Research On The Key Technologies Of The Machine Vision Of The Automatic Prober

Because of the fast development of IC industry, wafer test (semiconductor packaging and testing) in the IC packaging and testing industry is occupying more and more important role; and automatic probe station as the core equipment in the wafer test, research in foreign countries has been gradually mature, in the domestic although it started relatively late, but also more and more receives industry related companies and research institutions pay more and more attention.This paper studies the application of machine vision technology in the automatic prober, focus on the design of the center of the wafer detection, wafer alignment, concrete implementation scheme of needle height measuring three key functions and based on machine vision in edge detection, template matching, scattered focal ranging technology put forward some optimization scheme, actual effect and the application and optimization of the improved scheme provides complete testing scheme.The main contents of this paper include:The first chapter introduces the background of the topic, and explains the significance of the research, summarizes the development of the probe station and the application of machine vision technology, and finally lists the main research contents of this paper.The second chapter to probe station system structure are described; at the same time, designed the overall system architecture of the visual system; and the optical imaging system design put forward practical solutions and solutions to the technical difficulties; design the detailed process of needle function realization, based on the description of the core functions of the process needs to realize the image processing.The third chapter to the center of the wafer detection function realization principle are described; and based on edge extraction technology of concrete realization of the extraction of the edge of the wafer, and the extracted edge data to determine the location of the center of the wafer; finally on the function of edge errors in judgment and fixed position accuracy is not high, and puts forward the method based on image morphology and multi point fitting the coordinate of the circle center to the optimization and improvement.The fourth chapter of wafer alignment function realization principle are described; and the specific realization of wafer alignment on the coordinate axis based on template matching technology, at the same time, obtain the distance between lattice; finally, according to the function of background noise interference, positioning accuracy is not high and the need to improve the efficiency of the algorithm, is proposed based on the information of image edge template matching and based on local resampling technique of sub-pixel algorithm to optimize and improve.In the fifth chapter, author explains the measurement of needle height function realization principle; compared several ranging technology in automatic probe station applicability, and puts forward the application of scattered focal distance measuring technology for the needle height measurement is introduced; by coordinate system and the design of the system movement mechanism, to avoid the dependence of the inside and outside of the optical imaging system parameters. Finally based on the gray variance to image sharpness evaluation, and the curve fitting scheme to improve the positioning precision of ranging technology.The sixth chapter summarizes the main research content and innovation points, and the next step of the research is prospected.