Research On Motion Control For Compound Driven Reticle Stage Of Lithography

Reticle stage is the core motion mechanism of the motion control system oflithography tool, whose role is to carry the mask plate to accomplish the scanning taskwith wafer stage’s cooperation motion. In this paper, the most outstanding characteristicof the reticle stage is its macro/micro dual-stage actuator servo system. Macro-motionstage is responsible for the large travel and single degree motion; Micro-motion stage isresponsible for the little distance and6-DOF motion. This paper mostly focus on themotion control method of the reticle stage with macro/micro dual-stage.Firstly, in view of the structure of the macro-motion stage and micro-motion stage,this paper repectively analyses its motion characteristics and key problems to solved inthe control process, and does the analysis about how to meet the index requirement ofthe reticle stage system.Secondly, in view of the bi-side driving structure of the macro-motion stage, thispaper uses the cross-coupling strategy for synchronous control, and the simulation andexperiment has been done to prove its validity in the reticle stage system. Then, thispaper mainly does some correlation study of frctional PID control, investigate theeffects of its parameters on the control performance and apply frctional PID control tothe synchronous control of reticle stage. The simulation and experimental results provethat frctional PID control has obvious advantage in comparision of classical PIDcontrol.Thirdly, this paper does geometry decoupling for the6-DOF motion of micro-motion stage by decomposing it into two parts of calculation in3-DOF, and accomplishthe calculation for the actual system. Then this paper combines LESO and frctional PIDcontrol into the position control of VCM and achieve excellent control effect.Finally, this paper selects the macro following micro control method bycomprasion in the view of input-output and the coupling between macro and micro,apply the fractional PID control and LESO to the macro-micro control system designedand achieve excellent control effect.