DEVELOPMENT OF AN ELECTROCHEMICAL OXYGEN SENSOR FOR CZOCHRALSKI SILICON MELTS

An electrochemical oxygen sensor based on stabilized zirconia was deve loped for measurements of the oxygen concentration in molten silicon. The mixture of Mn and MnO was found to be an appropriate system for th e generation of the reference oxygen partial pressure which should be close to that of oxygen in the silicon melt. The free-energy of soluti on of oxygen in molten silicon was evaluated by calibration experiment s. A prototype sensor was tested to measure the oxygen content in the silicon melt in a commercial Czochralski puller. The difference in the radial oxygen concentration between center and periphery increased wi th increasing crucible rotation. This result is consistent with the ex perience in silicon crystal growth as well as with recent numerical an d experimental results on the impact of crucible rotation on the flow patterns in silicon melts in an industrial-size Czochralski crucible.