Research On Trajectory Planning Argorithm For The Two Wafer Stages Of Lithography

Production is one of the three major technical indicators of lithography, theincreasing of production rate will bring high economic value, so production is today’sfocus of the field of semiconductor manufacturing equipment. In the complete processof exposure of silicon wafer, wafer stage will have scanning step and exchange motion,the quality of trajectory of the wafer stage and exposure scanning path directly affect thelithography’s production efficiency. As a result, it’s necessary to design a reasonabletrajectory for the whole movement process of wafer stage. This thesis studied on threeissues in the motion of wafer stage: route planning of wafer scanning trajectoryplanning of scanning and step motion and the optimal control problem in the process ofwafer stage exchanging.Firstly, planned the path of the wafer scanning process, refined the mathematicalmodel of the problem, and translated this issue into traveling salesman problem, andthen take advantage of genetic algorithm optimization design the problem, finally usedMATLAB simulation to solve the problems of the wafer scanning path planning. Thetotal distance which using this method to optimal scanning path planning is decreasedby4.86%than traditional scanning method, which effectively improve the productionrate of lithography.Secondly, planned the trajectory of lithography’s step and scanning motion, thenanalyzed motion trajectory of S-curve in detail, and the implementation algorithm ofdifferent order S-curve is deduced, then designed different order S-curve for thescanning movement, designed the time-impact optimal5-order S-curve for the steppingmotion. Then optimized the process of the whole movement path of lithography,analyzed the methods of the wafer stage exchanging, and then designed a time optimalbang-bang control method and time-impact the optimal control method for the point-to-point movement in the process of wafer exchanging.Finally, the coupling model and simplified model of coarse-fine part of wafer stageand rectile system were established, verified the effectiveness of the design step andscanning motion trajectory optimization using MATLAB/SIMULINK, compared thedifferent order S-curve affection for the performance of control system, simulationshows high order S-curve can get more smooth curve and time-impact the optimalimprovement S-curve can be time impact are the ideal trajectory. Simulation verify thetime-impact optimal and bang-bang control methods in the process of wafer stageexchanging, simulation shows that the design optimization method significantly reducedthe wafer stage exchanging time and the impact of the process, those methods hasobtained the ideal effect. Finally, built experimental platform, designded the main program of main board and motion control card, did the experiments on trajectoryplanning algorithm, reached the micron positioning accuracy requirements of the Coarsetable.