Research And Application On Control System Of Large-Scale Hydride Vapor Phase Epitaxy (HVPE) Equipment

Gallium nitride(GaN)has a wide range of applications in charging market,5G Base Station,power system,semiconductor lighting,new energy automobile and other fields.Hydride Vapor Phase Epitaxy(HVPE)is currently the primary method to prepare high-quality GaN substrate materials.Nowadays,the quality,availability and price of GaN substrate cann't meet the market demand,so it is urgent to develop large-scale HVPE system equipment with high-quality and low-cost.This subject originated from National Key R&D Program of China.In view of the current situation that the GaN substrate growth equipment on the market cannot meet the requirements of 6-inch substrate growth,an automatic process control system of large-scale HVPE equipment was designed and developed,which completed the precise control of large-scale epitaxial uniform growth,realized the long-term stable growth of GaN materials and the automatic control of material growthAccording to the HVPE process flow and control requirements,an automatic process control system of GaN HVPE equipment was developed and designed independently.The overall control strategy adopts the three-level control mode of "host computer+PLC+field equipment",that is,the growth process editing,the temperature control algorithm and the operation of the monitoring system are completed on the the host computer;the PLC is connected with the host computer via an Ethernet interface,so as to complete the monitoring of growth process parameters and field equipment status;finally,the system functions are realized through the operation of the field instruments.Aiming at the problems of pressure control,process safety control and exhaust gas treatment of HVPE system,the specific solutions were proposed,and the corresponding systems were designed and implemented.The article focuses on the temperature control of the HVPE system,briefly describes the structure of reactor heating furnace and the requirements of temperature control in the process.The heating temperature control system was modeled after system analysis and corresponding experiments,and then two methods of fuzzy adaptive PID control and variable universe fuzzy adaptive PID control were discussed respectively.It is found that the latter has a better control effect by comparing the simulation results and the actual measurement results.Finally,this method was selected to realize the temperature control of HVPE system.In addition,this paper also analyzes the control algorithm with Smith prediction and discusses the feasibility of applying it to HVPE temperature control.HVPE control system selects SIEMENS S7-1200 PLC for use as the core controller and STEP 7 Professional of TIA for use to write PLC programs.The manual and automatic control programs are designed separately.The host computer monitoring system is developed based on Kingview 6.55,which is divided into two parts:process site monitoring and remote monitoring.The remote monitoring function is realized through the GRM OPC wireless communication module.In addition,the editing function of growth process is realized through the DDE communication between Excel and Kingview,and then the process data is transferred to PLC;the temperature control algorithm is implemented by Matlab,and the data channel between Matlab and Kingview is established based on the OPC mechanism,so as to transfer the real-time temperature data required for the operation of the algorithm and algorithm output.The HVPE control system developed in this paper has been successfully applied in the laboratory self-made HVPE equipment.Up to now,the system has been running well.The 6-inch GaN substrate material has been successfully prepared through half a year of equipment joint debugging and process testing.