Temperature Control System with Multi-closed Loops for Lithography Projection Lens

作     者：NIE Hongfei LI Xiaoping HE Yan 

作者机构：State Key Laboratory of Digital Manufacturing Equipment ＆ Technology Huazhong University of Science and Technology Wuhan 430074 China Tianhua College Shanghai Normal University Shanghai 201815 China 

出 版 物：《Chinese Journal of Mechanical Engineering》 (中国机械工程学报（英文版）)

年 卷 期：2009年第22卷第2期

页      面：207-213页

核心收录：

学科分类：080801[工学-电机与电器] 0808[工学-电气工程] 08[工学] 0835[工学-软件工程] 0802[工学-机械工程] 080201[工学-机械制造及其自动化] 

基　　金：supported by National Hi-tech Research and Development Program of China(863 Program, Grant No. 2002AA4Z300) National Basic Research Program of China (973 Program, Grant No. 2009CB724205) 

主　　题：projection lens remote indirect-temperature-control cascade control structure parallel cascade control structure nonlinear proportional-integral(PI) algorithm 

摘      要：Image quality is one of the most important specifications of optical lithography tool and is affected notably by temperature, vibration, and contamination of projection lens（PL）. Traditional method of local temperature control is easier to introduce vibration and contamination, so temperature control system with multi-closed loops is developed to control the temperature inside the PL, and to isolate the influence of vibration and contamination. A new remote indirect-temperature-control（RITC） method is proposed in which cooling water is circulated to perform indirect-temperature-control of the PL. Heater and cooler embedded temperature control unit（TCU） is used to condition the temperature of the cooling water, and the TCU must be kept away from the PL so that the influence of vibration and contamination can be avoided. A new multi-closed loops control structure incorporating an internal cascade control structure（CCS） and an external parallel cascade control structure（PCCS） is designed to prevent large inertia, multi-delay, and multi-disturbance of the RITC system. A nonlinear proportional-integral（PI） algorithm is applied to further enhance the convergence rate and precision of the control process. Contrast experiments of different control loops and algorithms were implemented to verify the impact on the control performance. It is shown that the temperature control system with multi-closed loops reaches a precision specification at ±0.006 ℃ with fast convergence rate, strong robustness, and self-adaptability. This method has been successfully used in an optical lithography tool which produces a pattern of 100 nm critical dimension（CD）, and its performances are satisfactory.