Application Of Integral And Second-order Sliding Mode Control In Lithography Dual Wafer Stages System

Ultra precision dual stages system is one of the most core subsystems in the lithography machine, it plays a crucial role in the process of wafer initial alignment, stepping, scanning and exposure, its tracking and positioning accuracy are directly determine the resolution of the lithography machine, and its performance is closely linked to the three indicators to measure the performance of the lithography machine. Therefore, in order to achieve the high speed and high precision of the dual stages motion, This paper focuses on motion control system for macro stage, micro stage,and the exchanging process of dual wafer stage, and then applied the sliding mode control method to the system of dual stages, and the accuracy and immunity of the whole system are greatly improved.At the very beginning, according to the whole structure and working principle of dual stages, and its process of the exchanging and the scanning exposure, the performance index of the system is analyzed. On the basis of the requirements of the performance index, the trajectory planning of single degree of freedom motion of the dual stages is carried out, and the selection of macro and micro actuator is completed.Secondly, take the macro stage of the dual stages as an example, An integral sliding mode control method is proposed on the basis of the SISO decoupling model of the wafer stage. The main feature of this method is that it can satisfy both the adjusting time and the steady state error, which can improve the performance of the control system. In order to suppress the chattering effect of the sliding mode control method, the boundary layer technique is used to improve the sliding mode item. By comparing the simulation result with the traditional PID control method, the feasibility and effectiveness of the integral sliding mode control in dual stages system is verified.Again, although the boundary layer method can effectively improve the chattering effect, the integral sliding mode control method lost its valuable properties of anti-vibration and anti-disturbance, and the anti-interference capability and the steady state performance of the system are affected, so the two order sliding mode control method is proposed to improve the integral sliding mode control method, and according to the problems existing in the feed forward control of the sliding mode control, the design of feed-forward control is improved, and the simulation results compared with the integral sliding mode control method, which proves the superiority of the improved method.Finally, the control system of dual wafer stage are designed and constructed, and solved some practical software and hardware problems of the control process, including the communication design for Multi-boards and internal communication design for board, and then the motion control experiment of the permanent magnet linear motor is carried out on the physical platform of the dual wafer stage, not only meet the accuracy requirements of the system, the exchanging process can be completed smoothly, but also makes the system performance has been greatly improved.