Study And Application Of AOI Technique For IC Wafer

Study on AOI for the IC wafer synthetically uses embedded technology, optical technology, digital image processing, AOI technology and so on. With the development of real-time and high precision system, The higher performance defect detection strategy and arithmetic become the key parts of deep- submicrometer IC inspection equipment.The paper is originated from the science and technology item of Guangdong province in 2004: Automatic inspection system of IC wafer micrograph based on digital image process, the item adopted digital image process in this and have achieve periodic results. on the basis of above, this paper mainly does some research in some key problems such as image acquisition and preprocession, IC micro-image mosaicing, automatically inspection algorithm of wire, CD(Critical Dimensions) measurement method. It mainly uses technology of embedded, digital image processing, automatic control, ANN pattern recognition and so on. The concrete contents are as follows:This paper analyzes the existing detection means for IC, experimental results show that the system based on image data acquisition card can't meets real-time requirement of IC inspection. System with IC micro image acquisition and preprocession was designed. Digital image convolver and median filter are implemented by FPGA.The paper deeply analyzes mass image mosaics technology ' based on two-dimensional according the characteristics of IC image. Motion calibrating for IC workpiece flat was realization. There are the main factor of mosaics precision for IC micro-image, the local mosaics error due to feature was not significant., the accumulated error due to mass image and so on, which were analyzed further. For improving the accuracy, the method was made the best of the advantage of existent characteristic. Suited position of seam-line between images was gained experimentalanalysis, Variable weight algorithm was designed for fused, the target can be standed out from fused images.Based on the method of referential, nonreferential and hybrid which are widely employed , the paper designed a new IC inspection method based on subpattern types, and the Neural Networks was applied to system. The key of the method is each arithmetic of the subpattern types be entirely different from others, It effectively solve complexity of algorithm, false detection and miss detection which is due to different method for different defect types. The paper introduces the sub-pixel measurement method of CD(Critical Dimensions) using HT(Hough Transform), analysis on the factors of influencing accurate measurement and the property of parallel lines HT.