Research On The Dynamic Characteristic Of Passive Compensation System

As the most sophisticated device for IC manufactory, step-and-scan lithographyhas become a neccessery instrument in morden society. As a significant part intwin-stage,balance mass system has alleviated the vibration inside the system andabsorbed the impact on base frame.Vibration isolation and shift control of balance masshas a great effect on location accuracy of wafer stage, therefore the compensation abilityof passive compensation system is rather important to location accuracy.In this paper, range and dynamic characteristic of balance mass in balance masssystem is analyzed. The request for vibration isolation efficiency of balance mass iscalculated according to the need. Calculation result indicated that the shift should becontroled under±17mm and±35mm in direction of X and Y respectively. Andvibration isolation should be controled under100N in direction of X and200N indirection of Y. Thus a mathematic model is made to optimize the key parameters of thepassive compensation system accordingly. And then, the effectiveness of the designedSpring and damping parameters is proved. And, thus the efficiency of vibrition isolationof wafer-stage and the shift control of balance mass were calculated.Exposureing route is analyzed and the trace of the movement of the wafer stage inmeasuring and exposuring is modified. Five oreder S curve of step-and-scan has beenanalyzed and designed. A simulation based on Matlab is run to verify the trace of themovement of twin-stage. In the simulation, high acceleration trajectory is used asexcitation of passive compensation systemA simulation based on Simulink is run to verify the dynamic characteristic ofpassive compensation system. Simulation result showed the movement curve in bothdirection X and Y of balance mass which has already been compensated by passivecompensation system.An experiment is run to test the vibrition isolation ablity of spring unit and damperunit. In the experiment, the whole compensation system is installed into balance masssystem, and an experiment is run. Experiment result indicated that whether the zeroingerror is controled under10%of index. And the error is analyzed, then an advancedmethod is proposed.Results from simulations and experiments indicated that, with the passivecompensation system,the shift of balance mass is controled under index,which satisfiedthe need； With a frequency of10Hz,the maximum force delivered to support frame isFx=86.6N, Fy=145N, respectly in direction X and Y which satisfied the need forvibrition isolation.In direction of X, a steady-state error of-0.254mm of balance mass isachievable.And in direction of Y,a steady-state error of1.125mm is achievable. Therefore, it can be concluded that the design of this system meet the need for shiftcontroling and vibrition isolation.