The Application Of Fuzzy Control In Semiconductor Clean Room Temperature And Humidity

With the development of semiconductor manufacturing industry, clean room has become one of the most concerned technologies in the world. As for semiconductor manufacturing industry, the most important function of clean room is to control the cleanness, temperature and humidity of the environment, and positive pressure, in order to make sure that processes are implemented under a good environment. Inside a clean room, MAU(make-up air unite) system, process exhaust system and FFU(fan filter unit) system are coordinated to meet the requirements of those clean room indicators. The key point of clean room environment control is temperature and humidity control, which need to be monitor and control 24 hours per day, and other indicators such as cleanness, intensity of illumination are relatively stable since the clean room had been setup.This project is aim to improve the temperature and humidity control of clean room, to enhance the control accuracy and reduce fluctuation, to raise the product yield indirectly. All temperature and humidity control have to be in accordance with the basic theory, including temperature and humidity disposal procedure, coupling relationship of temperature and relative humidity, and the method of decoupling of them.Firstly, this paper introduces basic concept of clean room and basic theory of temperature and humidity. Then according to the basic requirements of clean room, systematically divide the whole clean room temperature and humidity control system into make-up air unit,MAU, dry cooling coil, DCC, fan filter unit, FFU, and their control system, analize the improvement methods for control system partially and totally.As for control scheme,this paper focuses on the MAU and DCC to study the clean room air-condition system temperature and humidity control. This paper analizes air handling procedure with enthalpy chart, uses temperature and humidity decoupling mothed, introduces temperature and humidity PID base control strategy. In order to improve the control precision and energy saving efficiency, through adding split range controller inside control loop, controls warm/cool water and humidifier/dehumidifier to avoid wasting energy and control error fluctuating. Considering the shortcome of ordinary PID controller, addes fuzzy controller inside PID control loop to regulate PID parameter, as to enhance system adaptability under different circumstances, improve system control precision and reliability, finally narrow temperature and humidity fluctuation.This paper introduces Rockwell SLC500 serial 1746-553 PLC base redundent control system which has been used in semiconductor industry for years, and compatible Wonderware Intouch platform SCADA which provides the control and monitor system high reliability and compatibility.