Research And Design Of The MOCVD Control System Based On PLC

MOCVD ( Metal Organic Chemical Vapor Deposition ) is one kind of high grade semiconductor material growth technology, mainly applies in material growth domain and so on semiconductor material, nanometer material. The project of this paper is supported by Shaanxi Provincial Natural Science Foundation. According to the characteristics and requirements of Xidian Univ. MOCVD system, a research and design about the MOCVD control system based on programmable logic controller are carried out.This paper proposes the new design idea in view of the insufficiency and the flaw of the 1st MOCVD system. It takes the Simens programmable controller as the core controller of the MOCVD control system, and has the monitoring system. The temperature control of the reaction chamber designs two control modes: Temperature controller control and PLC control. This paper has used the brand-new design thought redesign control system software. There are many subprograms of the MOVCVD control system in automation, such as initial, main, step, loop, alarm, multi-channel time-sharing analog input, analog ramp, analog output, digital output etc. Increased the software encipher protection. A novel PID control based on neural network is presented to deal with the control problem for a nonlinear process with time-delay in this paper. Digital simulation and experiment results show that this new controller can improve the dynamic performance of temperature regulation system and robustness. Both simulation and practical application results show that this controller has strong robustness and the capabilities of self-learning and adaptive decoupling.Compares with the first generation of the MOCVD control system, it's performance of the MOCVD control system in this paper is more stable, consummate. It provides a new method to the MOCVD control system design, and it is good for further researched and developed of the MOCVD control system.