Simulation And Research On Dynamic Characteristics Of Lithography Dual Drive Wafer Stage

Step-scan lithography machine is the core device in the semiconductor manufacturer industry and the wafer stage system is core system of the lithography machine. In wafer stage system,the micropositioner is the central part of all the components. Analysing the dynamic characteristics of wafer stage makes for selecting the structure design and the control strategy. The realization of design index depends on the good dynamic characteristics of mechanical structure system in the lithography machine. So it is essential to analyse the dynamic characteristics of wafer stage in the lithography machine prototype development phase.This paper made a review of research on wafer stage of lithography at both home and abroad. It also analysed the finite element method and its application in the lithography protype development and simulation analysis phase. The finite element models of wafer stage was established through the reasonable simplification of the wafer stage three-dimensional object models. At the same time,the flotation characteristic of air bearing was simulated by the way of spring-damping element. The dynamic characteristics of lithography wafer stage were analysed through applying the finite element analysis software ANSYS based on the establishment of finite element model. The weakness of structure can be found through dynamic characteristics simulation in the design phase. It can offer the rationalization proposals and evidences for structure improvement and strategic selection of control. Previous to dynamic characteristics analysis,essential static analysis of wafer stage was also carried out in accordance with different operating condition.In view of some the wildly used engineering ceramic materials and the newly-developed ultra-low expansion materials in the ultra-precion wafer stage,thermal analyses and dynamic characteristics analyses of based board materials in the wafer stage was done. That provided visualized evidence for choosing based board materials of wafer stage. The thermal analyses were mainly steady-state analyses and thermal-structural coupled analyses. The dynamic characteristics analyses were mainly modal analysis. According to the analyses,it is known that Zerodur is the best material to be used for based board of wafer stage,while quartz ceramics and ULE do well too.For the base board of lithography wafer stage,the structural design is optimized with the method of orthogonal test and ANSYS topology analysis. Through analyzing,we obtain the structure is with less static deformation and higher natural frequence. At the same time,the structure and exchange process of original dual-stage system are optimized about its drawbacks,which can significantly reduce the times of acceleration and deceleration in the exchange process and promote production efficiency.