Research On Resistance Heating MOCVD Temperature Control System And Temperature Control Method

Metal organic chemical vapor deposition(MOCVD)is one of the most important methods for the production of semiconductor materials.The method has simple control,high product purity,easy doping and wide application range.The method affects the production of semiconductor materials by controlling the temperature in the reaction chamber and the gas flow rate.However,temperature is the most key factor affecting the performance of semiconductor materials.On the one hand,it needs to reach a certain temperature to growth semiconductor materials.If the temperature is too high or too low,that may cause side reactions to produce additional products,and affect the purity of the semiconductor materials.On the other hand,it is necessary to ensure a uniform temperature distribution in the reaction chamber.If the temperature difference of the graphite surface is increased,the surface of the produced semiconductor film is uneven.Therefore,it is important to study MOCVD temperature control for the production of semiconductor performance.This paper mainly studies the resistance heating MOCVD temperature control system and its control method.This paper mainly studies in the following aspects:(1)By using COMSOL multiphysics software to simulate the reaction chamber model,it can get the conclusion that the MOCVD temperature control system has nonlinear,time-varying and large hysteresis characteristics.In addition,the effects of heating power on the MOCVD temperature control system are discussed.(2)In this paper,the simplex method is used to optimize the power on different heaters,so that the surface temperature difference of graphite is less than 1 ?.According to the influence of the model structure on the temperature distribution of graphite surface,the idea of considering structure and control in system design is also proposed,which helps to improve the performance of the system.(3)In this paper,the static mathematical model of the system is obtained by experimental modeling method.There is a power relationship between the heaters,and there is also a relationship between the heater power and the surface temperature of the graphite at a steady state.In addition,the transfer function of the system is obtained by the method of system identification.(4)It is established that the simulation model of MOCVD temperature control system.And it is studied that the application of PID control,fuzzy control and internal model control in temperature control.Through simulation,it is found that the internal model PID can not only has a faster response speed,but also has a simple structure and convenient parameter adjustment.Through research analysis and system simulation,the temperature of graphite surface can be uniformly distributed and respond to system input quickly.This will provide guidance for the design and production of MOCVD equipment and help improve the performance of semiconductor materials.Although the paper has conducted in-depth research on the control algorithm of MOCVD temperature control system,there is still many questions for research in the future.On the one hand,the application of intelligent control algorithms such as neural networks can be considered.On the other hand,it is possible to study a control algorithm with strong anti-interference performance.