Research On Motion Control For 6-DOF Micro Stage Of Dual Wafer Stage

As the key part of lithography motion control system,the dual wafer stage plays an important role in the process of wafer alignment, leveling,focusing and exposure.As the core component of the dual wafer stage,6-DOF micro stage is the key to nanometer servo positioning precision of the system. This paper focuses on motion control system for 6-DOF micro stage of dual wafer stage.Firstly,this paper the structure of dual wafer stage is analysed in detail,then the control systems of macro stage module,micro stage module and exchanging stage module are designed, Finally the typical third-order S curve is chosen as the reference curve of the micro stage by analysing the index requirements of the micro stage of dual wafer stage.Secondly, the 6-DOF measurements of the micro stage are decoupled,then the location measurement information of the micro displacement sensors is converted into the 6-DOF displacement informations of the exposure point. The micro stage dynamics coupling is devided into two parts:the position dependent coupling and the force dependent coupling,then an effective 6-DOF dynamics model of the micro stage is builded on this basis. It proves the validity of the 6-DOF dynamics decouple model by simulation.Again, the existing interference of the micro stage is analysed,then the traditional sliding mode control algorithm is designed based on exponential reaching law to suppress the interference. The simulation results shows that the sliding mode control is better than PID control in terms of suppre ssing the interference effects; Because of the obvious chattering of traditional sliding mode control, the fast terminal sliding mode control based on dual power reaching law is designed to slove the problem, The simulation results shows that the algorithm solves the buffeting and the interference suppression is also very good.Finally, the hardware of the control system of micro stage is designed,also the synchronous control strategy of three motion control cards is determined dy analysing hardware structure of the motion control card.Next the software of the motion control card is designed. Finally, the experiment of 6-DOF stable suspension is done. The experiment shows that the 6-DOF precisions of micro satge meets the indicators.