The Design Of Control System In Six Degrees Of Freedom Lithography Wafer Stage

Lithography is the core of IC manufacturing equipment, mask platform workpiece table system is the core motion control system components, with the features such as scanning, the upper and lower pieces, positioning, leveling and focusing.The driver of this motion control board belongs to the driver module of character device, and its driver system realizes through standard VxWorks I/O system. The motion control performance of lithography has a very big impact.on efficiency and accuracy. Lithography technology is developing rapidly in recent years, the workpiece table mask platform sets are increasingly high performance of the system, which controls the design of the workpiece table made very high demands.The workpiece table system with 6 degrees of freedom as well as its quick response to the requirements of high accuracy, the coupling between the six degrees of freedom to the performance of the workpiece table system is a big impact, therefore, the need for the first decoupling design in order to further its control.Firstly, for the coupling of the workpiece table system,After the judging the degree of coupling, the study of some based on classical control theory, modern control theory, intelligent decoupling control theory, to compare their advantages and disadvantages, scope.choose the State feedback decoupling method which suits for the workpiece table system.Secondly, the workpiece table system is modeled, first by studying the parts needed to complete the function table, and movement characteristics, the establishment of an appropriate mechanical model, and select the appropriate units of motor sport as part of the workpiece drive components.Then studying the displacement relationship of the motor and the centroid of the workpiece table to establish the equations.By simultaneous up the Displacement relationship, mechanical relationship, electromagnetic force relationship, etc. Then establish the control model.Then, design the decoupling of system,changing the six degrees of freedom coupled MIMO system into one-to-one SISO system.Then choose three closed-loop method which used most widely in engineering to control the SISO system,to achieve a well performance. Notch filter designed to eliminate the adverse effects of mechanical resonance.Design is verified by simulation results.Finally, the trajectory of the workpiece station was planned, given the exposure of the wafer process.