2001 Volume 14 Issue 7 Pages 339-346
In this paper, multi-degrees-of-freedom (multi-DOF) system identification of semiconductor exposure apparatus supported by anti-vibration units is discussed. To meet nanometer order semiconductor lithography demands for alignment accuracy, vibration control is one of the most important technologies in the semiconductor exposure apparatus supported by anti-vibration units. A dynamical model of the plant is necessary in order to design the microvibration controller and to evaluate the performance of the control systems. The controlled object is essentially a multivariable system, because the plant has 6-DOF motional modes. All the DOF of the plant are simultaneously excited and the multi-DOF dynamical model is identified from the exciting signals and the vibration output signals. The model is practically constructed in a short time using subspace method in system identification theory. Identification results are evaluated through experimental data in comparison with a conventional frequency response method.