An ADRC-based CZ Silicon Single Crystal Growth Control Technology

Abstract

Czochralski method is the main method to produce silicon single crystal, therefore, its growth process and control method have always been the focus of the silicon industry. Single crystal growth process with an invariable diameter can be are influenced by temperature and pulling speed and rotational speed, crucible's tracking speed and rotational speed, growth physical environment, protective gas flowing speed and temperature, cooling water flowing speed and temperature, etc. while the parameters’ selection such as thermal field distribution in furnace, growth temperature compensation, growth speed is the basic condition of single crystal shape, therefore, a cascade control strategy by combining thermal field with growth speed is adopted in control system. Moreover, due to the lack of accurate mathematical model and the characteristics of non-linearity and variability, an active disturbance rejection control (ADRC) strategy is proposed in this paper. The experimental results show that the above control strategy can effectively control the growth of single crystal with an equal diameter, high control accuracy, strong anti-interference ability, insensitive to parameter changes, and has a certain degree of robustness.