Design And Implementation Of Atomic Layer Deposition Equipment Control System Based On PLC

Atomic layer deposition(ALD)technology is one of the leading nanoscale structure synthesis and thin film deposition techniques in advanced manufacturing.In recent years,it has played a significant role in many fields such as new energy photovoltaics,advanced displays,and advanced semiconductors.The present degree of automation in this technology is restricted,thereby impacting both product quality and production efficiency to a certain degree.At the same time,China’s research and development of ALD equipment is in its early stages,limited by foreign closed systems.Only a few companies have relevant research and development,and the automation level needs to be improved,which leads to a lack of core competitiveness.Therefore,it is necessary to establish a supporting scheme for control as soon as possible,which is very important to increase operational efficiency and enhance product quality stability.The aim of this study is to develop an automatic control system that satisfies the requirements of ALD technology,utilizing a small PLC,industrial touch screen,and upper PC configuration,improve automation level,and reduce the requirement for operators.Furthermore,it proposes combining active disturbance rejection control(ADRC)and pulse width modulation technology(PWM)to achieve precise temperature control for heating equipment with nonlinearity and time-varying characteristics.Firstly,this paper introduces the background and technology of atomic layer deposition equipment and its control system,determines the control requirements,selects the PLC,touch screen,sensors,and execution devices,and designs the equipment distribution-control circuit.On this basis,STEP 7-Micro WIN SMART v2.3 software is used to write the process logic for manual/automatic control,deposition cycles,signal reading and writing,etc.Moreover,the main interface,layer cycle interface,temperature control interface,operation strategy,and recipe read-write system of the touch screen are designed in Mcgs Pro configuration software,achieving the combination of automation control and human-machine interaction for atomic layer deposition equipment.Secondly,this paper thoroughly explains the principles and functions of each component involved in the ADRC.Additionally,the parameter tuning principles for each link of the ADRC are explored through simulation experiments.Furthermore,evaluating the performance differences between self-disturbance control and traditional PID control,this study constructs a mathematical model for the heating control system by integrating mechanism modeling and test analysis modeling.MATLAB/Simulink is utilized to conduct simulation experiments and compare performance indicators,such as rise time,overshoot,and disturbance rejection.The results indicate that the self-disturbance control method exhibits better performance than the conventional PID control in the identified performance indicators,such as rise time,overshoot,and disturbance rejection.Moreover,it is considered more appropriate for the time-varying heating system investigated in this research.Finally,the control algorithm for the heating part was implemented at the equipment level and validated in practice,followed by practical verification.A comparison between the actual results and the simulation results reveals that the temperature control effect meets the high-precision and high-uniformity temperature control requirements during the coating process.Through practical application,compared with traditional equipment,the device in this study saves an average of about 44% of process time through automatic operation.Under the premise of fast rise time,the highest overshoot temperature of the heating equipment is less than 1 ℃,ensuring the relative stability of the controlled temperature during the tracking process.Once the system has reached steady state,the temperature controlled error is below0.5℃,ensuring precise temperature control and meeting the temperature requirements for ALD technology.In summary,after comprehensive debugging,the equipment in this study has the advantages of high automation level,small error,and good stability,which meets the process requirements.