The Optimization Design Of MOCVD Control System Based On PLC

As a representative of the third generation of semiconductor materials, GaN, which has properties of high quantum efficiency inside and outsaid, high efficiency of light, high heat conductivity, high temperature resistant, anti-radiation, acid-bases, high-strength and high hardness etc, is the most advanced semiconductor materials in the word at the present time. MOCVD has the great advantage in the materials growth. 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.In this paper, the project comes from wide band gap semiconductor material growth technology and the development of MOCVD equipment, spectrum of military-type electronic components research project, GaN - MOCVD deep uv LED material growth equipment, National 863 Project. On the advantage of the first generation in the original MOCVD system, and for the growth of new growth process, some upgrading and optimization has been done over the entire system. The new process requirement has been increased to 120 steps, the previous cycle control program cannot meet the requirements. So does the former CPU. In summary, there are many subprograms of the MOCVD control system in automation, such as initial, main, step, loop, alarm, multi-channel time-sharing analog input, analog ramp, analog output, digital output etc. The text introduces the monitoring interface, and we have redesigned the VB program of the Excel formula table. So we solved the original system code to concentrate in the PC, which caused the systems operation to be slow, stable bad, moreover has also satisfied the new technological requirement well.Compared with the former MOCVD control system, the performance of the new system is stable and perfect, and it is also good for further researched and developed of the MOCVD control system.