Research And Application Of Crystal Growth System Based On Machine Vision

With the popularity of solar crystalline silicon, the requirement of Monocrystalline surges in the domestic international market. In particular, the demand of large-diameter single crystal increases rapidly. Currently, the technology of infrared indirect measurement using in the country can not measure the diameter of the crystal accurately, which results to the poor quality of crystal. It can not be met the market demand for large diameter crystals, so improving the preparation technology of Monocrystalline silicon is urgent. Based on this situation in the paper, using machine vision technology measure the diameter of the single crystal online, which was achieved automatic monitoring fully in the process of silicon single crystal generation and was reduced human intervention and provides highly accurate actual diameter data for the automatic crystal control equipment. The system meets the rapid demand for single crystals in the domestic semiconductor industry market.In this paper, using OpenCV database to software develop in the Visual C++6.0environment based on the machine vision technology. First, the CCD camera captures images of single crystal growth. Then, the image acquisition card converts the analog signal to the digital signal. Finally, Real-time transmitting to the computer, which are preprocessed by gray, gray image brightness adjustment and intermediate filter. The edge position of single crystal is detected accurately by the combination of edge detection and vertical projection. Measuring the diameter of non-full circle by formulating algorithm, which provides accurate crystal diameter for the automatic control of whole pulling process.It has five chapters. The first chapter is introduction, which concludes the background of the paper, the situation of single crystal furnace,the research status and advantage of machine vision detection and the main work of the paper. The second chapter is the hardware design of Czochralski single crystal diameter measurement system, which introduces the hardware structure of the system and the selection of CCD cameras, lenses and image acquisition card. The third chapter is the image analysis and diameter calculation. It analyzes the method of image data acquisition and image processing according to the characteristics of growth image of monocrystalline silicon rod, and presents a positioning method based on the combination of vertical projection and edge detection, then completes the measurement of diameter of monocrystalline silicon rod. The fourth chapter is the software design of Czochralski single crystal diameter measurement system. It mainly introduces the software development platform of the system application which includes the Visual C++6.0and computer vision library OpenCV, and describing the specific design of each software module of the whole system, then analyzing the whole system. The fifth chapter is the summary and prospect, which gives a summary of this paper and puts forward the measures to further perfect the system.