Stereo camera measurement system for crystal diameter and melt level in Czochralski process

Abstract

Accurate and reliable measurement of crystal diameter and melt level during the Czochralski (CZ) process is crucial for producing high-quality single crystals with a good yield. This thesis presents a study on the development and implementation of a prototype stereo vision measurement system, aimed at evaluating the feasibility of performing such measurements within the enclosed hot-zone puller chambers. The methodology incorporated advanced image processing algorithms and camera calibration techniques to ensure precise and reliable measurements.

Stereo vision was leveraged to capture detailed images from multiple perspectives, allowing for a more accurate measurement of the crystal diameter and melt level. The image processing algorithms were fine-tuned to detect the meniscus accurately, which is critical for determining the crystal diameter. Additionally, the camera calibration process was designed to minimize errors and enhance measurement accuracy.

The results of the prototype system indicated significant potential for application in a production environment, offering a non-intrusive and precise method for monitoring the CZ process. However, the study also highlighted areas requiring further refinement. Future work will focus on improving the measurement accuracy through advanced calibration and image processing techniques. Additionally, efforts will be directed towards integrating the stereo vision system with automated control mechanisms to optimize the crystal growth process, ultimately aiming to enhance the efficiency and quality of single crystal production.