Research On Measurement System Of Surface Deformation Of Silicon Wafer Packaging

The measurement of the surface deformation of the silicon wafer packaging is of great significance to ensure the performance and reliability of integrated circuit products,and analysis and optimization of the packaging process.This paper focuses on the needs for dynamic and high-precision measurement of the surface deformation of silicon wafer packaging.Based on the liquid crystal phase modulation interference measurement technology,the research and design of the surface deformation measurement system of silicon wafer packaging are as follows:(1)A phase modulation interferometric surface measurement method based on liquid crystal retarder is proposed to realize the dynamic measurement of surface deformation of silicon wafer packaging,and its principle is analyzed by Jones matrix.Due to the use of liquid crystal phase modulation to achieve fast phase shift operation based on millisecond-level,which is much faster than the deformation rate of the silicon wafer surface,it ensures the feasibility of dynamic measurement.(2)Based on the analysis of different interference phase extraction algorithms,a phase extraction algorithm based on advanced iteration and ellipse fitting is proposed for solving the problem because the advanced iterative algorithm depends on harsh conditions and is not suitable for dynamic measurement.The algorithm improves the calculation efficiency by filtering out the background light intensity,corrects the phase extraction error by ellipse fitting,and ensures the high accuracy of the measurement.A dynamic improvement algorithm is further proposed,which only requires two frames of interferogram,which can minimize the impact of dynamic environment and state.(3)A weighted deviation minimization unwrapping algorithm combined with wavelet denoising is proposed.In this method,the unwrapping accuracy is improved by minimizing the weighted deviation between the estimated unwrapping phase and the unknown adjacent pixels,and denoising the results with appropriate wavelet basis.(4)A set of measurement system for the surface deformation of silicon wafer packaging is made and tested,which verifies the reliability and accuracy of the system.