| Immersion lithography is the most advanced device in the manufacturing of theintegrated circuit. Resolution and overlay are the key specifications of the immersionlithography. The temperature of the immersion liquid is one of the factors that affect the twospecifications. In this thesis, according to the requirements of the immersion temperature, animmersion temperature control algorithm is designed.The algorithm introduced in the thesis modulates the temperature of the immersion liquidby exchanging heat with the process cooling water(PCW) through the heat exchangers. Byadjusting the flow rate of the PCW, the amount of the heat of immersion liquid can bechanged. As a result, the temperature of the immersion liquid is controlled.The thesis designs the schematic diagram of the system and proposes acascade-connected control structure. The two controllers correspond to the two flow servovalves. In the cascade structure, the inner loop changes the opening of the flow servo valvesto adapt to the setting values. The outer loop calculates the flow rate of the inner loopaccording to the system. Such structures can separate various disturbances in the system andovercome difficulties caused by the time delay and non-linear.The transfer functions of the objects in the system are derived including the heatexchangers, flow servo valves, pipes and sensors. The influence of the disturbances in theinlet is also discussed. Then the control character of the system is analyzed to be non-linear,multi-disturbance and time-delayed.A multi-stage fuzzy PI controller algorithm is designed, analyzed and simulated. Theresult is compared with ordinary PI controller to prove its efficiency. |
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