattering field analysis is carried out by studying the simplified model of a single fine line segment vector.Based on the BRDF and Rayleigh-Rice theory,through discretization simulation,the scattering field distribution on the wafer surface in the presence of fine line segment vectors of different lengths,widths,angles,and depths is analyzed and discussed,which provides a theoretical basis for subsequent system design.The design scheme of MPWDS system is given in detail.A Spiral scanning strategy is proposed for the point scanning path,the coordinate mapping relationship between the scanning path and the image coordinates is analyzed,and the reconstruction strategy from the PMT one-dimensional light intensity sequence to the two-dimensional image is given;the analysis and research of the line scan,The area array imaging camera model plans the scanning path based on the system design,and calculates and derives the restriction relationship between the system detection scanning efficiency and the system parameters.A defect extraction algorithm based on repeated substructure sequence(RSSDEA)is proposed.The image deflection angle is corrected by frequency domain transformation,and the image sequence of repeated sub-structure regions is segmented in the corrected image by using shape-based template matching,and the special data structure and the adaptive iterative algorithm based on statistics are used to get correct Die image.The standard graph is efficiently solved,so that the defect location and its characteristic information are finally obtained by using double threshold segmentation.Verify the content of this article through specific experiments.A wafer inspection device was built and the algorithm proposed in the article was applied to the image,which proved the effectiveness of the system proposed in this article for detecting patterned wafer defects;the throughput and inspection accuracy of different imaging methods were compared horizontally,and the article The proposed algorithm is compared with the traditional algorithm in longitudinal direction;the fan-shaped dark area phenomenon in the process of point scanning defect detection experiment is analyzed,explained and corrected.Finally,summarize the work of this paper,give solutions to the disadvantages and look forward to future follow-up research.