Diameter Control for Silicon Rod Growth

Abstract

In this paper we describe a system for diameter control of silicon rod growth by using PID control and image processing algorithms. Image processing algorithms are developed for measuring the radius of meniscus of silicon rods while pulling from the melt. We describe the image processing steps that are performed for segmentation of meniscus region line filtering in complex domain and radius estimation that is based on the bisectors of chords algorithm by incorporating angular information. We test 3 radius measurement methods of meniscus region and analyze the stability on synthetic images as well as on video from the growth process. We also performed an experiment where silicon rod was grown using the developed image processing and control algorithm. We obtained the final result of 2 mm radius stability on the silicon rod.